G-quadruplex antibody attenuates human gastric cancer cell proliferation and promotes apoptosis through hTERT/telomerase pathway

Y.-Q. Zhang, J.-H. Pei, S.-S. Shi, J. Zheng, J.-M. Wang, X.-S. Guo, G.-Y. Cui, X.-Y. Wang, H.-P. Zhang, W.-Q. Hu

Department of Biochemistry, Changzhi Medical College, Changzhi, Shanxi, Changzhi, China. yiqiangzhang@czmc.edu.cn

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• Oncology

OBJECTIVE: To investigate the expression of G-quadruplex antibody BG4 in human gastric cancer AGS cells and assess its functions in attenuating proliferation and promoting apoptosis in gastric cancer.

MATERIALS AND METHODS: BG4 high-expression gastric cancer AGS cell line was established by pEGFP-N1-BG4 transient transfection. AGS cells transfected with pEGFP-N1 plasmids were included into the pEGFP-N1 group and those not transfected with plasmids were included into the negative control group. Cell counting kit-8 (CCK8) assay was performed to examine the AGS cell proliferation ability, while flow cytometry was used to detect the cell cycle distribution and cell apoptosis. Cell migration was measured using Transwell migration and wound healing assay. Then the expression levels of cell apoptosis associated factors were determined. The mRNA and protein expressions of human telomerase reverse transcriptase (hTERT), B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X (Bax) were examined with real-time quantitative polymerase chain reaction (PCR) and Western blotting, respectively.

RESULTS: The results revealed that pEGFP-N1-BG4 group exhibited reduced proliferation and migration, induction of apoptosis. hTERT and Bcl-2 mRNA and protein levels in pEGFP-N1-BG4 group were down-regulated compared with those in the pEGFP-N1 group and control group, but there were no significant differences in Bax mRNA and protein levels compared with those in the pEGFP-N1 group and control group.

CONCLUSIONS: We showed that the expression of BG4 in the gastric cancer cell line AGS inhibits cell proliferation and promotes apoptosis though inducing telomere to form G-quadruplex structure and attenuating telomerase activity, thus resulting in reduced expression of hTERT and Bcl-2.

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