Inhibitory effects of curcumin on gastric cancer cells: A proteomic study of molecular targets

Curcumin, a natural anticancer agent, has been shown to inhibit cell growth in a number of tumor cell lines and animal models. We examined the inhibition of curcumin on cell viability and its induction of apoptosis using different gastric cancer cell lines (BGC-823, MKN-45 and SCG-7901). 3-(4,5-dimethyl-thiazol-2-yl)-2-5-diphenyltetrazolium-bromide (MTT) assay showed that curcumin inhibited cell growth in a dose- (1, 5, 10 and 30μM) and time- (24, 48, 72 and 96h) dependent manner; analysis of Annexin V binding showed that curcumin induced apoptosis at the dose of 10 and 30μM when the cells were treated for 24 and 48h. As cancers are caused by dysregulation of various proteins, we investigated target proteins associated with curcumin by two-dimensional gel electrophoresis (2-DE) and MALDI-TOF-TOF mass spectrometer. BGC-823cells were treated with 30μM curcumin for 24h and total protein was extracted for the 2-DE. In the first dimension of the 2-DE, protein samples (800μg) were applied to immobilized pH gradient (IPG) strips (24cm, pH 3–10, NL) and the isoelectric focusing (IEF) was performed using a step-wise voltage ramp; the second dimension was performed using 12.5% SDS-PAGE gel at 1W constant power per gel. In total, 75 proteins showed significant changes over 1.5-fold in curcumin-treated cells compared to control cells (Student's t-test, p