Induction of apoptotic cell death of cholangiocarcinoma cells by tiliacorinine from Tiliacora triandra: A mechanistic insight

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.

Evaluation of efficacy, safety and tolerability of high dose-intermittent calcitriol supplementation to advanced intrahepatic cholangiocarcinoma patients--a pilot study

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.