ABSTRACT
BACKGROUND: Cholangiocarcinoma (CCA) exhibits poor response to the present chemotherapeutic agents and frequently develops drug resistance. Finding novel anticancer drugs might enhance patient outcomes. Tiliacorinine, a bisbenzylisoquinoline alkaloid from the Thai medicinal plant Tiliacora triandra, effectively induced apoptosis of human CCA cell lines and inhibited tumor growth in mice. Here, we elucidate further the molecular mechanisms underlining the cytotoxicity of tiliacorinine and its implication in overcoming gemcitabine-resistance of CCA cells. METHODS: Cytotoxicity of tiliacorinine against CCA cell lines was assessed using MTT assay. The molecular signaling was determined using Western blot analysis. Molecular docking simulations were applied to predict the binding affinity and orientation of tiliacorinine to the possible binding site(s) of the target proteins. RESULTS: Tiliacorinine induced apoptotic cell death of CCA cells in a dose- and time-dependent manner. Tiliacorinine significantly suppressed the expression of anti-apoptotic proteins, Bcl-xL and XIAP; activated apoptotic machinery proteins, caspase-3, caspase-9, and PARP; and decreased the levels of pAkt and pSTAT3. EGF/EGFR activation model and molecular docking simulations revealed EGFR, Akt, and STAT3 as potent targets of tiliacorinine. Molecular docking simulations indicated a strong binding affinity of tiliacorinine to the ATP-binding pockets of EGFR, PI3K, Akt, JAK2, and SH2 domain of STAT3. Tiliacorinine could synergize with gemcitabine and restore the cytotoxicity of gemcitabine against gemcitabine-resistant CCA cells. CONCLUSION: Tiliacorinine effectively induced apoptosis via binding and blocking the actions of EGFR, Akt, and STAT3. GENERAL SIGNIFICANCE: Tiliacorinine is a novel multi-kinase inhibitor and possibly a potent anti-cancer agent, in cancers with high activation of EGFR.
Subject(s)
Antineoplastic Agents , Benzylisoquinolines , Bile Duct Neoplasms , Cholangiocarcinoma , Humans , Mice , Animals , Proto-Oncogene Proteins c-akt , Molecular Docking Simulation , Bile Duct Neoplasms/drug therapy , Bile Duct Neoplasms/pathology , Cell Line, Tumor , Apoptosis , Gemcitabine , Antineoplastic Agents/pharmacology , Cholangiocarcinoma/drug therapy , Cholangiocarcinoma/pathology , Benzylisoquinolines/pharmacology , Benzylisoquinolines/therapeutic use , Bile Ducts, Intrahepatic/metabolism , Bile Ducts, Intrahepatic/pathology , ErbB ReceptorsABSTRACT
Cholangiocarcinoma (CCA) is a fatal cancer with poor prognosis and less than 10% of CCA patients can be offered surgical cure. Conventional chemotherapy results in unfavorable outcomes. At present, plant-derived compounds are gaining interest as potential cancer therapeutics, particularly for treatment-refractory cancers. In this study, antitumor activity of tiliacorinine, the major alkaloid isolated from a tropical plant, on CCA was first demonstrated. Antiproliferative effects of tiliacorinine on human CCA cell lines were investigated using SRB assays. Acridine orange/ethidium bromide staining, flow cytometric analysis and DNA laddering assays were used for apoptotic determination. Apoptosis-related proteins were verified by Western blotting and antitumor activity of tiliacorinine in vivo was demonstrated in CCA xenografted mice. Tiliacorinine significantly inhibited proliferation of human CCA cell lines with IC50 4.5-7 µM by inducing apoptosis through caspase activation, up- regulation of BAX, and down-regulation of BclxL and XIAP. Tiliacorinine considerably reduced tumor growth in CCA xenografted mice. These results demonstrated antitumor effects of tiliacorinine on human CCA in vitro and in vivo. Tiliacorinine may be an effective agent for CCA treatment.
Subject(s)
Apoptosis/drug effects , Benzylisoquinolines/pharmacology , Bile Duct Neoplasms , Cell Proliferation/drug effects , Cholangiocarcinoma , Plant Extracts/pharmacology , Animals , Caspases/drug effects , Caspases/metabolism , Cell Line, Tumor , Drug Screening Assays, Antitumor , Humans , In Vitro Techniques , Mice , Xenograft Model Antitumor AssaysABSTRACT
Antitumor activity (growth suppression) of vitamin D has been demonstrated using cholangiocarcinoma (CCA) cell lines, CCA cell-grafted animal models, and human CCA tissue cultures. The present study aimed to determine the toxicity and tolerability of intermittent-high dose calcitriol in advanced inoperable intrahepatic CCA patients and to evaluate the therapeutic efficacy of combinations of calcitriol and 5-fluorouracil-based chemotherapeutic drugs. The patients were divided into 3 groups: the first (n=2) received intermittent-high dose oral calcitriol 12 µg/day for 3 days, i.e. Monday-Wednesday, per week up to 3 months. The treatment did not cause any serious adverse events, except hypercalcemia grade I, once in 72 administrations. The second group (n=3) received chemotherapeutic drugs (5-fluorouracil, Mitomycin C and Leucovorin) for 3 cycles, one patient showing a partial response. The third group (n=4) received high dose calcitriol in combination with chemotherapeutic-drugs. All 4 patients encountered serious adverse events and two of them were withdrawn after the first drug cycle. This pilot study suggests that, although high dose-intermittent calcitriol appeared to be safe and tolerated well in advanced intrahepatic CCA patients, co-administration with 5-fluorouracil-based chemotherapeutic drugs caused unexpected potentiation of their toxicity. Adjustment of the doses of both drugs is required to avoid such toxicity and to optimize therapeutic efficacy of anticancer drugs when they were combined with high dose-intermittent calcitriol.