Zeolite X from coal fly ash inhibits proliferation of human breast cancer cell lines (MCF-7) via induction of S phase arrest and apoptosis.

In this study, zeolite X synthesised from coal fly ash (CFA) was examined for its anti-proliferative effects on human breast cancer MCF-7 cells by in vitro studies and allied probable molecular mechanism were also assessed. MTT assay exposed that zeolite X showed a concentration-dependent inhibitory result on the proliferation of MCF-7 cells and caused early apoptotic death and does not induce cytotoxicity in non-cancerous cells (MCF-12A). Flow cytometric study specified the accrual of cells at S phase suggest induction of apoptosis which was avowed through fluorescence and confocal microscopy following annexin V-FITC/propidium iodide (PI). MCF-7 cells treated by 10, 15 and 20 µg/ml concentrations of zeolite X showed internucleosomal DNA fragments in ladder form, thereby indicates cell death is associated with apoptosis. Mechanistically, our data support the induction of apoptosis through the activation of mitochondrial dependent pathway as indicated by an up-regulation of Bax and downregulation of Bcl-2 ratio, the expulsion of cytochrome c from the mitochondria to the cytosol and cleavage of pro-caspase-3 into activation of caspase-3 in MCF-7 cells. Based on these outcomes zeolite X induced early apoptosis and strongly provided experimental evidence for the usage of zeolite X as an essential therapeutic agent in the prevention and therapy of human breast cancer.