The Expression of BTG2 and Its Regulatory Effect on Radiosensitivity of Lung Adenocarcinoma / 中国生物化学与分子生物学报

Among the types of lung cancer, lung adenocarcinoma accounts for the majority, and its overall survival rate is poor. B-cell translocation gene 2 (BTG2) is a member of the antiproliferative gene family, belonging to the BTG/TOB family. Many studies have shown that BTG2 was abnormally expressed in many types of tumors, but its regulatory role in the radiosensitivity of lung adenocarcinoma remained unclear. In this study, we explored the expression level of BTG2 in patients with lung adenocarcinoma and its correlation with clinical prognosis through online database and tissue samples of lung adenocarcinoma patient. The results indicated that the expression level of BTG2 decreased significantly in lung adenocarcinoma patient with radiation resistance. Bioinformatics analysis confirmed that BTG2 could respond to radiotherapy in lung adenocarcinoma cell lines, and its low expression in lung adenocarcinoma patients was associated with poor prognosis (P < 0.05). The lentivirus overexpressing BTG2 (OE-BTG2) was transfected into human lung adenocarcinoma cell lines to increase the expression level of BTG2 including A549 and H1299. And the effect of BTG2 overexpression on the radiosensitivity of lung adenocarcinoma cell lines was detected by clone formation assay. Clone formation experiment confirmed that overexpression of BTG2 could significantly enhance the radiosensitivity of A549 and H1299 cell lines (P < 0.05). The expression levels of BTG2 and apoptosis related protein-Bax were detected by Western blotting (WB) and immunohistochemistry (IHC). The effect of BTG2 on radiation sensitivity of lung adenocarcinoma was further detected via nude mouse in vivo. WB experiment confirmed that BTG2 upregulation could significantly increase the apoptosis level of A549 and H1299 cells after radiation. Moreover, BTG2 overexpression can markedly enhance the radiosensitivity of lung adenocarcinoma (P < 0.05) and increase the protein level of Bax after radiation in vivo. In conclusion, BTG2 had low expression in lung adenocarcinoma patients and its low expression level was closely related to the poor clinical prognosis. Overexpression of BTG2 can increase the radiosensitivity of lung adenocarcinoma cell lines and promote the process of apoptosis after radiation, indicating a new target for overcoming the radiation resistance of lung adenocarcinoma.

Protein Methylation and Interaction with the Antiproliferative Gene, BTG2(/TIS21/Pc3)

The last one and half a decade witnessed an outstanding re-emergence of attention and remarkable progress in the field of protein methylation. In the present article, we describe the early discoveries in research and review the role protein methylation played in the biological function of the antiproliferative gene, BTG2(/TIS21/PC3).

Construction of human BTG2 eukaryotic expression vector with FLAG tag and its expression in HeLa cells / 吉林大学学报(医学版)

Objective To construct an eukaryotic expression vector of human B-cell translocation gene 2 (BTG2), to express the FLAG-tagged BTG2 protein in HeLa cells,and to supply an experimental tool for investigating the function of BTG2 gene.Methods The full-length BTG2 fragment was obtained by PCR and inserted into the multiple cloning site of pcDNA3.1 (+)vector. Oligo DNA encoding FLAG tag was designed and inserted into pcDNA3.1(+)-BTG2 to construct another vector pcDNA3.1(+)-FLAG-BTG2.The HeLa cells were divided into pcDNA3.1(+)empty vector group,pcDNA3.1(+)-BTG2 group and pcDNA3.1(+)-FLAG-BTG2 group.The HeLa cells were transfected with recombinant plasmids.Western blotting using anti-FLAG antibody was performed to detect the expression of FLAG-BTG2 protein in HeLa cells.Results The sequence of the vector was verified by both BamH Ⅰ endonuclese digestion and DNA sequencing. The Western blotting analysis confirmed that FLAG-fused BTG2 was detected in pcDNA3.1(+)-FLAG-BTG2 group but not in empty vector or pcDNA3.1(+)-BTG2 groups. Conclusion The eukaryotic expression vector pcDNA3.1(+)-FLAG-BTG2 is successfully constructed and FLAG-tagged BTG2 protein is expressed in HeLa cells.

B-cell translocation gene 2 positively regulates GLP-1-stimulated insulin secretion via induction of PDX-1 in pancreatic beta-cells

Glucagon-like peptide-1 (GLP-1) is a potent glucoincretin hormone and an important agent for the treatment of type 2 diabetes. Here we demonstrate that B-cell translocation gene 2 (BTG2) is a crucial regulator in GLP-1-induced insulin gene expression and insulin secretion via upregulation of pancreatic duodenal homeobox-1 (PDX-1) in pancreatic beta-cells. GLP-1 treatment significantly increased BTG2, PDX-1 and insulin gene expression in pancreatic beta-cells. Notably, adenovirus-mediated overexpression of BTG2 significantly elevated insulin secretion, as well as insulin and PDX-1 gene expression. Physical interaction studies showed that BTG2 is associated with increased PDX-1 occupancy on the insulin gene promoter via a direct interaction with PDX-1. Exendin-4 (Ex-4), a GLP-1 agonist, and GLP-1 in pancreatic beta-cells increased insulin secretion through the BTG2-PDX-1-insulin pathway, which was blocked by endogenous BTG2 knockdown using a BTG2 small interfering RNA knockdown system. Finally, we revealed that Ex-4 and GLP-1 significantly elevated insulin secretion via upregulation of the BTG2-PDX-1 axis in pancreatic islets, and this phenomenon was abolished by endogenous BTG2 knockdown. Collectively, our current study provides a novel molecular mechanism by which GLP-1 positively regulates insulin gene expression via BTG2, suggesting that BTG2 has a key function in insulin secretion in pancreatic beta-cells.