AMFR

Gene Summary

Gene:AMFR; autocrine motility factor receptor, E3 ubiquitin protein ligase
Aliases: GP78, RNF45
Location:16q21
Summary:This locus encodes a glycosylated transmembrane receptor. Its ligand, autocrine motility factor, is a tumor motility-stimulating protein secreted by tumor cells. The encoded receptor is also a member of the E3 ubiquitin ligase family of proteins. It catalyzes ubiquitination and endoplasmic reticulum-associated degradation of specific proteins. [provided by RefSeq, Feb 2012]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:E3 ubiquitin-protein ligase AMFR
HPRD
Source:NCBIAccessed: 21 August, 2015

Ontology:

What does this gene/protein do?
Show (20)
Pathways:What pathways are this gene/protein implicaed in?
Show (1)

Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 21 August 2015 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Bladder Cancer
  • Breast Cancer
  • Neoplasm Metastasis
  • Oligonucleotide Array Sequence Analysis
  • Gene Expression
  • Pancreatic Cancer
  • Autocrine Communication
  • Squamous Cell Carcinoma
  • Neoplasm Invasiveness
  • Gene Expression Profiling
  • Receptors, Laminin
  • Mutation
  • Immunohistochemistry
  • Chromosome 16
  • Vascular Endothelial Growth Factor D
  • Mice, Inbred BALB C
  • Prostate Cancer
  • RHOA
  • Lymphatic Metastasis
  • Transfection
  • Tumor Markers
  • Adenocarcinoma
  • Cell Surface Receptors
  • Non-Small Cell Lung Cancer
  • Messenger RNA
  • Staging
  • Lung Cancer
  • Cancer Gene Expression Regulation
  • Ubiquitin-Protein Ligases
  • Laminin
  • Up-Regulation
  • Receptors, Autocrine Motility Factor
  • RTPCR
  • Glucose-6-Phosphate Isomerase
  • Receptors, Immunologic
  • Cell Proliferation
  • Cell Movement
  • Disease Progression
  • Receptors, Cytokine
  • Neoplasm Proteins
Tag cloud generated 21 August, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (6)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: AMFR (cancer-related)

Liu H, Yang Y, Xiao J, et al.
Semaphorin 4D expression is associated with a poor clinical outcome in cervical cancer patients.
Microvasc Res. 2014; 93:1-8 [PubMed] Related Publications
Lymphangiogenesis is thought to be essential for cancer progression, making it an important target in cancer therapy. Lymphangiogenic factors (VEGF-C and VEGF-D) are upregulated in various tumors/cancers, and play an important role in lymphangiogenesis and lymph node metastasis. Similarly, semaphorin 4D (Sema4D) is a potent inducer of angiogenesis, and its overexpression is associated with tumor progression and poor prognosis in a variety of malignancies. However, little is known regarding the functional relationship between Sema4D and VEGF-C/VEGF-D and in the mediation of lymphangiogenesis and lymph node metastasis and clinical outcome. The current study aimed to evaluate the effect of Sema4D expression on outcome in patients with cervical cancer, and to explore the molecular mechanism of Sema4D in tumor progression. We evaluated Sema4D expression, density of lymphatic vessels, and invasion of lymphatic vessels with immunohistochemical methods in 232 human cervical cancers with long-term follow-up. Sema4D expression was correlated with patho-clinical parameters and patients' outcome. A cervical cancer cell line was used to investigate the contribution of sema4D to tumor progression by studying the role of Sema4D in VEGF-C/-D and cell migration using reverse transcription-polymerase chain reaction and Western blotting. We observed that Sema4D expression was higher in metastatic cervical cancer than in nonmetastatic cervical cancer (P<0.001). CD34-positive or D2-40-positive lymphatic vessel density was significantly increased in cases with lymph node metastasis compared with those without lymph node metastasis. The increased Sema4D expression was associated with VEGF-C/-D, the presence of lymphatic invasion, the occurrence of lymph node metastasis, and FIGO stage. We also observed a novel association between Sema4D upregulation and poor prognosis in cervical cancer. In vitro, the Sema4D inhibitory antibody and Sema4D-shRNA suppressed VEGF-C and VEGF-D in the human cervical carcinoma cell lines HeLa, Siha, and Caski cells. Invasiveness assay demonstrated that Sema4D could augment the invasive potential of the tumor cells in the cervical cancer lines and induction of cellular invasiveness by Sema4D stimulation could be inhibited by knockdown of plexinB1 by siRNA. Further mechanistic investigations of tumor cell invasiveness showed that Sema4D could induce activation of GTPase Ras homolog gene family, member A (RhoA), MAPK and AKT. In addition, plexinB1 knockdown by siRNA could suppress the Sema4D signal transmitted to MAPK and Akt. Taken together, these results suggest that Sema4D autocrine within tumor cells contributes to enhanced invasion and tumor progression through increased motility of cervical cancer and VEGF-C/-D-mediated lymphangiogenesis. Sema4D might be useful as a molecular marker of poor prognosis in cervical cancer.

Samamé Pérez-Vargas JC, Biondani P, Maggi C, et al.
Role of cMET in the development and progression of colorectal cancer.
Int J Mol Sci. 2013; 14(9):18056-77 [PubMed] Free Access to Full Article Related Publications
Mesenchymal-epithelial transition (MET) is a member of a distinct subfamily of heterodimeric receptor tyrosine kinase receptors that specifically binds the hepatocyte growth factor (HGF). Binding to HGF leads to receptor dimerization/multimerization and phosphorylation, resulting in its catalytic activation. MET activation drives the malignant progression of several tumor types, including colorectal cancer (CRC), by promoting signaling cascades that mainly result in alterations of cell motility, survival, and proliferation. MET is aberrantly activated in many human cancers through various mechanisms, including point mutations, gene amplification, transcriptional up-regulation, or ligand autocrine loops. MET promotes cell scattering, invasion, and protection from apoptosis, thereby acting as an adjuvant pro-metastatic gene for many tumor types. In CRC, MET expression confers more aggressiveness and worse clinical prognosis. With all of this rationale, inhibitors that target the HGF/MET axis with different types of response have been developed. HGF and MET are new promising targets to understand the pathogenesis of CRC and for the development of new, targeted therapies.

Shang Y, Zhu Z
gp78 is specifically expressed in human prostate cancer rather than normal prostate tissue.
J Mol Histol. 2013; 44(6):653-9 [PubMed] Related Publications
Elevated expression of gp78 has been observed in many types of cancers including lung, stomach, colon, liver and skin cancer. But there is no report about its expression in prostate cancers. In this study, using immunohistochemical staining we found gp78 is highly expressed in prostate cancers especially early stage tumors, but not in normal prostate tissues. gp78 protein expression is heterogeneous. In some tumors it was expressed in basal cells, while others in stromal cells. For gp78 is a ubiquitin E3 ligase, we then investigated the expression pattern of its cognate E2 (ubiquitin conjugating enzyme)-Ube2g2 in prostate cancers. We found it was expressed in both cancerous and normal tissues of prostate without significant differences in expression level. And unlike gp78, it exhibited a homogeneous expression pattern in different cell types in prostate tissues. In conclusion, our results indicate that gp78 is expressed specifically in human prostate cancer rather than normal prostate tissues, it could be a putative biomarker for prostate cancer diagnosis.

Ortlepp C, Steudel C, Heiderich C, et al.
Autotaxin is expressed in FLT3-ITD positive acute myeloid leukemia and hematopoietic stem cells and promotes cell migration and proliferation.
Exp Hematol. 2013; 41(5):444-461.e4 [PubMed] Related Publications
Autotaxin (ATX) has been reported to act as a motility and growth factor in a variety of cancer cells. The ATX protein acts as a secreted lysophospholipase D by converting lysophosphatidylcholine (LPC) to lysophosphatidic acid (LPA), which signals via G-protein-coupled receptors and has important functions in cell migration and proliferation. This study demonstrates that ATX expression is specifically upregulated and functionally active in acute myeloid leukemia (AML) harboring an internal tandem duplication (ITD) mutation of the FLT3 receptor gene. Moreover, ATX expression was also found in normal human CD34+ progenitor cells and selected myeloid and lymphoid subpopulations. Enforced expression of mutant FLT3-ITD by retroviral vector transduction increased ATX mRNA in selected cell lines, whereas inhibition of FLT3-ITD signaling by sublethal doses of PKC412 or SU5614 led to a significant downregulation of ATX mRNA and protein levels. In the presence of LPC, ATX expression significantly increased proliferation. LPA induced proliferation, regardless of ATX expression, and induced chemotaxis in all tested human leukemic cell lines and human CD34(+) progenitors. LPC increased chemotaxis only in cells with high expression of endogenous ATX by at least 80%, demonstrating the autocrine action of ATX. Inhibition of ATX using a small molecule inhibitor selectively induced killing of ATX-expressing cell lines and reduced motility in these cells. Our data suggest that the production of bioactive LPA through ATX is involved in controlling proliferation and migration during hematopoiesis and that deregulation of ATX contributes to the pathogenesis of AML.

Tsujikawa T, Yaguchi T, Ohmura G, et al.
Autocrine and paracrine loops between cancer cells and macrophages promote lymph node metastasis via CCR4/CCL22 in head and neck squamous cell carcinoma.
Int J Cancer. 2013; 132(12):2755-66 [PubMed] Related Publications
Lymph node metastasis is a poor prognostic factor for patients with head and neck squamous cell carcinoma (HNSCC). However, its molecular mechanism has not yet been fully understood. In our study, we investigated the expression of CCR4 and its ligand CCL22 in the HNSCC tumor microenvironment and found that the CCR4/CCL22 axis was involved in lymph node metastasis of HNSCC. CCR4 was expressed in 20 of 31 (64.5%) human tongue cancer tissues, and its expression was significantly correlated with lymph node metastasis (p < 0.01) and lymphatic invasion (p < 0.05). CCR4 was expressed in three of five human HNSCC cell lines tested. CCR4(+) HNSCC cells, but not CCR4(-) cells, showed enhanced migration toward CCL22, indicating that functional CCR4 was expressed in HNSCC cell lines. CCL22 was also expressed in cancer cells (48.4% of tongue cancer tissues) or CD206(+) M2-like macrophages infiltrated in tumors and draining lymph nodes. CCL22 produced by cancer cells or CD206(high) M2-like macrophages increased the cell motility of CCR4(+) HNSCC cells in vitro in an autocrine or paracrine manner. In the mouse SCCVII in vivo model, CCR4(+) cancer cells, but not CCR4(-) cells, metastasized to lymph nodes which contained CCL22 producing M2-like macrophages. These results demonstrate that lymph node metastasis of CCR4(+) HNSCC is promoted by CCL22 in an autocrine or M2-like macrophage-dependent paracrine manner. Therefore, the CCR4/CCL22 axis may be an attractive target for the development of diagnostic and therapeutic strategies for patients with HNSCC.

Choudhury Y, Tay FC, Lam DH, et al.
Attenuated adenosine-to-inosine editing of microRNA-376a* promotes invasiveness of glioblastoma cells.
J Clin Invest. 2012; 122(11):4059-76 [PubMed] Free Access to Full Article Related Publications
In the human brain, microRNAs (miRNAs) from the microRNA-376 (miR-376) cluster undergo programmed "seed" sequence modifications by adenosine-to-inosine (A-to-I) editing. Emerging evidence suggests a link between impaired A-to-I editing and cancer, particularly in high-grade gliomas. We hypothesized that disruption of A-to-I editing alters expression of genes regulating glioma tumor phenotypes. By sequencing the miR-376 cluster, we show that the overall miRNA editing frequencies were reduced in human gliomas. Specifically in high-grade gliomas, miR-376a* accumulated entirely in an unedited form. Clinically, a significant correlation was found between accumulation of unedited miR-376a* and the extent of invasive tumor spread as measured by magnetic resonance imaging of patient brains. Using both in vitro and orthotopic xenograft mouse models, we demonstrated that the unedited miR-376a* promoted glioma cell migration and invasion, while the edited miR-376a* suppressed these features. The effects of the unedited miR-376a* were mediated by its sequence-dependent ability to target RAP2A and concomitant inability to target AMFR. Thus, the tumor-dependent introduction of a single base difference in the miR-376a* sequence dramatically alters the selection of its target genes and redirects its function from inhibiting to promoting glioma cell invasion. These findings uncover a new mechanism of miRNA deregulation and identify unedited miR-376a* as a potential therapeutic target in glioblastoma cells.

Majumder M, Tutunea-Fatan E, Xin X, et al.
Co-expression of α9β1 integrin and VEGF-D confers lymphatic metastatic ability to a human breast cancer cell line MDA-MB-468LN.
PLoS One. 2012; 7(4):e35094 [PubMed] Free Access to Full Article Related Publications
INTRODUCTION AND OBJECTIVES: Lymphatic metastasis is a common occurrence in human breast cancer, mechanisms remaining poorly understood. MDA-MB-468LN (468LN), a variant of the MDA-MB-468GFP (468GFP) human breast cancer cell line, produces extensive lymphatic metastasis in nude mice. 468LN cells differentially express α9β1 integrin, a receptor for lymphangiogenic factors VEGF-C/-D. We explored whether (1) differential production of VEGF-C/-D by 468LN cells provides an autocrine stimulus for cellular motility by interacting with α9β1 and a paracrine stimulus for lymphangiogenesis in vitro as measured with capillary-like tube formation by human lymphatic endothelial cells (HMVEC-dLy); (2) differential expression of α9 also promotes cellular motility/invasiveness by interacting with macrophage derived factors; (3) stable knock-down of VEGF-D or α9 in 468LN cells abrogates lymphangiogenesis and lymphatic metastasis in vivo in nude mice.
RESULTS: A comparison of expression of cyclo-oxygenase (COX)-2 (a VEGF-C/-D inducer), VEGF-C/-D and their receptors revealed little COX-2 expression by either cells. However, 468LN cells showed differential VEGF-D and α9β1 expression, VEGF-D secretion, proliferative, migratory/invasive capacities, latter functions being stimulated further with VEGF-D. The requirement of α9β1 for native and VEGF-D-stimulated proliferation, migration and Erk activation was demonstrated by treating with α9β1 blocking antibody or knock-down of α9. An autocrine role of VEGF-D in migration was shown by its impairment by silencing VEGF-D and restoration with VEGF-D. 468LN cells and their soluble products stimulated tube formation, migration/invasiveness of HMVEC-dLy cell in a VEGF-D dependent manner as indicated by the loss of stimulation by silencing VEGF-D in 468LN cells. Furthermore, 468LN cells showed α9-dependent stimulation of migration/invasiveness by macrophage products. Finally, capacity for intra-tumoral lymphangiogenesis and lymphatic metastasis in nude mice was completely abrogated by stable knock-down of either VEGF-D or α9 in 468LN cells.
CONCLUSION: Differential capacity for VEGF-D production and α9β1 integrin expression by 468LN cells jointly contributed to their lymphatic metastatic phenotype.

Schulz P, Fischer C, Detjen KM, et al.
Angiopoietin-2 drives lymphatic metastasis of pancreatic cancer.
FASEB J. 2011; 25(10):3325-35 [PubMed] Related Publications
Lymphatic metastasis constitutes a critical route of disease dissemination, which limits the prognosis of patients with pancreatic ductal adenocarcinoma (PDAC). As lymphangiogenesis has been implicated in stimulation of lymphatic metastasis by vascular endothelial growth factor-C (VEGF-C) and VEGF-D, we studied the effect of the angioregulatory growth factor angiopoietin-2 (Ang-2) on PDAC progression. Ang-2 was found to be expressed in transformed cells of human PDAC specimens, with corresponding Tie-2 receptors present on blood and lymphatic endothelium. In vitro in PDAC cells, Ang-2 was subject to autocrine/paracrine TGF-β stimulation (2-fold induction, P=0.0106) acting on the -61- to +476-bp element of the human Ang-2 promoter. In turn, Ang-2 regulated the expression of genes involved in cell motility and tumor suppression. Orthotopic PDAC xenografts with forced expression of Ang-2, but not Ang-1, displayed increased blood and lymphatic vessel density, and an enhanced rate of lymphatic metastasis (6.7- to 9.1-fold, P<0.01), which was prevented by sequestration of Ang-2 via coexpression of soluble Tie-2. Notably, elevated circulating Ang-2 in patients with PDAC correlated with the extent of lymphatic metastasis. Furthermore, median survival was reduced from 28.4 to 7.7 mo in patients with circulating Ang-2 ≥ 75th percentile (P=0.0005). These findings indicate that Ang-2 participates in the control of lymphatic metastasis, constitutes a noninvasive prognostic biomarker, and may provide an accessible therapeutic target in PDAC.

Peer CJ, Sissung TM, Figg WD
CHIP and gp78-mediated ubiquitination of CYP3A4: Implications for the pharmacology of anticancer agents.
Cancer Biol Ther. 2011; 11(6):549-51 [PubMed] Free Access to Full Article Related Publications
The autocrine motility factor receptor or glycoprotein-78 (gp78) and C-terminus of Hsp70-interacting protein (CHIP) are E3-ligases required for ubiquitination of cytochrome P450s of the 3A subfamily (CYP3A) in endoplasmic reticulum-associated degradation (ERAD). The CYP isozyme 3A4 (CYP3A4) is responsible for the metabolism of the majority of xenobiotics including anticancer agents. Much variability in clinical response to chemotherapy is observed and it has been suggested that variability in CYP3A4 expression could be a factor. The study reviewed in this journal club comments on the importance of further characterizing gp78 and CHIP as relevant proteins in ERAD of CYP3A4. This study demonstrated how both gp78 and CHIP play direct roles in reducing CYP3A4 protein content as well as CYP3A4 ubiquitination. Interestingly, when gp78 and CHIP were knocked down by siRNAs directed towards each protein, the stabilized CYP3A4 remained functional. This has implications for drug-drug interactions for agents metabolized by CYP3A4, which can influence drug exposure levels. This is relevant because most anticancer agents have very narrow therapeutic windows, thus even slight changes in CYP3A4 levels could alter the exposure of that drug and result in either insufficient efficacy or toxicity. Future studies must explore genetic variability in the ERAD pathway and identify new factors that influence CYP3A ERAD in order to better characterize how CYP3A variability affects anticancer drug pharmacology.

Wei P, Milbauer LC, Enenstein J, et al.
Differential endothelial cell gene expression by African Americans versus Caucasian Americans: a possible contribution to health disparity in vascular disease and cancer.
BMC Med. 2011; 9:2 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Health disparities and the high prevalence of cardiovascular disease continue to be perplexing worldwide health challenges. This study addresses the possibility that genetic differences affecting the biology of the vascular endothelium could be a factor contributing to the increased burden of cardiovascular disease and cancer among African Americans (AA) compared to Caucasian Americans (CA).
METHODS: From self-identified, healthy, 20 to 29-year-old AA (n = 21) and CA (n = 17), we established cultures of blood outgrowth endothelial cells (BOEC) and applied microarray profiling. BOEC have never been exposed to in vivo influences, and their gene expression reflects culture conditions (meticulously controlled) and donor genetics. Significance Analysis of Microarray identified differential expression of single genes. Gene Set Enrichment Analysis examined expression of pre-determined gene sets that survey nine biological systems relevant to endothelial biology.
RESULTS: At the highly stringent threshold of False Discovery Rate (FDR) = 0, 31 single genes were differentially expressed in AA. PSPH exhibited the greatest fold-change (AA > CA), but this was entirely accounted for by a homolog (PSPHL) hidden within the PSPH probe set. Among other significantly different genes were: for AA > CA, SOS1, AMFR, FGFR3; and for AA < CA, ARVCF, BIN3, EIF4B. Many more (221 transcripts for 204 genes) were differentially expressed at the less stringent threshold of FDR <.05. Using the biological systems approach, we identified shear response biology as being significantly different for AA versus CA, showing an apparent tonic increase of expression (AA > CA) for 46/157 genes within that system.
CONCLUSIONS: Many of the genes implicated here have substantial roles in endothelial biology. Shear stress response, a critical regulator of endothelial function and vascular homeostasis, may be different between AA and CA. These results potentially have direct implications for the role of endothelial cells in vascular disease (hypertension, stroke) and cancer (via angiogenesis). Also, they are consistent with our over-arching hypothesis that genetic influences stemming from ancestral continent-of-origin could impact upon endothelial cell biology and thereby contribute to disparity of vascular-related disease burden among AA. The method used here could be productively employed to bridge the gap between information from structural genomics (for example, disease association) and cell function and pathophysiology.

Grund S, Olsson B, Jernås M, et al.
The autocrine motility factor receptor is overexpressed on the surface of B cells in Binet C chronic lymphocytic leukemia.
Med Oncol. 2011; 28(4):1542-8 [PubMed] Related Publications
Chronic lymphocytic leukemia (CLL) is a heterogeneous disease with a clinical spectrum reaching from discrete lymphocytosis to extensive enlargement of lymph nodes, spleen and liver, and bone marrow failure. The aim of this study was to identify genes that differentiate between patients with disease stage A vs. C according to Binet in order to better understand the disease. To achieve this, we performed DNA microarray analysis on B cells from CLL patients with stage A and C according to Binet and matched controls. Between CLL patients and controls, there were 1,528 differentially expressed genes and 360 genes were differentially expressed between Binet A and C patients. Due to the sheer number of regulated genes, we focused on the autocrine motility factor receptor (AMFR). AMFR has not previously been investigated in hematological disorders, but high expression of AMFR correlates with a more advanced stage and invasive potential in several human tumors. AMFR mRNA expression was higher in Binet A compared with Binet C patients (P=0.0053) and healthy controls (P=0.0051). Total AMFR protein was higher in Binet A patients compared to Binet C as analyzed by intracellular flow cytometry. However, AMFR exist both in the ER involved in protein degradation and on the cell surface involved in metastasis and cell motility. Cell surface AMFR was increased in Binet C compared with Binet A+B (P=0.016). In conclusion, the mRNA levels reflect the total amount of AMFR, whereas cell surface expression is associated with progression in CLL.

Joshi B, Li L, Nabi IR
A role for KAI1 in promotion of cell proliferation and mammary gland hyperplasia by the gp78 ubiquitin ligase.
J Biol Chem. 2010; 285(12):8830-9 [PubMed] Free Access to Full Article Related Publications
Expression of gp78, an E3 ubiquitin ligase in endoplasmic reticulum-associated degradation, is associated with tumor malignancy. To study gp78 overexpression in mammary gland development and tumorigenicity, we generated murine mammary tumor virus (MMTV) long terminal repeat-driven gp78 transgenic mice. Embryos carrying the gp78 transgene cassette were implanted in FVB surrogate mothers, and two founders with high copy integration showed elevated gp78 expression at both transcript and protein levels at the virgin stage and at 12 days gestation. Transgenic mammary glands showed increased ductal branching, dense alveolar lobule formation, and secondary terminal end bud development. Bromodeoxyuridine staining showed increased proliferation in hyperplastic ductal regions at the virgin stage and at 12 days gestation compared with wild type mice. Reduced expression of the metastasis suppressor KAI1, a gp78 endoplasmic reticulum-associated degradation substrate, demonstrates that gp78 ubiquitin ligase activity is increased in MMTV-gp78 mammary gland. Similarly, metastatic MDA-435 cells exhibit increased gp78 expression, decreased KAI1 expression, and elevated proliferation compared with nonmetastatic MCF7 cells whose proliferation was enhanced upon knockdown of KAI1. Importantly, stable gp78 knockdown HEK293 cells showed increased KAI1 expression and reduced proliferation that was rescued upon KAI1 knockdown, demonstrating that gp78 regulation of cell proliferation is mediated by KAI1. Mammary tumorigenesis was not observed in repeatedly pregnant MMTV-long terminal repeat-gp78 transgenic mice over a period of 18 months post-birth. Elevated gp78 ubiquitin ligase activity is therefore not sufficient for mammary tumorigenesis. However, the hyperplastic phenotype observed in mammary glands of MMTV-gp78 transgenic mice identifies a novel role for gp78 expression in enhancing mammary epithelial cell proliferation and nontumorigenic ductal outgrowth.

Navab R, Liu J, Seiden-Long I, et al.
Co-overexpression of Met and hepatocyte growth factor promotes systemic metastasis in NCI-H460 non-small cell lung carcinoma cells.
Neoplasia. 2009; 11(12):1292-300 [PubMed] Free Access to Full Article Related Publications
Complete resection of early-stage non-small cell lung cancer (NSCLC) is potentially curative, yet approximately 50% of patients are at risk for developing metastatic recurrence. Met, the receptor for hepatocyte growth factor (HGF) is a receptor tyrosine kinase with demonstrated roles in regulating cellular proliferation, motility, morphogenesis, and apoptosis. Met receptor and its ligand, HGF, are commonly overexpressed in NSCLC, and their overexpression has been associated with poor prognosis, which could potentially involve a paracrine and/or autocrine activation loop. However, there is as yet no direct evidence that HGF-Met signaling directly promotes metastasis in NSCLC cells. Using retroviral transduction, we overexpressed the human c-met and hgf complementary DNA, alone or in combination in the NCI-H460 human large cell carcinoma cell line. The HGF/Met co-overexpressing (H460-HGF/Met) cells demonstrated enhanced tumorigenicity in xenograft SCID mice. When these cells are implanted orthotopically into the lungs of nude rats, only the H460-HGF/Met cells showed higher spontaneous metastases to distant organs including bone, brain, and kidney. These results provide evidence that autocrine overactivation of the Met- HGF loop enhances systemic metastases in NSCLC. Targeted interference of this loop may potentially be an effective adjuvant therapy to improve survival of early-stage NSCLC patients.

Lee Y, Kim SJ, Park HD, et al.
PAUF functions in the metastasis of human pancreatic cancer cells and upregulates CXCR4 expression.
Oncogene. 2010; 29(1):56-67 [PubMed] Related Publications
Pancreatic cancer is characterized by early metastatic spread, but the process of tumor cell dissemination is largely unknown. In this study we show that the soluble protein pancreatic adenocarcinoma upregulated factor (PAUF) has an important role in the metastasis and progression of the disease. Variations in the level of PAUF, either by overexpression or knockdown, resulted in altered migration, invasion and proliferation capacity of pancreatic cancer cells. Moreover, depletion of PAUF in metastatic cells dramatically abrogated the spread of the cells to distant organs in an orthotopic xenograft mouse model. PAUF elicited the activation of the extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and AKT intracellular signaling cascades and consequently their downstream transcription factors in an autocrine manner. Genome-wide expression analysis revealed that C-X-C chemokine receptor type 4 (CXCR4) expression was induced by PAUF overexpression but was repressed by PAUF knockdown. The PAUF-mediated increase in cancer cell motility was attenuated by the CXCR4 inhibitor, AMD3100, or by anti-CXCR4 antibody. Furthermore, immunohistochemical analysis of pancreatic tumor tissues clearly showed a significant positive correlation between PAUF and CXCR4 expression. Collectively, these findings indicate that PAUF enhances the metastatic potential of pancreatic cancer cells, at least in part, by upregulating CXCR4 expression.

Seim I, Amorim L, Walpole C, et al.
Ghrelin gene-related peptides: multifunctional endocrine / autocrine modulators in health and disease.
Clin Exp Pharmacol Physiol. 2010; 37(1):125-31 [PubMed] Related Publications
1. Ghrelin is a multifunctional peptide hormone that affects various processes, including growth hormone and insulin release, appetite regulation, gut motility, metabolism and cancer cell proliferation. Ghrelin is produced in the stomach and in other normal and pathological cell types. It may act as an endocrine or autocrine/paracrine factor. 2. The present article reviews recent findings in the study of ghrelin and its receptor that suggest that the ghrelin gene locus may give rise to a number of functional molecules (peptides and RNA transcripts) in addition to ghrelin. 3. The ghrelin gene encodes a precursor protein, preproghrelin, from which ghrelin and other potentially active peptides are derived by alternative mRNA splicing and/or proteolytic processing. The metabolic role of the peptide obestatin, derived from the preproghrelin C-terminal region, is contentious. However, obestatin has direct effects on cell proliferation. 4. The regulation of ghrelin expression and the mechanisms through which the peptide products arise are unclear. We have recently re-examined the organization of the ghrelin gene and identified several novel exons and transcripts. One transcript, which lacks the ghrelin-coding region of preproghrelin, contains the coding sequence of obestatin. 5. Furthermore, we have identified an overlapping gene on the antisense strand of ghrelin, namely GHRLOS, which generates transcripts that may function as non-coding regulatory RNAs or code for novel, short bioactive peptides. 6. The identification of these novel ghrelin-gene related transcripts and peptides raises critical questions regarding their physiological function and their potential role in obesity, diabetes and cancer.

Matsuda Y, Schlange T, Oakeley EJ, et al.
WNT signaling enhances breast cancer cell motility and blockade of the WNT pathway by sFRP1 suppresses MDA-MB-231 xenograft growth.
Breast Cancer Res. 2009; 11(3):R32 [PubMed] Free Access to Full Article Related Publications
INTRODUCTION: In breast cancer, deregulation of the WNT signaling pathway occurs by autocrine mechanisms. WNT ligands and Frizzled receptors are coexpressed in primary breast tumors and cancer cell lines. Moreover, many breast tumors show hypermethylation of the secreted Frizzled-related protein 1 (sFRP1) promoter region, causing low expression of this WNT antagonist. We have previously shown that the WNT pathway influences proliferation of breast cancer cell lines via activation of canonical signaling and epidermal growth factor receptor transactivation, and that interference with WNT signaling reduces proliferation. Here we examine the role of WNT signaling in breast tumor cell migration and on xenograft outgrowth.
METHODS: The breast cancer cell line MDA-MB-231 was used to study WNT signaling. We examined the effects of activating or blocking the WNT pathway on cell motility by treatment with WNT ligands or by ectopic sFPR1 expression, respectively. The ability of sFRP1-expressing MDA-MB-231 cells to grow as xenografts was also tested. Microarray analyses were carried out to identify targets with roles in MDA-MB-231/sFRP1 tumor growth inhibition.
RESULTS: We show that WNT stimulates the migratory ability of MDA-MB-231 cells. Furthermore, ectopic expression of sFRP1 in MDA-MB-231 cells blocks canonical WNT signaling and decreases their migratory potential. Moreover, the ability of MDA-MB-231/sFRP1-expressing cells to grow as xenografts in mammary glands and to form lung metastases is dramatically impaired. Microarray analyses led to the identification of two genes, CCND1 and CDKN1A, whose expression level is selectively altered in vivo in sFRP1-expressing tumors. The encoded proteins cyclin D1 and p21Cip1 were downregulated and upregulated, respectively, in sFRP1-expressing tumors, suggesting that they are downstream mediators of WNT signaling.
CONCLUSIONS: Our results show that the WNT pathway influences multiple biological properties of MDA-MB-231 breast cancer cells. WNT stimulates tumor cell motility; conversely sFRP1-mediated WNT pathway blockade reduces motility. Moreover, ectopic sFRP1 expression in MDA-MB-231 cells has a strong negative impact on tumor outgrowth and blocked lung metastases. These results suggest that interference with WNT signaling using sFRP1 to block the ligand- receptor interaction may be a valid therapeutic approach in breast cancer.

Ma PC, Tretiakova MS, MacKinnon AC, et al.
Expression and mutational analysis of MET in human solid cancers.
Genes Chromosomes Cancer. 2008; 47(12):1025-37 [PubMed] Free Access to Full Article Related Publications
MET receptor tyrosine kinase and its ligand hepatocyte growth factor (HGF) regulate a variety of cellular functions, many of which can be dysregulated in human cancers. Activated MET signaling can lead to cell motility and scattering, angiogenesis, proliferation, branching morphogenesis, invasion, and eventual metastasis. We performed systematic analysis of the expression of the MET receptor and its ligand HGF in tumor tissue microarrays (TMA) from human solid cancers. Standard immunohistochemistry (IHC) and a computerized automated scoring system were used. DNA sequencing for MET mutations in both nonkinase and kinase domains was also performed. MET was differentially overexpressed in human solid cancers. The ligand HGF was widely expressed in both tumors, primarily intratumoral, and nonmalignant tissues. The MET/HGF likely is functional and may be activated in autocrine fashion in vivo. MET and stem cell factor (SCF) were found to be positively stained in the bronchioalevolar junctions of lung tumors. A number of novel mutations of MET were identified, particularly in the extracellular semaphorin domain and the juxtamembrane domain. MET-HGF pathway can be assayed in TMAs and is often overexpressed in a wide variety of human solid cancers. MET can be activated through overexpression, mutation, or autocrine signaling in malignant cells. Mutations in the nonkinase regions of MET might play an important role in tumorigenesis and tumor progression. MET would be an important therapeutic antitumor target to be inhibited, and in lung cancer, MET may represent a cancer early progenitor cell marker.

Nussbaum T, Samarin J, Ehemann V, et al.
Autocrine insulin-like growth factor-II stimulation of tumor cell migration is a progression step in human hepatocarcinogenesis.
Hepatology. 2008; 48(1):146-56 [PubMed] Related Publications
UNLABELLED: The protumorigenic insulin-like growth factor (IGF)-II is highly expressed in a significant fraction of human hepatocellular carcinomas (HCC). However, a functional dissection that clarifies the contribution of IGF-II-binding receptors in tumor progression and a respective molecular characterization of IGF-II signaling has not been performed. Therefore, expression of IGF-II and its receptors IGF-receptor type I (IGF-IR) and insulin receptor (IR) was efficiently blocked using small interfering RNA (siRNA) in HCC cells. Despite functional IR-signaling, oncogenic IGF-II effects such as tumor cell viability, proliferation, and anti-apoptosis were solely transmitted by IGF-IR. Although IGF-II signaling was previously not described in the context of HCC cell migration, the IGF-II-dependent expression profile displayed a high percentage of genes involved in cell motility and adhesion. Indeed, IGF-II overexpression promoted HCC cell migration, especially in synergy with hepatocyte growth factor (HGF). The therapeutic relevance of IGF-II/IGF-IR signaling was tested in vitro and in a murine xenograft transplantation model using the IGF-IR inhibitor picropodophyllin (PPP). IGF-IR inhibition by small molecule treatment efficiently reduced IGF-II-dependent signaling and all protumorigenic properties of the IGF-II/IGF-IR pathway.
CONCLUSION: In human HCC cells, IGF-IR but not IR is involved in oncogenic IGF-II signaling. Autocrine stimulation of IGF-II induces HCC motility by integration of paracrine signals for full malignant competence. Thus, activation of IGF-II/IGF-IR signaling is likely a progression switch selected by function that promotes tumor cell dissemination and aggressive tumor behavior.

Chiu CG, St-Pierre P, Nabi IR, Wiseman SM
Autocrine motility factor receptor: a clinical review.
Expert Rev Anticancer Ther. 2008; 8(2):207-17 [PubMed] Related Publications
The ability to target and alter the metastatic activity of cancer cells is a key avenue for cancer therapeutics. While local tumor control is often achieved through surgical resection, patient morbidity and mortality is dependent upon the control of regional and distant spread of disease. Autocrine motility factor receptor (AMFR) is an internalizing cell surface receptor that also exhibits ubiquitin E3 ligase activity in the endoplasmic reticulum. Stimulation of AMFR by its ligand (autocrine motility factor/phosphoglucose isomerase) alters cellular adhesion, proliferation, motility, and apoptosis. Increased AMFR expression has been reported in numerous human cancer types. Review of these studies suggests that AMFR upregulation is significantly correlated with more advanced tumor stage and decreased survival for cancer of the lung, esophagus, stomach, colon, rectum, liver and skin. AMFR has also served as an independent predictor of poor disease prognosis in these tumor types. Significant associations between AMFR expression and other clinicopathologic parameters implicated in disease progression have also been reported. Further characterization of AMFR in human cancer and the development of an understanding of the molecular regulation of this protein is critical for its future role as a target for anticancer agents.

Tsai YC, Mendoza A, Mariano JM, et al.
The ubiquitin ligase gp78 promotes sarcoma metastasis by targeting KAI1 for degradation.
Nat Med. 2007; 13(12):1504-9 [PubMed] Related Publications
Metastasis is the primary cause of mortality from cancer, but the mechanisms leading to metastasis are poorly understood. In particular, relatively little is known about metastasis in cancers of mesenchymal origins, which are known as sarcomas. Approximately ten proteins have been characterized as 'metastasis suppressors', but how these proteins function and are regulated is, in general, not well understood. Gp78 (also known as AMFR or RNF45) is a RING finger E3 ubiquitin ligase that is integral to the endoplasmic reticulum (ER) and involved in ER-associated degradation (ERAD) of diverse substrates. Here we report that expression of gp78 has a causal role in the metastasis of an aggressive human sarcoma and that this prometastatic activity requires the E3 activity of gp78. Further, gp78 associates with and targets the transmembrane metastasis suppressor, KAI1 (also known as CD82), for degradation. Suppression of gp78 increases KAI1 abundance and reduces the metastatic potential of tumor cells, an effect that is largely blocked by concomitant suppression of KAI1. An inverse relationship between these proteins was confirmed in a human sarcoma tissue microarray. Whereas most previous efforts have focused on genetic mechanisms for the loss of metastasis suppressor genes, our results provide new evidence for post-translational downregulation of a metastasis suppressor by its ubiquitin ligase, resulting in abrogation of its metastasis-suppressing effects.

Hoelzinger DB, Nakada M, Demuth T, et al.
Autotaxin: a secreted autocrine/paracrine factor that promotes glioma invasion.
J Neurooncol. 2008; 86(3):297-309 [PubMed] Related Publications
Glioblastoma multiforme (GBM) is inherently invasive, and it is from the invasive cell population that the tumor recurs. The GBM invasion transcriptome reveals over-expression of various autocrine factors that could act as motility drivers, such as autotaxin (ATX). Some of these factors could also have paracrine roles, modulating the behavior of cells in the peri-tumoral brain parenchyma. ATX generates lysophosphatidic acid (LPA), which signals through LPA receptors expressed by GBM as well as in astrocytes, oligodendrocytes (ODC) and microglia; their activation manifest cell specific effects. ATX stimulates invasion of GBM cells in vitro and ex vivo invasion assays. ATX activity enhances GBM adhesion in cells expressing the LPA1 receptor, as well as stimulating rac activation. GBM secreted ATX can also have paracrine effects: ATX activity results in reduced ODC adhesion. ODC monolayer invasion showed that U87 and U251 GBM cells expressing ATX invaded through an ODC monolayer significantly more than cells depleted of ATX or cells expressing inactive ATX, suggesting that GBM cells secreting ATX find ODCs less of a barrier than cells that do not express ATX. Secreted factors that drive GBM invasion can have autocrine and paracrine roles; one stimulates GBM motility and the other results in ODC dis-adhesion.

Kojic LD, Joshi B, Lajoie P, et al.
Raft-dependent endocytosis of autocrine motility factor is phosphatidylinositol 3-kinase-dependent in breast carcinoma cells.
J Biol Chem. 2007; 282(40):29305-13 [PubMed] Related Publications
Autocrine motility factor (AMF) is internalized via a receptor-mediated, dynamin-dependent, cholesterol-sensitive raft pathway to the smooth endoplasmic reticulum that is negatively regulated by caveolin-1. Expression of AMF and its receptor (AMFR) is associated with tumor progression and malignancy; however, the extent to which the raft-dependent uptake of AMF is tumor cell-specific has yet to be addressed. By Western blot and cell surface fluorescence-activated cell sorter (FACS) analysis, AMFR expression is increased in tumorigenic MCF7 and metastatic MDA-231 and MDA-435 breast cancer cell lines relative to dysplastic MCF10A mammary epithelial cells. AMF uptake, determined by FACS measurement of protease-insensitive internalized fluorescein-conjugated AMF, was increased in MCF7 and MDA-435 cells relative to MCF-10A and caveolin-1-expressing MDA-231 cells. Uptake of fluorescein-conjugated AMF was dynamin-dependent, methyl-beta-cyclodextrin- and genistein-sensitive, reduced upon overexpression of caveolin-1 in MDA-435 cells, and increased upon short hairpin RNA reduction of caveolin-1 in MDA-231 cells. Tissue microarray analysis of invasive primary human breast carcinomas showed that AMFR expression had no impact on survival but did correlate significantly with expression of phospho-Akt. Phospho-Akt expression was increased in AMF-internalizing MCF7 and MDA-435 breast carcinoma cells. AMF uptake in these cells was reduced by phosphatidylinositol 3-kinase inhibition but not by regulators of macropinocytosis such as amiloride, phorbol ester, or actin cytoskeleton disruption by cytochalasin D. The raft-dependent endocytosis of AMF therefore follows a distinct phosphatidylinositol 3-kinase-dependent pathway that is up-regulated in more aggressive tumor cells.

Birrer MJ, Johnson ME, Hao K, et al.
Whole genome oligonucleotide-based array comparative genomic hybridization analysis identified fibroblast growth factor 1 as a prognostic marker for advanced-stage serous ovarian adenocarcinomas.
J Clin Oncol. 2007; 25(16):2281-7 [PubMed] Related Publications
PURPOSE: To identify markers that can predict overall survival in patients with high-grade advanced stage serous adenocarcinomas.
PATIENTS AND METHODS: Oligonucleotide array comparative genomic hybridization (aCGH) was performed on 42 microdissected high-grade serous ovarian tumor samples. aCGH segments were obtained and a prediction Cox model was built and validated by the standard leave one out analysis. Both DNA and mRNA copy numbers of selected genes located on the candidate aCGH segments were determined by quantitative polymerase chain reaction (qPCR) and quantitative reverse transcriptase PCR (qRT-PCR) analyses. The gene that showed the highest correlation was further validated on an independent set of specimens and was selected for further functional studies.
RESULTS: Two chromosomal regions, 4p16.3 and 5q31-5q35.3, exhibited the strongest correlation with overall survival (P < .01). From the 5q31 region, fibroblast growth factor 1 (FGF-1) was selected for further validation study. FGF-1 mRNA copy number was significantly correlated with DNA copy number and protein expression levels (P = .021 and < .001), and both FGF-1 mRNA and protein levels were significantly associated with overall survival (P = .018 and .042). This association was validated for protein expression on an independent set of 81 samples, significant to P = .006. Further studies showed significant correlation between FGF-1 protein expression and CD31+ staining in the tumor stroma (P = .024). Finally, both cancer cells and endothelial cells treated with exogenous FGF-1 showed a significant increase in cell motility and survival.
CONCLUSION: Amplification of FGF-1 at 5q31 in ovarian cancer tissues leads to increased angiogenesis, and autocrine stimulation of cancer cells, which may result in poorer overall survival in patents with high-grade advanced stage serous ovarian cancer.

Wang W, Yang LY, Yang ZL, et al.
Elevated expression of autocrine motility factor receptor correlates with overexpression of RhoC and indicates poor prognosis in hepatocellular carcinoma.
Dig Dis Sci. 2007; 52(3):770-5 [PubMed] Related Publications
Our previous study identified RhoC as an invasion and metastasis marker in hepatocellular carcinoma patients. Recent document suggested RhoGTPase is required for autocrine motility factor signaling. In this study, we questioned whether there is a correlation between expression of autocrine motility factor receptor and RhoC. Furthermore, we questioned whether elevated expression of autocrine motility factor correlates with metastasis and poor prognosis of HCC. The mRNA expression level of AMFR and RhoC were examined by RT-PCR in 25 cases of HCC and pericarcinomatous liver tissues (PCLT). In addition, the correlation between the expression level of AMFR and clinical pathologic parameters was analyzed. Furthermore, follow-up information was collected to evaluate the prognostic value of AMFR for HCC patients. Our results showed that the expression of AMFR and RhoC significantly increased in HCC compared with PCLT; extrahepatic metastatic lesions expressed significantly higher levels of AMFR and RhoC than corresponding intrahepatic HCC tissues. There is a highly significant correlation of AMFR expression levels with tumor vein invasion, number of tumor nodes, and tumor stage. Anticipatively, positive correlation was observed between mRNA expression of AMFR and RhoC gene. Furthermore, the HCC patients with high-expression of AMFR had significant high recurrence/metastasis and shorter survival than those with low-expression of AMFR. Together, our findings suggested a strong correlation between the expression of AMFR and RhoC and also a correlation between overexpression of them and invasion and metastasis of HCC. Furthermore, our data indicated AMFR as a potential prognosis for HCC.

Tanizaki Y, Sato Y, Oka H, et al.
Expression of autocrine motility factor mRNA is a poor prognostic factor in high-grade astrocytoma.
Pathol Int. 2006; 56(9):510-5 [PubMed] Related Publications
It has been reported that tumor infiltration is correlated with the expression of autocrine motility factor (AMF) and its receptor 78 kDa glycoprotein (gp78). The purpose of the present study was to detect AMF and gp78 mRNA expression levels and their localization in high-grade astrocytomas (glioblastoma and anaplastic astrocytoma) and to determine whether AMF and gp78 are important prognostic factors. A total of 32 formalin-fixed and paraffin-embedded glioblastomas and 23 formalin-fixed and paraffin-embedded anaplastic astrocytomas was used. The expressions of AMF and gp78 mRNA were detected using the highly sensitive in situ hybridization method. The expression of AMF mRNA was detected in 27 of 32 glioblastomas (84.4%) and 11 of 23 anaplastic astrocytomas (47.8%). The positivity of AMF mRNA was significantly higher in glioblastomas than in anaplastic astrocytomas (P = 0.0094), but gp78 mRNA was detected in most cases and no statistical significance was observed. The overall survival of patients with AMF expression was significantly shorter than patients without AMF expression (P = 0.0175). In anaplastic astrocytomas, the overall survival of patients with AMF expression was also significantly shorter than in patients without AMF expression (P = 0.0058). This study demonstrated that AMF is a poor prognostic factor in high-grade astrocytomas.

Mercurio AM, Lipscomb EA, Bachelder RE
Non-angiogenic functions of VEGF in breast cancer.
J Mammary Gland Biol Neoplasia. 2005; 10(4):283-90 [PubMed] Related Publications
This review advances the hypothesis that the function of vascular endothelial growth factor (VEGF) in breast cancer is not limited to angiogenesis, and that VEGF signaling in breast carcinoma cells is important for the ability of these cells to evade apoptosis and progress towards invasive and metastatic disease. In other terms, VEGF signaling provides a selective advantage for the survival and dissemination of breast carcinoma cells that may be independent of angiogenesis. The key component of this hypothesis is that breast carcinoma cells express specific VEGF receptors and that these receptors respond to autocrine VEGF, resulting in the activation of signaling pathways that impede apoptosis and promote cell migration. A related hypothesis, which is developed in this review, is that the alpha6beta4 integrin, which has been implicated in the survival and motility of breast cancer cells, can stimulate the translation of VEGF mRNA and, consequently, autocrine VEGF signaling. These findings imply that VEGF and VEGF receptor-based therapeutics, in addition to targeting angiogenesis, may also target tumor cells directly.

Hombach-Klonisch S, Bialek J, Trojanowicz B, et al.
Relaxin enhances the oncogenic potential of human thyroid carcinoma cells.
Am J Pathol. 2006; 169(2):617-32 [PubMed] Free Access to Full Article Related Publications
The role of members of the insulin-like superfamily in human thyroid carcinoma is primarily unknown. Here we demonstrate the presence of RLN2 relaxin and relaxin receptor LGR7 in human papillary, follicular, and undifferentiated anaplastic thyroid carcinoma suggesting a specific involvement of relaxin-LGR7 signaling in thyroid carcinoma. Stable transfectants of the LGR7-positive human follicular thyroid carcinoma cell lines FTC-133 and FTC-238 that secrete bioactive proRLN2 revealed this hormone to act as a multifunctional endocrine factor in thyroid carcinoma cells. Although RLN2 did not act as a mitogen, it acted as an autocrine/paracrine factor and significantly increased anchorage-independent growth and thyroid carcinoma cell motility and invasiveness through elastin matrices. Suppression of LGR7 expression by LGR7-siRNA abolished the RLN2-mediated accelerated tumor cell motility. The increased elastinolytic activity correlated with enhanced production and secretion of the lysosomal proteinases cathepsin-D (cath-D) and cath-L forms hereby identified as new RLN2 target molecules in human neoplastic thyrocytes. We found the intracellular distribution of procath-L specifically altered in RLN2 transfectants, providing first evidence for selective actions of relaxin on the powerful elastinolytic cath-L production, storage, and secretion in thyroid carcinoma cells. Thus, relaxin enhances the oncogenic potential and acts as novel endocrine modulator of invasiveness in human thyroid carcinoma cells.

Athauda G, Giubellino A, Coleman JA, et al.
c-Met ectodomain shedding rate correlates with malignant potential.
Clin Cancer Res. 2006; 12(14 Pt 1):4154-62 [PubMed] Related Publications
PURPOSE: Many proteins are proteolytically released from the cell surface by a process known as ectodomain shedding. Shedding occurs under normal physiologic conditions and can be increased in certain pathologies. Among the many receptors for which ectodomain shedding has been shown is c-Met, the hepatocyte growth factor (HGF) receptor tyrosine kinase. HGF stimulates mitogenesis, motogenesis, and morphogenesis in a variety of cellular targets during development, homeostasis, and tissue regeneration. Inappropriate HGF signaling resulting in unregulated cell proliferation, motility, and invasion occurs in several human malignancies. This can occur through paracrine signaling, autocrine loop formation, receptor mutation, gene amplification, or gene rearrangement, accompanied frequently with overexpression of ligand and/or receptor proteins. We hypothesized that c-Met overexpression in cancer might result in increased ectodomain shedding, and that its measure could be a useful biomarker of tumor progression.
EXPERIMENTAL DESIGN: We developed a sensitive electrochemiluminescent immunoassay to quantitate c-Met protein in cell lysates, culture supernatants, and biological samples.
RESULTS: A survey of cultured cell models of oncogenic transformation revealed significant direct correlations (P < 0.001, t test or ANOVA) between malignant potential and the rate of c-Met ectodomain shedding that was independent of steady-state receptor expression level. Moreover, weekly plasma and urine samples from mice harboring s.c. human tumor xenografts (n = 4 per group) displayed soluble human c-Met levels that were measurable before tumors became palpable and that correlated directly with tumor volume (R2 > 0.92, linear regression).
CONCLUSIONS: For a variety of human cancers, c-Met ectodomain shedding may provide a reliable and practical indicator of malignant potential and overall tumor burden.

Tsunoda S, Okumura T, Ito T, et al.
Significance of nerve growth factor overexpression and its autocrine loop in oesophageal squamous cell carcinoma.
Br J Cancer. 2006; 95(3):322-30 [PubMed] Free Access to Full Article Related Publications
Nerve growth factor (NGF) is overexpressed not only in nervous system, but also in several types of cancers. However, the role of NGF in oesophageal squamous cell carcinoma (OESCC) remains unclear. Here, we show the first evidence of NGF-TrkA autocrine loop and clinical significance of NGF overexpression in OESCC. Immunohistochemical study of 109 OESCC specimens revealed that NGF overexpression, found in 63 out of 109 patients (57.8%), was associated with lymph node metastasis, distant metastasis, higher TNM stage, poorer tumour differentiation, and poorer survival. NGF overexpression was also associated with strong expression of TrkA and negative expression of low-affinity neurotrophin receptor (p75NTR). Semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) of 19 surgical specimens showed upregulation of NGF mRNA in 17 out of 19 (89%) patients. All five OESCC cell lines tested in vitro secreted detectable NGF in enzyme-linked immunosorbent assay, and expressed TrkA and p75NTR on RT-PCR and Western blot. The motility of HSA/c, one of the OESCC cell lines overexpressing NGF, was significantly decreased by either neutralising anti-NGF antibody, an inhibitor of TrkA, or NGF-small interfering RNA in transwell migration assay. Our findings suggest that NGF is of potential interest not only as a prognostic factor, but also as a novel therapeutic target in OESCC.

Hishizawa M, Imada K, Sakai T, et al.
Antibody responses associated with the graft-versus-leukemia effect in adult T-cell leukemia.
Int J Hematol. 2006; 83(4):351-5 [PubMed] Related Publications
Adult T-cell leukemia (ATL) is a peripheral T-cell neoplasm caused by human T-cell leukemia virus type 1 (HTLV-1). The prognosis of ATL, especially the acute and lymphoma subtypes, is poor with conventional and high-dose chemotherapy. The effectiveness of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for ATL has been reported, suggesting the presence of a graft-versus-leukemia (GVL) effect against this malignancy. To identify the target antigens associated with tumor rejection, we used SEREX (serological identification of antigens by recombinant cDNA expression cloning) to screen ATL complementary DNA expression libraries with sera from an ATL patient who had a GVL response after allo-HSCT. Among the isolated clones, autocrine motility factor receptor (AMFR), which encodes a glycosylated transmembrane protein, was found to have selective reactivity with the sera obtained during tumor regression. Real-time reverse transcription polymerase chain reaction analysis for AMFR showed highest expression in the testis among normal tissues. Furthermore, aberrant AMFR expression was found in at least some ATL patients. Taken together, these findings suggest that AMFR may be one of the GVL antigens that provoke effective antitumor immunity against ATL in allogeneic settings.

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