In cholestatic liver diseases, bile acids induce hepatocyte apoptosis and thus cause liver injury, but hepatic stellate cells (HSCs) survive in the presence of bile acids. We attempted to analyze anti-apoptotic signaling pathways in HSCs against bile acid-induced apoptosis. In immortalized human HSCs and primarily cultured rat HSCs, bile acid treatment increased the expression levels of cyclooxygenase-2 (COX-2) and Mcl-1. COX-2 induction was found to be due to transcriptional enhancement dependent on p42/44, p3s MAPK, and JNK activation,whereas Mcl-1 induction resulted from bile acid-mediated protein stabilization in a Raf-1-dependent manner. Moreover, the inhibitions of either COX-2 activity by celecoxib or Mcl-1 induction by siRNA transfection rendered HSCs susceptible to bile acid-induced apoptosis. These results imply that the bile acid-mediated inductions of COX-2 and Mcl-1 may lead to HSC survival in cholestatic liver diseases. (c) 2006 Elsevier Inc. All rights reserved.