Evaluation of the Effects of Chlorophyllin on Apoptosis Induction, Inhibition of Cellular Proliferation and mRNA Expression of CASP8, CASP9, APC and β-catenin

Chlorophyllin is a semi-synthetic derivative of chlorophyll with antioxidant and antimutagen properties that controls the enzymes involved in the metabolism of xenobiotics and in the induction of apoptosis. In this study, we evaluated the effects of chlorophyllin on apoptosis induction, inhibition of cell proliferation, and gene expression in the human colorectal adenocarcinoma cell line HT29. Chlorophyllin significantly reduced cell survival after 48 h at 100 μg/mL and after 24 h at 500 or 1,000 μg/mL, respectively based on both MTT cytotoxicity and cell proliferation kinetics assays. These effects were dose dependent. Chlorophyllin did not induce apoptosis after 24 h at any concentration. Chlorophyllin downregulated the cell cycle genes APC and β-catenin (CTNNB1) but did not affect the expression of apoptotic induction genes in the extrinsic pathway (CASP8) or the intrinsic pathway (CASP9). At the studied concentrations, the inhibitory effect of chlorophyllin on cell growth was directly related to the regulation of β-catenin gene expression and not to APC expression, because APC was mutated and inactive. The studied concentrations suggest no potential for chlorophyllin as an apoptosis inducer based on cytomorphological changes or gene expression changes of the studied caspases.