The expression of SH-PTP2 (SYP), a novel protein tyrosine phosphatase with src homology 2, was examined in human gastric carcinoma cell lines and gastric carcinoma tissues as well as corresponding non-neoplastic mucosas by Northern and Western blotting. The expression of SH-PTP2 mRNA was detected in all 8 gastric carcinoma cell lines at various levels. Most of the cell lines expressed SH-PTP2 protein of 70 kd which corresponds to tyrosine-phosphorylated form, whereas only one cell line expressed unphosphorylated form of SH-PTP2; Fourteen (66.6%) of 21 gastric carcinomas expressed SH-PTP2 mRNA at higher level than non-neoplastic mucosas. Furthermore, most of the gastric carcinomas displayed higher levels of tyrosine-phosphorylated form of SH-PTP2, while non-neoplastic mucosas tended to express unphosphorylated SH-PTP2 protein. These results suggest that the increased expression and tyrosine-phosphorylation of SH-PTP2 may participate in stomach carcinogenesis.

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