Homma M K, Homma Y, Namba M, Yuasa Y
Department of Hygiene and Oncology, Tokyo Medical and Dental University, School of Medicine, Japan.
J Cell Biochem. 1994 Aug;55(4):477-85. doi: 10.1002/jcb.240550407.
The production of the second messenger molecules diacylglycerol and inositol 1,4,5-trisphosphate is mediated by activated phosphatidylinositol-specific phospholipase C (PLC) enzymes. We report the enhancement of the phosphoinositide metabolism pathway in KMS-4 and KMS-8 cells, both of which are human colorectal carcinoma cell lines derived from familial adenomatous polyposis patients. In these cells, the cellular contents of diacylglycerol and inositol 1,4,5-trisphosphate were constitutively increased and the PLC activity in vitro was significantly high, as compared with those in normal colon cells or in other sporadic colorectal carcinoma cells. Northern and Western analyses showed the high expression levels of both PLC-gamma 1 and PLC-delta 1 in KMS-4 and KMS-8 cells. Moreover, we detected the enhancement of protein-tyrosine kinase activity and tyrosine phosphorylation of PLC-gamma 1 in these KMS cells. These results suggest the involvement of activated phosphoinositide signaling pathways in the colorectal tumorigenesis of familial adenomatous polyposis.
