PTPN3 and PTPN4 Tyrosine Phosphatase Expression in Human Gastric Adenocarcinoma

Abstract

Background: Degenerated PCR primers, designed according to the consensus tyrosine phosphatase catalytic motifs, were used in order to amplify expressed protein-tyrosine phosphatase molecules from human gastric cancer-derived cells. From such profiles, more than twenty different types of tyrosine phosphatase were identified from gastric cancer tissue. A non-receptor tyrosine phosphatase, PTPN4, was found to be expressed in a tumor-tissue profile with only low frequency. The most closely-related gene to tyrosine phosphatase, PTPN3, has been shown to be mutated in cases of human colorectal cancer, but its expression is cases of gastric cancer is not known. Materials and Methods: The mRNA expression of PTPN3 and PTPN4 by RT-PCR was investigated, and the protein expression status of PTPN3 was examined, using immunohistochemistry, to elucidate clinicopathological associations of the PTPN3 and PTPN4 family within human stomach cancer. Results: PTPN3 and PTPN4 were expressed in all gastric cancer cell lines and clinical cancer tissue specimens examined. Following the examination of 92 gastric cancer patients' pathological specimens, PTPN3 expression showed no statistical significance with respect to the patients' survival. A statistically significant correlation between PTPN3 staining and the differentiation status of gastric cancer tissue was, however, observed. Conclusion: This finding indicates that both PTPN3 and PTPN4 are expressed within human gastric cancer cells and that PTPN3 seems to play an important role in gastric cancer differentiation and the progression of malignancy.