Apoptosis-Induced Cell Death due to Oleanolic Acid in HaCaT Keratinocyte Cells -a Proof-of-Principle Approach for Chemopreventive Drug Development

Oleanolic acid (OA) is a naturally occurring triterpenoid in food materials and is a component of the leavesand roots of Olea europaea, Viscum album L., Aralia chinensis L. and more than 120 other plant species. Thereare several reports validating its antitumor activity against different cancer cells apart from its hepatoprotectiveactivity. However, antitumor activity against skin cancer has not beed studied well thus far. Hence the presentstudy of effects of OA against HaCaT (immortalized keratinocyte) cells - a cell-based epithelial model systemfor toxicity/ethnopharmacology-based studies - was conducted. Radical scavenging activity (DPPH•) and FRAPwere determined spectrophotometrically. Proliferation was assessed by XTT assay at 24, 48 and 72 hrs withexposure to various concentrations (12.5-200 μM) of OA. Apoptotic induction potential of OA was demonstratedusing a cellular DNA fragmentation ELISA method. Morphological studies were also carried out to elucidateits antitumor potential. The results revealed that OA induces apoptosis by altering cellular morphology aswell as DNA integrity in HaCaT cells in a dose-dependent manner, with comparatively low cytotoxicity. Themoderate toxicity observed in HaCaT cells, with induction of apoptosis, possibly suggests greater involvementof programmed-cell death-mediated mechanisms. We conclude that OA has relatively low toxicity and has thepotential to induce apoptosis in HaCaT cells and hence provides a substantial and sound scientific basis forfurther validation studies.