Role of HGF/c-Met in the treatment of colorectal cancer with liver metastasis.

The system of hepatocyte growth factor (HGF) and its receptor c-Met plays a critical role in tumor invasive growth and metastasis. The mortality rate of colorectal cancer (CRC), one of the most commonly diagnosed malignancies, is increased by it gradual development into metastasis, most frequently in the liver. Overexpression of c-Met, the protein tyrosine kinase receptor for the HCF/scatter factor, has been implicated in the progression and metastasis of human colorectal carcinoma. In this study, we aimed to investigate the role of c-Met in CRC liver metastasis and illustrate the clinical impact of regulating HGF/c-Met signaling in patients with CRC liver metastasis. We found that (I) higher levels of c-Met expression (mRNA and Protein) in CRC liver metastasis than primary CRC by assessing the patient tissue samples; (II) a positive correlation of c-Met expression with tumor stages of CRC liver metastasis, as well as c-Met expression in CRC, live metastasis concurred with regional lymph node metastasis; (III) the clinical impact of downregulation of HGF/c-Met signaling on the reduction of proliferation and invasion in CRC liver metastasis. Therefore, we demonstrate that the regulation of HGF/c-Met pathways may be a promising strategy in the treatment of patients with CRC liver metastasis.

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.

Recombinant lentivirus with enhanced expression of caudal-related homeobox protein 2 inhibits human colorectal cancer cell proliferation in vitro.

Caudal-related homeobox protein 2 (CDX2), a tumor suppressor in the adult colon, is overexpressed under a non-cancer specific cytomegalovirus promoter in certain tumor cells; furthermore, non-specific expression of CDX2 may result in aberrant side effects in normal cells. The human telomerase reverse transcriptase (hTERT) promoter is active in the majority of cancer cells but not in normal cells. Hypoxia is a key feature of solid tumors, and targeted genes may be significantly upregulated by five copies of hypoxia-response elements (HREs) under hypoxic conditions. However, the effect of CDX2 overexpression, as controlled by five copies of HREs and the hTERT promoter, on human colorectal cancer (CRC) cell proliferation in vitro remains to be fully elucidated. In the current study, a recombinant lentivirus containing the CDX2 gene under the control of five HREs and the hTERT promoter was generated. An immunofluorescence assay was used to detect CDX2 expression by the 5 HhC lentivirus, whereas an MTT assay was used to detect the effects of CoCl2 on the viability of LoVo cells. Western blot analysis was conducted in order to determine the relative ratios of recombinant CDX2 protein to the internal control ß-actin, following 5 HhC/LoVo cell culture under normoxic and hypoxic conditions (100, 200, 300, 400 or 500 µmol/l CoCl2) for 24 h, then for 12, 24 or 36 h with the optimal concentration (300 µmol/l) of CoCl2. Reverse transcription polymerase chain reaction analysis was used to determine the transcription of recombinant CDX2 mRNA following culture of 5 HhC/LoVo cells under normoxic or hypoxic conditions. Finally, a cloning assay was used to detect the proliferative ability of 5 HhC/LoVo and 5 Hh cells. High CDX2 expression was observed in hTERT-positive LoVo cells under hypoxic conditions, an effect which was mimicked by treatment with CoCl2 to inhibit LoVo cell proliferation in vitro. High expression of CDX2 therefore provides a promising strategy for the development of novel targeted treatments and gene therapy for CRC.