Inhibition of cell cycle progression and apoptotic activity of resveratrol in human intrahepatic cholangiocarcinoma cell lines

Background: Cholangiocarcinoma (CCA) is a cancer of the bile duct epithelium and is characterized by a poor prognosis and unresponsiveness to conventional treatments. Effective therapeutic agents for CCA are urgently needed. Resveratrol, a phytoalexin found in several fruits, has been reported to inhibit growth of various cancer cell lines.

Objective: We investigated the effect of resveratrol on the intrahepatic CCA-derived KKU-100 and KKU-M156 cell lines.

Materials and methods: The cell lines used were established from Thai CCA patients (KKU-100, a poorlydifferentiated adenocarcinoma and KKU-M156, a moderately-differentiated adenocarcinoma). The mechanisms of an antiproliferative effect of resveratrol on these cell lines were determined using sulforhodamine B assay, flow cytometry, ethidium bromide/acridine orange staining, DNA fragmentation, and Western blotting analysis.

Results: Resveratrol significantly inhibited CCA cell growth in a dose- and time-dependent manner. Resveratrol induced cell cycle arrest at the G0/G1 phase in KKU-100 by decreasing cyclin D1, cyclin E, cyclin-dependent kinase (Cdk)2 and Cdk4 levels and increasing p53, Cdk inhibitors (CDKIs) p21 and p27 levels. By comparison, resveratrol induced cell cycle arrest at the S and G2 phases in KKU-M156 cells by increasing cyclin E, Cdk2, p53, p21 and p27 levels and decreasing cyclin B1 and Cdk1 levels. Subsequently, resveratrol induced apoptosis of both cell lines by increasing the Bax/Bcl-2 ratio and apoptosis-inducing factor, and decreasing survivin and subsequent activation of caspase-9 and -3 and DNA fragmentation.

Conclusion: Our study highlighted for the first time that resveratrol had different effects on cell cycle progression and apoptosis mechanisms in different CCA cell types. Resveratrol inhibits growth of the KKU-100 and KKUM156 cell lines by arresting different phases of the cell cycle and inducing a mitochondrial-dependent apoptosis pathway, through both caspase-dependent and -independent means. These results suggest that resveratrol could be developed as a chemotherapeutic agent against CCA.