Mutational analysis of PTPRT phosphatase domains in common human cancers

A recent report revealed that the protein-tyrosine phosphatase, receptor-type, T (PTPRT) gene is somatically mutated in several types of human cancer, suggesting that the mutated PTPRT gene is a tumor suppressor gene in human cancers. However, because previously the mutational search has focused primarily on colon cancers, data on PTPRT mutations in other types of human cancer have largely been lacking. Here, we performed a mutational analysis of the PTPRT phosphatase domain by polymerase chain reaction-based single-strand conformation polymorphism (PCR-SSCP) assay in 345 cases of common human cancers, including colon carcinomas, hepatocellular carcinomas, acute leukemias, gastric carcinomas, breast carcinomas and non-small cell lung cancers. We detected PTPRT phosphatase domain mutations in 1 of 105 colon carcinomas (1%) and 1 of 48 gastric carcinomas (2%), but none in acute leukemias, hepatocellular carcinomas, breast carcinomas and non-small cell lung cancers. The PTPRT mutation detected in the colon carcinoma was a missense mutation and the mutation in the gastric carcinomas was a splice-site mutation. Contrary to the previous report on the frequent PTPTR phosphatase domain mutations in colon cancers, this study demonstrated that the somatic mutation of the PTPRT phosphatase domain rarely occurred in common human cancers. The data suggested that alterations of the PTPRT-mediated signaling pathway by PTPRT phosphatase domain mutation may not play a critical role in the development of common human cancers.