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 κB kinase-β (IKK-β), 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-β 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-κB pathway inhibition.