Tetrandrine sensitizes vincristine to induce apoptosis in SGC-7901/VCR cells through MAPK signaling pathway

Abstract

Objective To explore the molecular mechanism of tetrandrine sensitizing vincristine to induce apoptosis of gastric cancer SGC-7901/VCR cells. Methods SGC-7901/VCR cells were treated with tetrandrine (0, 2, 4, 6 and 8 μmol/L) and vincristine (0, 50, 100, 150 and 200 nmol/L) alone or in combination for 48 h. MTT assay was used to detect cell viability, and flow cytometry was adopted to observe apoptosis. The expression of apoptosis-related proteins PARP-1, cleaved-Casepase 9, cleaved-Casepase 3, Bcl2, and MAPK signal transduction pathway related proteins P38, p-P38, JNK, p-JNK, ERK and p-ERK were detected by Western blotting. After SGC-7901/VCR cells were pretreated with p38-MAPK inhibitor SB203580, JNK-MAPK inhibitor SP600125, or ERK-MAPK inhibitor PD98059 for 2 h and followed by the treatment of tetrandrine combined with vincristine for 48 h, the apoptosis and the expression levels of related proteins were observed once again. SGC-7901/VCR cells were treated with tetrandrine and vincristine alone or combined for 24 h, cell cycle was detected by flow cytometry, and the expression of CDC2 and p-CDC2 were detected by Western blotting. Results Co-administration of tetrandrine and vincristine resulted in decreases in cell viability in a dose-dependent manner in SGC-7901/VCR cells, with a synergistic effect, and led to increases in cell apoptosis (P < 0.05), which were associated with degradation of PARP, cleavage/activation of Caspase 3 and Caspase 9. Furthermore, combination of tetrandrine and vincristine markedly increased the levels of phospho-p38 and phospho-JNK and decreased the level of phospho-ERK. Pretreatment of p38 inhibitor SB203580 or JNK inhibitor SP600125 attenuated the combination-induced apoptosis (P < 0.05). In contrast, pretreatment of ERK inhibitor PD98059 potentiated the combination-induced apoptosis (P < 0.05). Combination treatment caused S/G2 cycle block of SGC-7901/VCR cells (P < 0.05). Conclusion Tetrandrine sensitizes vincristine to inhibit cell proliferation and induces apoptosis in SGC-7901/VCR cells. MAPK signaling pathway may play a critical role in the combination-induced apoptosis in the cells.

Keywords

• tetrandrine
• vincristine
• sgc-7901/vcr cells
• apoptosis
• mapk