| Activin A, a member of transforming growth factor-P superfamily, is a glycoprotein, initially separated from the ovary, and is a multifunctional growth and differentiation factor. Activin A has various biological functions and plays important roles in the early formation of embryos, hematopoietic cell proliferation and differentiation and apoptosis of tumor cells. Apoptosis, also called programmed cell death, is in a complex and active cell death way, and is regulated by relative gene either under normal or pathological condition. Apoptosis is also an essential mechanism for orgnism cleaving aged, damaged and mutated cells. Abnormal apoptosis can induce many deseases, such as neurological and neural development-related diseases, the formation of various tumors. Cell apoptosis pathways mainly include three kinds:the death receptor pathway, the mitochondrial pathway and endoplasmic reticulum stress pathway. Previous studies have shown that activin A induce B cell apoptosis by the mitochondrial pathway, but whether activinA can induce apoptosis of lung adenocarcinoma cells via endoplasmic reticulum stress pathway is still lack of relevant reseach reports.In the present study, lung adenocarcinoma cell line Lewis cells of mouse and lung adenocarcinoma cell line A549 cells of human were used as research object to discuss the effect of activin A on mouse and human lung adenocarcinoma cells’ proliferation and apoptosis, at the same time to analyze the expression of the endoplasmic reticulum stress pathway-associated proteins caspase12, Chop and GADD34. Moreover we established knock-down GADD34 gene expression Lewis cell line (shGADD34/Lewis) that is infected by lentivirus canrried relative genes for further determining whether activinA can induce lung adenocarcinoma apoptosis through the endoplasmic reticulum stress pathway.In this study, we firstly detected cell proliferation by MTT, BrdU and CSFE fluorescence labeling methods and detected the apoptosis cell with Annexin-V/PI double staining by flow cytometry. The result suggests that activinA could obviously inhibit the proliferation of mouse lung adenocarcinoma cell line Lewis cells and induce Lewis cells apoptosis, and activinA could also induce apoptosis of human lung adenocarcinoma cell line A549 cells and inhibit A549 cells proliferation. Furthermore, RT-PCR was used to examine expressions of the endoplasmic reticulum stress pathway-associated proteins caspase12, Chop and GADD34 mRNA. The results showed that expressions of caspase12, Chop and GADD34 mRNA in Lewis cells were significantly promoted after activinA treatment for 12h. Finally, in order to confirm that activinA induce the apoptosis of lung adenocarcinoma through the endoplasmic reticulum stress pathway, we use Lewis cells that are infected with GADD34 shRNA lentiviral and Lewis cells that infected with empty lentiviral as control group. The result revealed that knock-down GADD34 gene can significantly weaken the effect of activin A on inhibiting Lewis cells proliferation and inducing Lewis cells apoptosis.Taking together, these results indicate that activin A can inhibit both mouse lung adenocarcinoma cell line Lewis cells and human lung adenocarcinoma cell line A549 cells proliferation and induce the apoptosis of Lewis cells and A549 cells. Activin A can promote the mRNA expression level of caspase12, chop and GADD34, which are the endoplasmic reticulum stress pathway-associated protein. Knock-down GADD34 gene can significantly attenuate the effect of activin A on inhibiting Lewis cells proliferation and inducing Lewis cells apoptosis. Therefore, activin A may be the potential drug for treating lung adenocarcinoma by the way that induces lung adenocarcinoma cells apoptosis via the endoplasmic reticulum stress pathway. |
