AKT2

Gene Summary

Gene:AKT2; v-akt murine thymoma viral oncogene homolog 2
Aliases: PKBB, PRKBB, HIHGHH, PKBBETA, RAC-BETA
Location:19q13.1-q13.2
Summary:This gene is a putative oncogene encoding a protein belonging to a subfamily of serine/threonine kinases containing SH2-like (Src homology 2-like) domains. The gene was shown to be amplified and overexpressed in 2 of 8 ovarian carcinoma cell lines and 2 of 15 primary ovarian tumors. Overexpression contributes to the malignant phenotype of a subset of human ductal pancreatic cancers. The encoded protein is a general protein kinase capable of phophorylating several known proteins. [provided by RefSeq, Jul 2008]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:RAC-beta serine/threonine-protein kinase
HPRD
Source:NCBIAccessed: 16 March, 2015

Ontology:

What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 16 March 2015 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 16 March, 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: AKT2 (cancer-related)

Xiong S, Wang Q, Liu SV, et al.
Effects of luteinizing hormone receptor signaling in prostate cancer cells.
Prostate. 2015; 75(2):141-50 [PubMed] Related Publications
BACKGROUND: The importance of androgen signaling in prostate cancer (PC) is well described and prostate cancer cells retain the ability to directly synthesize androgens. Luteinizing hormone (LH) can induce expression of steroidogenic enzymes and trigger androgen production, but the regulation of this process is not well-described. Here, we explored the impact of silencing LH receptor (LHR) silencing on androgen synthesis and on several relevant signaling pathways in PC.
METHODS: LHR mRNA and protein expression was evaluated in LNCaP PC cells treated with LHR-siRNA. MTS assay was used to measure the effect of LHR-siRNA on proliferation in LNCaP and 22RV1 PC cells. Treated LNCaP and LAPC-3 cells were also assayed for differences in androgen synthesis and expression of steroidogenic enzymes, PSA, AR, and critical signaling molecules including PKA, ERK1/2, PI3K, AKT2, and HER2.
RESULTS: We confirmed that functional LHR is expressed in both androgen-sensitive and castrate-resistant PC specimens. Treatment with LHR-siRNA effectively silenced LHR gene and protein expression and prevented LH-mediated proliferation and androgen synthesis in prostate cancer cells. LHR silencing also downregulated expression of AR, PSA, PKA, ERK1/2, PI3K, AKT2, and HER2.
CONCLUSION: Collectively, these data demonstrate that silencing LHR expression suppresses androgen synthesis and signaling and the LH-LHR pathway may represent a viable therapeutic strategy in PC.

Hu B, Emdad L, Bacolod MD, et al.
Astrocyte elevated gene-1 interacts with Akt isoform 2 to control glioma growth, survival, and pathogenesis.
Cancer Res. 2014; 74(24):7321-32 [PubMed] Article available free on PMC after 15/12/2015 Related Publications
The oncogene astrocyte elevated gene-1 (AEG-1; MTDH) is highly expressed in glioblastoma multiforme (GBM) and many other types of cancer, where it activates multiple signaling pathways that drive proliferation, invasion, angiogenesis, chemoresistance, radioresistance, and metastasis. AEG-1 activates the Akt signaling pathway and Akt and c-Myc are positive regulators of AEG-1 transcription, generating a positive feedback loop between AEG-1 and Akt in regulating tumorigenesis. Here, we describe in GBM cells a direct interaction between an internal domain of AEG-1 and the PH domain of Akt2, a major driver in GBM. Expression and interaction of AEG-1 and Akt2 are elevated in GBM and contribute to tumor cell survival, proliferation, and invasion. Clinically, in silico gene expression and immunohistochemical analyses of patient specimens showed that AEG-1 and Akt2 expression correlated with GBM progression and reduced patient survival. AEG-1-Akt2 interaction prolonged stabilization of Akt2 phosphorylation at S474, regulating downstream signaling cascades that enable cell proliferation and survival. Disrupting AEG-1-Akt2 interaction by competitive binding of the Akt2-PH domain led to reduced cell viability and invasion. When combined with AEG-1 silencing, conditional expression of Akt2-PH markedly increased survival in an orthotopic mouse model of human GBM. Our study uncovers a novel molecular mechanism by which AEG-1 augments glioma progression and offers a rationale to block AEG-1-Akt2 signaling function as a novel GBM treatment.

Kang W, Tong JH, Lung RW, et al.
let-7b/g silencing activates AKT signaling to promote gastric carcinogenesis.
J Transl Med. 2014; 12:281 [PubMed] Article available free on PMC after 15/12/2015 Related Publications
BACKGROUND: Aberrant AKT activation contributes to gastric cancer cell survival and chemotherapy resistance, however its regulation is poorly understood. microRNAs have been established to be important regulators in gastric carcinogenesis. Here, we showed the functional role and putative target of let-7b and let-7g (let-7b/g) in gastric carcinogenesis.
METHODS: The expression of let-7b/g in gastric cancer cell lines and primary tumors were evaluated by miRNA qRT-PCR. The putative target gene of let-7b/g was explored by TargetScan followed by further validation. Functional analyses including MTT proliferation, monolayer colony formation, cell invasion assays and in vivo study were performed in both ectopic expression and knockdown approaches.
RESULTS: let-7b/g was found down-regulated in gastric cancer and its downregulation was associated with poor survival and correlated with lymph node metastasis. let-7b/g inhibited AKT2 expression by directly binding to its 3'UTR, reduced p-AKT (S473) activation and suppressed expression of the downstream effector pS6. AKT2 mRNA expression showed negative correlation with the expression of let-7b/g in primary tumors. Short interfering RNA (siRNA) mediated knockdown of AKT2 phenocopied the tumor-suppressive effects of let-7b/g. Moreover, AKT2 re-expression partly abrogated the growth-inhibitory effect of let-7b/g.
CONCLUSION: In conclusion, our findings reveal decreased let-7b/g contributes to aberrant AKT activation in gastric tumorigenesis and provide a potential therapeutic strategy for gastric cancer.

Liang Q, Yao X, Tang S, et al.
Integrative identification of Epstein-Barr virus-associated mutations and epigenetic alterations in gastric cancer.
Gastroenterology. 2014; 147(6):1350-62.e4 [PubMed] Related Publications
BACKGROUND & AIMS: The mechanisms by which Epstein-Barr virus (EBV) contributes to the development of gastric cancer are unclear. We investigated EBV-associated genomic and epigenomic variations in gastric cancer cells and tumors.
METHODS: We performed whole-genome, transcriptome, and epigenome sequence analyses of a gastric adenocarcinoma cell line (AGS cells), before and after EBV infection. We then looked for alterations in gastric tumor samples, with (n = 34) or without (n = 100) EBV infection, collected from patients at the Prince of Wales Hospital, Chinese University of Hong Kong (from 1998 through 2004), or the First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China (from 1999 through 2006).
RESULTS: Transcriptome analysis showed that infected cells expressed 9 EBV genes previously detected in EBV-associated gastric tumors and 71 EBV genes not previously reported in gastric tumors. Ten viral genes that had not been reported previously in gastric cancer but were expressed most highly in EBV-infected cells also were expressed in primary EBV-positive gastric tumors. Whole-genome sequence analysis identified 45 EBV-associated nonsynonymous mutations. These mutations, in genes such as AKT2, CCNA1, MAP3K4, and TGFBR1, were associated significantly with EBV-positive gastric tumors, compared with EBV-negative tumors. An activating mutation in AKT2 was associated with reduced survival times of patients with EBV-positive gastric cancer (P = .006); this mutation was found to dysregulate mitogen-activated protein kinase signaling. Integrated epigenome and transcriptome analyses identified 216 genes transcriptionally down-regulated by EBV-associated hypermethylation; methylation of ACSS1, FAM3B, IHH, and TRABD increased significantly in EBV-positive tumors. Overexpression of Indian hedgehog (IHH) and TraB domain containing (TRABD) increased proliferation and colony formation of gastric cancer cells, whereas knockdown of these genes reduced these activities. We found 5 signaling pathways (axon guidance, focal adhesion formation, interactions among cytokines and receptors, mitogen-activated protein kinase signaling, and actin cytoskeleton regulation) to be affected commonly by EBV-associated genomic and epigenomic alterations.
CONCLUSIONS: By using genomic, transcriptome, and epigenomic comparisons of EBV infected vs noninfected gastric cancer cells and tumor samples, we identified alterations in genes, gene expression, and methylation that affect different signaling networks. These might be involved in EBV-associated gastric carcinogenesis.

Dumble M, Crouthamel MC, Zhang SY, et al.
Discovery of novel AKT inhibitors with enhanced anti-tumor effects in combination with the MEK inhibitor.
PLoS One. 2014; 9(6):e100880 [PubMed] Article available free on PMC after 15/12/2015 Related Publications
Tumor cells upregulate many cell signaling pathways, with AKT being one of the key kinases to be activated in a variety of malignancies. GSK2110183 and GSK2141795 are orally bioavailable, potent inhibitors of the AKT kinases that have progressed to human clinical studies. Both compounds are selective, ATP-competitive inhibitors of AKT 1, 2 and 3. Cells treated with either compound show decreased phosphorylation of several substrates downstream of AKT. Both compounds have desirable pharmaceutical properties and daily oral dosing results in a sustained inhibition of AKT activity as well as inhibition of tumor growth in several mouse tumor models of various histologic origins. Improved kinase selectivity was associated with reduced effects on glucose homeostasis as compared to previously reported ATP-competitive AKT kinase inhibitors. In a diverse cell line proliferation screen, AKT inhibitors showed increased potency in cell lines with an activated AKT pathway (via PI3K/PTEN mutation or loss) while cell lines with activating mutations in the MAPK pathway (KRAS/BRAF) were less sensitive to AKT inhibition. Further investigation in mouse models of KRAS driven pancreatic cancer confirmed that combining the AKT inhibitor, GSK2141795 with a MEK inhibitor (GSK2110212; trametinib) resulted in an enhanced anti-tumor effect accompanied with greater reduction in phospho-S6 levels. Taken together these results support clinical evaluation of the AKT inhibitors in cancer, especially in combination with MEK inhibitor.

Sahlberg SH, Spiegelberg D, Glimelius B, et al.
Evaluation of cancer stem cell markers CD133, CD44, CD24: association with AKT isoforms and radiation resistance in colon cancer cells.
PLoS One. 2014; 9(4):e94621 [PubMed] Article available free on PMC after 15/12/2015 Related Publications
The cell surface proteins CD133, CD24 and CD44 are putative markers for cancer stem cell populations in colon cancer, associated with aggressive cancer types and poor prognosis. It is important to understand how these markers may predict treatment outcomes, determined by factors such as radioresistance. The scope of this study was to assess the connection between EGFR, CD133, CD24, and CD44 (including isoforms) expression levels and radiation sensitivity, and furthermore analyze the influence of AKT isoforms on the expression patterns of these markers, to better understand the underlying molecular mechanisms in the cell. Three colon cancer cell-lines were used, HT-29, DLD-1, and HCT116, together with DLD-1 isogenic AKT knock-out cell-lines. All three cell-lines (HT-29, HCT116 and DLD-1) expressed varying amounts of CD133, CD24 and CD44 and the top ten percent of CD133 and CD44 expressing cells (CD133high/CD44high) were more resistant to gamma radiation than the ten percent with lowest expression (CD133low/CD44low). The AKT expression was lower in the fraction of cells with low CD133/CD44. Depletion of AKT1 or AKT2 using knock out cells showed for the first time that CD133 expression was associated with AKT1 but not AKT2, whereas the CD44 expression was influenced by the presence of either AKT1 or AKT2. There were several genes in the cell adhesion pathway which had significantly higher expression in the AKT2 KO cell-line compared to the AKT1 KO cell-line; however important genes in the epithelial to mesenchymal transition pathway (CDH1, VIM, TWIST1, SNAI1, SNAI2, ZEB1, ZEB2, FN1, FOXC2 and CDH2) did not differ. Our results demonstrate that CD133high/CD44high expressing colon cancer cells are associated with AKT and increased radiation resistance, and that different AKT isoforms have varying effects on the expression of cancer stem cell markers, which is an important consideration when targeting AKT in a clinical setting.

Yu Z, Xu Z, Disante G, et al.
miR-17/20 sensitization of breast cancer cells to chemotherapy-induced apoptosis requires Akt1.
Oncotarget. 2014; 5(4):1083-90 [PubMed] Article available free on PMC after 15/12/2015 Related Publications
The serine threonine kinase Akt1 has been implicated in the control of cellular metabolism, survival and growth. Herein, disruption of the ubiquitously expressed member of the Akt family of genes, Akt1, in the mouse, demonstrates a requirement for Akt1 in miRNA-mediated cellular apoptosis. The miR-17/20 cluster is known to inhibit breast cancer cellular proliferation through G1/S cell cycle arrest via binding to the cyclin D1 3'UTR. Here we show that miR-17/20 overexpression sensitizes cells to apoptosis induced by either Doxorubicin or UV irradiation in MCF-7 cells via Akt1. miR-17/20 mediates apoptosis via increased p53 expression which promotes Akt degradation. Akt1⁻/⁻ mammary epithelial cells which express Akt2 and Akt3 demonstrated increased apoptosis to DNA damaging agents. Akt1 deficiency abolished the miR-17/20-mediated apoptosis. These results demonstrated a novel pathway through which miR17/20 regulate p53 and Akt controlling breast cancer cell apoptosis.

Meric-Bernstam F, Frampton GM, Ferrer-Lozano J, et al.
Concordance of genomic alterations between primary and recurrent breast cancer.
Mol Cancer Ther. 2014; 13(5):1382-9 [PubMed] Article available free on PMC after 01/05/2015 Related Publications
There is growing interest in delivering genomically informed cancer therapy. Our aim was to determine the concordance of genomic alterations between primary and recurrent breast cancer. Targeted next-generation sequencing was performed on formalin-fixed paraffin-embedded (FFPE) samples, profiling 3,320 exons of 182 cancer-related genes plus 37 introns from 14 genes often rearranged in cancer. Point mutations, indels, copy-number alterations (CNA), and select rearrangements were assessed in 74 tumors from 43 patients (36 primary and 38 recurrence/metastases). Alterations potentially targetable with established or investigational therapeutics were considered "actionable." Alterations were detected in 55 genes (mean 3.95 alterations/sample, range 1-12), including mutations in PIK3CA, TP53, ARID1A, PTEN, AKT1, NF1, FBXW7, and FGFR3 and amplifications in MCL1, CCND1, FGFR1, MYC, IGF1R, MDM2, MDM4, AKT3, CDK4, and AKT2. In 33 matched primary and recurrent tumors, 97 of 112 (86.6%) somatic mutations were concordant. Of identified CNAs, 136 of 159 (85.5%) were concordant: 37 (23.3%) were concordant, but below the reporting threshold in one of the matched samples, and 23 (14.5%) discordant. There was an increased frequency of CDK4/MDM2 amplifications in recurrences, as well as gains and losses of other actionable alterations. Forty of 43 (93%) patients had actionable alterations that could inform targeted treatment options. In conclusion, deep genomic profiling of cancer-related genes reveals potentially actionable alterations in most patients with breast cancer. Overall there was high concordance between primary and recurrent tumors. Analysis of recurrent tumors before treatment may provide additional insights, as both gains and losses of targets are observed.

Gonçalves V, Henriques A, Pereira J, et al.
Phosphorylation of SRSF1 by SRPK1 regulates alternative splicing of tumor-related Rac1b in colorectal cells.
RNA. 2014; 20(4):474-82 [PubMed] Article available free on PMC after 01/04/2015 Related Publications
The premessenger RNA of the majority of human genes can generate various transcripts through alternative splicing, and different tissues or disease states show specific patterns of splicing variants. These patterns depend on the relative concentrations of the splicing factors present in the cell nucleus, either as a consequence of their expression levels or of post-translational modifications, such as protein phosphorylation, which are determined by signal transduction pathways. Here, we analyzed the contribution of protein kinases to the regulation of alternative splicing variant Rac1b that is overexpressed in certain tumor types. In colorectal cells, we found that depletion of AKT2, AKT3, GSK3β, and SRPK1 significantly decreased endogenous Rac1b levels. Although knockdown of AKT2 and AKT3 affected only Rac1b protein levels suggesting a post-splicing effect, the depletion of GSK3β or SRPK1 decreased Rac1b alternative splicing, an effect mediated through changes in splicing factor SRSF1. In particular, the knockdown of SRPK1 or inhibition of its catalytic activity reduced phosphorylation and subsequent translocation of SRSF1 to the nucleus, limiting its availability to promote the inclusion of alternative exon 3b into the Rac1 pre-mRNA. Altogether, the data identify SRSF1 as a prime regulator of Rac1b expression in colorectal cells and provide further mechanistic insight into how the regulation of alternative splicing events by protein kinases can contribute to sustain tumor cell survival.

André F, Bachelot T, Commo F, et al.
Comparative genomic hybridisation array and DNA sequencing to direct treatment of metastatic breast cancer: a multicentre, prospective trial (SAFIR01/UNICANCER).
Lancet Oncol. 2014; 15(3):267-74 [PubMed] Related Publications
BACKGROUND: Breast cancer is characterised by genomic alterations. We did a multicentre molecular screening study to identify abnormalities in individual patients with the aim of providing targeted therapy matched to individuals' genomic alterations.
METHODS: From June 16, 2011, to July 30, 2012, we recruited patients who had breast cancer with a metastasis accessible for biopsy in 18 centres in France. Comparative genomic hybridisation (CGH) array and Sanger sequencing on PIK3CA (exon 10 and 21) and AKT1 (exon 4) were used to assess metastatic biopsy samples in five centres. Therapeutic targets were decided on the basis of identified genomic alterations. The primary objective was to include 30% of patients in clinical trials testing a targeted therapy and, therefore, the primary outcome was the proportion of patients to whom a targeted therapy could be offered. For the primary endpoint, the analyses were done on the overall population registered for the trial. This trial is registered with ClinicalTrials.gov, number NCT01414933.
FINDINGS: 423 patients were included, and biopsy samples were obtained from 407 (metastatic breast cancer was not found in four). CGH array and Sanger sequencing were feasible in 283 (67%) and 297 (70%) patients, respectively. A targetable genomic alteration was identified in 195 (46%) patients, most frequently in PIK3CA (74 [25%] of 297 identified genomic alterations), CCND1 (53 [19%]), and FGFR1 (36 [13%]). 117 (39%) of 297 patients with genomic tests available presented with rare genomic alterations (defined as occurring in less than 5% of the general population), including AKT1 mutations, and EGFR, MDM2, FGFR2, AKT2, IGF1R, and MET high-level amplifications. Therapy could be personalised in 55 (13%) of 423 patients. Of the 43 patients who were assessable and received targeted therapy, four (9%) had an objective response, and nine others (21%) had stable disease for more than 16 weeks. Serious (grade 3 or higher) adverse events related to biopsy were reported in four (1%) of enrolled patients, including pneumothorax (grade 3, one patient), pain (grade 3, one patient), haematoma (grade 3, one patient), and haemorrhagic shock (grade 3, one patient).
INTERPRETATION: Personalisation of medicine for metastatic breast cancer is feasible, including for rare genomic alterations.
FUNDING: French National Cancer Institute, Breast Cancer Research Foundation, Odyssea, Operation Parrains Chercheurs.

Tamim S, Vo DT, Uren PJ, et al.
Genomic analyses reveal broad impact of miR-137 on genes associated with malignant transformation and neuronal differentiation in glioblastoma cells.
PLoS One. 2014; 9(1):e85591 [PubMed] Article available free on PMC after 01/04/2015 Related Publications
miR-137 plays critical roles in the nervous system and tumor development; an increase in its expression is required for neuronal differentiation while its reduction is implicated in gliomagenesis. To evaluate the potential of miR-137 in glioblastoma therapy, we conducted genome-wide target mapping in glioblastoma cells by measuring the level of association between PABP and mRNAs in cells transfected with miR-137 mimics vs. controls via RIPSeq. Impact on mRNA levels was also measured by RNASeq. By combining the results of both experimental approaches, 1468 genes were found to be negatively impacted by miR-137--among them, 595 (40%) contain miR-137 predicted sites. The most relevant targets include oncogenic proteins and key players in neurogenesis like c-KIT, YBX1, AKT2, CDC42, CDK6 and TGFβ2. Interestingly, we observed that several identified miR-137 targets are also predicted to be regulated by miR-124, miR-128 and miR-7, which are equally implicated in neuronal differentiation and gliomagenesis. We suggest that the concomitant increase of these four miRNAs in neuronal stem cells or their repression in tumor cells could produce a robust regulatory effect with major consequences to neuronal differentiation and tumorigenesis.

Grabinski N, Möllmann K, Milde-Langosch K, et al.
AKT3 regulates ErbB2, ErbB3 and estrogen receptor α expression and contributes to endocrine therapy resistance of ErbB2(+) breast tumor cells from Balb-neuT mice.
Cell Signal. 2014; 26(5):1021-9 [PubMed] Related Publications
ErbB2(+) breast cancer is an aggressive breast cancer subtype generally associated with lower estrogen receptor alpha (ERα) expression and more aggressive tumor behavior compared to ERα(+)/ErbB2(-) breast cancer. The ErbB2(+) phenotype is associated with resistance to endocrine therapy, e.g. the selective estrogen receptor modulator Tamoxifen. However, the mechanisms underlying endocrine resistance are not fully understood. Here, we investigated the impact of AKT signaling and distinct functional roles of AKT isoforms in ErbB2(+) breast cancer from Balb-neuT mice. AKT isoform specific in vitro kinase assays revealed that AKT3 is activated in Balb-neuT breast tumors in comparison to normal murine breast tissue. Knock-down of AKT3, but not of AKT1 or AKT2, led to reduced expression and tyrosine-phosphorylation of ErbB2 and ErbB3 in Balb-neuT-derived mammary tumor cells. In contrast, expression of ERα was strongly up-regulated and phosphorylation of the AKT substrate Foxo3a which regulates ERα transcription was decreased in AKT3 knockdown cells. These data suggest that ERα expression is down regulated via AKT3/Foxo3a signaling in ErbB2(+) breast cancer cells. Furthermore, up-regulation of ERα after depletion of AKT3 resulted in a significant increase in Tamoxifen responsiveness of Balb-neuT-derived mammary tumor cells. In addition, Tamoxifen resistant human breast cancer cell lines showed increased AKT3 expression and activity in comparison to Tamoxifen responsive MCF-7 cells. Finally, by AKT isoform specific in vitro kinase assays of human breast cancer samples, AKT3 activity was detected in ErbB2(+) and triple negative tumors but not in ERα(+) breast cancer. Our data indicate that AKT3 regulates the expression of ErbB2, ErbB3 and ERα and demonstrate that down-regulation of activated AKT3 can sensitize ErbB2(+) breast cancer cells for treatment with Tamoxifen. Therefore, AKT3 targeting might be a new promising strategy for therapy of ErbB2(+)/ERα(-) breast cancer and might further increase the responsiveness to an endocrine therapy approach.

Banck MS, Beutler AS
Advances in small bowel neuroendocrine neoplasia.
Curr Opin Gastroenterol. 2014; 30(2):163-7 [PubMed] Related Publications
PURPOSE OF REVIEW: This review aims at summarizing progress in clinical trials and basic science redefining the diagnosis and treatment of well differentiated small intestine neuroendocrine tumors (SI-NET).
RECENT FINDINGS: Two clinical trials demonstrated antitumor activity of the long-acting somatostatin analogues octreotide long-acting release and lanreotide for advanced SI-NET. The mammalian target of rapamycin (mTOR) inhibitor everolimus is another treatment option for patients with SI-NET, but awaits definitive proof of benefit in the ongoing RAD001 In Advanced Neuroendocrine Tumors study (RADIANT-4). Two whole exome/genome-sequencing studies reported in the past year provided the first genome-wide analysis of large sets of SI-NET at nucleotide resolution. Candidate therapeutically relevant alterations were found to affect SRC, SMAD genes, aurora kinase A, epidermal growth factor receptor, heat shock protein 90, and platelet-derived growth factor receptor as well as mutually exclusive amplification of RAC-alpha serine/threonine-protein kinase (AKT1) or AKT2 and other alterations of PI3K/Akt/mTOR signaling genes. The gene CDKN1B is inactivated by small insertions/deletions in 8% of patients with SI-NET suggesting cell cycle inhibitors as new candidate drugs for SI-NET. Circulating tumor cells and tumor-derived RNA in the blood are promising clinical tests for SI-NET.
SUMMARY: Clinical and genomic research may merge in the near future to re-shape clinical trials and to define the 'personalized' treatment options for patients with SI-NET.

Bhatt S, Mutharasan P, Garcia OA, et al.
The inflammatory gene pathway is not a major contributor to polycystic ovary snydrome.
J Clin Endocrinol Metab. 2014; 99(3):E567-71 [PubMed] Article available free on PMC after 01/04/2015 Related Publications
CONTEXT: Although inflammation is clearly associated with obesity, diabetes, and insulin resistance, the role of chronic inflammation in the etiology of polycystic ovary syndrome (PCOS) is unclear.
OBJECTIVE: To determine whether chronic inflammation plays a causal role in the etiology of PCOS, we tested for an association between PCOS and genetic markers mapping to 80 members of the inflammatory pathway.
DESIGN: This was a case-control association study.
SETTING: The setting was an academic medical center.
PATIENTS OR PARTICIPANTS: A total of 905 index case patients with PCOS and 955 control women (108 intensively phenotyped subjects with normal androgen levels and regular menses and 847 minimally phenotyped subjects with regular menses and no history of PCOS).
INTERVENTIONS: Subjects were genotyped at single nucleotide polymorphisms mapping to 80 inflammatory genes. Logistic regression was used to test for an association between 822 single nucleotide polymorphisms and PCOS after adjustment for population stratification, body mass index, and/or age. In the index patients, we also tested for association with 11 quantitative traits (body mass index and testosterone, fasting insulin, fasting glucose, 2-hour postchallenge glucose, LH, FSH, total cholesterol, high-density lipoprotein, low-density lipoprotein, and triglyceride levels).
MAIN OUTCOME MEASURES: The evidence for an association with PCOS and with 11 quantitative traits was investigated.
RESULTS: Nominally significant evidence for an association was observed with MAP3K7, IKBKG, TNFRS11A, AKT2, IL6R, and IRF1, but no results remained statistically significant after adjustment for multiple testing.
CONCLUSIONS: Genetic variation in the inflammatory pathway is not a major contributor to the etiology of PCOS or related quantitative traits in women with PCOS.

Wang L, Yao J, Zhang X, et al.
miRNA-302b suppresses human hepatocellular carcinoma by targeting AKT2.
Mol Cancer Res. 2014; 12(2):190-202 [PubMed] Related Publications
UNLABELLED: miRNAs (miR) play a critical role in human cancers, including hepatocellular carcinoma. Although miR-302b has been suggested to function as a tumor repressor in other cancers, its role in hepatocellular carcinoma is unknown. This study investigated the expression and functional role of miR-302b in human hepatocellular carcinoma. The expression level of miR-302b is dramatically decreased in clinical hepatocellular carcinoma specimens, as compared with their respective nonneoplastic counterparts, and in hepatocellular carcinoma cell lines. Overexpression of miR-302b suppressed hepatocellular carcinoma cell proliferation and G1-S transition in vitro, whereas inhibition of miR-302b promoted hepatocellular carcinoma cell proliferation and G1-S transition. Using a luciferase reporter assay, AKT2 was determined to be a direct target of miR-302b. Subsequent investigation revealed that miR-302b expression was inversely correlated with AKT2 expression in hepatocellular carcinoma tissue samples. Importantly, silencing AKT2 recapitulated the cellular and molecular effects seen upon miR-302b overexpression, which included inhibiting hepatocellular carcinoma cell proliferation, suppressing G1 regulators (Cyclin A, Cyclin D1, CDK2) and increasing p27Kip1 phosphorylation at Ser10. Restoration of AKT2 counteracted the effects of miR-302b expression. Moreover, miR-302b was able to repress tumor growth of hepatocellular carcinoma cells in vivo.
IMPLICATIONS: Taken together, miR-302b inhibits HCC cell proliferation and growth in vitro and in vivo by targeting AKT2.

Chin YR, Yoshida T, Marusyk A, et al.
Targeting Akt3 signaling in triple-negative breast cancer.
Cancer Res. 2014; 74(3):964-73 [PubMed] Article available free on PMC after 01/04/2015 Related Publications
Triple-negative breast cancer (TNBC) is currently the only major breast tumor subtype without effective targeted therapy and, as a consequence, in general has a poor outcome. To identify new therapeutic targets in TNBC, we performed a short hairpin RNA (shRNA) screen for protein kinases commonly amplified and overexpressed in breast cancer. Using this approach, we identified AKT3 as a gene preferentially required for the growth of TNBCs. Downregulation of Akt3 significantly inhibits the growth of TNBC lines in three-dimensional (3D) spheroid cultures and in mouse xenograft models, whereas loss of Akt1 or Akt2 have more modest effects. Akt3 silencing markedly upregulates the p27 cell-cycle inhibitor and this is critical for the ability of Akt3 to inhibit spheroid growth. In contrast with Akt1, Akt3 silencing results in only a minor enhancement of migration and does not promote invasion. Depletion of Akt3 in TNBC sensitizes cells to the pan-Akt inhibitor GSK690693. These results imply that Akt3 has a specific function in TNBCs; thus, its therapeutic targeting may provide a new treatment option for this tumor subtype.

Dobashi Y, Sato E, Oda Y, et al.
Significance of Akt activation and AKT gene increases in soft tissue tumors.
Hum Pathol. 2014; 45(1):127-36 [PubMed] Related Publications
To clarify the aberrations of AKT genes, their protein products and clinicopathologic significance in bone and soft tissue tumors, expression profiles of total Akt, its isoforms and activated Akt, and increases in copy number of AKT1/AKT2 genes were examined. Immunohistochemical analysis in 77 cases revealed overexpression of total Akt, Akt1, Akt2, and phosphorylated Akt in 84.4%, 67.5%, 72.7%, and 71.4%, respectively. Positive results were also observed in benign lesions but at a lower frequency. Overexpression of Akt1 was more frequent than that of Akt2 in well-differentiated liposarcoma (6/7 versus 3/7 cases) and schwannoma (4/4 versus 1/4 cases), whereas Akt2 overexpression and Akt activation were more frequent than Akt1 overexpression in malignant nerve sheath (3/4 and 4/4, respectively, versus 2/4 cases) and muscular tumors (8/9 and 8/9 versus 4/9 cases). By fluorescence in situ hybridization analysis, increase of gene copy number was observed in 13.3% for AKT1 and in 25.0% for AKT2 due to polysomy of chromosome 14 or 19, respectively, but not gene amplification. One case of schwannoma exhibited polysomy of both chromosomes 14 and 19. Akt activation was correlated with total Akt cytoplasmic localization (P = .0031) and subsequent metastasis (P = .0454). Moreover, AKT2 gene increase correlated with tumor size (P = .0352) and metastasis (P = .0344). In conclusion, in a defined subset of bone and soft tissue tumors, including benign tumors, Akt was frequently overexpressed and activated, and AKT1/2 copy number was increased. Because abnormality of Akt/AKT correlated with clinicopathologic profiles, novel therapies targeting isoform-specific Akts may be useful for these particular types of tumors.

Zhang Y, Guo X, Yang M, et al.
Identification of AKT kinases as unfavorable prognostic factors for hepatocellular carcinoma by a combination of expression profile, interaction network analysis and clinical validation.
Mol Biosyst. 2014; 10(2):215-22 [PubMed] Related Publications
BACKGROUND & AIM: identification of key markers that differentiate occurrence and progression of hepatocellular carcinoma (HCC) is of great significance to develop novel prognostic factors and improve therapeutic strategies. The aim of this study was to screen novel markers for HCC by combining expression profile, interaction network analysis and clinical validation.
METHODS & RESULTS: HCC significant molecules which were differentially expressed in HCC tissues were obtained from five existing HCC related databases (OncoDB.HCC, HCC.net, dbHCCvar, EHCO and Liverome). The protein-protein interaction network of HCC significant proteins was constructed and 331 candidate HCC markers were identified by calculating four topological features of the network ('Degree', 'Betweenness', 'Closeness' and 'K-coreness'). According to the enrichment analysis on Gene ontology items and KEGG pathways, these candidate HCC markers were more frequently involved in cellular protein metabolic processes, translational elongation and intracellular signaling cascade, which are associated with cancer development and metastasis. Among 331 candidate HCC markers, the three AKT kinase family members (AKT1-AKT3) were selected for clinical validation by immunohistochemistry analysis using 130 HCC specimens and matched adjacent non-neoplastic liver tissues. Interestingly, the upregulation of AKT1, AKT2 and AKT3 proteins were all significantly associated with tumor aggressiveness and poor prognosis in patients with HCC.
CONCLUSION: this study provided an integrated analysis by combining expression profile and interaction network analysis to identify a list of biologically significant HCC related markers and pathways. Further experimental validation also indicated that AKT1, AKT2 and AKT3 proteins may all be novel unfavorable prognostic factors for patients with HCC.

Wang Z, Hou J, Lu L, et al.
Small ribosomal protein subunit S7 suppresses ovarian tumorigenesis through regulation of the PI3K/AKT and MAPK pathways.
PLoS One. 2013; 8(11):e79117 [PubMed] Article available free on PMC after 01/04/2015 Related Publications
Small ribosomal protein subunit S7 (RPS7) has been reported to be associated with various malignancies, but the role of RPS7 in ovarian cancer remains unclear. In this study, we found that silencing of RPS7 by a specific shRNA promoted ovarian cancer cell proliferation, accelerated cell cycle progression, and slightly reduced cell apoptosis and response to cisplatin treatment. Knockdown of RPS7 resulted in increased expression of P85α, P110α, and AKT2. Although the basal levels of ERK1/2, MEK1/2, and P38 were inconsistently altered in ovarian cancer cells, the phosphorylated forms of MEK1/2 (Ser217/221), ERK1/2 (Thr202/Tyr204), JNK1/2 (Thr183/Tyr185), and P38 (Thr180/Tyr182) were consistently reduced after RPS7 was silenced. Both the in vitro anchorage-independent colony formation and in vivo animal tumor formation capability of cells were enhanced after RPS7 was depleted. We also showed that silencing of RPS7 enhanced ovarian cancer cell migration and invasion. In sum, our results suggest that RPS7 suppresses ovarian tumorigenesis and metastasis through PI3K/AKT and MAPK signal pathways. Thus, RPS7 may be used as a potential marker for diagnosis and treatment of ovarian cancer.

Cizkova M, Vacher S, Meseure D, et al.
PIK3R1 underexpression is an independent prognostic marker in breast cancer.
BMC Cancer. 2013; 13:545 [PubMed] Article available free on PMC after 01/04/2015 Related Publications
BACKGROUND: The present study focused on the prognostic roles of PIK3CA and PIK3R1 genes and additional PI3K pathway-associated genes in breast cancer.
METHODS: The mutational and mRNA expression status of PIK3CA, PIK3R1 and AKT1, and expression status of other genes involved in the PI3K pathway (EGFR, PDK1, PTEN, AKT2, AKT3, GOLPH3, WEE1, P70S6K) were assessed in a series of 458 breast cancer samples.
RESULTS: PIK3CA mutations were identified in 151 samples (33.0%) in exons 1, 2, 9 and 20. PIK3R1 mutations were found in 10 samples (2.2%) and underexpression in 283 samples (61.8%). AKT1 mutations were found in 15 samples (3.3%) and overexpression in 116 samples (25.3%). PIK3R1 underexpression tended to mutual exclusivity with PIK3CA mutations (p = 0.00097). PIK3CA mutations were associated with better metastasis-free survival and PIK3R1 underexpression was associated with poorer metastasis-free survival (p = 0.014 and p = 0.00028, respectively). By combining PIK3CA mutation and PIK3R1 expression status, four prognostic groups were identified with significantly different metastasis-free survival (p = 0.00046). On Cox multivariate regression analysis, the prognostic significance of PIK3R1 underexpression was confirmed in the total population (p = 0.0013) and in breast cancer subgroups.
CONCLUSIONS: PIK3CA mutations and PIK3R1 underexpression show opposite effects on patient outcome and could become useful prognostic and predictive factors in breast cancer.

Wang L, Yao J, Shi X, et al.
MicroRNA-302b suppresses cell proliferation by targeting EGFR in human hepatocellular carcinoma SMMC-7721 cells.
BMC Cancer. 2013; 13:448 [PubMed] Article available free on PMC after 01/04/2015 Related Publications
BACKGROUND: MicroRNAs are regulators that can play an essential role in tumorigenesis. Although miR-302 families have been suggested to be tumor repressors in human cancer, the mechanism by which they suppress tumor development remains to be defined. In this study, we discover that miR302b suppresses tumor proliferation may due to directly targeting EGFR in human hepatocellular carcinoma (HCC).
METHODS: QRT-PCR was used to assess miR-302b and EGFR expression in 27 pairs of clinical hepatocellular carcinoma tissues and their corresponding adjacent nontumorous liver tissues. MTT, colony formation, immunofluorescence staining, and cell cycle assays were used to examine the tumor suppressor role of miR302b in cell proliferation. Luciferase assays were performed to assess the EGFR was a novel target of miR-302b. Western blot assay was used to validate the protein expression level.
RESULTS: We demonstrated that miR-302b was frequently down-regulated, whereas EGFR was up-regulated in 27 pairs of clinical HCC and non-tumorous counterparts. The dual-luciferase reporter assays revealed that EGFR was a novel target of miR-302b. Re-expression of miR-302b resulted in the inhibition of proliferation in hepatocellular carcinoma SMMC-7721 cells. The silencing of EGFR by miR-302b or siEGFR led to down-regulation of proliferation-related proteins, such as AKT2, CCND1, and CDK2.
CONCLUSION: miR-302b suppresses HCC growth may due to targeting the EGFR/AKT2/CCND1 pathway.

Li Q, Yang J, Yu Q, et al.
Associations between single-nucleotide polymorphisms in the PI3K-PTEN-AKT-mTOR pathway and increased risk of brain metastasis in patients with non-small cell lung cancer.
Clin Cancer Res. 2013; 19(22):6252-60 [PubMed] Related Publications
PURPOSE: Non-small cell lung cancer (NSCLC) metastasizes fairly often to the brain, but identifying which patients will develop brain metastases is problematic. The phosphoinositide 3-kinase (PI3K)-AKT-mTOR signaling pathway is important in the control of cell growth, tumorigenesis, and cell invasion. We hypothesized that genotype variants in this pathway could predict brain metastasis in patients with NSCLC.
METHODS: We genotyped 16 single-nucleotide polymorphisms (SNP) in five core genes (PIK3CA, PTEN, AKT1, AKT2, and FRAP1) by using DNA from blood samples of 317 patients with NSCLC, and evaluated potential associations with the subsequent development of brain metastasis, the cumulative incidence of which was estimated with Kaplan-Meier analysis. Multivariate Cox regression analysis was used to analyze correlations between genotype variants and the occurrence of brain metastasis.
RESULTS: In analysis of individual SNPs, the GT/GG genotype of AKT1: rs2498804, CT/TT genotype of AKT1: rs2494732, and AG/AA genotype of PIK3CA: rs2699887 were associated with higher risk of brain metastasis at 24-month follow-up [respective HRs, 1.860, 95% confidence interval (CI) 1.199-2.885, P = 0.006; HR 1.902, 95% CI 1.259-2.875, P = 0.002; and HR 1.933, 95% CI 1.168-3.200, P = 0.010]. We further found that these SNPs had a cumulative effect on brain metastasis risk, with that risk being highest for patients carrying both of these unfavorable genotypes (P = 0.003).
CONCLUSIONS: Confirmation of our findings, the first to indicate that genetic variations in PI3K-AKT-mTOR can predict brain metastasis, in prospective studies would facilitate stratification of patients for brain metastasis prevention trials.

Song Q, Sheng W, Zhang X, et al.
ILEI drives epithelial to mesenchymal transition and metastatic progression in the lung cancer cell line A549.
Tumour Biol. 2014; 35(2):1377-82 [PubMed] Related Publications
Transforming growth factor beta (TGF-β) induces epithelial-mesenchymal transition (EMT) accompanied by cellular differentiation and migration. Despite extensive transcriptomic profiling, identification of TGF-β-inducible, EMT-specific genes during metastatic progression of lung cancer remains elusive. Here, we functionally validate a previously described post-transcriptional pathway by which TGF-β modulates expression of interleukin-like EMT inducer (ILEI), and EMT itself. We show that poly r(C)-binding protein 1 (PCBP1) binds ILEI transcript and repress its translation. TGF-β activation leads to phosphorylation at serine-43 of PCBP1 by protein kinase Bβ/Akt2, inducing its release from the ILEI transcript and translational activation. Modulation of hnRNP E1 expression modification altered TGF-β-mediated reversal of translational silencing of ILEI transcripts and EMT. Furthermore, ILEI could induce, as well as maintain, CD24(low)CD44(high) subpopulation in A549 cells treated with TGF-β, which might explain its capability to induce metastatic progression. These results thus validate the existence of an evolutionary conserved TGF-β-inducible post-transcriptional regulon that controls EMT and subsequent metastatic progression of lung cancer.

Cohen MM
The AKT genes and their roles in various disorders.
Am J Med Genet A. 2013; 161A(12):2931-7 [PubMed] Related Publications
AKT (AK mouse plus Transforming or Thymoma) is a common oncogene expressed in most tissues. Both AKT2 and AKT3, although important, have more limited distributions. The regulation of all three genes depends on two receptors-a receptor tyrosine kinase with a growth factor ligand, and a G protein coupled receptor, also with a ligand together with an explanation of how their downsteam components function. AKT2 is amplified or overexpressed in cancer with a higher frequency than those found with AKT1. AKT1 is cardioprotective to the heart by supporting its physiological growth and function. AKT2 is closely linked to Type II diabetes and the implications of various types of mutations are discussed. Various AKT3 mutations are important in neurological disorders, such as microcephaly, hemimegalencephaly, and megalencephaly syndromes. Finally, a reduced level of AKT1 in the frontal cortex has been found during post-mortem brain studies of schizophrenic patients in the populations of many countries.

Lorenzato A, Biolatti M, Delogu G, et al.
AKT activation drives the nuclear localization of CSE1L and a pro-oncogenic transcriptional activation in ovarian cancer cells.
Exp Cell Res. 2013; 319(17):2627-36 [PubMed] Related Publications
The human homolog of the yeast cse1 gene (CSE1L) is over-expressed in ovarian cancer. CSE1L forms complex with Ran and importin-α and has roles in nucleocytoplasmic traffic and gene expression. CSE1L accumulated in the nucleus of ovarian cancer cell lines, while it was localized also in the cytoplasm of other cancer cell lines. Nuclear localization depended on AKT, which was constitutively active in ovarian cancer cells, as the CSE1L protein translocated to the cytoplasm when AKT was inactivated. Moreover, the expression of a constitutively active AKT forced the translocation of CSE1L from the cytoplasm to the nucleus in other cancer cells. Nuclear accrual of CSE1L was associated to the nuclear accumulation of the phosphorylated Ran Binding protein 3 (RanBP3), which depended on AKT as well. Also in samples of human ovarian cancer, AKT activation was associated to nuclear accumulation of CSE1L and phosphorylation of RanBP3. Expression profiling of ovarian cancer cells after CSE1L silencing showed that CSE1L was required for the expression of genes promoting invasion and metastasis. In agreement, CSE1L silencing impaired motility and invasiveness of ovarian cancer cells. Altogether these data show that in ovarian cancer cells activated AKT by affecting RanBP3 phosphorylation determines the nuclear accumulation of CSE1L and likely the nuclear concentration of transcription factors conveying pro-oncogenic signals.

Guo H, Gao M, Lu Y, et al.
Coordinate phosphorylation of multiple residues on single AKT1 and AKT2 molecules.
Oncogene. 2014; 33(26):3463-72 [PubMed] Article available free on PMC after 26/06/2015 Related Publications
Aberrant AKT activation is prevalent across multiple human cancer lineages providing an important new target for therapy. Twenty-two independent phosphorylation sites have been identified on specific AKT isoforms likely contributing to differential isoform regulation. However, the mechanisms regulating phosphorylation of individual AKT isoform molecules have not been elucidated because of the lack of robust approaches able to assess phosphorylation of multiple sites on a single AKT molecule. Using a nanofluidic proteomic immunoassay (NIA), consisting of isoelectric focusing followed by sensitive chemiluminescence detection, we demonstrate that under basal and ligand-induced conditions that the pattern of phosphorylation events is markedly different between AKT1 and AKT2. Indeed, there are at least 12 AKT1 peaks and at least 5 AKT2 peaks consistent with complex combinations of phosphorylation of different sites on individual AKT molecules. Following insulin stimulation, AKT1 was phosphorylated at Thr308 in the T-loop and Ser473 in the hydrophobic domain. In contrast, AKT2 was only phosphorylated at the equivalent sites (Thr309 and Ser474) at low levels. Further, Thr308 and Ser473 phosphorylation occurred predominantly on the same AKT1 molecules, whereas Thr309 and Ser474 were phosphorylated primarily on different AKT2 molecules. Although basal AKT2 phosphorylation was sensitive to inhibition of phosphatidylinositol 3-kinase (PI3K), basal AKT1 phosphorylation was essentially resistant. PI3K inhibition decreased pThr451 on AKT2 but not pThr450 on AKT1. Thus, NIA technology provides an ability to characterize coordinate phosphorylation of individual AKT molecules providing important information about AKT isoform-specific phosphorylation, which is required for optimal development and implementation of drugs targeting aberrant AKT activation.

Paul P, Volny N, Lee S, et al.
Gli1 transcriptional activity is negatively regulated by AKT2 in neuroblastoma.
Oncotarget. 2013; 4(8):1149-57 [PubMed] Article available free on PMC after 26/06/2015 Related Publications
Activation of the Hedgehog (Hh) signaling pathway has been implicated in a variety of malignancies including neuroblastoma. Expression of Gli1, a downstream effector of Hh, correlates with a favorable prognosis in patients with neuroblastoma. Moreover, Gli1 overexpression reduces mitotic index and induces transcription of genes involved in the differentiation of neuroblastoma cells; however, much remains unknown regarding the regulation of Gli1 transcriptional activity. Here, we report a novel negative regulation of Gli1 transcriptional activity by PI3K/AKT2 signal transduction pathway. Constitutively active PI3K subunit, p110α, inhibited Gli1 transcriptional activity in neuroblastoma cells, whereas, overexpression of an inactive form of PI3K subunit, p85, enhanced its activity. Specifically, the AKT2 isoform inhibited Gli1 luciferase activity. Silencing AKT2 using siRNA increased Gli1 transcriptional activity and conversely, overexpression of constitutively active AKT2 (myr-AKT2) decreased Gli1 transcriptional activity. Furthermore, Gli1 overexpression-mediated decrease in anchorage-independent growth was rescued by AKT2 overexpression. We also demonstrated that AKT2 overexpression regulates the nuclear-cytoplasmic distribution of exogenous Gli1 protein in neuroblastoma cells by relieving a GSK3β-mediated destabilization of SUFU, a negative regulator of Gli1 nuclear translocation. Inhibition of nuclear Gli1 accumulation may explain for the suppression of the tumor-suppressive function of Gli1. Collectively, our findings suggest an important role of Gli1 as a tumor suppressor in neuroblastoma, and offer a mechanism by which AKT2 regulates the subcellular localization, and in turn, inhibits the tumor-suppressive function of Gli1 in neuroblastoma.

Fernández-Pérez MP, Montenegro MF, Sáez-Ayala M, et al.
Suppression of antifolate resistance by targeting the myosin Va trafficking pathway in melanoma.
Neoplasia. 2013; 15(7):826-39 [PubMed] Article available free on PMC after 26/06/2015 Related Publications
Human melanoma is a significant clinical problem. As most melanoma patients relapse with lethal drug-resistant disease, understanding and preventing mechanism(s) of resistance is one of the highest priorities to improve melanoma therapy. Melanosomal sequestration and the cellular exportation of cytotoxic drugs have been proposed to be important melanoma-specific mechanisms that contribute to multidrug resistance in melanoma. Concretely, we found that treatment of melanoma with methotrexate (MTX) altered melanogenesis and accelerated the exportation of melanosomes; however, the cellular and molecular processes by which MTX is trapped into melanosomes and exported out of cells have not been elucidated. In this study, we identified myosin Va (MyoVa) as a possible mediator of these cellular processes. The results demonstrated that melanoma treatment with MTX leads to Akt2-dependent MyoVa phosphorylation, which enhances its ability to interact with melanosomes and accelerates their exportation. To understand the mechanism(s) by which MTX activates Akt2, we examined the effects of this drug on the activity of protein phosphatase 2A, an Akt inhibitor activated by the methylation of its catalytic subunit. Taken together, this study identified a novel trafficking pathway in melanoma that promotes tumor resistance through Akt2/MyoVa activation. Because of these findings, we explored several MTX combination therapies to increase the susceptibility of melanoma to this drug. By avoiding MTX exportation, we observed that the E2F1 apoptotic pathway is functional in melanoma, and its induction activates p73 and apoptosis protease-activating factor 1 following a p53-autonomous proapoptotic signaling event.

Chew TW, Liu XJ, Liu L, et al.
Crosstalk of Ras and Rho: activation of RhoA abates Kras-induced liver tumorigenesis in transgenic zebrafish models.
Oncogene. 2014; 33(21):2717-27 [PubMed] Related Publications
RAS and Rho small GTPases are key molecular switches that control cell dynamics, cell growth and tissue development through their distinct signaling pathways. Although much has been learnt about their individual functions in both cell and animal models, the physiological and pathophysiological consequences of their signaling crosstalk in multi-cellular context in vivo remain largely unknown, especially in liver development and liver tumorigenesis. Furthermore, the roles of RhoA in RAS-mediated transformation and their crosstalk in vitro remain highly controversial. When challenged with carcinogens, zebrafish developed liver cancer that resembles the human liver cancer both molecularly and histopathologically. Capitalizing on the growing importance and relevance of zebrafish (Danio rerio) as an alternate cancer model, we have generated liver-specific, Tet-on-inducible transgenic lines expressing oncogenic Kras(G12V), RhoA, constitutively active RhoA(G14V) or dominant-negative RhoA(T19N). Double-transgenic lines expressing Kras(G12V) with one of the three RhoA genes were also generated. Based on quantitative bioimaging and molecular markers for genetic and signaling aberrations, we showed that the induced expression of oncogenic Kras during early development led to liver enlargement and hepatocyte proliferation, associated with elevated Erk phosphorylation, activation of Akt2 and modulation of its two downstream targets, p21Cip and S6 kinase. Such an increase in liver size and Akt2 expression was augmented by dominant-negative RhoA(T19N), but was abrogated by the constitutive-active RhoA(G14V). Consequently, induced expression of the oncogenic Kras in adult transgenic fish led to the development of hepatocellular carcinomas. Survival studies further revealed that the co-expression of dominant-negative RhoA(T19N) with oncogenic Kras increased the mortality rate compared with the other single or double-transgenic lines. This study provides evidence of the previously unappreciated signaling crosstalk between Kras and RhoA in regulating liver overgrowth and liver tumorigenesis. Our results also implicate that activating Rho could be beneficial to suppress the Kras-induced liver malignancies.

Shi W, Hou X, Li X, et al.
Differential gene expressions of the MAPK signaling pathway in enterovirus 71-infected rhabdomyosarcoma cells.
Braz J Infect Dis. 2013 Jul-Aug; 17(4):410-7 [PubMed] Related Publications
BACKGROUND: Mitogen-activated protein kinase (MAPK) signaling pathway plays an important role in response to viral infection. The aim of this study was to explore the function and mechanism of MAPK signaling pathway in enterovirus 71 (EV71) infection of human rhabdomyosarcoma (RD) cells.
METHODS: Apoptosis of RD cells was observed using annexin V-FITC/PI binding assay under a fluorescence microscope. Cellular RNA was extracted and transcribed to cDNA. The expressions of 56 genes of MAPK signaling pathway in EV71-infected RD cells at 8h and 20h after infection were analyzed by PCR array. The levels of IL-2, IL-4, IL-10, and TNF-α in the supernatant of RD cells infected with EV71 at different time points were measured by ELISA.
RESULTS: The viability of RD cells decreased obviously within 48h after EV71 infection. Compared with the control group, EV71 infection resulted in the significantly enhanced releases of IL-2, IL-4, IL-10 and TNF-α from infected RD cells (p<0.05). At 8h after infection, the expressions of c-Jun, c-Fos, IFN-β, MEKK1, MLK3 and NIK genes in EV71-infected RD cells were up-regulated by 2.08-6.12-fold, whereas other 19 genes (e.g. AKT1, AKT2, E2F1, IKK and NF-κB1) exhibited down-regulation. However, at 20h after infection, those MAPK signaling molecules including MEKK1, ASK1, MLK2, MLK3, NIK, MEK1, MEK2, MEK4, MEK7, ERK1, JNK1 and JNK2 were up-regulated. In addition, the expressions of AKT2, ELK1, c-Jun, c-Fos, NF-κB p65, PI3K and STAT1 were also increased.
CONCLUSION: EV71 infection induces the differential gene expressions of MAPK signaling pathway such as ERK, JNK and PI3K/AKT in RD cells, which may be associated with the secretions of inflammatory cytokines and host cell apoptosis.

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