| ObjectiveTo detect the expression level of microRNA-182(miR-182) in colorectal cancer and adjacent noncancerous tissues, and investigate the potential role of miR-182in colorectal cancer tumorigenesis, progression and prognosis. In addition, we also detect the expression level of miR-182in metastatic cancers and compare with the level of miR-182in non-metastatic cancers. We next investigate its effect on the migration of colorectal cancer cells in vitro. To investigate the potential role of miR-182in the metastasis of colorectal cancer.Methods1. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to analyze the expression of miR-182in173pairs of colorectal cancer and adjacent noncancerous tissues (including148non-metastatic cancers and25metastatic cancers).2. The relationship between miR-182expression and clinicopathological characteristics in colorectal cancer tissues were estimated using Mann-Whitney U test or Kruskal-Wallis test, as appropriate.3. Survival curves of miR-182and other clinicopathological characteristics in colorectal cancer were constructed with the Kaplan-Meier method and compared by log-rank test.4. A Cox proportional hazards regression analysis was used for prognostic values of miR-182and other clinicopathological characteristics in colorectal cancer.5. MiR-182mimics and miR-negative control were transfected into the HT-29cells using Lipofectamine2000at the optimal multiplicity of infection (MOI) according to the manufacturer’s instructions. The expression of miR-182in transfected HT-29cells was detected by qRT-PCR. 6. Using transwell assay in vitro to observe the migration cells in miR-182over-expression group, negative control and blank group. Then we detected the migration ability of miR-182on HT-29cells.Results1. The expression of miR-182was found up-regulated in colorectal cancer tissues compared with adjacent noncancerous tissues (p＜0.001), and the expression of miR-182was also found higher in metastatic cancer tissues than non-metastatic cancer tissues (p=0.0166). Results showed that there was a large variability in the expression of miR-182across the tissues, with median value of0.147(interquartile range,0.075-0.277) in colorectal non-metastatic cancer tissues, the median value of0.051(interquartile range,0.019-0.117) in adjacent noncancerous tissues, the median value of0.254(interquartile range,0.134-0.538) in colorectal metastatic cancer tissues, and the median value of0.045(interquartile range,0.014-0.131) in adjacent noncancerous tissues.2. Relationship between clinicopathological characteristics and miR-182expression in colorectal cancer tissues The up-regulation of miR-182was significantly correlated with large tumor size (p=0.016), positive regional lymph nodes metastasis (p=0.008) and advanced TNM stage (p=0.020). In contrast, no correlation was detected in the expression level of miR-182with age, gender, tumor location, local invasion and histology grade (all at p＞0.05, respectively).3. Correlation between miR-182levels and patients’ survival Of the148patients, the cumulative5-year overall survival rate was56.8%. Patients with colorectal cancer were categorized as high miR-182expression and low miR-182expression (based on the median expression). The5-year cumulative probability of survival for high miR-182expression patients (43.2%) was significantly lower than patients with low miR-182expression (70.3%)(p=0.001). In addition, we observed that survival time was also associated with local invasion (p=0.022), regional lymph nodes metastasis (p＜0.001) and TNM stage (p＜0.001) by Kaplan-Meier analysis and log-rank test. In contrast, no correlation was detected in the patients’survival with age, gender, tumor location, tumor size and histology grade (all at p＞0.05, respectively).4. Cox proportional hazards risk analysis indicated that miR-182was an independent prognostic factor for colorectal cancer Bootstrap Cox proportional hazards regression analysis, at the univariate level, revealed a statistically significant correlation between overall survival and miR-182level (HR=2.313;95%CI,1.379-3.879;p=0.001), local invasion (HR=2.214;95%CI,1.094-4.483;p=0.027), regional lymph nodes metastasis (HR=3.523;95%CI,2.105-5.899;p＜0.001) and TNM stage (HR=2.975;95%CI1.943-4.555;p＜0.001). The results of multivariate analysis demonstrated that miR-182(HR=1.790;95%CI,1.057-3.032;p=0.030) and regional lymph nodes metastasis (HR=2.899;95%CI,1.704-4.933;p＜0.001) maintained their significance as independent prognostic factors for overall survival rates.5. The up-regulated miR-182promotes migration ability of HT-29cells by transwell assay in vitro The expression of miR-182was significantly higher in miR-182over-expression group than negative control and miR-negative control after transfection about24h (p<0.05, respectively). The migration cells were significantly higher in miR-182over-expression group (61±9) than negative control (29±5) and blank group (27±4)(all at p＞0.05, respectively).Conclusions1. The expression of miR-182was significantly higher in colorectal cancer tissues and its level was significantly correlated with tumor size, regional lymph nodes metastasis and TNM stage, which suggested that higher level of miR-182expression may play critical roles in colorectal cancer tumorigenesis and progression.2. The5-year cumulative probability of survival for high miR-182expression patients was significantly lower than patients with low miR-182expression, and Cox proportional hazards risk analysis indicated that miR-182was an independent prognostic factor for colorectal cancer. Those findings indicated that miR-182could be used as a potential prognostic biomarker and therapeutic target in the management of colorectal cancer.3. The expression of miR-182was found up-regulated in colorectal metastatic cancer tissues, and significantly higher than colorectal non-metastatic cancer tissues. In addition, the up-regulated miR-182promotes colorectal cancer cell migration in vitro, suggesting a potential target for the prevention and therapy of metastasis in colorectal cancer. |
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