Ursolic Acid Induced Apoptosis In HT-29 Cells

Objective: To investigate whether ursolic acid can inhibit cell proliferation and induce apoptosis in the human colorectal carcinoma HT-29 cell line and and to explore the molecular mechanisms.Methods: The human colorectal carcinoma HT-29 cell were treated with ursolic acid of different concentration. The proliferation inhibition was examined by MTT assay. Morphological study, terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) method and flow cytometry were used to detect apoptosis. Immunohistochemical method to detect the expression of apoptosis related gene caspase-9, bcl-2. The semi-quantification of protein expression was analyzed by pathological image-analysis software.Results: UA inhibited the proliferation in HT-29 cell moderately. HT-29 cell treated with ursolic acid were induced to apoptosis. The morphology of HT-29 changed as chromatin condensation, chromatin crescent formation, nucleus fragmentation and apoptotic body formation. Cell cycle was arrested in the G₀/G₁ phrase. Typical apoptotic sub-G1 peak was found by flow cytometry. The maximum apoptosis rate was 11.63%. The expression of caspase-9 gene was enhanced. The expression of bcl-2 gene decreased. All these effects were in dose-dependent and time-dependent manner.Conclusion: Apoptosis in HT-29 cell is one of the key mechanisms of ursolic acid to antitumor activities for the treatment of cancer. The apoptosis was associated with the up-regulation of the expression of caspase-9 protein and the down-regulation of the expression of bcl-2 protein.