Changes of phosphatidylcholine-specific phospholipase C in hepatocarcinogenesis and in the proliferation and differentiation of rat liver cancer cells.
The biological significance of phosphatidylcholine-specific phospholipase C (PC-PLC) in hepatocarcinogenesis and the proliferation and differentiation of rat liver cancer cells was investigated. The Ca2+-dependent activities of PC-PLC gradually increased during N-nitrosodiethylamine (DEN)-induced hepatocarcinogenesis and peaked at weeks 18-20 when the tumour formed. There was a close relationship between Ca2+-dependent PC-PLC activities and cellular DNA content, membranous gamma-glutamyltranspeptidase (gamma-GT), and tyrosine protein kinase. In contrast, Ca2+-independent PC-PLC activities decreased during hepatocarcinogenesis. Similarly, when CBRH-7919 rat liver cancer cells were treated with phorbol 12-myristate 13-acetate, a proliferation stimulator of the cells, gamma-GT and Ca2+-dependent activities of PC-PLC and the expression of alpha-fetoprotein increased significantly. However, when these cells were induced by retinoic acid to differentiate, Ca2+-dependent PC-PLC and gamma-GT activities decreased significantly, together with alpha-fetoprotein expression. There was a close relationship between Ca2+-dependent PC-PLC and gamma-GT activities during differentiation as there was during proliferation. We suppose that Ca2+-dependent PC-PLC is involved in rat hepatocarcinogenesis induced by DEN and that it plays an important role in the phorbol ester-induced proliferation or retinoic acid-induced differentiation of liver cancer cells.
Wu
X
X
Key lab of Glycoconjugate Research, Ministry of Public Health, Shanghai Medical University, Shanghai, China.
Lu
H
H
Zhou
L
L
Huang
Y
Y
Chen
H
H
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D003994:Bucladesine / Q000494:pharmacology; D002273:Carcinogens / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D008113:Liver Neoplasms; D008297:Male; D010703:Phorbol Esters / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000201:enzymology; D010738:Type C Phospholipases / Q000378:metabolism*
D000970:Antineoplastic Agents; D002273:Carcinogens; D010703:Phorbol Esters; D014212:Tretinoin; D003994:Bucladesine; D010738:Type C Phospholipases; C105598:phosphatidylcholine-specific phospholipase C