Increased Expression of Phospholipase C-γ1 in Human Gastric Cancer Tissues

Abstract

Phospholipase C (PLC) plays a central role in signal transduction and is important in cellular growth, differentiation and transformation. There are currently ten known mammalian isozymes of PLC reported to date. However, their biological implication in carcinogenesis and in disease is not fully understood. Here we examined the relative content of various PLC isozymes present in 50 paired surgical specimens from human gastric cancer patients. Western blot analysis demonstrated considerablely higher levels of PLC-gl protein in gastric cancer tissues from 41 of 50 specimens as compared to that of normal mucosa. On immunohistochemistry, distinct speckles or clumps of PLC-gl staining were observed in the cytoplasms of primary malignant lesions as well as the invading cancer cell nests, in contrast to the normal tissues which were negative. Little differences in other isozymes were found. Only PLC-d1 was slightly increased in about two thirds of the patients, however, to a much lesser extent. In conclusion, although the causes of increased PLC-gl in gastric carcinomas remain to be explored further, the elevated level of PLC-gl suggests an altered signal transduction pathways in gastric carcinomas and may indicate an important role played by PLC-g1 in pathogenesis and proliferation of cancer cells.