Gene Summary

Gene:MPL; MPL proto-oncogene, thrombopoietin receptor
Summary:In 1990 an oncogene, v-mpl, was identified from the murine myeloproliferative leukemia virus that was capable of immortalizing bone marrow hematopoietic cells from different lineages. In 1992 the human homologue, named, c-mpl, was cloned. Sequence data revealed that c-mpl encoded a protein that was homologous with members of the hematopoietic receptor superfamily. Presence of anti-sense oligodeoxynucleotides of c-mpl inhibited megakaryocyte colony formation. The ligand for c-mpl, thrombopoietin, was cloned in 1994. Thrombopoietin was shown to be the major regulator of megakaryocytopoiesis and platelet formation. The protein encoded by the c-mpl gene, CD110, is a 635 amino acid transmembrane domain, with two extracellular cytokine receptor domains and two intracellular cytokine receptor box motifs . TPO-R deficient mice were severely thrombocytopenic, emphasizing the important role of CD110 and thrombopoietin in megakaryocyte and platelet formation. Upon binding of thrombopoietin CD110 is dimerized and the JAK family of non-receptor tyrosine kinases, as well as the STAT family, the MAPK family, the adaptor protein Shc and the receptors themselves become tyrosine phosphorylated. [provided by RefSeq, Jul 2008]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:thrombopoietin receptor
Source:NCBIAccessed: 01 September, 2019


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 (1994-2019)
Graph generated 01 September 2019 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.

  • Genetic Predisposition
  • United Kingdom
  • Valine
  • Sensitivity and Specificity
  • Receptors, Cytokine
  • Transduction
  • Adolescents
  • Hematopoietic Stem Cells
  • Spliceosomes
  • Neoplastic Cell Transformation
  • src-Family Kinases
  • Signal Transduction
  • Myeloproliferative Disorders
  • Neoplasm Proteins
  • Reference Standards
  • Trans-Activators
  • Chromosome 1
  • ras Proteins
  • Disease Progression
  • DNA Mutational Analysis
  • TNF
  • Haematological Malignancies
  • Primary Myelofibrosis
  • Uniparental Disomy
  • Protein Kinase Inhibitors
  • Stem Cell Niche
  • Single Nucleotide Polymorphism
  • Exons
  • Cancer Gene Expression Regulation
  • Substrate Specificity
  • Proto-Oncogene Proteins
  • Thrombocytosis
  • Venous Thrombosis
  • JAK2
  • Calreticulin
  • Phenotype
  • Leukaemia
  • Messenger RNA
  • Acute Myeloid Leukaemia
  • Base Sequence
  • Mutation
Tag cloud generated 01 September, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (3)

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: MPL (cancer-related)

Yan Z, Ohuchida K, Zheng B, et al.
CD110 promotes pancreatic cancer progression and its expression is correlated with poor prognosis.
J Cancer Res Clin Oncol. 2019; 145(5):1147-1164 [PubMed] Related Publications
PURPOSE: This study aimed at investigating the function and significance of CD110 expression in pancreatic cancer.
METHODS: We performed immunohistochemical staining for CD110 expression in tumor samples from 86 patients with pancreatic cancer. We evaluated clinical outcomes and other clinicopathological factors to determine the significance of CD110 on survival and liver metastasis. We examine thrombopoietin-CD110 signaling in cancer cell extravasation in vitro and in vivo. We investigated the effects of CD110 knockdown on liver metastasis in a splenic xenograft mouse model.
RESULTS: CD110 expression in cancer cells was associated with low-histological-grade invasive ductal carcinoma, and patients with high CD110 expression had poorer prognosis (P = 0.0003). High CD110 expression was an independent predictor of liver metastasis (P = 0.0422). Knockdown of CD110 expression significantly attenuated cell migration and invasion. Treatment with thrombopoietin promoted pancreatic cancer cell extravasation. In the presence of thrombopoietin, CD110 increased cell viability through the activation of the ERK-MYC signaling pathway. Knockdown of CD110 expression inhibited liver metastases in the mouse model.
CONCLUSIONS: CD110 promotes pancreatic cancer progression and it may serve as a predictive factor for liver metastasis.

[Consensus on clinical diagnosis, treatment and prevention management of chemotherapy induced thrombocytopenia in China(2018)].
Zhonghua Zhong Liu Za Zhi. 2018; 40(9):714-720 [PubMed] Related Publications
Chemotherapy induced thrombocytopenia (CIT) is a common side-effect of chemotherapy in cancer patients, which lead to dose and cycle reduction or chemotherapy delay, or even the need of platelet transfusion. Therefore, CIT significantly increases the cost of treatment, reduces the efficacy of chemotherapy and the quality of life, and shortens the survival time of patients. The main treatments of CIT include transfusion of platelets, recombinant human thrombopoietin (rhTPO), and recombinant human interleukin-11 (rhIL-11). RhIL-11 is the first approved thrombocytopoietic cytokine. Interleukin-11 has been shown to be effective in the treatment of thrombocytopenia. RhTPO is a recombinant full-length glycosylated thrombopoietin, which is a ligand for c-Mpl protein. Several observations indicated that administration of rhTPO before and after chemotherapy might be beneficial to patients, which enhances platelet recovery and reduces thrombocytopenia after moderately myelosuppressive regimens. In recent years, the application of rhTPO in CIT treatment has dramatically changed the management and treatment plan of CIT. The China Society of Clinical Oncology (CSCO) published a consensus on CIT in 2014. Based on this, the expert committee updated "Consensus on clinical diagnosis, treatment and prevention management of chemotherapy induced thrombocytopenia in China (2018)" according to the recent literature and clinical research. The new evidence-based practice consensus for CIT aims to provide more reasonable diagnosis, treatment of prevention regimens for CIT patients to maintain the normal platelet counts.

Han L, Czech J, Maurer A, et al.
Mutant NRAS Q61K is responsible for MAPK pathway activation in the MARIMO cell line and renders these cells independent of the CALR-MPL-JAK2-STAT5 pathway.
Leukemia. 2018; 32(9):2087-2090 [PubMed] Related Publications

Li ZL, Gao L, Zhang H, et al.
[Detection and Diagnostic Values of JAK2, CALR, MPL Gene Mutations in 208 Cases of BCR/ABL1 Negative Chronic Myeloproliferative Diseases].
Zhongguo Shi Yan Xue Ye Xue Za Zhi. 2018; 26(4):1122-1128 [PubMed] Related Publications
OBJECTIVE: To detect the JAK2, CALR and MPL gene mutations in patients with BCR/ABL1 negative chronic myeloproliferative diseases(BCR/ABL1-CMPD)and to evaluate their diagnostic value.
METHODS: Two hundred and eight cases of BCR/ABL1-CMPD comprising of 146 cases of essential thrombocythemia(ET), 37 cases of polycythemia vera(PV)and 25 cases of primary myelofibrosis(PMF)from March 2012 to December 2015 were enrolled in the BCR/ABL1-CMPD, while 124 cases of secondary thrombocythemia and 73 cases of secondary polycythemia were enrolled in the control group. The genomic DNA and total RNA Were isolated from bone marrow or peripheral blood, then the exons 12 to 20 of JAK2 gene, exon 10 of MPL gene and exons 3 to 9 of CALR gene were analyzed by using DNA sequencing.
RESULTS: among 146 ET patients, the JAK2, CALR or MPL mutations were found in: 138 cases(94.5%)including 86 cases with JAK2V617F mutation(58.9%)and 2 cases(1.4%)with exon 12 of JAK2 mutations. CALR mutations were detected in 41 cases(28.1%), among them type 1(c.1092_1143del)in 22 cases, type 2(c.1154_1155insTTGTC)in 11 cases, and type 5(c. 1091_1142del), type 8(c.1104_1137del), type 41(c.1107_1137del), type 42(c.1125_1125del)in one case respectively. In addition, 4 cases were detected withother mutations of the CALR gene(c.1107_1115del, c.1111_1144 del, c.1101 A>C, c.1112_1117del). Moreover, 9 cases harbored MPL mutations(6.2%). Secondly, 31 patients were detected with JAK2V617F mutation(83.8%)in 37 cases of PV, and JAK2 exon 12 mutations were found in 2 cases(5.4%). Besides, CALR mutations were detected in 2 cases(5.4%), including 1 case of type I, the other of novel mutation of CALR. Thirdly, 19 in 25 cases of PMF were detected with JAK2V617F mutation(76%), 2 cases with CALR mutations(8%). 4 patients(16%), JAK2, CALR or MPL mutations were not detected, but among them 3 cases were found harboring other genetic abnormalities. Fourthly, no mutations of JAK2, MPL and CALR genes were detected in 124 patients with secondary thrombocytosis and 73 cases with secondary polycythemia.
CONCLUSION: Combined detection of JAK2, CALR and MPL gene mutations can cover the vast majority of patients with BCR/ABL1-negative myeloproliferative neoplasms. For higher frequencies of the mutations of CALR in ET patients, CALR mutation can be used as a new diagnostic marker in ET patients with JAK2 and MPL wild type.

Lang T, Nie Y, Wang Z, et al.
Correlation analysis between JAK2, MPL, and CALR mutations in patients with myeloproliferative neoplasms of Chinese Uygur and Han nationality and their clinical characteristics.
J Int Med Res. 2018; 46(11):4650-4659 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Genetic factors play a role in the etiology of BCR-ABL-negative myeloproliferative neoplasms (MPNs). This study explored the relationship between mutations in the Janus kinase 2 gene ( JAK2), MPL, and the calreticulin gene ( CALR) in Uygur and Han Chinese patients with BCR-ABL fusion gene-negative MPN and corresponding clinical features.
METHODS: A total of 492 BCR-ABL-negative MPN patients treated in our hospital from May 2013 to August 2016 were enrolled. Genomic DNA was extracted from peripheral blood and used for PCR amplification and DNA sequencing. Mutations including JAK2 V617F, MPL W515L/K, and those in JAK2 exon 12 and CALR were analyzed and compared with patient clinical characteristics.
RESULTS: Of the 492 MPN patients, 169 were Uygur and 323 were Han. In these two patient groups, JAK2 mutations were detected in 39.64% and 52.63%, respectively, CALR mutations were detected in 10.06% and 20.43%, respectively, and MPL mutations were detected in 0.93% of Han patients. The age, white blood cell count, platelet levels, and hemoglobin levels in JAK2 in Han patients were higher than those in Uygur patients.
CONCLUSION: Han MPN patients harboring JAK2 mutations had higher level of age, WBC, PLT, and Hb than Uyghur patients with the same mutations.

Araki M, Yang Y, Imai M, et al.
Homomultimerization of mutant calreticulin is a prerequisite for MPL binding and activation.
Leukemia. 2019; 33(1):122-131 [PubMed] Related Publications
Studies have previously shown that mutant calreticulin (CALR), found in a subset of patients with myeloproliferative neoplasms (MPNs), interacts with and subsequently promotes the activation of the thrombopoietin receptor (MPL). However, the molecular mechanism behind the activity of mutant CALR remains unknown. Here we show that mutant, but not wild-type, CALR interacts to form a homomultimeric complex. This intermolecular interaction among mutant CALR proteins depends on their carboxyl-terminal domain, which is generated by a unique frameshift mutation found in patients with MPN. With a competition assay, we demonstrated that the formation of mutant CALR homomultimers is required for the binding and activation of MPL. Since association with MPL is required for the oncogenicity of mutant CALR, we propose a model in which the constitutive activation of the MPL downstream pathway by mutant CALR multimers induces the development of MPN. This study provides a potential novel therapeutic strategy against mutant CALR-dependent tumorigenesis via targeting the intermolecular interaction among mutant CALR proteins.

Rabade N, Subramanian PG, Kodgule R, et al.
Molecular genetics of BCR-ABL1 negative myeloproliferative neoplasms in India.
Indian J Pathol Microbiol. 2018 Apr-Jun; 61(2):209-213 [PubMed] Related Publications
Introduction: Over the past decade, we have moved on from a predominantly morphological and clinical classification of myeloproliferative neoplasms (MPN) to a more evolved classification that accounts for the molecular heterogeneity that is unique to this subgroup of hematological malignancies. This usually incorporates mutations in Janus kinase 2 (JAK2), MPL, and calreticulin (CALR) genes. In this manuscript, we report the frequency of these mutations in a cohort of Indian patients at a tertiary cancer center.
Materials and Methods: One hundred and thirty cases of MPN were included in this study. These cases were diagnosed and classified based on the World Health Organization 2008 criteria. JAK2 and MPL mutations were detected using high sensitivity allele-specific polymerase chain reaction using fluorescent labeled primers followed by capillary electrophoresis. A subset of JAK2 and CALR mutations were assessed using a fragment length assay.
Results: Among the MPN, we had 20 cases of polycythemia vera (PV), 34 cases of essential thrombocythemia (ET), and 59 of myelofibrosis (MF). JAK2, MPL, and CALR mutations were mutually exclusive of each other. Seventeen cases were categorized as MPN unclassifiable (MPN-U). JAK2p.V617F and MPL mutations were present in 60% (78 of 130) and 5.3% (7 of 130) of all MPN. All the PV cases harbored the JAK2 p.V617F mutation. A total of 23.8% (31 of 130) of patients harbored CALR mutations. CALR exon 9 mutations were detected in 60.8% (14 of 23) and 50% (5 of 10) of JAK2 and MPL negative MF and ET cases, respectively. MPN-U cases included three JAK2 p.V617F positive, two MPL p.W515 L, and 12 CALR positive cases. Ten different types of CALR indels (8 deletions and 2 insertions) were detected of which Type I and Type II mutations were the most common, occurring at a frequency of 45.1% (14 of 31) and 22.5% (7 of 31), respectively.
Discussion and Conclusion: We report frequencies of JAK2 p. V617F, MPL exon 10 and CALR mutations in 130 patients similar to those reported in western literature. These mutations carry not only diagnostic but also prognostic relevance.

Klairmont MM, Cheng J, Schwartzberg L, et al.
Chronic myeloid leukemia, BCR-ABL1-positive with CALR and MPL mutations.
Int J Lab Hematol. 2018; 40(3):e41-e42 [PubMed] Related Publications

Elf S, Abdelfattah NS, Baral AJ, et al.
Defining the requirements for the pathogenic interaction between mutant calreticulin and MPL in MPN.
Blood. 2018; 131(7):782-786 [PubMed] Free Access to Full Article Related Publications
Mutations in calreticulin (

Miao J, Leblebjian H, Scullion B, Parnes A
A single center experience with romiplostim for the management of chemotherapy-induced thrombocytopenia.
Am J Hematol. 2018; 93(4):E86-E88 [PubMed] Related Publications

Mansier O, Luque Paz D, Ianotto JC, et al.
Clinical and biological characterization of MPN patients harboring two driver mutations, a French intergroup of myeloproliferative neoplasms (FIM) study.
Am J Hematol. 2018; 93(4):E84-E86 [PubMed] Related Publications

Masarova L, Alhuraiji A, Bose P, et al.
Significance of thrombocytopenia in patients with primary and postessential thrombocythemia/polycythemia vera myelofibrosis.
Eur J Haematol. 2018; 100(3):257-263 [PubMed] Free Access to Full Article Related Publications
Severe thrombocytopenia (platelets <50 × 10

Chapman J, Geyer JT, Khanlari M, et al.
Myeloid neoplasms with features intermediate between primary myelofibrosis and chronic myelomonocytic leukemia.
Mod Pathol. 2018; 31(3):429-441 [PubMed] Related Publications
Monocytosis can develop during disease course in primary myelofibrosis simulating that seen in chronic myelomonocytic leukemia, and should not lead to disease reclassification. In contrast, at presentation, rare cases have clinical, morphologic, and molecular genetic features truly intermediate between primary myelofibrosis and chronic myelomonocytic leukemia. The taxonomy and natural history of these diseases are unclear. We identified cases which either: (1) fulfilled the 2008 World Health Organization criteria for primary myelofibrosis but had absolute monocytosis and, when available, chronic myelomonocytic leukemia-related mutations (ASXL1, SRSF2, TET2) or (2) fulfilled criteria of chronic myelomonocytic leukemia but had megakaryocytic proliferation and atypia, marrow fibrosis, and myeloproliferative-type driver mutations (JAK2, MPL, CALR). Patients with established primary myelofibrosis who developed monocytosis and those with chronic myelomonocytic leukemia with marrow fibrosis were excluded. By combining the pathology databases of two large institutions, six eligible cases were identified. Patients were predominantly male and elderly with monocytosis at diagnosis (average 17.5%/2.3 × 10

Tefferi A, Nicolosi M, Mudireddy M, et al.
Driver mutations and prognosis in primary myelofibrosis: Mayo-Careggi MPN alliance study of 1,095 patients.
Am J Hematol. 2018; 93(3):348-355 [PubMed] Related Publications
The 2013 discovery of calreticulin (CALR) mutations in myeloproliferative neoplasms was attended by their association with longer survival in primary myelofibrosis (PMF). Subsequent studies have suggested prognostic distinction between type 1/like and type 2/like CALR mutations and detrimental effect from triple-negative mutational status. Among 709 Mayo Clinic patients with PMF, 467 (66%) harbored JAK2, 112 (16%) CALR type 1/like, 24 (3.4%) CALR type 2/like, 38 (5.4%) MPL mutations and 68 (10%) were triple-negative. Survival was longer with type 1/like CALR, compared to JAK2 (HR 2.6, 95% CI 1.9-3.5), type 2/like CALR (HR 2.5, 95% CI 1.4-4.5), MPL (HR 1.8, 95% CI 1.1-2.9) and triple-negative mutational status (HR 2.4, 95% CI 1.6-3.6), but otherwise similar between the non-type 1/like CALR mutational states (P = .41). In multivariable analysis, the absence of type 1/like CALR (P < .001; HR 2, 95% CI 1.4-2.7), presence of ASXL1/SRSF2 mutations (P < .001; HR 1.9, 95% CI 1.5-2.4) and DIPSS-plus (P < .001) were each predictive of inferior survival. Furthermore, among 210 patients with ASXL1/SRSF2 mutations, survival was significantly longer in the presence vs. absence of type 1/like CALR mutations (median 5.8 vs. 2.9 years; P < .001). Triple-negative status did not disclose additional prognostic information for overall or leukemia-free survival. The observations regarding the prognostic distinction between CALR mutation variants were validated in an external cohort of 386 patients from the University of Florence Careggi hospital. We conclude that type 1/like CALR mutations in PMF not only predict superior survival, but also partially amend the detrimental effect of high molecular risk mutations.

Teichman J, Taher A, Hashi A, et al.
A sticky situation: myocardial infarction in a young woman with immune thrombocytopenia on eltrombopag and a history of mediastinal radiation.
J Thromb Thrombolysis. 2018; 45(1):192-195 [PubMed] Related Publications
More recent immune thrombocytopenia (ITP) treatment strategies enhance platelet production with the use of thrombopoietin receptor agonists (TPO-RA) such as eltrombopag. Patients receiving TPO-RA agents may be at an increased risk of thromboembolism, however the pathophysiology and common underlying risk factors are not well understood. We present the case of a young asplenic woman on eltrombopag for chronic ITP with acute myocardial infarction involving the right coronary artery. Past medical history was significant for remote mediastinal radiation for lymphoma and splenectomy for ITP. She had no other risk factors for coronary artery disease. She underwent coronary catheterization and balloon angioplasty to the culprit lesion, although stenting was deferred due to concerns with dual antiplatelet therapy. She was discharged from hospital on single antiplatelet therapy with acetylsalicylic acid. We believe that the patient's ITP, recent eltrombopag use, surgical asplenia and history of mediastinal radiation synergistically contributed to her myocardial infarction. The risks of bleeding and thromboembolism must be carefully weighed in patients receiving TPO-RA therapy.

Nieborowska-Skorska M, Maifrede S, Dasgupta Y, et al.
Ruxolitinib-induced defects in DNA repair cause sensitivity to PARP inhibitors in myeloproliferative neoplasms.
Blood. 2017; 130(26):2848-2859 [PubMed] Free Access to Full Article Related Publications
Myeloproliferative neoplasms (MPNs) often carry JAK2(V617F), MPL(W515L), or CALR(del52) mutations. Current treatment options for MPNs include cytoreduction by hydroxyurea and JAK1/2 inhibition by ruxolitinib, both of which are not curative. We show here that cell lines expressing JAK2(V617F), MPL(W515L), or CALR(del52) accumulated reactive oxygen species-induced DNA double-strand breaks (DSBs) and were modestly sensitive to poly-ADP-ribose polymerase (PARP) inhibitors olaparib and BMN673. At the same time, primary MPN cell samples from individual patients displayed a high degree of variability in sensitivity to these drugs. Ruxolitinib inhibited 2 major DSB repair mechanisms, BRCA-mediated homologous recombination and DNA-dependent protein kinase-mediated nonhomologous end-joining, and, when combined with olaparib, caused abundant accumulation of toxic DSBs resulting in enhanced elimination of MPN primary cells, including the disease-initiating cells from the majority of patients. Moreover, the combination of BMN673, ruxolitinib, and hydroxyurea was highly effective in vivo against JAK2(V617F)

Patterson-Fortin J, Moliterno AR
Molecular Pathogenesis of Myeloproliferative Neoplasms: Influence of Age and Gender.
Curr Hematol Malig Rep. 2017; 12(5):424-431 [PubMed] Related Publications
The myeloproliferative neoplasms polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) display distinct clinical and pathologic features but are characterized by mutations in JAK2, MPL, and CALR leading to activation of the JAK-STAT pathway. This review addresses the pathogenesis and mechanisms of these mutant alleles and the unique interactions of both of age and gender.

ElNahass YH, Mahmoud HK, Mattar MM, et al.
MPN10 score and survival of molecularly annotated myeloproliferative neoplasm patients.
Leuk Lymphoma. 2018; 59(4):844-854 [PubMed] Related Publications
JAK2, CALR, MPL and triple-negative mutational status has a direct impact on symptom severity and disease burden assessed by MPN10 score in myeloproliferative neoplasms (MPNs). Among 93 patients; median MPN10 score was 48 (5-76) in JAK2 mutants versus 25 (4-80) in JAK2 negative (p < .001); 22.5 (4-65) in CALR mutants versus 35 (5-80) in CALR negative (p < .050) and 21 (10-48) in triple negative versus 40 (4-80) in JAK2/CALR/MPL mutants (p < .001). At three years, progression free and overall survival of JAK2-positive versus JAK2-negative patients were 62% versus 100% (p < .001); 85% versus 100% (p = .011) and were 100% versus 78% (p = .067); 100% versus 92% (p = .197) in CALR-positive versus CALR-negative patients and 100% versus 75% (p = .004); 100% versus 90% (p = .015) in triple negative versus mutant patients, respectively. MPN10 score in association with driver gene mutations can be used as a predictor of survival in MPN patients.

Araki M, Komatsu N
Novel molecular mechanism of cellular transformation by a mutant molecular chaperone in myeloproliferative neoplasms.
Cancer Sci. 2017; 108(10):1907-1912 [PubMed] Free Access to Full Article Related Publications
Deregulation of the cytokine-receptor signaling pathway plays a significant role in tumorigenesis. Such deregulation is frequently caused by alterations in the genes involved in the signaling pathway. At the end of 2013, recurrent somatic mutations in the calreticulin (CALR) gene that encodes a molecular chaperone were identified in a subset of patients with Philadelphia-chromosome negative myeloproliferative neoplasms (MPN). The present review focuses on the role of CALR mutations in the oncogenic transformations observed in MPN. All the CALR mutations were found to generate a + 1 frameshift in the reading frame on exon 9, which encodes the carboxy (C)-terminus end of CALR, and thus conferred a common mutant-specific sequence in all the CALR mutants. The mutant CALR (but not the wild-type) constitutively activates the thrombopoietin (TPO) receptor, myeloproliferative leukemia protein (MPL), even in the absence of TPO to induce cellular transformation. Preferential interaction between the mutant CALR and MPL is achieved by a presumptive conformational change induced by the mutant-specific C-terminus domain, which allows N-domain binding to MPL. Even though mutant CALR is expressed on the cell surface and is secreted out of cells, it only presents autocrine capacity for MPL activation. These findings define a novel molecular mechanism by which the mutant molecular chaperone constitutively activates the cytokine receptor to induce cellular transformation.

Wolschke C, Badbaran A, Zabelina T, et al.
Impact of molecular residual disease post allografting in myelofibrosis patients.
Bone Marrow Transplant. 2017; 52(11):1526-1529 [PubMed] Related Publications
We screened 136 patients with myelofibrosis and a median age of 58 years who underwent allogeneic stem cell transplantation (AHSCT) for molecular residual disease for JAKV617F (n=101), thrombopoietin receptor gene (MPL) (n=4) or calreticulin (CALR) (n=31) mutation in peripheral blood on day +100 and +180 after AHSCT. After a median follow-up of 78 months, the 5-year estimated overall survival was 60% (95% confidence interval (CI): 50-70%) and the cumulative incidence of relapse at 5 years was 26% (95% CI: 18-34%) for the entire study population. The percentage of molecular clearance on day 100 was higher in CALR-mutated patients (92%) in comparison with MPL- (75%) and JAKV617F-mutated patients (67%). Patients with detectable mutation at day +100 or at day +180 had a significant higher risk of clinical relapse at 5 years than molecular-negative patients (62% vs 10%, P<0.001) and 70% vs 10%, P<0.001, respectively) irrespectively of the underlying mutation. In a multivariate analysis, high-risk diseases status (hazard ratio (HR) 2.5; 95% CI: 1.18-5.25, P=0.016) and detectable MRD at day 180 (HR 8.36, 95% CI: 2.76-25.30, P<0.001) were significant factors for a higher risk of relapse.

Fenaux P, Muus P, Kantarjian H, et al.
Romiplostim monotherapy in thrombocytopenic patients with myelodysplastic syndromes: long-term safety and efficacy.
Br J Haematol. 2017; 178(6):906-913 [PubMed] Free Access to Full Article Related Publications
Romiplostim can improve platelet counts in about 50% of patients with low- or intermediate 1-risk (lower risk) myelodysplastic syndromes (MDS) and thrombocytopenia, but its long-term toxicity and efficacy are not known. This open-label extension study evaluated the long-term safety and efficacy of romiplostim in 60 patients with lower risk MDS and platelet counts ≤50 × 10

Guo BB, Allcock RJ, Mirzai B, et al.
Megakaryocytes in Myeloproliferative Neoplasms Have Unique Somatic Mutations.
Am J Pathol. 2017; 187(7):1512-1522 [PubMed] Free Access to Full Article Related Publications
Myeloproliferative neoplasms (MPNs) are a group of related clonal hemopoietic stem cell disorders associated with hyperproliferation of myeloid cells. They are driven by mutations in the hemopoietic stem cell, most notably JAK2

Harada H
Guest Editorial: Understanding of MPN and MDS/MPN based on molecular pathogenesis and clinical aspects.
Int J Hematol. 2017; 105(6):709-710 [PubMed] Related Publications

Liu S, Ye Z, Gao Y, et al.
Generation of human iPSCs from an essential thrombocythemia patient carrying a V501L mutation in the MPL gene.
Stem Cell Res. 2017; 18:57-59 [PubMed] Related Publications
Activating point mutations in the MPL gene encoding the thrombopoietin receptor are found in 3%-10% of essential thrombocythemia (ET) and myelofibrosis patients. Here, we report the derivation of induced pluripotent stem cells (iPSCs) from an ET patient with a heterozygous MPL V501L mutation. Peripheral blood CD34

O'Sullivan JM, Harrison CN
JAK-STAT signaling in the therapeutic landscape of myeloproliferative neoplasms.
Mol Cell Endocrinol. 2017; 451:71-79 [PubMed] Related Publications
Myeloproliferative neoplasms (MPN) are a group of disorders defined by clonal proliferation of mature myeloid cells with overlapping clinical features. The driver mutations of these disorders, namely JAK2 (Janus Kinase), MPL (Myeloproliferative Leukaemia Virus) and CALR (Calreticulin) upregulate JAK-STAT signaling with increase in downstream transcription and gene expression. Epigenetic mutations are prevalent in MPNs but their interplay with aberrant JAK-STAT signaling is not known. This understanding lead to development of first targeted treatment in MPN; ruxolitinib for primary myelofibrosis. This has shown clinical benefit in overall survival and symptoms improvement but has yet to show significant disease modifying effects. This review will focus on contemporaneous understanding of altered JAK-STAT signaling in MPN and targeted treatments in clinical practice.

Mead AJ, Mullally A
Myeloproliferative neoplasm stem cells.
Blood. 2017; 129(12):1607-1616 [PubMed] Free Access to Full Article Related Publications
Myeloproliferative neoplasms (MPNs) arise in the hematopoietic stem cell (HSC) compartment as a result of the acquisition of somatic mutations in a single HSC that provides a selective advantage to mutant HSC over normal HSC and promotes myeloid differentiation to engender a myeloproliferative phenotype. This population of somatically mutated HSC, which initiates and sustains MPNs, is termed MPN stem cells. In >95% of cases, mutations that drive the development of an MPN phenotype occur in a mutually exclusive manner in 1 of 3 genes:

Araki M, Morishita S, Komatsu N
Gene mutations in myeloproliferative neoplasms.
Rinsho Ketsueki. 2016; 57(12):2526-2534 [PubMed] Related Publications
This review outlines recent advances in the understanding of gene alterations and the genetic background associated with myeloproliferative neoplasms (MPNs), as well as describing the roles of these genetic factors in the development of MPNs. JAK2, CALR, and MPL mutations that are specifically found in patients with MPNs have been shown to constitutively activate cytokine receptors. Other mutations that are commonly found in hematopoietic malignancies have been demonstrated to synergize with disease-specific mutations and to accelerate the development of MPN, or to define the disease subtype. However, some of these mutations are found in healthy elderly persons, such that the mechanism of MPN development remains elusive. Further analyses including those for genetic factors associated with the occurrence of MPN will lead to a complete understanding of MPN development.

Vainchenker W, Kralovics R
Genetic basis and molecular pathophysiology of classical myeloproliferative neoplasms.
Blood. 2017; 129(6):667-679 [PubMed] Related Publications
The genetic landscape of classical myeloproliferative neoplasm (MPN) is in large part elucidated. The MPN-restricted driver mutations, including those in

Rumi E, Cazzola M
Diagnosis, risk stratification, and response evaluation in classical myeloproliferative neoplasms.
Blood. 2017; 129(6):680-692 [PubMed] Free Access to Full Article Related Publications
Philadelphia-negative classical myeloproliferative neoplasms (MPNs) include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). The 2016 revision of the

Ebrahim EK, Assem MM, Amin AI, et al.
FLT3 Internal Tandem Duplication Mutation, cMPL and CD34 Expressions Predict Low Survival in Acute Myeloid Leukemia Patients.
Ann Clin Lab Sci. 2016; 46(6):592-600 [PubMed] Related Publications
OBJECTIVES: To detect FMS-like tyrosine kinase-3 internal tandem duplicate (FLT3 ITD) mutation, Myeloproliferative leukemia virus oncogene (cMPL) and Ephrin A 4 receptor (EphA4) expressions in Acute myeloid leukemia (AML) and their correlation to patient's clinicopathological characteristics and survival.
METHODS: RNA was extracted from blood samples of 58 AML patients (39 adults and 19 children) and 20 age and sex matched controls. FLT3 ITD mutation, cMPL and EphA4 expression was studied using RT-PCR and correlated to the clinical and survival data of the patients.
RESULTS: FLT3 ITD mutation, cMPL and EphA4 expression was positive in 35.9%, 76.9% and 56.4% of adult AML patients respectively and in 15.8%, 47.4% and 36.8% of pediatric AML patients respectively. 76.9% of adult and 89.5% of pediatric patients expressed CD33. 64.1 % of adults and 42.1% of children expressed CD34. CD34 expression was significantly associated with both FLT3 ITD mutation and cMPL expression. CD34, FLT3 and cMPL negative cases have significantly higher overall survival than positive cases.
CONCLUSION: CD34 expression is significantly associated with both FLT3 ITD mutation and cMPL expression which could be used as a marker for low survival. Normal FLT3 and negative expression of CD34 and cMPL may predict a longer overall survival. Further studies are needed to investigate the mechanism that may correlate CD34 to both markers.

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