In vitro effects and the related molecular mechanism of galangin and quercetin on human gastric cancer cell line (SGC-7901)

Abstract

Natural flavonoids are proven to be powerful against various cancers, but few studies have investigated the potential effects of two flavonoids galangin and quercetin on a human gastric cancer cell line (SGC-7901). In vitro growth inhibition and apoptosis of the two flavonoids on the SGC-7901 cells as well as potential mechanism about apoptosis induction are reported in the present study. The assaying results showed that the two flavonoids at 40-200 µmol/L for 24-72 hours conferred lower cell viability of 14.1-90.3% in dose- and time-dependent manner, and at 160 µmol/L for 24-48 hours enhanced the proportion of apoptotic cells into 13.3-27.4% and 40.6-65.6%, respectively. Galangin was more powerful than quercetin to inhibit cell growth, induce apoptosis and decrease mitochondrial membrane potential (MMP). Oligonucleotide micro array, real-time RT-PCR and Western-blot analyses revealed expression changes of the genes and proteins in the treated cells, clarifying a mechanism related to apoptosis induction. The two flavonoids activated caspase-8, which cleaved Bid into tBid; simultaneously, Bax transferred from cytosol into mitochondria to decrease MMP; consequentially, cytochrome c released from mitochondria activated caspase-9, and then caspase-9 activated caspase-3, which executed the apoptosis. That is, the apoptosis occurred via a mitochondrial pathway involving caspase-8/Bid/Bax activation.