Effect of Glycyrrhiza uralensis Fisch. endophytes combined with cisplatin on proliferation and apoptosis of A549 cells

Abstract:

Objective To investigate the effect of Glycyrrhiza uralensis Fisch. endophyte JTZB55 combined with cisplatin on proliferation and apoptosis of human lung cancer A549 cells and the possible mechanism.Methods MTT assay was used to determine the effect of JTZB55 and/or cisplatin on the survival rate of A549 cells. According to the synergistic index，the subsequent experimental concentration was screened out，and A549 cells were divided into normal control group，2 μg/mL cisplatin group，800 μg/mL JTZB55 group，and 2 μg/mL cisplatin + 800 μg/mL JTZB55 group. Flow cytometry was used to determine the effect of drugs in each group on the apoptosis of A549 cells. Western blot was used to measure the expression levels of mitochondrial apoptosis and endoplasmic reticulum stress pathway-related proteins in cells treated with drugs in each group.Results MTT results showed that the survival rate of A549 cells was decreased significantly after cisplatin and JTZB55 were administrated. Compared with the cisplatin group，the cell survival rate in the combination group was significantly decreased（P<0.05），and the synergistic index of 800 μg/mL JTZB55 combined with 2 μg/mL cisplatin was the highest. The results of flow cytometry showed that both JTZB55 and cisplatin could promote the apoptosis of A549 cells（P<0.01），and the apoptosis rate of A549 cells was significantly increased in the combination group（P<0.01）. Western blot results showed that cisplatin combined with JTZB55 could significantly decrease the expression of B cell lymphoma/leukemia-2（Bcl-2） protein and up-regulate the expression of Bcl-2 associated X（Bax），cytochrome C（CytC），cysteine aspartate protease-3（Caspase-3），cysteine aspartate protease-8（Caspase-8），cysteine aspartate protease-9（Caspase-9），glucose regulated protein 78（GRP78），and CCAAT/enhancer-binding protein-homologous protein（CHOP）（P<0.05）.Conclusion JTZB55 can enhance the inhibitory effect of cisplatin on the proliferation of A549 cells and promote the apoptosis of A549 cells. The mechanism may be related to the down-regulation of Bcl-2 and up-regulation of Bax，CytC，Caspase-3，Caspase-8，Caspase-9，GRP78，and CHOP.