Effects of AZT and RNA-protein complex (FA-2-b-β) extracted from Liang Jin mushroom on apoptosis of gastric cancer cells

Abstract

To investigate the synergistic effects of 3'-azido-3'-deoxythymidine (AZT) and FA-2-b-beta extracted from Ling Jin mushroom on apoptosis of gastric cancer cells MKN45 in vitro. MTT analysis was made to examine the inhibition rate of MKN45 cells treated with AZT (2.5, 5, 10 and 20 mg/L) and FA-2-b-beta (5, 10, 20 and 40 mg/L) singly and combinatively for 24, 48 and 72 h. Apoptotic effects were evaluated by morphological methods, DNA agarose gel electrophoresis and flow cytometry, respectively. Telomerase activity was estimated by TRAP-ELISA. The mRNA expression of caspase-3 and Bcl-2 were detected by RT-PCR. AZT and FA-2-b-beta could significantly inhibit MKN45 cell proliferation and induce its apoptosis. MKN45 cells were inhibited in dose- and time- dependent manner. The inhibition effect of AZT combined with FA-2-b-beta was obviously better than that used singly (0.469 +/- 0.022 vs 1.075 +/- 0.055, P < 0.05, 0.325 +/- 0.029 vs 0.469 +/- 0.022 P < 0.01). AZT used singly and combination of FA-2-b-beta could decrease the activity of tumor cell telomerase, and AZT has synergistic function with FA-2-b-beta. A certain concentration of AZT could up-regulate the expression of caspase-3 mRNA (r = 0.9969, P < 0.01), which was positively related to apoptosis rate, and could down-regulate the expression of Bcl-2 mRNA, which was negatively related to apoptosis rate (r = 0.926, P < 0.01). Furthermore, the effect of AZT combined with FA-2-b-beta was significantly higher than that used singly. Combination of AZT and FA-2-b-beta has an obviously synergetic effect in the gastric cancer cells MKN45, which has provided a new approach to the treatment of gastric cancer clinically.