To investigate the effect of PDTC (inhibitor of NF-κb) on apoptosis of human gastric cancer cell line SGC-7901 induced by tumor necrosis factor α (TNF-α) and explore the related mechanisms.
After the treatment with different concentrations of PDTC, TNF-α or PDTC combined with TNF-α on gastric cancer cell line SGC-7901, the growth inhibition of SGC-7901 was measured by MTT assay. Hoechst was used to assess SGC-7901 cell apoptosis. The protein expressions of survivin and caspase-3 were detected by Western blot assay.
The growth inhibition rate of SGC-7901 induced by PDTC (15, 30, 60, 100 μmol/L) was (12.14±0.91)%, (20.00±1.11)%, (37.63±1.01)% and (41.46±1.07)%. Different concentrations of PDTC all inhibited the growth of SGC-7901 significantly (all P<0.01), The growth inhibition rate of SGC-7901 induced by 25 mg/L TNF-α was (2.38±0.67)%, which could not significantly inhibit the growth of SGC-7901 [control (1.50±0.81)%], while TNF-α of 50, 100, 150 mg/L could inhibit the growth of SGC-7901 significantly [(4.53±0.85)%, (4.43±0.70)% and (4.74±1.07)%, all P<0.05]. PDTC (15 μmol/L) combined with TNF-α (25, 50, 100, 150 mg/L) significantly increased the cell growth inhibition rate compared with TNF-α alone or PDTC 15 μmol/L alone (all P<0.01). Hoechst assay showed that 100 mg/L TNF-α, 15 μmol/L PDTC and combination of above two all induced cell apoptosis (P<0.01), and the combination group had significantly higher percentage of cell apoptosis (P<0.01). Survivin protein was significantly down-regulated in combination group as compared with single TNF-α (100 mg/L) group, but was not significant down-regulated as compared with single PDTC (15 μmol/L) group. Caspase-3 protein expression was significantly increased in combination group as compared with other two groups.
PDTC can enhance the cell apoptosis induced by TNF-α, which may be associated with the blocking of TNF-α-activated NF-κB signaling pathway by PDTC, the down-regulation of survivin expression, and up-regulation of caspase-3 expression.