Exp Mol Med.  2010 Nov;42(11):787-797. 10.3858/emm.2010.42.11.082.

Enhancement of parthenolide-induced apoptosis by a PKC-alpha inhibition through heme oxygenase-1 blockage in cholangiocarcinoma cells

Affiliations
  • 1Division of Gastroenterology and Hepatology, Department of Internal Medicine, Chonbuk National University Medical School and Hospital, Jeonju 561-712, Korea. daeghon@chonbuk.ac.kr

Abstract

Cholangiocarcinoma (CC) is a chemoresistant intrahepatic bile duct carcinoma with a poor prognosis. The aims of this study were to identify molecular pathways that enhance sesquiterpene lactone parthenolide (PTL)-induced anticancer effects on CC cells. The effects of PTL on apoptosis and hemoxygenase-1 (HO-1) induction were examined in CC cell lines. The enhancement of PTL-mediated apoptosis by modulation of HO-1 expression and the mechanisms involved were also examined in an in vitro cell system. Low PTL concentrations (5 to 10 micrometer) led to Nrf2-dependent HO-1 induction, which attenuated the apoptogenic effect of PTL in Choi-CK and SCK cells. PTL-mediated apoptosis was enhanced by the protein kinase C-alpha inhibitor Ro317549 (Ro) through inhibition of expression and nuclear translocation of Nrf2, resulting in blockage of HO-1 expression. Finally, HO-1 silencing resulted in enhancement of apoptotic cell death in CC cells. The combination of PTL and Ro efficiently improved tumor growth inhibition compared to treatment with either agent alone in an in vivo subcutaneous tumor model. In conclusion, the modulation of HO-1 expression substantially improved the anticancer effect of PTL. The combination of PTL and Ro could prove to be a valuable chemotherapeutic strategy for CC.

Keyword

cholangiocarcinoma; drug therapy; heme oxygenase-1; parthenolide; protein kinase C-alpha

MeSH Terms

Active Transport, Cell Nucleus/drug effects
Antineoplastic Agents/chemistry/*pharmacology
Apoptosis/drug effects/genetics
Cell Line, Tumor
Cell Nucleus/*metabolism
Cholangiocarcinoma/drug therapy/*metabolism/pathology
Drug Resistance, Neoplasm/drug effects/genetics
Enzyme Activation
Enzyme Inhibitors/pharmacology
Heme Oxygenase-1/genetics/*metabolism
Humans
Lactones/chemistry
NF-E2-Related Factor 2/genetics/*metabolism
Protein Kinase C-alpha/antagonists & inhibitors
RNA, Small Interfering/genetics
Sesquiterpenes/chemistry/*pharmacology
Signal Transduction/drug effects
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