Biogenic Silver Nanoparticles Synthesized Using Mexican Poppy Plant Inhibits Cell Growth in Cancer Cells through Activation of Intrinsic Apoptosis Pathway

In the present investigation, biogenic silver nanoparticles were synthesized using aqueous extract of Mexican poppy plant Argemone mexicana (AM-Ag NPs); their involvement in striking cytotoxicity and genotoxicity potential was explored. The biosynthesis of nanoparticles was confirmed by ultraviolet-visible spectroscopy (UV-Vis) and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform-infrared spectrometry (FTIR) and X-ray diffraction (XRD). The mechanism of inhibition of cell proliferation by Ag NPs was illustrated using human cervical adenocarcinoma (HeLa), human breast adenocarcinoma (MCF-7) and human colon adenocarcinoma (HCT-15) cells. In selected cancer cells, molecular mechanism involved in induction of apoptosis in response to biogenic Ag NPs was demonstrated by DNA fragmentation assay, and alteration in expression of apoptotic genes including caspase-3 and p53 was analyzed by RT-PCR and western blotting. The overall results construed that biosynthesized AM-Ag NPs exhibited cytotoxicity effect against tested HeLa, MCF-7 and HCT-15 cell lines in a dose dependent manner where 20 µg/mL concentration of AM-Ag NPs killed more than 95% of HeLa and MCF-7 cells after 24 h exposure, whereas HCT-15 cells required 50 µg/mL AM-Ag NPs to inhibit 95% cell growth. AM-Ag NPs significantly induced cellular DNA damage in HeLa and MCF-7 cells when treated up to 20 µg/mL and HCT-15 cells exposed up to 50 µg/mL concentrations for 24 h. It is evident from our finding that the underlying mechanism of cell death in cancer cells exposed to AM-Ag NPs was intrinsic apoptosis pathway mediated by activation of caspase-3 and p53 genes.