Apoptotic and cytostatic actions of maslinic acid in colorectal cancer cells through possible IKK-β inhibition

Objective: To explore the anti-cancer activity of maslinic acid against colorectal cancer (CRC) cell lines and its possible mechanism. Methods: The inhibitory effect of maslinic acid was screened against five CRC cell lines (HT-29, HCT 116, SW480, SW48, and LS 174T) via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Apoptosis and cell cycle analyses were carried out using annexin V-FITC/propidium iodide staining and propidium iodide staining, respectively and subjected to fluorescence-activated cell sorting analysis. Protein expression studies of inhibitor of kappa B kinase-beta (IKK-beta), checkpoint kinase 1 (Chk1) and cyclin D1 were conducted using the JESS system. Results: Maslinic acid exhibited growth inhibitory effect in a dose- and time-dependent manner in HT-29 and HCT 116 cell lines. A more prominent apoptosis induced by maslinic acid was observed in HCT 116 cell line. However, in HT-29 cell line, maslinic acid induced cell cycle arrest by inhibiting the G1S transition, which was accompanied by the downregulation of cyclin D1. The expression of unphosphorylated IKK-beta protein was increased in both (HT-29 and HCT 116) cell lines after maslinic acid treatment. Conclusions: Maslinic acid inhibits the growth of HT-29 and HCT 116 cells in a different manner, induces cell cycle arrest in HT-29 cells and causes apoptosis in HCT 116 cells partially via NF-kappa B pathway inhibition.