RESUMO
Caudalrelated homeobox transcription factor 2 (CDX2) is a transcription factor, which is specifically expressed in the adult intestine. It is essential for the development and homeostasis of the intestinal epithelium and its functions as a tumor suppressor have been demonstrated in the adult colon. The present study aimed to examine the inhibitory effects of the overexpression of CDX2 on subcutaneouslytransplanted tumors, derived from LoVo colon cancer cells, in nude mice, and to provide experimental evidence for the biotherapy of colon cancer. A pEGFPC1CDX2 eukaryotic expression vector was transfected into the LoVo cells via lipofection, and LoVo cells stablyexpressing CDX2 (pEGFPC1CDX2 cells) were obtained using G418 selection. A nude mouse subcutaneouslytransplanted tumor model was established by inoculating the nude mice with the pEGFPC1CDX2 cells, and the effects of overexpression of CDX2 on transplanted tumor growth in the LoVo cells were observed. Western blotting results demonstrated that the protein expression of CDX2 in the LoVo cells was higher in the pEGFPC1CDX2 cell group, compared with that in the pEGFPC1 cell group and the untreated cell group. At 20 days postinoculation with either pEGFPC1CDX2 or pEGFPC1, the transplanted tumor masses were significantly lower in the pEGFPC1CDX2 group, compared with those in the pEGFPC1 and untreated groups. Immunohistochemistry revealed that the expression levels of CDX2 and matrix metalloproteinase2 (MMP2) were detected in each group, and the protein expression of CDX2 was increased in the tumor tissues from the nude mice in the pEGFPC1CDX2 group. However the expression of MMP2 was downregulated in the tumor tissues of the nude mice in the pEGFPC1CDX2 group. Taken together, these data suggested that pEGFPC1CDX2 cells exhibited suppressed tumor growth in vivo. Overexpression of CDX2 was observed in transplanted tumors in the pEGFPC1CDX2 group, and the gene expression of MMP2 was reduced. These results indicate that CDX2 inhibited the growth of colorectal tumor cells, possibly by downregulating the gene expression.