Overexpression of caudal-related homeobox transcription factor 2 inhibits the growth of transplanted colorectal tumors in nude mice.

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.

Analysis of key genes and pathways associated with colorectal cancer with microarray technology.

OBJECTIVE: Microarray data were analyzed to explore key genes and their functions in progression of colorectal cancer (CRC). METHODS: Two microarray data sets were downloaded from Gene Expression Omnibus (GEO) database and differentially expressed genes (DEGs) were identified using corresponding packages of R. Functional enrichment analysis was performed with DAVID tools to uncover their biological functions. RESULTS: 631 and 590 DEGs were obtained from the two data sets, respectively. A total of 32 common DEGs were then screened out with the rank product method. The significantly enriched GO terms included inflammatory response, response to wounding and response to drugs. Two interleukin-related domains were revealed in the domain analysis. KEGG pathway enrichment analysis showed that the PPAR signaling pathway and the renin-angiotensin system were enriched in the DEGs. CONCLUSIONS: Our study to systemically characterize gene expression changes in CRC with microarray technology revealed changes in a range of key genes, pathways and function modules. Their utility in diagnosis and treatment now require exploration.

Effects of homeodomain protein CDX2 expression on the proliferation and migration of lovo colon cancer cells.

The homeobox gene, CDX2, plays a major role in development, especially in the gut, and also functions as a tumor suppressor in the adult colon. In the present study, we investigated the effects of CDX2 expression on the proliferation, migration, and apoptosis of the human colon cancer cell line, Lovo. Lovo cells exogenously expressing CDX2 exhibited no significant differences in the percentage of cells in G1- and S-phase or in apoptosis, as determined by flow cytometry. MTT assay also confirmed that CDX2 expression had no effect on proliferation in these cells. Interestingly, conditioned medium collected from CDX2-overexpressing Lovo cells showed a significant decrease in secretion of MMP-2 and the invasive potential of these cells was significantly inhibited. Collectively, these data suggest that CDX2 may play a critical role in the migration and metastasis of colon carcinoma and over-expression of CDX2 in colon cancer cells markedly inhibits invasion. Based on these results, exogenous expression of CDX2 might be a promising option in the treatment of colon carcinoma.