| Colorectal cancer is one of the most common malignancies. In the United States and other developed countries, it is the third in cancer incidence, second in mortality. Recent decades, China has showing a obvious increased incidence of colorectal cancer trend. Although medical science and technology has got great development, the therapy and prognosis of colorectal cancer has not achieved remarkable results. Early colorectal cancer patients 5-year survival rate is about 90 percent. However, late 5-year survival rate is still only 10%, without significantly improvement. Metastasis and recurrence of human colorectal cancer is the biggest health hazards. Colorectal cancer metastasis is a complicated process, involving multiple steps and factors, the specific pathogenesis is still unclear. Therefore, further research the invasion and metastasis of colorectal cancer pathogenesis, will provide great significance to the early to judge, timely diagnosis and treatment, prognosis improvement of clinical colorectal cancer metastasis.MicroRNAs(abbreviation miRNAs), which are a class of non-coding small RNA, and consists of 21-25 nucleotide, participate in the level of gene post-transcriptional regulation. MiRNAs bind to complementary sites in the 3'-untranslated region (UTR) of target mRNAs and subsequently promote mRNA degradation or inhibit its target in the translation. They play important roles in protein cell proliferation, differentiation and apoptosis, gene regulation and the generating of the disease. MiRNAs can restrain many oncogenes and tumor-suppressor genes, which have an effect on tumorigenesis. Studies have confirmed there is a case that multiple miRNAs abnormal expression in colorectal cancer associated with different clinical stages, differentiation and other clinicopathologic features respectively, suggesting that miRNAs largely influence colorectal cancer incidence, progression and metastasis mechanisms, prognosis judgments. These results offer a new viewpoint for the research of colorectal cancer tumorigenesis, including its invasion and metastasis, and will eventually provide a new treatment strategy to colorectal cancer prognostic and treatments.During the research which we used miRNA microarray to study the colon cancer mechanism about NGX6, a colon cancer metastasis suppressor gene, a facts has been found:compared to colon cancer cell without NGX6 transfected, miR-126 in NGX6 transfected cell lines is upregulated; Further more, this has been confirmed by Real-time PCR. All of these suggest that miR-126 may be associated with colon cancer metastasis.Research shows that miR-126 is closely related with various malignant tumors, such as lung cancer, stomach caner, breast cancer, colon cancer, and so on. What's more, it has been reported miR-126 expression is often missing in colon cancer. How dose miR-126 involve in the development and progression of colon cancer?For further research on miR-126 in colorectal cancer development mechanism, especially in the pathological process of invasion and metastasis, our study is designed to investigate the biological function of miR-126 in different colon cancer cell lines, further identify its downstream target genes, provide new targets for diagnosis and treatment of colon cancer metastasis.1. Real-time PCR detect miR-126 expression in colon cancer cellsWe adopt Real-time PCR detect the expression of miR-126 in the HT-29, SW480, SW620 colon cancer cell lines and adjacent normal tissue of colon cancer. The results show that miR-126 relative expression levels in three Colon cancer cells was significantly lower than in adjacent normal tissue (P<0.01).2. MiR-126 cell biology function research in colon cancer cell linesIn colon cancer HT-29 cells transfected with miR-126 mimics, we use MTT assay to text tumor cell proliferation. The results showed that the growth activity of the cells transfected miR-126 mimics was significantly lower than the other cells in the 48,72,96,120 hours; In colon cancer SW480, SW620 cells after the overexpression of miR-126, wound-healing experiment and Transwell migration assay was to test cell migration, and Transwell invasion assay detect cell invasion. The results showed that miR-126 mimics inhibit SW480, SW620 cell migration and invasion. These experiments pointed out that miR-126 in colon cancer cells may play a role as a tumor suppressor gene.3. MiR-126 bioinformatics analysis and its downstream target gene prediction and experimental verificationMiR-126 basic information was analysised by miRBase software. Then, we found that CXCR4 may be the target gene of miR-126 through MicrocosmTargets software. It showed that CXCR4 has a closely relation ship with metastasis of cancer cell invasion. To identify the miR-126 target genes, our study has constructed PMIR vector involving CXCR4 and miR-126 binding site sequence and its deletion mutation sequence, respectively. Luciferase reporter system and western-blotting analysis were used to verify miR-126 target genes. These experiments confirmed CXCR4 as a direct target gene of miR-126.CONCLUSION:1.In HT-29, SW480, SW620 three colon cancer cell lines, the expression of miR-126 was downregulated; miR-126 inhibit the proliferation of HT-29 cell, also the cell migration and invasion of SW480 and SW620 cell. These suggested that miR-126 in colon cancer cells may play a role as a tumor suppressor gene.2. CXCR4 gene is a target gene of miR-126 in colon cancer. |
PDF Full Text Request