Important roles of protein tyrosine phosphatase PTPN12 in tumor progression.

Protein tyrosine phosphatases (PTPs), which are ubiquitously expressed in hematopoietic and non-hematopoietic cells, are critical for regulating cell proliferation as well as differentiation in the physiology of multicellular organisms. PTPs regulate the intracellular signaling mechanism of immune cells via dephosphorylation of multiple targets and are associated with the onset of various autoimmune diseases through genomic alterations. PTPs also affect disease through their role in innate and/or acquired immunity. By modulating multiple substrates, PTPN12, a member of the proline-, glutamic acid-, serine- and threonine-rich (PEST) family of PTPs, is an important regulator of cell migration and adhesion. According to its newly identified roles and functions, PTPN12 is considered a promising therapeutic target against critical diseases, including cancer, diabetes, metabolic disease and autoimmune diseases. In this review, we provide an overview of PTPs and discuss the critical roles of PTPN12/PTP-PEST in tumor progression.

Prognostic Value of Phosphotyrosine Phosphatases in Hepatocellular Carcinoma.

BACKGROUND/AIMS: During the occurrence and progression of hepatocellular carcinoma (HCC), phosphotyrosine phosphatases (PTPs) are usually described as tumor suppressors or proto-oncogenes, and to some degree are correlated with the prognosis of HCC. METHODS: A total of 321 patients from the Cancer Genome Atlas (TCGA) database and 180 patients from our validated cohort with hepatocellular carcinoma were recruited in this study. Kaplan-Meier, univariate and multivariate Cox proportional hazards model were used to evaluate the risk factors for survival. Quantitative real-time PCR (qRT-PCR) and immunohistochemistry (IHC) were applied to detect the expression levels of PTP genes. RESULTS: After screening the data of TCGA, we identified five PTPs as HCC overall survival related PTP genes, among which only three (PTPN12, PTPRN, PTPN18) exhibited differential expression levels in our 180 paired HCC and adjacent tissues (P< 0.001). Further analysis revealed that expression of PTPN18 was positively, but PTPRN was negatively associated with prognosis of HCC both in TCGA cohort and our own cohort. As to PTPN12, results turned out to be opposite according to HBV status. In detail, higher expression of PTPN12 was associated with better outcome in HBV group but worse prognosis in Non-HBV group. CONCLUSION: Our results suggested that PTPN12, PTPRN and PTPN18 were independent prognostic factors in HCC.

Protein tyrosine phosphatase nonreceptor type 12 suppresses the proliferation of renal cell carcinoma by inhibiting the activity of the PI3K/mTOR pathway.

PURPOSE: To determine the expression and functions of protein tyrosine phosphatase nonreceptor type 12 (PTPN12) in renal cell carcinoma (RCC). METHODS: All RCC tissue and corresponding normal kidney tissue from 116 RCC patients undergoing radical nephrectomy were examined. PTPN12 expression was detected by immunohistochemistry, and PTPN12 mRNA expression by real-time polymerase chain reaction (RT-PCR). PTPN12 expression was increased by stable transfection with a pcDEF3 vector containing full-length cDNA of PTPN12 and was decreased by RNAi in 4 RCC cell lines. Proliferative analysis of RCC cells was done using a WST-1 assay and animal xenograft study. RESULTS: PTPN12 expression in RCC tissue was significantly decreased compared with normal kidney tissue, and was overexpressed in larger tumors, metastasis, and high pathological grades. CONCLUSIONS: PTPN12 expression decreases in human RCC, it is involved in progression and metastasis, and is an independent prognostic factor in RCC. Restoring PTPN12 activity could be a new therapeutic approach in advanced RCC.

Tyrosine-protein phosphatase non-receptor type 12 expression is a good prognostic factor in resectable non-small cell lung cancer.

Tyrosine-protein phosphatase non-receptor type 12 (PTPN12) has been considered to be a tumor suppressor in human cancer, but its clinical and prognostic significance in non-small cell lung cancer (NSCLC) has not been well elucidated.A retrospective analysis of 215 patients with surgically resected NSCLCs from Sun Yat-Sen University Cancer Center between April 2002 and March 2005 was performed using immunohistochemistry and Western Blot to analyze PTPN12 expression. The association between PTPN12 expression and patient survival was investigated.Western Blots showed that the expression level of PTPN12 were higher in normal paracancerous lung tissues than in NSCLC tissues. High PTPN12 expression was less common in the presence than in the absence of visceral pleural invasion (p=0.038). Patients with PTPN12-high tumors had a longer disease-free survival (DFS) (P<0.001) and overall survival (OS) (p<0.001), especially for those with non-squamous cell carcinoma (non-SCC) (DFS, p<0.001; OS, p<0.001). Multivariate analysis confirmed that PTPN12 positivity was associated with increased survival duration (DFS, p<0.001; OS, p<0.001), independent of prognostic indicator.High PTPN12 expressive levels are associated with favorable survival duration in patients with NSCLC, especially those with non-SCC. Our study suggests that PTPN12 expression is a valuable prognostic biomarker for NSCLC patients.