Clinical application of
cisplatin against
cholangiocarcinoma is often associated with resistance and toxicity posing urgent demand for combination
therapy. In this study, we evaluated the combined anticancer effect of
cisplatin and
histone deacetylase inhibitors (HDACIs),
suberoylanilide hydroxamic acid (SAHA) and trichostatin A (
TSA), on the
cholangiocarcinoma KKU-100 and KKU-M214 cell lines. Antiproliferative activity was evaluated using MTT assay. Apoptosis induction and cell cycle arrest were analyzed by flow cytometry. Cell cycle and apoptosis regulating
proteins were evaluated by western blot analysis. MTT assay showed that
cisplatin, SAHA and
TSA dose-dependently reduced the viability of KKU-100 and KKU-M214 cells. The combination of
cisplatin and HDACIs exerted significantly more cytotoxicity than the single drugs. Combination indices below 1.0 reflect synergism between
cisplatin and HDACIs, leading to positive
dose reductions of
cisplatin and HDACIs.
Cisplatin and HDACIs alone induced G0/G1 phase arrest in KKU-100 cells, but the
drug combinations increased sub-G1 percent more than either
drug. However,
cisplatin and HDACIs alone or in combination increased only the sub-G1 percent in KKU-M214 cells. Annexin V-
FITC staining revealed that
cisplatin and HDACIs combinations induced more apoptotic cell death of both KKU-100 and KKU-M214 cells than the single
drug. In KKU-100 cells, growth inhibition was accompanied by upregulation of p53 and p21 and downregulation of CDK4 and Bcl-2 due to exposure to
cisplatin, SAHA and
TSA alone or in combination. Moreover, combination of agents exerted higher impacts on
protein expression. Single agents or combination did not affect p53 expression, however, combination of
cisplatin and HDACIs increased the expression of p21 in KKU-M214 cells. Taken together,
cisplatin and HDACIs combination may improve the therapeutic outcome in
cholangiocarcinoma patients.