| Colorectal carcinoma(CRC) is a type of malignant solid tumor arising from large intestines with increasing incidences and poor prognosis. Mi RNAs can exert various biological functions in tumors by influencing the expression of oncogenes and/or tumor suppressors. Mi RNAs downregulated in cancer were shown to inhibit the expression of proto-oncogenes under normal conditions. Conversely, upregulation of certain mi RNAs, so called oncomi Rs, leads to downregulation of tumor suppressor genes. Therefore, mi RNA can act as a tumor suppressor gene or an oncogene, and treatment strategies based on mi RNA is likely to translate into an effective therapy to the colon cancer.Mi RNA has been well documented to be associated with the etiology and biology of CRCs, such as mi R-155, and mi R-155 has exhibited good application prospects on cancer prevention, diagnosis, treatment, and clinical aspects. However, the molecular mechanism by which mi R-155 affects CRC has not been well identified. The most common signal path change in colon cancer is Wnt pathway. Wnt/β-catenin signaling pathway plays an important role in the early onset of colon cancer. Therefore, the purpose of this study was to investigate mi R-155’s role in the CRC function and its action mechanism, and to explore the possible target in the CRC tissues and cell linesMethods: 1. Real-time quantitative PCR and(or)Northern blot were used to detect expression levels of mi R-15 and Wnt/β-catenin signaling pathway related target genes(Axin2, CD44 and LGR5) in CRC tissue and(or) cell lines. 2. A mouse model of colon cancer xenograft was used to determine the effect of mi R-155 on colon tumor growth in mice. 3. Western blot was used to detect expression levels of cell proliferation biomarker Ki-67, HBP1, β- catenin protein levels. 4. TOPFlash reporter gene assay was utilized to determine the effect of mi R-155 on Wnt / β-catenin signaling pathway in CRC cell lines. 5. Cell cycles were determined flow cytometry, with cell cycle analysis using Mod Fit software. 6. Cell activity was detected by MTT, and cell proliferation rate was calculated. 7. mi R-155 target genes were predicted with bioinformatics method by online database Target Scan(http://www.targetscan.org) 8. Reporter gene vectors was used for mi R-155 target m RNA verification 9. Spearman analysis was used to analyze correlation between the level of mi R-155 survival of patients with colon cancerResults The results of Real-time PCR and Northern blot analysis showed that mi R-155 was overexpressed in the CRC, compared with paired normal colon tissues, and that mi R- 155 expression levels in CRC cell lines were significantly increased, compared with normal mi R-155 in colonic epithelial cells. When transfected with mi R-155 inhibitor, the proliferation rates of CRC cell lines were significantly decreased and the Wnt / β-catenin signaling pathway was blocked. Inhibition of mi R-155 expression in mice reduced the growth of colon cancer xenografts. The HMG-box transcription factor 1(HBP1) was confirmed as a new target of mi R-155 by Bioinformatics methods, and mediated its effect on CRC and Wnt/β-catenin pathway. In addition, Spearman analysis showed that the CRC patients with higher serum mi R-155 have a shortened survival time.Conclusions Mi R-155 contributed to the progression and growth of CRC by enhancing Wnt/β-catenin pathway in a HBP1-associated mechanism. Mi R-155 may be a promising therapeutic target for clinical CRC treatment. |
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