OBJECTIVETo inhibit the proliferation and metastasis of colon cancer cells by increasing the expression level of B-cell translocation gene-2 (BTG2).

METHODSWestern blot assay was used to detect the expression level of BTG2 protein in the normal intestinal epithelial HIEC cells and three colon cancer cell lines SW620, HT-29 and LS174T. The expression of BTG2 protein in normal colonic epithelial tissue, colon adenoma and colon cancer tissue was detected by immunohistochemistry. The plasmid with BTG2 gene full-length sequence was transfected into colon cancer SW620 cells, and the expression of BTG2 protein was detected by Western blot. The cell growth curve was drawn by MTT test. The Ki-67-positive rate was calculated using immunofluorescence staining. The cell migration of colon cancer cells was detected by scratch test and Transwell double chamber culture system, and the pseudopodia growth of tumor cells was detected by Matrigel 3D culture system.

RESULTSWestern blot results showed that BTG2 relative expression levels were 0.83 ± 0.12, 0.18 ± 0.04, 0.20 ± 0.05 and 0.36 ± 0.07 in normal human intestinal epithelial cells HIEC, and human colon cancer cell line SW620, HT-29 and LS174T, respectively. The results of immunohistochemistry showed that the positive expression of BTG2 protein in normal colorectal tissue, colorectal adenoma and colorectal carcinoma tissues were 82.5% (33/40), 77.5%(31/40) and 17.5% (7/40), respectively, with a significant difference between two groups (P < 0.05). Immunofluorescence results showed that the positive rate of Ki-67 in the control group, empty vector group and BTG2 transfection group was (76.2 ± 8.0)%, (81.4 ± 9.7)% and (50.1 ± 7.1)%, respectively, showing a significant difference between two groups (P < 0.05). The scratch test results showed that in the control group, empty vector group and BTG2 transfection group, the distance of SW620 cells between two sides was (79.27 ± 11.24) µm, (80.65 ± 12.17) µm and (124.77 ± 19.63) µm, respectively, with a significant difference between two groups (P < 0.05). Transwell results showed that in the control group, empty plasmid group and BTG2 transfection group, the SW620 cell migration rate was (78.5 ± 13.1)%, (73.2 ± 12.9)% and (47.4 ± 9.1)%, respectively, showing a significant difference between two groups (P < 0.05). The number of neurospheres of BTG2 transfection group was decreased SW620, which had poor ductility.

CONCLUSIONSBTG2 gene is involved in colon cancer cell proliferation and metastasis, and effectively restores the function of BTG2 protein. Therefore, it may be expected to become a new option in gene therapy for colon cancer.