Missense polymorphisms of PTPRJ and PTPN13 genes affect susceptibility to a variety of human cancers

PTPN13 rs989902 and CHEK2 rs738722 are associated with esophageal cancer

PURPOSE

Individual genetic background can play an essential role in determining the development of esophageal squamous cell carcinoma (ESCC). PTPN13 and CHEK2 play important roles in the pathogenesis of ESCC. This case-control study aimed to analyze the association between gene polymorphisms and ESCC susceptibility.

METHODS

DNA was extracted from the peripheral blood of patients. The Agena MassARRAY platform was used for the genotyping. Statistical analysis was conducted using the chi-squared test or Fisher's exact test, logistic regression analysis, and stratification analysis.

RESULTS

The 'G' allele of rs989902 (PTPN13) and the 'T' allele of rs738722 (CHEK2) were both associated with an increased risk of ESCC (rs989902: OR = 1.23, 95% CI = 1.02-1.47, p = 0.028; rs738722: OR = 1.28, 95% CI = 1.06-1.55, p = 0.011). Stratification analysis showed that SNPs (rs989902 and rs738722) were notably correlated with an increased risk of ESCC after stratification for age, sex, smoking, and drinking status. In addition, rs738722 might be associated with lower stage, while rs989902 had a lower risk of metastasis.

CONCLUSION

Our findings display that PTPN13 rs989902 and CHEK2 rs738722 are associated with an increased risk of ESCC in the Chinese Han population.

Hereditable variants of classical protein tyrosine phosphatase genes: Will they prove innocent or guilty?

Protein tyrosine phosphatases, together with protein tyrosine kinases, control many molecular signaling steps that control life at cellular and organismal levels. Impairing alterations in the genes encoding the involved proteins is expected to profoundly affect the quality of life-if compatible with life at all. Here, we review the current knowledge on the effects of germline variants that have been reported for genes encoding a subset of the protein tyrosine phosphatase superfamily; that of the thirty seven classical members. The conclusion must be that the newest genome research tools produced an avalanche of data that suggest 'guilt by association' for individual genes to specific disorders. Future research should face the challenge to investigate these accusations thoroughly and convincingly, to reach a mature genotype-phenotype map for this intriguing protein family.

The Structure, Function and Regulation of Protein Tyrosine Phosphatase Receptor Type J and Its Role in Diseases

Protein tyrosine phosphatase receptor type J (PTPRJ), also known as DEP-1, HPTPη, or CD148, belongs to the R3 subfamily of receptor protein tyrosine phosphatases (RPTPs). It was first identified as an antioncogene due to its protein level being significantly downregulated in most epithelial tumors and cancer cell lines (e.g., colon, lung, thyroid, breast, and pancreas). PTPRJ regulates mouse optic nerve projection by inhibiting the phosphorylation of the erythropoietin-producing hepatocellular carcinoma (Eph) receptor and abelson murine leukemia viral oncogene homolog 1 (c-Abl). PTPRJ is crucial for metabolism. Recent studies have demonstrated that PTPRJ dephosphorylates JAK2 at positions Y813 and Y868 to inhibit leptin signaling. Akt is more phosphorylated at the Ser473 and Thr308 sites in Ptprj^-/- mice, suggesting that PTPRJ may be a novel negative regulator of insulin signaling. PTPRJ also plays an important role in balancing the pro- and anti-osteoclastogenic activity of the M-CSF receptor (M-CSFR), and in maintaining NFATc1 expression during the late stages of osteoclastogenesis to promote bone-resorbing osteoclast (OCL) maturation. Furthermore, multiple receptor tyrosine kinases (RTKs) as substrates of PTPRJ are probably a potential therapeutic target for many types of diseases, such as cancer, neurodegenerative diseases, and metabolic diseases, by inhibiting their phosphorylation activity. In light of the important roles that PTPRJ plays in many diseases, this review summarizes the structural features of the protein, its expression pattern, and the physiological and pathological functions of PTPRJ, to provide new ideas for treating PTPRJ as a potential therapeutic target for related metabolic diseases and cancer.

Update on Management of Squamous Cell Esophageal Cancer

PURPOSE OF THE REVIEW

Esophageal cancer is the sixth most common cause of cancer death globally. Squamous cell carcinoma of the esophagus (ESCC) is the predominant histologic type in the world. Treatment strategies have evolved in the last decade and new paradigms are replacing traditional approaches at all stages of cancer. This review will summarize the epidemiology, diagnosis, staging, and treatment of esophageal squamous cell carcinoma.

RECENT FINDINGS

Novel approaches to screening may be cost-effective in regions with a high incidence of ESCC. Multi-disciplinary evaluation and treatment has become the standard of care. Endoscopic resection may be an option for early stage ESCC. Minimally invasive esophagectomy can be performed safely as a primary therapy or after-induction chemoradiation. Several recent studies have found a survival benefit to immunotherapy for patients with metastatic or persistent disease. Multi-disciplinary evaluation and multi-modal therapy including cytotoxic chemotherapy, radiation, surgery, and immunotherapy have improved survival compared to surgery alone.

The effects of CD148 Q276P/R326Q polymorphisms in A431D epidermoid cancer cell proliferation and epidermal growth factor receptor signaling

BACKGROUND

CD148 is a transmembrane protein tyrosine phosphatase that is expressed in multiple cell types. Previous studies have shown that CD148 dephosphorylates growth factor receptors and their signaling molecules, including EGFR and ERK1/2, and negatively regulates cancer cell growth. Furthermore, research of clinical patients has shown that highly linked CD148 gene polymorphisms, Gln276Pro (Q276P) and Arg326Gln (R326Q), are associated with an increased risk of several types of cancer. However, the biological effects of these missense mutations have not been studied.

AIM

We aimed to determine the biological effects of CD148 Q276P/R326Q mutations in cancer cell proliferation and growth factor signaling, with emphasis on EGFR signaling.

METHODS

CD148 forms, wild-type (WT) or Q276P/R326Q, were retrovirally introduced into A431D epidermoid carcinoma cells that lacks CD148 expression. The stable cells that express comparable levels of CD148 were sorted by flow cytometry. A431D cells infected with empty retrovirus was used as a control. CD148 localization, cell proliferation rate, EGFR signaling, and the response to thrombospondin-1 (TSP1), a CD148 ligand, were assessed by immunostaining, cell proliferation assay, enzyme-linked immunosorbent assay, and Western blotting.

RESULTS

Both CD148 forms (WT, Q276P/R326Q) were distributed to cell surface and all three cell lines expressed same level of EGFR. Compared to control cells, the A431D cells that express CD148 forms showed significantly lower cell proliferation rates. EGF-induced EGFR and ERK1/2 phosphorylation as well as cell proliferation were also significantly reduced in these cells. Furthermore, TSP1 inhibited cell proliferation in CD148 (WT, Q276P/R326Q)-expressing A431D cells, while it showed no effects in control cells. However, significant differences were not observed between CD148 WT and Q276P/R326Q cells.

CONCLUSION

Our data demonstrates that Q276P/R326Q mutations do not have major effects on TSP1-CD148 interaction as well as on CD148's cellular localization and activity to inhibit EGFR signaling and cell proliferation.

Discovering Genotype Variants in an Infant with VACTERL through Clinical Exome Sequencing: A Support for Personalized Risk Assessment and Disease Prevention

Congenital anomalies may have an increased risk of noncommunicable diseases (NCDs) We performed a clinical exome analysis in an infant affected by "Vertebral, Anorectal, Cardiac, Tracheoesophageal, Genitourinary, and Limb" (VACTERL) malformation association to identify potential biomarkers that may be helpful for preventing malignancy risk or other chronic processes. Among the variants, six variants that may be linked with VACTERL were identified in the exome analysis. The variants c.501G>C on OLR1 and c.-8C>G on PSMA6 were previously associated with myocardial infarction. The variants c.1936A>G on AKAP10 and c.575A>G on PON1 are linked to defects in cardiac conduction and artery disease, respectively. Alterations in metabolism were also suggested by the variants c.860G>A on EPHX2 and c.214C>A on GHRL. In addition, three variants associated with colon cancer were discovered. Specifically, the reported variants were c.723G>A on CCND1 and c.91T>A on AURKA proto-oncogenes as well as c.827A>C in the tumor suppressor PTPRJ. A further inspection identified 15 rare variants carried by cancer genes. Specifically, these mutations are located on five tumor suppressors (SDHA, RB1CC1, PTCH1, DMBT1, BCR) and eight proto-oncogenes (MERTK, CSF1R, MYB, ROS1, PCM1, FGFR2, MYH11, BRCC3) and have an allele frequency lower than 0.01 in the Genome Aggregation Database (GnomAD). We observed that the cardiac and metabolic phenotypic traits are linked with the genotype of the patient. In addition, the risk of developing neoplasia cannot be excluded a priori. Long-term surgical issues of patients with VATER syndrome could benefit from the clinical exome sequencing of a personalized risk assessment for the appearance of further disease in pubertal timing and adult age.

Association Between rs12037447, rs146732504, rs151078858, rs55723436, and rs6094136 Polymorphisms and Kawasaki Disease in the Population of Polish Children

Background: Kawasaki disease (KD) is an acute self-limited febrile vasculitis that mainly affects young children. Coronary artery involvement is the most serious complication in children with KD. It is currently the leading cause of acquired cardiac disease in children from developed countries. Literature data indicate a significant role of genetic susceptibility to KD. Objective: The aim of this study was to perform the first Genome-Wide Association Study (GWAS) in a population of Polish children with KD and identify susceptible genes involved in the pathogenesis of KD. Materials and Methods: The blood samples of Kawasaki disease patients (n = 119) were collected between 2016 and 2020, isolated and stored at the Department of Pediatrics, Nutrition and Metabolic Diseases, Children's Memorial Health Institute in Warsaw. The control group was based on Polish donors (n = 6,071) registered as the POPULOUS collection at the Biobank Lab of The Department of Molecular Biophysics in University of Lodz. DNA samples were genotyped for 558,231 Single Nucleotide Polymorphisms (SNPs) using the 24 × 1 Infinium HTS Human Core Exome microarrays according to the protocol provided by the manufacturer. In order to discover and verify genetic risk-factors for KD, association analysis was carried out using PLINK 1.9. Results: Of all 164,395 variants, 5 were shown to occur statistically (p_adjusted < 0.05) more frequent in Kawasaki disease patients than in controls. Those are: rs12037447 in non-coding sequence (p_adjusted = 8.329 × 10^-4, OR = 8.697, 95% CI; 3.629-20.84) and rs146732504 in KIF25 (p_adjusted = 0.007354, OR = 11.42, 95% CI; 3.79-34.43), rs151078858 in PTPRJ (p_adjusted = 0.04513, OR = 8.116, 95% CI; 3.134-21.01), rs55723436 in SPECC1L (p_adjusted = 0.04596, OR = 5.596, 95% CI; 2.669-11.74), rs6094136 in RPN2 (p_adjusted = 0.04755, OR = 10.08, 95% CI; 3.385-30.01) genes. Conclusion: Polymorphisms of genes KIF25, PTRPJ, SPECC1L, RNP2 may be linked with the incidence of Kawasaki disease in Polish children.

Dual Role of the PTPN13 Tyrosine Phosphatase in Cancer

In this review article, we present the current knowledge on PTPN13, a class I non-receptor protein tyrosine phosphatase identified in 1994. We focus particularly on its role in cancer, where PTPN13 acts as an oncogenic protein and also a tumor suppressor. To try to understand these apparent contradictory functions, we discuss PTPN13 implication in the FAS and oncogenic tyrosine kinase signaling pathways and in the associated biological activities, as well as its post-transcriptional and epigenetic regulation. Then, we describe PTPN13 clinical significance as a prognostic marker in different cancer types and its impact on anti-cancer treatment sensitivity. Finally, we present future research axes following recent findings on its role in cell junction regulation that implicate PTPN13 in cell death and cell migration, two major hallmarks of tumor formation and progression.

Centenarian Exomes as a Tool for Evaluating the Clinical Relevance of Germline Tumor Suppressor Mutations

Objectives:

The aim of the present study was to evaluate the clinical relevance of mutations in tumor suppressor genes using whole-exome sequencing data from centenarians and young healthy individuals.

Methods:

Two pools, one of centenarians and one of young individuals, were constructed and whole-exome sequencing was performed. We examined the whole-exome sequencing data of Bulgarian individuals for carriership of tumor suppressor gene variants.

Results:

Of all variants annotated in both pools, 5080 (0.06%) are variants in tumor suppressor genes but only 46 show significant difference in allele frequencies between the two studied groups. Four variants (0.004%) are pathogenic/risk factors according to single nucleotide polymorphism database: rs1566734 in PTPRJ, rs861539 in XRCC3, rs203462 in AKAP10, and rs486907 in RNASEL.

Discussion:

Based on their high minor allele frequencies and presence in the centenarian group, we could reclassify them from pathogenic/risk factors to benign. Our study shows that centenarian exomes can be used for re-evaluating the clinically uncertain variants.

CD148 Serves as a Prognostic Marker of Gastric Cancer and Hinders Tumor Progression by Dephosphorylating EGFR

CD148 is a member of the receptor-type protein tyrosine phosphatase family encoded by the PTPRJ gene and has controversial impacts on cancers. In this study, we investigated the clinical significance of CD148 in gastric cancer and the possible mechanisms. Suppressed CD148 expression indicated adverse pathological features and poor outcomes in gastric cancer patients. CD148 overexpression impeded tumor proliferation, motility, and invasiveness, while CD148 knock-down or knockout promoted the ability of gastric cancer cells to grow and metastasize in vitro and in vivo. Mechanistically, CD148 negatively regulated EGFR phosphorylation of multiple tyrosine residues, including Y1173, Y1068, and Y1092, and remarkably inhibited downstream PI3K/AKT and MEK/ERK pathways. In silico analysis revealed that gene deletions or missense/truncated mutations of PTPRJ gene rarely occurred in gastric cancers. Instead, a 3' UTR-specific methylation might regulate CD148 expression, and the potential regulators were TET2 and TET3. Collectively, our results suggest that CD148 is a convincing prognostic marker as well as a potential therapeutic target for gastric cancer.

iTRAQ plasma proteomics analysis for candidate biomarkers of type 2 incipient diabetic nephropathy

Background

Diabetic nephropathy is the most frequent cause of end-stage renal disease worldwide. Identification of biomarkers for diabetic nephropathy for early diagnosis may be the key to avoiding damage from this condition.

Methods

Proteomic iTRAQ technology was first used to identify differentially expressed plasma proteins in type 2 incipient diabetic nephropathy (IDN) using a Q-Exactive mass spectrometer.

Results

Compared with controls, 57 proteins (32 upregulated and 25 downregulated proteins) were identified. Furthermore, the gelsolin, collectin-11, PTPRJ, and AKAP-7 proteins were confirmed by Western blots as candidate biomarkers for type 2 IDN through ROC analysis.

Conclusions

These findings offer a theoretical basis for the early treatment of diabetic nephropathy.

A missense variant in PTPN12 associated with the risk of colorectal cancer by modifying Ras/MEK/ERK signaling

BACKGROUND

The classical protein tyrosine phosphatases (PTPs) have been widely reported to be associated with various human malignancies including colorectal cancer (CRC). However, there are few comprehensive analyses of the association between the classical PTP genes and CRC risk.

METHODS

First, a bioinformatics analysis was performed to identify missense variants within the classical PTP gene family. Second, exome-wide association data and an independent population study were conducted to evaluate effects of candidate variants on CRC risk. Finally, functional assays based on signaling pathways were applied to uncover the potential pathogenic mechanism.

RESULTS

We identified that PTPN12 rs3750050 G allele presented a 19% increase the risk of CRC, with an OR of 1.19 (95% CI = 1.09-1.30, P =  1.015×10^-4) under an additive model in the combined analysis. Furthermore, biochemical assays illustrated that rs3750050 could impair the inhibitory effect of PTPN12 on Ras/MEK/ERK signaling by impeding SHC dephosphorylation, increase the expression of cyclin D1 and ultimately lead to aberrant cell proliferation, thus contributing to CRC pathogenesis.

CONCLUSION

Our study highlights that PTPN12 rs3750050 could increase CRC risk by modifying Ras/MEK/ERK signaling. This work provides a novel insight into the roles of genetic variants within PTP genes in the pathogenesis of CRC.

Meta-analysis of association between Arg326Gln (rs1503185) and Gln276Pro (rs1566734) polymorphisms of PTPRJ gene and cancer risk

Protein tyrosine phosphatase receptor type J (PTPRJ, DEP1) is a tumour suppressor gene that negatively regulates such processes as angiogenesis, cell proliferation and migration and is one of the genes important for tumour development. Similar to other phosphatase genes, PTPRJ is also described as an oncogene. Among various genetic changes characteristic for this gene, single nucleotide polymorphisms (SNPs) constituting benign genetic variants that can modulate its function have been described. We focused on Gln276Pro and Arg326Gln missense polymorphisms and performed a meta-analysis using data from 2930 and 852 patients for Gln276Pro and Arg326Gln respectively in different cancers. A meta-analysis was performed based on five articles accessed via the PubMed and Research Gate databases. Our meta-analysis revealed that for Arg326Gln, the presence of the Arg (C) allele was associated with lower risk of some cancers, the strongest association was observed for colorectal cancer patients, and there was no association between Gln276Pro (G>T) polymorphism and cancer risk. The polymorphisms Arg326Gln and Gln276Pro of the PTPRJ gene are not associated with an increased risk of cancer except for the Arg326Gln polymorphism in colorectal cancer. Large-scale studies should be performed to verify the impact of this SNP on individual susceptibility to colorectal cancer for given individuals.

Somatic inactivating PTPRJ mutations and dysregulated pathways identified in canine malignant melanoma by integrated comparative genomic analysis

Canine malignant melanoma, a significant cause of mortality in domestic dogs, is a powerful comparative model for human melanoma, but little is known about its genetic etiology. We mapped the genomic landscape of canine melanoma through multi-platform analysis of 37 tumors (31 mucosal, 3 acral, 2 cutaneous, and 1 uveal) and 17 matching constitutional samples including long- and short-insert whole genome sequencing, RNA sequencing, array comparative genomic hybridization, single nucleotide polymorphism array, and targeted Sanger sequencing analyses. We identified novel predominantly truncating mutations in the putative tumor suppressor gene PTPRJ in 19% of cases. No BRAF mutations were detected, but activating RAS mutations (24% of cases) occurred in conserved hotspots in all cutaneous and acral and 13% of mucosal subtypes. MDM2 amplifications (24%) and TP53 mutations (19%) were mutually exclusive. Additional low-frequency recurrent alterations were observed amidst low point mutation rates, an absence of ultraviolet light mutational signatures, and an abundance of copy number and structural alterations. Mutations that modulate cell proliferation and cell cycle control were common and highlight therapeutic axes such as MEK and MDM2 inhibition. This mutational landscape resembles that seen in BRAF wild-type and sun-shielded human melanoma subtypes. Overall, these data inform biological comparisons between canine and human melanoma while suggesting actionable targets in both species.

Tumor suppressive protein phosphatases in human cancer: Emerging targets for therapeutic intervention and tumor stratification

Aberrant protein phosphorylation is one of the hallmarks of cancer cells, and in many cases a prerequisite to sustain tumor development and progression. Like protein kinases, protein phosphatases are key regulators of cell signaling. However, their contribution to aberrant signaling in cancer cells is overall less well appreciated, and therefore, their clinical potential remains largely unexploited. In this review, we provide an overview of tumor suppressive protein phosphatases in human cancer. Along their mechanisms of inactivation in defined cancer contexts, we give an overview of their functional roles in diverse signaling pathways that contribute to their tumor suppressive abilities. Finally, we discuss their emerging roles as predictive or prognostic markers, their potential as synthetic lethality targets, and the current feasibility of their reactivation with pharmacologic compounds as promising new cancer therapies. We conclude that their inclusion in clinical practice has obvious potential to significantly improve therapeutic outcome in various ways, and should now definitely be pushed forward.

The PTPN13 Y2081D (T>G) (rs989902) polymorphism is associated with an increased risk of sporadic colorectal cancer

AIM

Colorectal cancer (CRC) is one of the most common cancers worldwide and, although the majority of cases are sporadic, its development and progression depends on a range of factors: environmental, genetic and epigenetic. A variety of genetic pathways have been described as being crucial in CRC, including protein tyrosine phosphatases (PTPs). PTPN13 (also called FAP-1) is a non-receptor PTP and interacts with a number of important components of growth and apoptosis pathways. It is also involved in the inhibition of Fas-induced apoptosis.

METHOD

The single nucleotide polymorphism genotype at Y2081D (T>G) (rs989902) of PTPN13 exon 39 was determined in DNA extracted from blood samples from 174 sporadic CRC patients and 176 healthy individuals. Also, a meta-analysis was performed based on three articles accessed via the PubMed and ResearchGate databases.

RESULTS

The risk of CRC was 2.087 times greater for patients with the GG genotype than for those with the TT genotype (P = 0.0475). In the meta-analysis, a significantly increased risk of cancer associated with the G allele was observed in the squamous cell carcinoma of the head and neck subgroup (TT vs GG+GT, OR 1.23, 95% CI [1.02, 1.47], P = 0.0258), and a significantly decreased risk in the breast cancer subgroup (TT vs GG+GT, OR 0.63, 95% CI [0.41, 0.96], P = 0.0334) and in the CRC subgroup (GT+TT vs GG, OR 0.51, 95% CI [0.41, 0.95], P = 0.0333).

CONCLUSION

PTPN13 rs989902 is significantly associated with the risk of CRC in the Polish population. Given that this report provides the first evidence of an association of PTPN13 rs989902 with the risk of CRC in a Caucasian population, further large scale studies are necessary to confirm this finding.

Tumor Suppressor PTPRJ Is a Target of miR-155 in Colorectal Cancer

PTPRJ is known for its antiproliferative role. Loss of heterozygosity (LOH) of PTPRJ has frequently been observed in various human cancers including colorectal cancer (CRC), lung cancer, and breast cancer. However, the function and mechanism of PTPRJ in CRC are not well understood. At the present study, we show that ectopic expression of PTPRJ inhibits cell growth, migration, and invasiveness in CRC cell line HCT116. Moreover, PTPRJ inhibits the tumorigenecity of HCT116 in a xenograft tumor model. MiR-155, the well-known oncomiR in CRC, is identified as an upstream factor of PTPRJ. MiR-155 directly binds to the 3' untranslated region of PTPRJ mRNA and suppresses the mRNA and protein levels of PTPRJ. Furthermore, the growth-promoting and AKT signaling activation effect of miR-155 was abrogated by PTPRJ overexpression, and vice versa. Our study reveals the crucial role of miR-155/PTPRJ/AKT axis in proliferation and migration of CRC cells and suggests a therapeutic potential of PTPRJ. J. Cell. Biochem. 118: 3391-3400, 2017. © 2017 Wiley Periodicals, Inc.

EphrinB1: novel microtubule associated protein whose expression affects taxane sensitivity

Microtubules (MTs) are components of the cytoskeleton made up of polymerized alpha and beta tubulin dimers. MT structure and function must be maintained throughout the cell cycle to ensure proper execution of mitosis and cellular homeostasis. The protein tyrosine phosphatase, PTPN13, localizes to distinct compartments during mitosis and cytokinesis. We have previously demonstrated that the HPV16 E6 oncoprotein binds PTPN13 and leads to its degradation. Thus, we speculated that HPV infection may affect cellular proliferation by altering the localization of a PTPN13 phosphatase substrate, EphrinB1, during mitosis. Here we report that EphrinB1 co-localizes with MTs during all phases of the cell cycle. Specifically, a cleaved, unphosphorylated EphrinB1 fragment directly binds tubulin, while its phosphorylated form lacks MT binding capacity. These findings suggest that EphrinB1 is a novel microtubule associated protein (MAP). Importantly, we show that in the context of HPV16 E6 expression, EphrinB1 affects taxane response in vitro. We speculate that this reflects PTPN13's modulation of EphrinB1 phosphorylation and suggest that EphrinB1 is an important contributor to taxane sensitivity/resistance phenotypes in epithelial cancers. Thus, HPV infection or functional mutations of PTPN13 in non-viral cancers may predict taxane sensitivity.

MicroRNA-328 enhances cellular motility through posttranscriptional regulation of PTPRJ in human hepatocellular carcinoma

OBJECTIVE

Interaction between microRNA (miR-328) and PTPRJ (protein tyrosine phosphatase, receptor type, J) has been reported to be responsible for miR-328-dependent increase in epithelial cancer cell proliferation. However, the role of miR-328 and PTPRJ in hepatocellular carcinoma (HCC) remains unclear. The aim of this study was to investigate the clinical significance of miR-328 and/or PTPRJ expression in human HCC and determine their precise biological functions in this malignancy.

METHODS

Expression levels of miR-328 and PTPRJ messenger RNA (mRNA) in 100 pairs of HCC and adjacent noncancerous tissues were detected using quantitative real-time reverse transcription polymerase chain reaction. The associations between miR-328 and/or PTPRJ expression and various clinicopathological features of HCC patients were further statistically assessed. Then, the functions of miR-328 and PTPRJ in migration and invasion of two human HCC cell lines were determined by transwell assays.

RESULTS

miR-328 and PTPRJ mRNA expression levels were markedly upregulated and down-regulated in HCC tissues, respectively, compared to adjacent noncancerous tissues. Notably, the upregulation of miR-328 in HCC tissues was significantly correlated with the downregulation of PTPRJ mRNA in HCC tissues (r=-0.362, P=0.01). In addition, miR-328-high and/or PTPRJ-low expression were found to be closely correlated with high Edmondson-Steiner grading (all P<0.05) and advanced tumor-node-metastasis stage (all P<0.05). Moreover, the restoration of miR-328 dramatically promoted HCC cell migration and invasion by repressing PTPRJ expression. Interestingly, the loss of PTPRJ expression could significantly attenuate the inhibitory effects of knockdown miR-328 on the migration and invasion of HCC cells.

CONCLUSION

These findings demonstrated that the dysregulation of miR-328 and PTPRJ may be associated with tumor progression of HCC patients. Functionally, miR-328 may serve as a crucial oncogene and be implicated in the motility of HCC cells at least in part by the suppression of PTPRJ.

Allele-specific imbalance mapping at human orthologs of mouse susceptibility to colon cancer (Scc) loci

Colorectal cancer (CRC) can be classified into different types. Chromosomal instable (CIN) colon cancers are thought to be the most common type of colon cancer. The risk of developing a CIN-related CRC is due in part to inherited risk factors. Genome-wide association studies have yielded over 40 single nucleotide polymorphisms (SNPs) associated with CRC risk, but these only account for a subset of risk alleles. Some of this missing heritability may be due to gene-gene interactions. We developed a strategy to identify interacting candidate genes/loci for CRC risk that utilizes both linkage and RNA-seq data from mouse models in combination with allele-specific imbalance (ASI) studies in human tumors. We applied our strategy to three previously identified CRC susceptibility loci in the mouse that show evidence of genetic interaction: Scc4, Scc5 and Scc13. 525 SNPs from genes showing differential expression in the mouse and/or a previous role in cancer from the literature were evaluated for allele-specific imbalance in 194 paired human normal/tumor DNAs from CIN-related CRCs. One hundred three SNPs showing suggestive evidence of ASI (31 variants with uncorrected p values < 0.05) were genotyped in a validation set of 296 paired DNAs. Two variants in SNX10 (SCC13) showed significant evidence of allelic selection after multiple comparisons testing. Future studies will evaluate the role of these variants in combination with interacting genetic partners in colon cancer risk in mouse and humans.

Targeting ERBB receptors shifts their partners and triggers persistent ERK signaling through a novel ERBB/EFNB1 complex

Most squamous cell carcinomas of the head and neck (HNSCC) overexpress ERBB1/EGFR, but EGF receptor (EGFR)-targeted therapies have yielded disappointing clinical results in treatment of this cancer. Here, we describe a novel interaction between EGFR and the ligand EphrinB1 (EFNB1), and we show that EFNB1 phosphorylation and downstream signaling persists in the presence of cetuximab. Mechanistically, cetuximab drives a shift in EGFR dimerization partners within the signaling complex, suggesting that targeted drugs may trigger partner rearrangements that allow persistent pathway activation. EFNB1 attenuation slowed tumor growth and increased survival in a murine model of HNSCC, suggesting a substantial contribution of EFNB1 signaling to HNSCC development. Together, our findings suggest that EFNB1 is part of the EGFR signaling complex and may mediate drug resistance in HNSCC as well as other solid tumors.

Protein tyrosine phosphatases as novel targets in breast cancer therapy

Breast cancer is linked to hyperactivation of protein tyrosine kinases (PTKs), and recent studies have unveiled that selective tyrosine dephosphorylation by protein tyrosine phosphatases (PTPs) of specific substrates, including PTKs, may activate or inactivate oncogenic pathways in human breast cancer cell growth-related processes. Here, we review the current knowledge on the involvement of PTPs in breast cancer, as major regulators of breast cancer therapy-targeted PTKs, such as HER1/EGFR, HER2/Neu, and Src. The functional interplay between PTKs and PTK-activating or -inactivating PTPs, and its implications in novel breast cancer therapies based on targeting of specific PTPs, are discussed.

Protein tyrosine phosphatase variants in human hereditary disorders and disease susceptibilities

Reversible tyrosine phosphorylation of proteins is a key regulatory mechanism to steer normal development and physiological functioning of multicellular organisms. Phosphotyrosine dephosphorylation is exerted by members of the super-family of protein tyrosine phosphatase (PTP) enzymes and many play such essential roles that a wide variety of hereditary disorders and disease susceptibilities in man are caused by PTP alleles. More than two decades of PTP research has resulted in a collection of PTP genetic variants with corresponding consequences at the molecular, cellular and physiological level. Here we present a comprehensive overview of these PTP gene variants that have been linked to disease states in man. Although the findings have direct bearing for disease diagnostics and for research on disease etiology, more work is necessary to translate this into therapies that alleviate the burden of these hereditary disorders and disease susceptibilities in man.

SHP2 is overexpressed and inhibits pSTAT1-mediated APM component expression, T-cell attracting chemokine secretion, and CTL recognition in head and neck cancer cells

PURPOSE

Human leukocyte antigen (HLA) class I antigen processing machinery (APM) component downregulation permits escape of malignant cells from recognition by cytotoxic T lymphocytes (CTL) and correlates with poor prognosis in patients with head and neck cancer (HNC). Activated STAT1 (pSTAT1) is necessary for APM component expression in HNC cells. We investigated whether an overexpressed phosphatase was responsible for basal suppression of pSTAT1 and subsequent APM component-mediated immune escape in HNC cells.

EXPERIMENTAL DESIGN

Immunohistochemical staining and reverse transcription PCR of paired HNC tumors was performed for the phosphatases src homology domain-containing phosphatase (SHP)-1 and SHP2. Depletion of phosphatase activity in HNC and STAT1(-/-) tumor cells was achieved by siRNA knockdown. HLA class I-restricted, tumor antigen-specific CTL were used in IFN-γ ELISPOT assays against HNC cells. Chemokine secretion was measured after SHP2 depletion in HNC cells.

RESULTS

SHP2, but not SHP1, was significantly upregulated in HNC tissues. In HNC cells, SHP2 depletion significantly upregulated expression of pSTAT1 and HLA class I APM components. Overexpression of SHP2 in nonmalignant keratinocytes inhibited IFN-γ-mediated STAT1 phosphorylation, and SHP2 depletion in STAT1(-/-) tumor cells did not significantly induce IFN-γ-mediated APM component expression, verifying STAT1 dependence of SHP2 activity. SHP2 depletion induced recognition of HNC cells by HLA class I-restricted CTL and secretion of inflammatory, T-cell attracting chemokines, RANTES and IP10.

CONCLUSION

These findings suggest for the first time an important role for SHP2 in APM-mediated escape of HNC cells from CTL recognition. Targeting SHP2 could enhance T-cell-based cancer immunotherapy.

The protein tyrosine phosphatase receptor type J is regulated by the pVHL-HIF axis in clear cell renal cell carcinoma

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.

A new method for post Genome-Wide Association Study (GWAS) analysis of colorectal cancer in Taiwan

Recently, single nucleotide polymorphisms (SNPs) located in specific loci or genes have been identified associated with susceptibility to colorectal cancer (CRC) in Genome-Wide Association Studies (GWAS). However, in different ethnicities and regions, the genetic variations and the environmental factors can widely vary. Therefore, here we propose a post-GWAS analysis method to investigate the CRC susceptibility SNPs in Taiwan by conducting a replication analysis and bioinformatics analysis. One hundred and forty-four significant SNPs from published GWAS results were collected by a literature survey, and two hundred and eighteen CRC samples and 385 normal samples were collected for post-GWAS analysis. Finally, twenty-six significant SNPs were identified and reported as associated with susceptibility to colorectal cancer, other cancers, obesity, and celiac disease in a previous GWAS study. Functional analysis results of 26 SNPs indicate that most biological processes identified are involved in regulating immune responses and apoptosis. In addition, an efficient prediction model was constructed by applying Jackknife feature selection and ANOVA testing. As compared to another risk prediction model of CRC for European Caucasians population, which performs 0.616 of AUC by using 54 SNPs, the proposed model shows good performance in predicting CRC risk within the Taiwanese population, i.e., 0.724 AUC by using 16 SNPs. We believe that the proposed risk prediction model is highly promising for predicting CRC risk within the Taiwanese population. In addition, the functional analysis results could be helpful to explore the potential associated regulatory mechanisms that may be involved in CRC development.

Protein tyrosine phosphatases in cancer: friends and foes!

Tyrosine phosphorylation of proteins serves as an exquisite switch in controlling several key oncogenic signaling pathways involved in cell proliferation, apoptosis, migration, and invasion. Since protein tyrosine phosphatases (PTPs) counteract protein kinases by removing phosphate moieties on target proteins, one may intuitively think that PTPs would act as tumor suppressors. Indeed, one of the most described PTPs, namely, the phosphatase and tensin homolog (PTEN), is a tumor suppressor. However, a growing body of evidence suggests that PTPs can also function as potent oncoproteins. In this chapter, we provide a broad historical overview of the PTPs, their mechanism of action, and posttranslational modifications. Then, we focus on the dual properties of classical PTPs (receptor and nonreceptor) and dual-specificity phosphatases in cancer and summarize the current knowledge of the signaling pathways regulated by key PTPs in human cancer. In conclusion, we present our perspective on the potential of these PTPs to serve as therapeutic targets in cancer.

Identification of germline susceptibility loci in ETV6-RUNX1-rearranged childhood acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is a malignant disease of the white blood cells. The etiology of ALL is believed to be multifactorial and likely to involve an interplay of environmental and genetic variables. We performed a genome-wide association study of 355 750 single-nucleotide polymorphisms (SNPs) in 474 controls and 419 childhood ALL cases characterized by a t(12;21)(p13;q22) - the most common chromosomal translocation observed in childhood ALL - which leads to an ETV6-RUNX1 gene fusion. The eight most strongly associated SNPs were followed-up in 951 ETV6-RUNX1-positive cases and 3061 controls from Germany/Austria and Italy, respectively. We identified a novel, genome-wide significant risk locus at 3q28 (TP63, rs17505102, P(CMH)=8.94 × 10(-9), OR=0.65). The separate analysis of the combined German/Austrian sample only, revealed additional genome-wide significant associations at 11q11 (OR8U8, rs1945213, P=9.14 × 10(-11), OR=0.69) and 8p21.3 (near INTS10, rs920590, P=6.12 × 10(-9), OR=1.36). These associations and another association at 11p11.2 (PTPRJ, rs3942852, P=4.95 × 10(-7), OR=0.72) remained significant in the German/Austrian replication panel after correction for multiple testing. Our findings demonstrate that germline genetic variation can specifically contribute to the risk of ETV6-RUNX1-positive childhood ALL. The identification of TP63 and PTPRJ as susceptibility genes emphasize the role of the TP53 gene family and the importance of proteins regulating cellular processes in connection with tumorigenesis.

Inside the human cancer tyrosine phosphatome

Members of the protein tyrosine phosphatase (Ptp) family dephosphorylate target proteins and counter the activities of protein tyrosine kinases that are involved in cellular phosphorylation and signalling. As such, certain PTPs might be tumour suppressors. Indeed, PTPs play an important part in the inhibition or control of growth, but accumulating evidence indicates that some PTPs may exert oncogenic functions. Recent large-scale genetic analyses of various human tumours have highlighted the relevance of PTPs either as putative tumour suppressors or as candidate oncoproteins. Progress in understanding the regulation and function of PTPs has provided insights into which PTPs might be potential therapeutic targets in human cancer.

Role of PTPRJ genotype in papillary thyroid carcinoma risk

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.