RESUMO
Cholangiocarcinoma (CCA), an aggressive malignancy arising from the biliary epithelium, exhibits a high incidence in Thailand. CCA usually lacks specific symptoms and is typically diagnosed in its advanced stages, presenting significant treatment challenges. Current CCA therapeutic options, including surgery, chemotherapy, and radiation, have limited success rates and often cause side effects. Nature-derived compounds hold promise for reducing undesirable adverse effects and are an excellent source of anticancer drugs. Corosolic acid (CA), a triterpenoid found in Lagerstroemia speciosa L. leaves, exhibits anticancer properties; however, the effectiveness of CA against CCA and its molecular mechanisms remained unexplored. Herein, the anti-CCA and apoptosis-inducing effects of CA were investigated using various techniques, i.e., the MTT assay, flow cytometry with FITC-labeled Annexin V (Annexin V-FITC) and propidium iodide double staining, JC-1 staining, western blot analysis, caspase-3 activity assay, and molecular dynamics (MD) simulations. CA inhibited the proliferation of KKU-213A and KKU-213B CCA cells and triggered apoptosis through alterations in mitochondrial membrane potential (ΔΨm), and increases in the Bax/Bcl-2 expression ratio, cytochrome c release, and caspase-3 activity. As indicated by MD simulations, CA has the potential to bind to Bcl-2 through hydrogen bonds between amino acid residues R146 and N143. These findings underscore the potential of CA as a promising candidate for treatment of CCA.
RESUMO
BACKGROUND: Ursolic acid (UA) is a natural triterpenoid which possesses anti-cancer activity. However, little is known regarding the activity and molecular mechanism of UA in cholangiocarcinoma (CCA). Thus, we investigated the effects of UA on growth inhibition and apoptosis induction through biomolecular changes in KKU-213 and KKU-055 CCA cell lines. METHODS: The anti-proliferative effect of UA against CCA cells was evaluated using SRB assay. Changes in biomolecules were assessed by SR-FTIR microspectroscopy combined with PCA and conventional methods (i.e., Annexin V-FITC/PI staining for lipid alteration and apoptosis induction; Western blot analysis and caspase-3/7 activity assay for apoptotic protein detection). RESULTS: UA suppressed the proliferation of CCA cells in a dose- and time-dependent manner. SR-FTIR data revealed a significant alteration in lipids attributable to changes in apoptotic cell membranes, confirmed by Annexin V-FITC/PI staining. SR-FTIR data showed that UA promoted changes in the protein secondary structure. Elevated expression of Bax and decreased expression of Bcl-2 and survivin/BIRC5 along with augmented caspase-3/7 activity supported alterations in apoptosis-related proteins. CONCLUSIONS: SR-FTIR microspectroscopy was successfully used as a label-free technique to monitor apoptosis-induced biomolecular changes in UA-treated CCA cells. UA exerted the cytotoxic and apoptotic activities in CCA cells through alterations in membrane lipids and apoptotic proteins. UA could be a potential anti-CCA candidate and a chemical starting point for the discovery of novel anti-cancer agents. SIGNIFICANCE: Our present study showed the first evidence that UA exhibited the anti-proliferative and pro-apoptotic activities toward CCA cells through changes in biomolecules, notably lipids and proteins.
