PTPRQ; protein tyrosine phosphatase, receptor type, Q (12q21.2)

Gene Summary

Gene:PTPRQ; protein tyrosine phosphatase, receptor type, Q
Aliases: DFNB84, DFNB84A, PTPGMC1, R-PTP-Q
Summary:This locus encodes a member of the type III receptor-like protein-tyrosine phosphatase family. The encoded protein catalyzes the dephosphorylation of phosphotyrosine and phosphatidylinositol and plays roles in cellular proliferation and differentiation. Mutations at this locus have been linked to autosomal recessive deafness. [provided by RefSeq, Mar 2014]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:phosphatidylinositol phosphatase PTPRQ
Updated:12 December, 2014


What does this gene/protein do?
PTPRQ is implicated in:
- inner ear morphogenesis
- integral to membrane
- protein tyrosine phosphatase activity
- regulation of fat cell differentiation
Data from Gene Ontology via CGAP

Cancer Overview

Research Indicators

Publications Per Year (1989-2014)
Graph generated 12 December 2014 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.

  • Transcription Factor AP-1
  • Receptor-Like Protein Tyrosine Phosphatases, Class 3
  • Colorectal Cancer
  • Thyroid Cancer
  • Genetic Markers
  • Genotype
  • Sequence Tagged Sites
  • Polymorphism
  • Young Adult
  • Promoter Regions
  • U937 Cells
  • Signal Transduction
  • VHL
  • Protein Tyrosine Phosphatases
  • Breast Cancer
  • Transfection
  • Genetic Predisposition
  • Sequence Homology, Nucleic Acid
  • DNA Sequence Analysis
  • Cancer Gene Expression Regulation
  • Vimentin
  • Phosphorylation
  • fms-Like Tyrosine Kinase 3
  • Species Specificity
  • Gene Silencing
  • Tumor Markers
  • Neoplastic Cell Transformation
  • Vidarabine
  • Molecular Sequence Data
  • DNA Methylation
  • Single Nucleotide Polymorphism
  • Tissue Distribution
  • Down-Regulation
  • Polymerase Chain Reaction
  • Haplotypes
  • Loss of Heterozygosity
  • p38 Mitogen-Activated Protein Kinases
  • Case-Control Studies
  • Chromosome 12
  • Up-Regulation
Tag cloud generated 12 December, 2014 using data from PubMed, MeSH and CancerIndex

Notable (3)

Scope includes mutations and abnormal protein expression.

Entity Topic PubMed Papers
Breast CancerPTPRQ and Breast Cancer View Publications7
Thyroid CancerPTPRQ and Thyroid Cancer View Publications5
Colorectal CancerPTPRQ and Colorectal Cancer View Publications7

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

Related Links

Latest Publications: PTPRQ (cancer-related)

Li SY, Li R, Chen YL, et al.
Aberrant PTPRO methylation in tumor tissues as a potential biomarker that predicts clinical outcomes in breast cancer patients.
BMC Genet. 2014; 15:67 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Aberrant hypermethylation of gene promoter regions is a primary mechanism by which tumor suppressor genes become inactivated in breast cancer. Epigenetic inactivation of the protein tyrosine phosphatase receptor-type O gene (PTPRO) has been described in several types of cancer.
RESULTS: We screened primary breast cancer tissues for PTPRO promoter hypermethylation and assessed potential associations with pathological features and patient outcome. We also evaluated its potential as a breast cancer biomarker. PTPRO methylation was observed in 53 of 98 (54%) breast cancer tissues but not in adjacent normal tissue. Among matched peripheral blood samples from breast cancer patients, 33 of 98 (34%) exhibited methylated PTPRO in plasma. In contrast, no methylated PTPRO was observed in normal peripheral blood from 30 healthy individuals. PTPRO methylation was positively associated with lymph node involvement (P = 0.014), poorly differentiated histology (P = 0.037), depth of invasion (P = 0.004), and HER2 amplification (P = 0.001). Multivariate analysis indicated that aberrant PTPRO methylation could serve as an independent predictor for overall survival hazard ratio (HR): 2.7; 95% CI: 1.1-6.2; P = 0.023), especially for patients with HER2-positive (hazard ratio (HR): 7.5; 95% CI: 1.8-31.3; P = 0.006), but not in ER + and PR + subpopulation. In addition, demethylation induced by 5-azacytidine led to gene reactivation in PTPRO-methylated and -silenced breast cancer cell lines.
CONCLUSIONS: Here, we report that tumor PTPRO methylation is a strong prognostic factor in breast cancer. Methylation of PTPRO silences its expression and plays an important role in breast carcinogenesis. The data we present here may provide insight into the development of novel therapies for breast cancer treatment. Additionally, detection of PTPRO methylation in peripheral blood of breast cancer patients may provide a noninvasive means to diagnose and monitor the disease.

Related: Breast Cancer

Behjati S, Tarpey PS, Sheldon H, et al.
Recurrent PTPRB and PLCG1 mutations in angiosarcoma.
Nat Genet. 2014; 46(4):376-9 [PubMed] Free Access to Full Article Related Publications
Angiosarcoma is an aggressive malignancy that arises spontaneously or secondarily to ionizing radiation or chronic lymphoedema. Previous work has identified aberrant angiogenesis, including occasional somatic mutations in angiogenesis signaling genes, as a key driver of angiosarcoma. Here we employed whole-genome, whole-exome and targeted sequencing to study the somatic changes underpinning primary and secondary angiosarcoma. We identified recurrent mutations in two genes, PTPRB and PLCG1, which are intimately linked to angiogenesis. The endothelial phosphatase PTPRB, a negative regulator of vascular growth factor tyrosine kinases, harbored predominantly truncating mutations in 10 of 39 tumors (26%). PLCG1, a signal transducer of tyrosine kinases, encoded a recurrent, likely activating p.Arg707Gln missense variant in 3 of 34 cases (9%). Overall, 15 of 39 tumors (38%) harbored at least one driver mutation in angiogenesis signaling genes. Our findings inform and reinforce current therapeutic efforts to target angiogenesis signaling in angiosarcoma.

Related: Angiogenesis and Cancer VEGFA

Egan JB, Barrett MT, Champion MD, et al.
Whole genome analyses of a well-differentiated liposarcoma reveals novel SYT1 and DDR2 rearrangements.
PLoS One. 2014; 9(2):e87113 [PubMed] Free Access to Full Article Related Publications
Liposarcoma is the most common soft tissue sarcoma, but little is known about the genomic basis of this disease. Given the low cell content of this tumor type, we utilized flow cytometry to isolate the diploid normal and aneuploid tumor populations from a well-differentiated liposarcoma prior to array comparative genomic hybridization and whole genome sequencing. This work revealed massive highly focal amplifications throughout the aneuploid tumor genome including MDM2, a gene that has previously been found to be amplified in well-differentiated liposarcoma. Structural analysis revealed massive rearrangement of chromosome 12 and 11 gene fusions, some of which may be part of double minute chromosomes commonly present in well-differentiated liposarcoma. We identified a hotspot of genomic instability localized to a region of chromosome 12 that includes a highly conserved, putative L1 retrotransposon element, LOC100507498 which resides within a gene cluster (NAV3, SYT1, PAWR) where 6 of the 11 fusion events occurred. Interestingly, a potential gene fusion was also identified in amplified DDR2, which is a potential therapeutic target of kinase inhibitors such as dastinib, that are not routinely used in the treatment of patients with liposarcoma. Furthermore, 7 somatic, damaging single nucleotide variants have also been identified, including D125N in the PTPRQ protein. In conclusion, this work is the first to report the entire genome of a well-differentiated liposarcoma with novel chromosomal rearrangements associated with amplification of therapeutically targetable genes such as MDM2 and DDR2.

Related: Chromosome 11 Chromosome 12

Huang YT, Li FF, Ke C, et al.
PTPRO promoter methylation is predictive of poorer outcome for HER2-positive breast cancer: indication for personalized therapy.
J Transl Med. 2013; 11:245 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Protein Tyrosine Phosphatase Receptor-type O (PTPRO) has recently been in the spotlight as a tumor suppressor, whose encoding gene is frequently methylated in cancers. We examined the methylation status of the PTPRO gene promoter in breast cancer and evaluated the correlation between PTPRO promoter methylation and both clinicopathological parameters and prognosis of breast cancer patients.
METHODS: Two hundred twenty-one formalin-fixed, paraffin-embedded (FFPE) tumor tissues, 20 FFPE normal adjacent tissues and 24 matched plasma samples, collected from primary breast cancer patients, were assessed for PTPRO gene promoter methylation using methylation-specific PCR. Associations of promoter methylation with clinicopathological parameters were evaluated. Kaplan-Meier survival analysis and Cox proportional hazards models were used to estimate the effect on survival.
RESULTS: 175 samples gave identifiable PCR products, of which 130 cases (74.3%) had PTPRO gene promoter methylation. PTPRO methylation correlated with higher histological grade (P = 0.028), but not other clinical parameters. Multivariate analysis indicated that overall survival (OS) was significantly poorer in HER2-positive, but not ER-positive patients with methylated-PTPRO. Methylated-PTPRO was detectable in matched plasma samples and only observed in plasma from patients whose corresponding primary tumors were also methylated.
CONCLUSIONS: PTPRO methylation is a common event in the primary breast cancer and can be reliably detected in peripheral blood samples. PTPRO methylation is associated with poor survival only in HER2-positive patients, suggesting use of PTPRO methylation as a prognostic factor for breast cancer and for optimizing individualized therapy for HER2-positive patients.

Related: Breast Cancer

Hsu SH, Motiwala T, Roy S, et al.
Methylation of the PTPRO gene in human hepatocellular carcinoma and identification of VCP as its substrate.
J Cell Biochem. 2013; 114(8):1810-8 [PubMed] Free Access to Full Article Related Publications
We have previously reported that the gene encoding protein tyrosine phosphatase receptor type-O (PTPRO) is suppressed by promoter methylation in a rat model of hepatocellular carcinoma (HCC) and it functions as tumor suppressor in leukemia and lung cancer. Here, we explored the methylation and expression of PTPRO as well as its function in human HCC. MassARRAY analysis of primary human HCC and matching liver samples (n = 24) revealed significantly higher (P = 0.004) methylation density at the promoter CGI in tumors. Combined bisulfite restriction analysis (COBRA) of another set of human HCC samples (n = 17) demonstrated that the CGI was methylated in 29% of tumors where expression of PTPRO was lower than that in corresponding matching livers. A substrate-trapping mutant of PTPRO that stabilizes the bound substrates was used to identify its novel substrate(s). VCP/p97 was found to be a PTPRO substrate by mass spectrometry of the peptides pulled down by the substrate-trapping mutant of PTPRO. Tyrosyl dephosphorylation of VCP following ectopic expression of wild-type PTPRO in H293T and HepG2 cells confirmed that it is a bona fide substrate of PTPRO. Treatment of PTPRO overexpressing HepG2 cells with Doxorubicin, a DNA damaging drug commonly used in therapy of primary HCC, sensitized these cells to this potent anticancer drug that correlated with dephosphorylation of VCP. Taken together, these results demonstrate methylation and downregulation of PTPRO in a subset of primary human HCC and establish VCP as a novel functionally important substrate of this tyrosine phosphatase that could be a potential molecular target for HCC therapy.

Related: Doxorubicin Liver Cancer

Aya-Bonilla C, Green MR, Camilleri E, et al.
High-resolution loss of heterozygosity screening implicates PTPRJ as a potential tumor suppressor gene that affects susceptibility to Non-Hodgkin's lymphoma.
Genes Chromosomes Cancer. 2013; 52(5):467-79 [PubMed] Related Publications
We employed a Hidden-Markov-Model (HMM) algorithm in loss of heterozygosity (LOH) analysis of high-density single nucleotide polymorphism (SNP) array data from Non-Hodgkin's lymphoma (NHL) entities, follicular lymphoma (FL), and diffuse large B-cell lymphoma (DLBCL). This revealed a high frequency of LOH over the chromosomal region 11p11.2, containing the gene encoding the protein tyrosine phosphatase receptor type J (PTPRJ). Although PTPRJ regulates components of key survival pathways in B-cells (i.e., BCR, MAPK, and PI3K signaling), its role in B-cell development is poorly understood. LOH of PTPRJ has been described in several types of cancer but not in any hematological malignancy. Interestingly, FL cases with LOH exhibited down-regulation of PTPRJ, in contrast no significant variation of expression was shown in DLBCLs. In addition, sequence screening in Exons 5 and 13 of PTPRJ identified the G973A (rs2270993), T1054C (rs2270992), A1182C (rs1566734), and G2971C (rs4752904) coding SNPs (cSNPs). The A1182 allele was significantly more frequent in FLs and in NHLs with LOH. Significant over-representation of the C1054 (rs2270992) and the C2971 (rs4752904) alleles were also observed in LOH cases. A haplotype analysis also revealed a significant lower frequency of haplotype GTCG in NHL cases, but it was only detected in cases with retention. Conversely, haplotype GCAC was over-representated in cases with LOH. Altogether, these results indicate that the inactivation of PTPRJ may be a common lymphomagenic mechanism in these NHL subtypes and that haplotypes in PTPRJ gene may play a role in susceptibility to NHL, by affecting activation of PTPRJ in these B-cell lymphomas.

Related: Non Hodgkin's Lymphoma PTPRJ

Casagrande S, Ruf M, Rechsteiner M, et al.
The protein tyrosine phosphatase receptor type J is regulated by the pVHL-HIF axis in clear cell renal cell carcinoma.
J Pathol. 2013; 229(4):525-34 [PubMed] Related Publications
Mass spectrometry analysis of renal cancer cell lines recently suggested that the protein-tyrosine phosphatase receptor type J (PTPRJ), an important regulator of tyrosine kinase receptors, is tightly linked to the von Hippel-Lindau protein (pVHL). Therefore, we aimed to characterize the biological relevance of PTPRJ for clear cell renal cell carcinoma (ccRCC). In pVHL-negative ccRCC cell lines, both RNA and protein expression levels of PTPRJ were lower than those in the corresponding pVHL reconstituted cells. Quantitative RT-PCR and western blot analysis of ccRCC with known VHL mutation status and normal matched tissues as well as RNA in situ hybridization on a tissue microarray (TMA) confirmed a decrease of PTPRJ expression in more than 80% of ccRCCs, but in only 12% of papillary RCCs. ccRCC patients with no or reduced PTPRJ mRNA expression had a less favourable outcome than those with a normal expression status (p = 0.05). Sequence analysis of 32 PTPRJ mRNA-negative ccRCC samples showed five known polymorphisms but no mutations, implying other mechanisms leading to PTPRJ's down-regulation. Selective silencing of HIF-α by siRNA and reporter gene assays demonstrated that pVHL inactivation reduces PTPRJ expression through a HIF-dependent mechanism, which is mainly driven by HIF-2α stabilization. Our results suggest PTPRJ as a member of a pVHL-controlled pathway whose suppression by HIF is critical for ccRCC development.

Related: HIF1A Kidney Cancer Polymorphisms VHL PTPRJ

Yu M, Lin G, Arshadi N, et al.
Expression profiling during mammary epithelial cell three-dimensional morphogenesis identifies PTPRO as a novel regulator of morphogenesis and ErbB2-mediated transformation.
Mol Cell Biol. 2012; 32(19):3913-24 [PubMed] Free Access to Full Article Related Publications
Identification of genes that are upregulated during mammary epithelial cell morphogenesis may reveal novel regulators of tumorigenesis. We have demonstrated that gene expression programs in mammary epithelial cells grown in monolayer cultures differ significantly from those in three-dimensional (3D) cultures. We identify a protein tyrosine phosphate, PTPRO, that was upregulated in mature MCF-10A mammary epithelial 3D structures but had low to undetectable levels in monolayer cultures. Downregulation of PTPRO by RNA interference inhibited proliferation arrest during morphogenesis. Low levels of PTPRO expression correlated with reduced survival for breast cancer patients, suggesting a tumor suppressor function. Furthermore, we showed that the receptor tyrosine kinase ErbB2/HER2 is a direct substrate of PTPRO and that loss of PTPRO increased ErbB2-induced cell proliferation and transformation, together with tyrosine phosphorylation of ErbB2. Moreover, in patients with ErbB2-positive breast tumors, low PTPRO expression correlated with poor clinical prognosis compared to ErbB2-positive patients with high levels of PTPRO. Thus, PTPRO is a novel regulator of ErbB2 signaling, a potential tumor suppressor, and a novel prognostic marker for patients with ErbB2-positive breast cancers. We have identified the protein tyrosine phosphatase PTPRO as a regulator of three-dimensional epithelial morphogenesis of mammary epithelial cells and as a regulator of ErbB2-mediated transformation. In addition, we demonstrated that ErbB2 is a direct substrate of PTPRO and that decreased expression of PTPRO predicts poor prognosis for ErbB2-positive breast cancer patients. Thus, our results identify PTPRO as a novel regulator of mammary epithelial transformation, a potential tumor suppressor, and a predictive biomarker for breast cancer.

Related: Breast Cancer

Smart CE, Askarian Amiri ME, Wronski A, et al.
Expression and function of the protein tyrosine phosphatase receptor J (PTPRJ) in normal mammary epithelial cells and breast tumors.
PLoS One. 2012; 7(7):e40742 [PubMed] Free Access to Full Article Related Publications
The protein tyrosine phosphatase receptor J, PTPRJ, is a tumor suppressor gene that has been implicated in a range of cancers, including breast cancer, yet little is known about its role in normal breast physiology or in mammary gland tumorigenesis. In this paper we show that PTPRJ mRNA is expressed in normal breast tissue and reduced in corresponding tumors. Meta-analysis revealed that the gene encoding PTPRJ is frequently lost in breast tumors and that low expression of the transcript associated with poorer overall survival at 20 years. Immunohistochemistry of PTPRJ protein in normal human breast tissue revealed a distinctive apical localisation in the luminal cells of alveoli and ducts. Qualitative analysis of a cohort of invasive ductal carcinomas revealed retention of normal apical PTPRJ localization where tubule formation was maintained but that tumors mostly exhibited diffuse cytoplasmic staining, indicating that dysregulation of localisation associated with loss of tissue architecture in tumorigenesis. The murine ortholog, Ptprj, exhibited a similar localisation in normal mammary gland, and was differentially regulated throughout lactational development, and in an in vitro model of mammary epithelial differentiation. Furthermore, ectopic expression of human PTPRJ in HC11 murine mammary epithelial cells inhibited dome formation. These data indicate that PTPRJ may regulate differentiation of normal mammary epithelia and that dysregulation of protein localisation may be associated with tumorigenesis.

Related: Breast Cancer PTPRJ

Obara W, Ohsawa R, Kanehira M, et al.
Cancer peptide vaccine therapy developed from oncoantigens identified through genome-wide expression profile analysis for bladder cancer.
Jpn J Clin Oncol. 2012; 42(7):591-600 [PubMed] Related Publications
OBJECTIVE: The field of cancer vaccine therapy is currently expected to become the fourth option in the treatment of cancer after surgery, chemotherapy and radiation therapy. We developed a novel cancer peptide vaccine therapy for bladder cancer through a genome-wide expression profile analysis.
METHODS: Among a number of oncoproteins that are transactivated in cancer cells, we focused on M phase phosphoprotein 1 and DEP domain containing 1, both of which are cancer-testis antigens playing critical roles in the growth of bladder cancer cells, as candidate molecules for the development of drugs for bladder cancer. In an attempt to identify the peptide epitope from these oncoantigens, we conducted a clinical trial using these peptides for patients with advanced bladder cancer.
RESULTS: We identified HLA-A24-restricted peptide epitopes corresponding to parts of M phase phosphoprotein 1 and DEP domain containing 1 proteins, which could induce peptide-specific cytotoxic T lymphocytes. Using these peptides, we found that M phase phosphoprotein 1- and DEP domain containing 1-derived peptide vaccines could be well tolerated without any serious adverse events, and effectively induced peptide-specific cytotoxic T lymphocytes in vivo.
CONCLUSIONS: The novel approach adopted in the treatment with peptide vaccines is considered to be a promising therapy for bladder cancer.

Related: Bladder Cancer Bladder Cancer - Molecular Biology PTPRJ

Godfrey R, Arora D, Bauer R, et al.
Cell transformation by FLT3 ITD in acute myeloid leukemia involves oxidative inactivation of the tumor suppressor protein-tyrosine phosphatase DEP-1/ PTPRJ.
Blood. 2012; 119(19):4499-511 [PubMed] Related Publications
Signal transduction of FMS-like tyrosine kinase 3 (FLT3) is regulated by protein-tyrosine phosphatases (PTPs). We recently identified the PTP DEP-1/CD148/PTPRJ as a novel negative regulator of FLT3. This study addressed the role of DEP-1 for regulation of the acute myeloid leukemia (AML)-related mutant FLT3 internal tandem duplication (ITD) protein. Our experiments revealed that DEP-1 was expressed but dysfunctional in cells transformed by FLT3 ITD. This was caused by enzymatic inactivation of DEP-1 through oxidation of the DEP-1 catalytic cysteine. In intact cells, including primary AML cells, FLT3 ITD kinase inhibition reactivated DEP-1. DEP-1 reactivation was also achieved by counteracting the high levels of reactive oxygen species (ROS) production detected in FLT3 ITD-expressing cell lines by inhibition of reduced NAD phosphate (NADPH)-oxidases, or by overexpression of catalase or peroxiredoxin-1 (Prx-1). Interference with ROS production in 32D cells inhibited cell transformation by FLT3 ITD in a DEP-1-dependent manner, because RNAi-mediated depletion of DEP-1 partially abrogated the inhibitory effect of ROS quenching. Reactivation of DEP-1 by stable overexpression of Prx-1 extended survival of mice in the 32D cell/C3H/HeJ mouse model of FLT3 ITD-driven myeloproliferative disease. The study thus uncovered DEP-1 oxidation as a novel event contributing to cell transformation by FLT3 ITD.

Related: Acute Myeloid Leukemia (AML) FLT3 gene PTPRJ

You YJ, Chen YP, Zheng XX, et al.
Aberrant methylation of the PTPRO gene in peripheral blood as a potential biomarker in esophageal squamous cell carcinoma patients.
Cancer Lett. 2012; 315(2):138-44 [PubMed] Free Access to Full Article Related Publications
Epigenetic inactivation of protein tyrosine phosphatase receptor-type O (PTPRO), a new member of the PTP family, has been described in several forms of cancer. We evaluated PTPRO promoter hypermethylation as a potential biomarker in esophageal squamous cell carcinoma (ESCC). This alteration was observed in 27 (75%) of 36 primary tumors and correlated significantly with depth of invasion (T-stage, P = 0.013). Among matched peripheral blood samples from ESCC patients, 13 (36.1%) of 36 exhibited detectable methylated PTPRO in plasma, while 15 (41.7%) of 36 had this abnormality in buffy coat. No methylated PTPRO was observed in normal peripheral blood samples from 10 healthy individuals. In addition, demethylation by 5-aza-dC treatment led to gene reactivation in PTPRO-methylated and -silenced ESCC cell lines. To our knowledge, this is the first report of methylated PTPRO as a noninvasive tumor biomarker in peripheral blood. These findings suggest that hypermethylated PTPRO occurs frequently in ESCC. Further, detection in peripheral blood of ESCC patients suggests potential clinical application for noninvasive diagnosis and disease monitoring.

Related: Cancer of the Esophagus Esophageal Cancer

Motiwala T, Zanesi N, Datta J, et al.
AP-1 elements and TCL1 protein regulate expression of the gene encoding protein tyrosine phosphatase PTPROt in leukemia.
Blood. 2011; 118(23):6132-40 [PubMed] Free Access to Full Article Related Publications
We previously demonstrated that the gene encoding PTPROt, the truncated form of protein tyrosine phosphatase receptor type O expressed predominantly in hematopoietic cells, is a candidate tumor suppressor and is down-regulated in chronic lymphocytic leukemia (CLL). Here, we show that PTPROt expression is significantly reduced in CD19(+) spleen B cells from Eμ-T cell leukemia 1 (TCL1) transgenic mice relative to the wild-type mice. Strikingly, as much as a 60% decrease in PTPROt expression occurs at 7 weeks independently of promoter methylation. To elucidate the potential mechanism for this early suppression of PTPROt in these mice, we explored the role of activating protein-1 (AP-1) in its expression. We first demonstrate that AP-1 activation by 12-O-tetradecanoylphorbol-13-acetate induces PTPROt expression with concurrent recruitment of c-fos and c-jun to its promoter. The PTPROt promoter is also responsive to over- and underexpression of AP-1, confirming the role of AP-1 in PTPROt expression. Next, we demonstrate that TCL1 can repress the PTPROt promoter by altering c-fos expression and c-jun activation state. Finally, using primary CLL cells we have shown an inverse relationship between TCL1 and PTPROt expression. These findings further substantiate the role of TCL1 in PTPROt suppression and its importance in the pathogenesis of CLL.

Related: Chronic Lymphocytic Leukemia (CLL) CLL - Molecular Biology TCL1A gene

Arora D, Stopp S, Böhmer SA, et al.
Protein-tyrosine phosphatase DEP-1 controls receptor tyrosine kinase FLT3 signaling.
J Biol Chem. 2011; 286(13):10918-29 [PubMed] Free Access to Full Article Related Publications
Fms-like tyrosine kinase 3 (FLT3) plays an important role in hematopoietic differentiation, and constitutively active FLT3 mutant proteins contribute to the development of acute myeloid leukemia. Little is known about the protein-tyrosine phosphatases (PTP) affecting the signaling activity of FLT3. To identify such PTP, myeloid cells expressing wild type FLT3 were infected with a panel of lentiviral pseudotypes carrying shRNA expression cassettes targeting different PTP. Out of 20 PTP tested, expressed in hematopoietic cells, or presumed to be involved in oncogenesis or tumor suppression, DEP-1 (PTPRJ) was identified as a PTP negatively regulating FLT3 phosphorylation and signaling. Stable 32D myeloid cell lines with strongly reduced DEP-1 levels showed site-selective hyperphosphorylation of FLT3. In particular, the sites pTyr-589, pTyr-591, and pTyr-842 involved in the FLT3 ligand (FL)-mediated activation of FLT3 were hyperphosphorylated the most. Similarly, acute depletion of DEP-1 in the human AML cell line THP-1 caused elevated FLT3 phosphorylation. Direct interaction of DEP-1 and FLT3 was demonstrated by "substrate trapping" experiments showing association of DEP-1 D1205A or C1239S mutant proteins with FLT3 by co-immunoprecipitation. Moreover, activated FLT3 could be dephosphorylated by recombinant DEP-1 in vitro. Enhanced FLT3 phosphorylation in DEP-1-depleted cells was accompanied by enhanced FLT3-dependent activation of ERK and cell proliferation. Stable overexpression of DEP-1 in 32D cells and transient overexpression with FLT3 in HEK293 cells resulted in reduction of FL-mediated FLT3 signaling activity. Furthermore, FL-stimulated colony formation of 32D cells expressing FLT3 in methylcellulose was induced in response to shRNA-mediated DEP-1 knockdown. This transforming effect of DEP-1 knockdown was consistent with a moderately increased activation of STAT5 upon FL stimulation but did not translate into myeloproliferative disease formation in the 32D-C3H/HeJ mouse model. The data indicate that DEP-1 is negatively regulating FLT3 signaling activity and that its loss may contribute to but is not sufficient for leukemogenic cell transformation.

Related: Leukemia Signal Transduction FLT3 gene PTPRJ

Petermann A, Haase D, Wetzel A, et al.
Loss of the protein-tyrosine phosphatase DEP-1/PTPRJ drives meningioma cell motility.
Brain Pathol. 2011; 21(4):405-18 [PubMed] Related Publications
DEP-1/PTPRJ is a transmembrane protein-tyrosine phosphatase which has been proposed as a suppressor of epithelial tumors. We have found loss of heterozygosity (LOH) of the PTPRJ gene and loss of DEP-1 protein expression in a subset of human meningiomas. RNAi-mediated suppression of DEP-1 in DEP-1 positive meningioma cell lines caused enhanced motility and colony formation in semi-solid media. Cells devoid of DEP-1 exhibited enhanced signaling of endogenous platelet-derived growth factor (PDGF) receptors, and reduced paxillin phosphorylation upon seeding. Moreover, DEP-1 loss caused diminished adhesion to different matrices, and impaired cell spreading. DEP-1-deficient meningioma cells exhibited invasive growth in an orthotopic xenotransplantation model in nude mice, indicating that elevated motility translates into a biological phenotype in vivo. We propose that negative regulation of PDGF receptor signaling and positive regulation of adhesion signaling by DEP-1 cooperate in inhibition of meningioma cell motility, and possibly tumor invasiveness. These phenotypes of DEP-1 loss reveal functions of DEP-1 in adherent cells, and may be more generally relevant for tumorigenesis.

Related: Signal Transduction PTPRJ

Iuliano R, Palmieri D, He H, et al.
Role of PTPRJ genotype in papillary thyroid carcinoma risk.
Endocr Relat Cancer. 2010; 17(4):1001-6 [PubMed] Free Access to Full Article Related Publications
The strong genetic predisposition to papillary thyroid carcinoma (PTC) might be due to a combination of low-penetrance susceptibility variants. Thus, the research into gene variants involved in the increase of susceptibility to PTC is a relevant field of investigation. The gene coding for the receptor-type tyrosine phosphatase PTPRJ has been proposed as a cancer susceptibility gene, and its role as a tumor suppressor gene is well established in thyroid carcinogenesis. In this study, we want to ascertain the role of PTPRJ genotype in the risk for PTC. We performed a case-control study in which we determined the PTPRJ genotype for the non-synonymous Gln276Pro and Asp872Glu polymorphisms by PCR amplification and sequencing. We calculated allele and genotype frequencies for the considered polymorphisms of PTPRJ in a total sample of 299 cases (PTC patients) and 339 controls (healthy subjects) selected from Caucasian populations. We observed a significantly higher frequency of homozygotes for the Asp872 allele in the group of PTC patients than in the control group (odds ratio=1.61, 95% confidence interval 1.15-2.25, P=0.0053). We observed a non-significant increased frequency of homozygotes for Gln276Pro polymorphism in PTC cases in two distinct Caucasian populations. Therefore, the results reported here show that the homozygous genotype for Asp872 of PTPRJ is associated with an increased risk to develop PTC.

Related: Polymorphisms Thyroid Cancer PTPRJ

Motiwala T, Datta J, Kutay H, et al.
Lyn kinase and ZAP70 are substrates of PTPROt in B-cells: Lyn inactivation by PTPROt sensitizes leukemia cells to VEGF-R inhibitor pazopanib.
J Cell Biochem. 2010; 110(4):846-56 [PubMed] Free Access to Full Article Related Publications
We have recently shown that the gene encoding the truncated form of protein tyrosine phosphatase receptor-type O (PTPROt) expressed predominantly in hematopoietic cells is epigenetically silenced in human primary chronic lymphocytic leukemia (B-CLL). To determine whether increased phosphorylation of the PTPROt substrates following PTPROt suppression alters signal transduction pathway(s) that impart a growth advantage to the leukemic lymphocytes, it is critical to discern the key substrates of PTPROt. Here, we used substrate-trapping assay to identify two novel substrates of PTPROt, the tyrosine kinases Lyn and ZAP70. Both Lyn and ZAP70 were dephosphorylated by wild-type PTPROt, but not by its catalytic site (CS) mutant. A critical phosphorylation site in Lyn, Y397, essential for its activity was dephosphorylated by PTPROt. Consequently, the activity of Lyn kinase was compromised when co-expressed with PTPROt-WT compared to vector control or upon co-expression with PTPROt-CS. Ectopic expression of PTPROt in Raji cells reduced phosphorylation of Lyn in the absence of any change in its protein levels. These results have revealed the physiological importance of PTPROt in regulating B-cell receptor signaling at Lyn kinase. Further, ectopic expression of PTPROt also sensitized the cells to the VEGF-R inhibitor Pazopanib.

Related: Chronic Lymphocytic Leukemia (CLL) CLL - Molecular Biology Pazopanib (Votrient)

Nagy N, Klein G, Klein E
To the genesis of Burkitt lymphoma: regulation of apoptosis by EBNA-1 and SAP may determine the fate of Ig-myc translocation carrying B lymphocytes.
Semin Cancer Biol. 2009; 19(6):407-10 [PubMed] Related Publications
Chromosomal translocations that juxtapose one of the three immunoglobulin loci to the c-myc protooncogene are the hallmark of Burkitt lymphomas (BLs), whether they carry the Epstein Barr Virus (EBV) or not. Ig/myc translocations occur as accidents of normal B lymphocyte differentiation. Unless protected, the translocation carrying cells are apoptosis prone. However, the high B cell stimulatory cytokine level found in the two BL prone conditions, in chronic hyperendemic malaria and HIV infection, may rescue them. X-linked lymphoproliferative disease (XLP) is due to the lack of functional SAP protein, a consequence of mutation or deletion of the SAP gene. We and others have shown that SAP is pro-apoptotic. Here we summarize our finding that 8 of 10 EBV carrying, but none of 9 EBV negative BL lines express SAP. We suggest that the apoptosis prone Ig/myc translocation carrying EBV negative precursors of BL can only grow into lymphomas if they do not express SAP. However, their EBV positive counterparts are permissive for SAP expression, due to the anti-apoptotic function of EBNA-1.

Related: Apoptosis

Juszczynski P, Chen L, O'Donnell E, et al.
BCL6 modulates tonic BCR signaling in diffuse large B-cell lymphomas by repressing the SYK phosphatase, PTPROt.
Blood. 2009; 114(26):5315-21 [PubMed] Free Access to Full Article Related Publications
Tonic B-cell receptor (BCR) signaling is a key survival pathway during normal B-cell ontogenesis and in a subset of diffuse large B-cell lymphomas (DLBCLs). We previously demonstrated that BCR-dependent DLBCL cell lines and primary tumors underwent apoptosis after treatment with an ATP-competitive inhibitor of the BCR-associated spleen tyrosine kinase (SYK). These "BCR-type" tumors also have more abundant expression of the transcriptional repressor, BCL6, and increased sensitivity to BCL6 inhibition. Herein, we evaluated potential connections between BCL6-mediated transcriptional repression and SYK-dependent BCR signaling. In transcriptionally profiled normal B-cell subsets (naive, germinal center, and memory B cells) and in primary DLBCLs, there were reciprocal patterns of expression of BCL6 and the SYK tyrosine phosphatase PTPROt. BCL6 repressed PTPROt transcription via a direct interaction with functional BCL6 binding sites in the PTPROt promoter. Enforced expression of BCL6 in normal naive B cells and RNAi-mediated depletion of BCL6 in germinal center B cells directly modulated PTPROt expression. In "BCR-type" DLBCLs, BCL6 depletion increased PTPROt expression and decreased phosphorylation of SYK and the downstream adaptor protein BLNK. Because BCL6 augments BCR signaling and BCL6 and SYK are both promising therapeutic targets in many DLBCLs, combined inhibition of these functionally related pathways warrants further study.

Related: Signal Transduction BCL6

Mita Y, Yasuda Y, Sakai A, et al.
Missense polymorphisms of PTPRJ and PTPN13 genes affect susceptibility to a variety of human cancers.
J Cancer Res Clin Oncol. 2010; 136(2):249-59 [PubMed] Related Publications
PURPOSE: We investigated the association between incidence of various cancers and four single nucleotide polymorphisms (SNPs), two each in two protein tyrosine phosphatase (PTP) genes, PTPRJ and PTPN13, by a case-control study conducted in Japan.
METHODS: The study samples comprised 819 cancer-free controls and 569 cancer cases including lung, head and neck, colorectal, and esophageal cancers.
RESULTS: Compared with the major homozygotes at the Arg326Gln SNP in PTPRJ, a likely homologue of the mouse SCC1 (susceptible to colon cancer), Arg/Gln or Gln/Gln genotypes exhibited an increased colorectal cancer risk with adjusted odds ratios (aOR) of 1.71 (P = 0.021) and 3.74 (P = 4.14 x 10(-4)), respectively. Increased risks were observed with one or more of the combination genotypes of Gln276Pro and Arg326Gln in PTPRJ for most cancer types (aOR range 10.13-55.08, Bonferroni-corrected P = 0.0454-7.20 x 10(-9)). In the PTPN13, major homozygotes of Ile1522Met showed an increased risk for lung squamous cell carcinomas (aOR 1.86), compared to the heterozygotes. Increased risks were observed with at least one of the combination genotypes of the two SNPs, Ile1522Met and Tyr2081Asp, for all but esophageal cancer examined (aOR 3.36-13.75), compared with double heterozygotes. Moreover, these high risks were seen also when all cancer cases were combined (aOR 1.81-6.84).
CONCLUSIONS: PTPRJ and PTPN13 SNPs were found to influence susceptibility to a wide spectrum of cancers. Because allelic frequencies of these SNPs are relatively common in many ethnic groups, these findings are worthy of further study.

Related: Colorectal (Bowel) Cancer Cancer of the Esophagus Esophageal Cancer Head and Neck Cancers Head and Neck Cancers - Molecular Biology Lung Cancer Cancer Prevention and Risk Reduction PTPRJ

Ramaswamy B, Majumder S, Roy S, et al.
Estrogen-mediated suppression of the gene encoding protein tyrosine phosphatase PTPRO in human breast cancer: mechanism and role in tamoxifen sensitivity.
Mol Endocrinol. 2009; 23(2):176-87 [PubMed] Free Access to Full Article Related Publications
We have previously demonstrated the tumor suppressor characteristics of protein tyrosine phosphatase receptor-type O (PTPRO) in leukemia and lung cancer, including its suppression by promoter methylation. Here, we show tumor-specific methylation of the PTPRO CpG island in primary human breast cancer. PTPRO expression was significantly reduced in established breast cancer cell lines MCF-7 and MDA-MB-231 due to promoter methylation compared with its expression in normal human mammary epithelial cells (48R and 184). Further, the silenced gene could be demethylated and reactivated in MCF-7 and MDA-MB-231 cells upon treatment with 5-Azacytidine, a DNA hypomethylating agent. Because PTPRO promoter harbors estrogen-responsive elements and 17beta-estradiol (E2) plays a role in breast carcinogenesis, we examined the effect of E2 and its antagonist tamoxifen on PTPRO expression in human mammary epithelial cells and PTPRO-expressing breast cancer cell line Hs578t. Treatment with E2 significantly curtailed PTPRO expression in 48R and Hs578t cells, which was facilitated by ectopic expression of estrogen receptor (ER)beta but not ERalpha. On the contrary, treatment with tamoxifen increased PTPRO expression. Further, knockdown of ERbeta by small interfering RNA abolished these effects of E2 and tamoxifen. Chromatin immunoprecipitation assay showed association of c-Fos and c-Jun with PTPRO promoter in untreated cells, which was augmented by tamoxifen-mediated recruitment of ERbeta to the promoter. Estradiol treatment resulted in dissociation of c-Fos and c-Jun from the promoter. Ectopic expression of PTPRO in the nonexpressing MCF-7 cells sensitized them to growth-suppressive effects of tamoxifen. These data suggest that estrogen-mediated suppression of PTPRO is probably one of the early events in estrogen-induced tumorigenesis and that expression of PTPRO could facilitate endocrine therapy of breast cancer.

Related: Breast Cancer

Toland AE, Rozek LS, Presswala S, et al.
PTPRJ haplotypes and colorectal cancer risk.
Cancer Epidemiol Biomarkers Prev. 2008; 17(10):2782-5 [PubMed] Related Publications
Recent studies from mouse mapping studies for cancer susceptibility have successfully led to the identification of a handful of susceptibility genes. Ptprj was identified as a strong candidate gene for mouse locus susceptibility to colorectal cancer 1, and one variant, rs1566734, showed evidence of preferential allelic imbalance in human colorectal tumors. Haplotypes in human PTPRJ have also been associated with protective effects for breast cancer risk. To determine if variants or haplotype in PTPRJ confer protective or risk effects for colorectal cancer (CRC), we genotyped rs1566734 and six additional PTPRJ haplotype tagging single nucleotide polymorphisms (SNP) in CRC cases and controls from the Molecular Epidemiology of Colorectal Cancer study. There was no evidence for cancer risk with rs1566734 in 1,897 cases and 1,954 controls with a homozygote odds ratio of 1.09 and 95% confidence interval of 0.85 to 1.39. The 6 tagging SNPs resulted in 6 main haplotypes (frequencies, >1%). None of the six tagSNPs individually showed significant evidence for risk; however, rs1503185 showed a nonsignificant protective effect. One haplotype was overrepresented in cases compared with controls, corresponding to a 34% increase in risk CRC, but there was no significant difference overall in haplotype frequencies between cases and controls (global test P statistic=0.19). From this study, we observe no significant increase in risk for human CRC with variants or haplotypes in PTPRJ. Additional studies are warranted to study possible PTPRJ-interacting loci, which are observed with Scc1 in the mouse models for CRC susceptibility.

Related: Colorectal (Bowel) Cancer PTPRJ

Preusser M, Hoischen A, Novak K, et al.
Angiocentric glioma: report of clinico-pathologic and genetic findings in 8 cases.
Am J Surg Pathol. 2007; 31(11):1709-18 [PubMed] Related Publications
Angiocentric glioma has recently been described as a novel epilepsy associated tumor with distinct clinico-pathologic features. We report the clinical and pathologic findings in 8 additional cases of this rare tumor type and extend its characterization by genomic profiling. Almost all patients had a history of long-standing drug-resistant epilepsy. Cortico-subcortical tumors were located in the temporal and parietal lobes. Seizures began at 3 to 14 years of age and surgery was performed at 6 to 70 years. Histologically, the tumors were characterized by diffuse growth and prominent perivascular tumor cell arrangements with features of astrocytic/ependymal differentiation, but lacking neoplastic neuronal features. Necrosis and vascular proliferation were not observed and mitoses were sparse or absent. MIB-1 proliferation indices ranged from <1% to 5%. Immunohistochemically, all cases stained positively for glial fibrillary acidic protein, vimentin, protein S100B, variably for podoplanin, and showed epithelial membrane antigen-positive cytoplasmic dots. Electron microscopy showed ependymal characteristics in 2 of 3 cases investigated. An analysis of genomic imbalances by chromosomal comparative genomic hybridization revealed loss of chromosomal bands 6q24 to q25 as the only alteration in 1 of 8 cases. In 1 of 3 cases, a high-resolution screen by array-comparative genomic hybridization identified a copy number gain of 2 adjacent clones from chromosomal band 11p11.2 containing the protein-tyrosine phosphatase receptor type J (PTPRJ) gene. All patients are seizure free and without evidence of tumor recurrence at follow-up times ranging from 1/2 to 6.9 years. Our findings support 2 previous reports proposing that angiocentric glioma is a novel glial tumor entity of low-grade malignancy.

Related: Childhood Brain Tumours Childhood Brain Tumors Chromosome 11 Chromosome 6 Brain Stem Glioma - Childhood MUC1 gene S100B PTPRJ

Motiwala T, Majumder S, Kutay H, et al.
Methylation and silencing of protein tyrosine phosphatase receptor type O in chronic lymphocytic leukemia.
Clin Cancer Res. 2007; 13(11):3174-81 [PubMed] Free Access to Full Article Related Publications
PURPOSE: Previous studies in our laboratory have shown the progressive methylation and suppression of the gene encoding protein tyrosine phosphatase, PTPRO, in the livers of rats fed a methyl-deficient diet that induces hepatocarcinogenesis. Subsequently, we observed the methylation of PTPRO in primary human lung tumors and also showed its potential tumor suppressor characteristics. The present study was undertaken to investigate whether the truncated form of PTPRO (PTPROt), specifically expressed in naïve B lymphocytes, was also methylated and suppressed in chronic lymphocytic leukemia (CLL), a disease generally affecting B lymphocytes.
EXPERIMENTAL DESIGN AND RESULTS: Initial screening showed that 60% of the 52 CLL samples analyzed using methylation-specific PCR assay were methylated compared with B lymphocytes from normal individuals, which were not methylated. The expression of PTPROt, as measured by semiquantitative reverse transcription-PCR, inversely correlated with methylation in the few samples tested. Analysis of additional samples (n = 50) by combined bisulfite restriction analysis showed that the PTPRO CpG island was methylated in 82% of patients with CLL compared with B lymphocytes from normal individuals. Furthermore, overall expression of PTPRO was reduced in CLL relative to normal lymphocytes. The PTPRO gene was also suppressed by methylation in the CLL cell line WaC3CD5, where it could be reactivated upon treatment with the DNA hypomethylating agent 5-AzaC. Ectopic expression of PTPROt in a nonexpressing cell line increased growth inhibition with fludarabine treatment, a therapy commonly used for CLL.
CONCLUSION: This study reveals the potential role of PTPRO methylation and silencing in CLL tumorigenesis and also provides a novel molecular target in the epigenetic therapy.

Related: Chronic Lymphocytic Leukemia (CLL) CLL - Molecular Biology Fludarabine

Iervolino A, Iuliano R, Trapasso F, et al.
The receptor-type protein tyrosine phosphatase J antagonizes the biochemical and biological effects of RET-derived oncoproteins.
Cancer Res. 2006; 66(12):6280-7 [PubMed] Related Publications
Thyroid cancer is frequently associated with the oncogenic conversion of the RET receptor tyrosine kinase. RET gene rearrangements, which lead to the generation of chimeric RET/papillary thyroid carcinoma (PTC) oncogenes, occur in PTC, whereas RET point mutations occur in familial multiple endocrine neoplasia type 2 (MEN2) and sporadic medullary thyroid carcinomas (MTC). We showed previously that the expression of the receptor-type protein tyrosine phosphatase J (PTPRJ) is suppressed in neoplastically transformed follicular thyroid cells. We now report that PTPRJ coimmunoprecipitates with wild-type RET and with the MEN2A-associated RET(C634R) oncoprotein but not with the RET/PTC1 and RET-MEN2B isoforms. Using mutated forms of PTPRJ and RET-MEN2A, we show that the integrity of the respective catalytic domains is required for the PTPRJ/RET-MEN2A interaction. PTPRJ expression induces dephosphorylation of the RET(C634R) and, probably via an indirect mechanism, RET/PTC1 oncoproteins on two key RET autophosphorylation sites (Tyr1062 and Tyr905). This results in a significant decrease of RET-induced Shc and extracellular signal-regulated kinase 1/2 phosphorylation levels. In line with this finding, adoptive PTPRJ expression reduced the oncogenic activity of RET(C634R) in an in vitro focus formation assay of NIH3T3 cells. As expected from the coimmunoprecipitation results, the RET(M918T) oncoprotein, which is associated to MEN2B and sporadic MTC, was resistant to the dephosphorylating activity of PTPRJ. Taken together, these findings identify RET as a novel substrate of PTPRJ and suggest that PTPRJ expression levels may affect tumor phenotype associated with RET/PTC1 and RET(C634R) mutants. On the other hand, resistance to PTPRJ may be part of the mechanism of RET oncogenic conversion secondary to the M918T mutation.

Related: RET Thyroid Cancer PTPRJ

van Puijenbroek M, Dierssen JW, Stanssens P, et al.
Mass spectrometry-based loss of heterozygosity analysis of single-nucleotide polymorphism loci in paraffin embedded tumors using the MassEXTEND assay: single-nucleotide polymorphism loss of heterozygosity analysis of the protein tyrosine phosphatase receptor type J in familial colorectal cancer.
J Mol Diagn. 2005; 7(5):623-30 [PubMed] Free Access to Full Article Related Publications
As the number of identified single-nucleotide polymorphisms (SNPs) increases, high-throughput methods are required to characterize the informative loci in large patient series. We investigated the feasibility of MassEXTEND LOH analysis using Sequenom's MassArray RT software, a mass spectrometry method, as an alternative to determine loss of heterozygosity (LOH). For this purpose, we studied the c.827A>C SNP (1176A>C p.Gln276Pro) in protein tyrosine phosphatase receptor type-J (PTPRJ), which is frequently deleted in human cancers. In sporadic colorectal cancer (CRC), c.827A>C showed allele-specific LOH of the c.827A allele, which is important because LOH of PTPRJ may be an early event during sporadic CRC. To elucidate the impact of this low-penetrance gene on familial CRC, we studied c.827A>C in 222 familial CRC cases and 156 controls. In 6.2% of the A/C genotyped CRC samples, LOH of c.827A was observed with MassEXTEND LOH analysis and confirmed by conventional sequencing. Furthermore, a case with LOH of c.827A showed no LOH in 22 synchronously detected adenomas, including one with malignant transformation. The importance of the PTPRJ- c.827A>C SNP appears to be limited in familial CRC. We conclude that MassEXTEND LOH analysis (using Sequenom's MassARRAY RT software) is a sensitive, high-throughput, and cost-effective method to screen SNP loci for LOH in formalin-fixed paraffin-embedded tissue.

Related: Colorectal (Bowel) Cancer PTPRJ

Lesueur F, Pharoah PD, Laing S, et al.
Allelic association of the human homologue of the mouse modifier Ptprj with breast cancer.
Hum Mol Genet. 2005; 14(16):2349-56 [PubMed] Related Publications
Human homologues of mouse cancer modifier genes may play a role in cancer risk and prognosis. A proportion of the familial risk of common cancers may be attributable to variants in such genes, each contributing to a small effect. The protein tyrosine phosphatase receptor type J (PTPRJ) has been recently identified as being the protein encoded by the Scc1 mouse gene (susceptibility to colon cancer-1). In addition, the PTPRJ gene has been shown to be somatically altered in several human cancer types such as colon, lung and breast cancers and to have the characteristics of a tumour-suppressor gene. The purpose of this study was to determine whether common variants in the PTPRJ gene represent low penetrance breast cancer susceptibility alleles. To test this hypothesis, we assessed single nucleotide polymorphisms (SNPs) tagging the common SNPs and haplotypes of the gene in 4512 cases and 4554 controls from the East Anglian population. We observed a difference in the haplotype frequency distributions between cases and controls (P = 0.0023, OR = 0.81 [0.72-0.92]). Thus, carrying a specific PTPRJ haplotype confers a protective effect on the risk of breast cancer. This result establishes the principle that mouse cancer modifier genes are candidates for low penetrance human breast cancer susceptibility genes.

Related: Breast Cancer PTPRJ

Powell N, Dudley E, Morishita M, et al.
Single nucleotide polymorphism analysis in the human phosphatase PTPrj gene using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry.
Rapid Commun Mass Spectrom. 2004; 18(19):2249-54 [PubMed] Related Publications
Data derived from analysis of single nucleotide polymorphisms (SNPs) are being applied in many diverse fields, from medical studies of disease mechanisms and individual drug response, to population genetics for tracking migration and mixing of ancestral groups and also in forensic science for the identification of human remains and identification of individuals from bodily samples. All these applications have in common the need to generate data for multiple loci from large numbers of samples. Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) is a promising platform for the generation of such data and we present a simple, flexible and robust technique for SNP determination. We demonstrate these features by typing two SNPs (Q276P and R326Q) in the human phosphatase gene PTPrj, which has been implicated in the aetiology of colon, lung, breast and thyroid cancers. A nucleotide depletion primer extension assay using no commercial kits or dideoxyNTPs was used to genotype a panel of DNAs derived from thyroid cancer patients and normal volunteers. The results obtained were in perfect agreement with those generated via restriction fragment length polymorphism analysis. No significant association was noted between possession of either allelic variant and a disease state, but the technique was validated as simple, flexible and appropriate for application in this context. Furthermore, it was highly cost-effective and required minimal optimisation, rendering it ideal for this type of pilot study.

Related: Thyroid Cancer PTPRJ

Iuliano R, Le Pera I, Cristofaro C, et al.
The tyrosine phosphatase PTPRJ/DEP-1 genotype affects thyroid carcinogenesis.
Oncogene. 2004; 23(52):8432-8 [PubMed] Related Publications
We recently isolated the r-PTPeta gene, which encodes a receptor-type tyrosine phosphatase protein that suppresses the neoplastic phenotype of retrovirally transformed rat thyroid cells. The human homologue gene PTPRJ/DEP-1 is deleted in various tumors. Moreover, the Gln276Pro polymorphism, located in the extracellular region of the gene, seems to play a critical role in susceptibility to some human neoplasias. Here we report the loss of heterozygosity (LOH) of PTPRJ in 11/76 (14.5%) informative thyroid tumors (including adenomas and carcinomas). We also looked for the Gln276Pro, Arg326Gln and Asp872Glu polymorphisms in exons 5, 6 and 13 of PTPRJ in 88 patients with thyroid tumors and in 54 healthy individuals. We found that the PTPRJ genotypes homozygous for the Gln276Pro and Arg326Gln polymorphisms, and the Asp872 allele were more frequent in thyroid carcinoma patients than in healthy individuals (P=0.032). In addition, PTPRJ LOH was more frequent in thyroid carcinomas of heterozygotes for Gln276Pro and Arg326Gln compared with homozygotes (P=0.006). This suggests that the presence of hemizygosity for these polymorphisms in the tumor facilitates tumor progression. These results indicate that the genotypic profile of PTPRJ affects susceptibility to thyroid carcinomas, and that allelic loss of this gene is involved in thyroid carcinogenesis.

Related: Polymorphisms Thyroid Cancer PTPRJ

Trapasso F, Yendamuri S, Dumon KR, et al.
Restoration of receptor-type protein tyrosine phosphatase eta function inhibits human pancreatic carcinoma cell growth in vitro and in vivo.
Carcinogenesis. 2004; 25(11):2107-14 [PubMed] Related Publications
DEP-1/HPTPeta, a receptor-type protein tyrosine phosphatase, is a candidate tumor suppressor gene because its expression was blocked in rat and human thyroid transformed cells, and its restoration reverted their neoplastic phenotype. In addition, loss of DEP-1/HPTPeta heterozygosity has been described in mammary, lung and colon primary tumors. We now show that DEP-1/HPTPeta is drastically reduced in several cell lines originating from human epithelial pancreatic carcinomas compared with normal pancreatic tissue. We also show that the infection of AsPC1 and PSN1 cells with a recombinant adenovirus carrying r-PTPeta cDNA (the rat homolog of DEP-1/HPTPeta) inhibits their proliferation. Flow cytometric analysis of the infected cells demonstrated that restoration of r-PTPeta activity disrupts their cell cycle and leads to apoptosis. Finally, the growth of PSN1 xenograft tumors was blocked by the intratumoral injection of a recombinant adeno-associated virus carrying r-PTPeta. The data suggest that restoration of DEP-1/HPTPeta expression could be a useful tool for the gene therapy of human pancreatic cancers.

Related: Cancer of the Pancreas Pancreatic Cancer PTPRJ


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