Abstract

Cholangiocarcinoma (CCA) is a malignant tumor derived from bile duct epithelial cells that has high incidence in the Northeastern area of Thailand. It is associated with the infection of liver fluke (Opisthorchis viverrini). Chemotherapeutic treatment of CCA is often ineffective due to its resistance to drugs. Therefore, new effective agents for treatment of CCA are urgently required. RSPP 050 analog is a modified compound of andrographolide which has previously been reported to potently inhibit proliferation in many cancer cell lines. In the present study, we aim to investigate the anti-proliferative effect of RSPP 050 on cholangiocarcinoma cells (KKU-M213). Cell viability of KKU-M213 was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The IC₅₀ values were 9.4±3.12 µM, 3.47±0.75 µM, and 3.44±0.5 µM at 24, 48 and 72 h, respectively. To investigate the induction of apoptosis in KKU-M213 cells by RSPP 050, APO-BrdU™ TUNEL assay was conducted. RSPP 050 markedly increased the number of apoptotic cells compared to the untreated control. By using 4'-6-diamidino-2-phenylindole(DAPI) staining, RSPP 050 at 10 µM for 24 h, increased the chromatin condensation about 25±0.12% compared with 0.1% DMSO treated cells (2±0.04%) and the percentage of nuclear fragmentation of 50±0.33% compared to 0.1% DMSO treated cells (4±0.01%). These results suggest that RSPP 050 potently inhibited proliferation of KKU-M213 cells by inducing apoptosis. It would be useful for further development as the therapeutic agent for treatment of cholangiocarcinoma.

Key words: Andrographolide analog, apoptosis, cholangiocarcinoma.