Document Type : Research Articles
Division of Parasitology, Department of Preclinical Science, Faculty of Medicine, Thammasat University, Pathumthani, Thailand.
Center of Excellence in Molecular Biology and Pharmacology of Malaria and Cholangiocarcinoma, Thammasat University, Pathumthani, Thailand.
Drug Discovery and Development Center, Office of Advanced Science and Technology, Thammasat University, Pathumthani, Thailand.
Division of Anatomy, Department of Preclinical Science, Faculty of Medicine, Thammasat University, Pathumthani, Thailand.
Research Unit in Nutraceuticals and Food Safety, Faculty of Medicine, Thammasat University, Pathumthani, Thailand.
Graduate Program in Bioclinical Sciences, Chulabhorn International College of Medicine, Thammasat University, Pathumthani, 12120, Thailand.
Objective: The study aimed to investigate the inhibitory effects of AL on the ERK signaling molecules (ERK, p-ERK, cyclin D, and eIF4B) and the growth and proliferation of CCA cells. Materials and methods: The viability of the three CCA cell lines CL-6, HuCCT1, and HuH28 was determined using MTT assay. The effect of Ras/ERK inhibitors on protein expression in the presence of AL extract was investigated. The protein extracted from each CCA cell following exposure to AL and/or Ras/ERK inhibitors were separated on 12.5% SDS-PAGE. The analysis of mRNA expression following 48 and 72 hours of AL exposure in comparison with 0 hours (non-exposed cells) was performed by using RT-PCR. Results: The potency of cytotoxic activity of AL (by MTT assay) was about three times higher than the standard drug 5-fluorouracil. The IC50 (concentration that inhibits cell growth by 50%) of AL for the CL-6, HuCCT-1 and HuH28 cell lines were 29.77±6.64, 35.45±4.96, and 35.32±6.69 µg/mL (mean+SD), respectively. The cells were exposed to AL extract at the IC50 for 0, 12, 24, 48, and 72 hours in the absence and presence of Ras/ERK inhibitors (salirasib and XMD8-92). Protein expression was determined by Western blot analysis. The results suggested the lack of significant inhibitory effect of AL on ERK at 48 and 72 hours of exposure in all CCA cell types. On the other hand, a significant inhibitory effect was observed with p-ERK expression in all CCA cell types. Cyclin D was significantly down-regulated at 72 hours of exposure in all cell types with different potencies. The expression of eIF4B was markedly inhibited in HuCCT-1 but slightly inhibited in CL-6 and HuH28 cells. Real-time PCR analysis revealed significant down-regulation of ERK following 72 hours of AL exposure in the HuCCT1 and HuH28, but not CL-6 cell. Conclusion: The ERK signaling cascade and downstream molecules are potential targets of action of AL in CCA.