Rice Bran Phytic Acid Induced Apoptosis Through Regulation of Bcl-2/Bax and p53 Genes in HepG2 Human Hepatocellular Carcinoma Cells

Abstract

Phytic acid (PA) has been reported to have positive nutritional benefits and prevent cancer formation. Thisstudy investigated the anticancer activity of rice bran PA against hepatocellular carcinoma (HepG2) cells.Cytotoxicty of PA (0.5 to 4mM) was examined by MTT and LDH assays after 24 and 48h treatment. Apoptoticactivity was evaluated by expression analysis of apoptosis-regulatory genes [i.e. p53, Bcl-2, Bax, Caspase-3 and-9] by reverse transcriptase-PCR and DNA fragmentation assay. The results showed antioxidant activity of PAin Fe3+ reducing power assay (p≤0.03). PA inhibited the growth of HepG2 cells in a concentration dependentmanner (p≤0.04). After 48h treatment, cell viability was recorded 84.7, 74.4, 65.6, 49.6, 36.0 and 23.8% in MTTassay and 92.6, 77.0%, 66.8%, 51.2, 40.3 and 32.3% in LDH assay at concentrations of 1, 1.5, 2.0, 2.5, 3.0, and3.5mM, respectively. Hence, treatment of PA for 24h, recorded viability of cells 93.5, 88.6, 55.5, 34.6 and 24.4%in MTT assay and 94.2, 86.1%, 59.7%, 42.3 and 31.6%, in LDH assay at concentrations of 1, 2.2, 3.0, 3.6 and4.0mM, respectively. PA treated HepG2 cells showed up-regulation of p53, Bax, Caspase-3 and -9, and downregulationof Bcl-2 gene (p≤0.01). At the IC50 (2.49mM) of PA, the p53, Bax, Caspase-3 and-9 genes were upregulatedby 6.03, 7.37, 19.7 and 14.5 fold respectively. Also, the fragmented genomic DNA in PA treated cellsprovided evidence of apoptosis. Our study confirmed the biological activity of PA and demonstrated growthinhibition and induction of apoptosis in HepG2 cells with modulation of the expression of apoptosis-regulatorygenes.