In situ hybridization analysis of the expression of miR-106b in colonic cancer

Background: MicroRNA-106b (miR-106b) is thought to be an oncogenic microRNA that promotes tumor growth and metastasis. The potential predictive value of miR-106b was studied in colonic cancer patients.

Methods: The expression of miR-106b was examined in 180 colonic cancer cases using in situ hybridization (ISH) technique and was evaluated semi-quantitatively by examining the staining index. The Correlation of miR-106b expression and clinic-pathological features was analyzed by Spearman Rank Correlation. Wilcoxon signed rank test was used for assessing the expression difference of miRNA-106b between colonic cancerous and para-cancerous ones, and their effects on patient survival were analyzed by a log-rank test and the Kaplan-Meier method.

Results: MiR-106b was higher expressed in para-cancerous tissues, compared with colonic cancerous ones (P < 0.001). A positive correlation of miR-106b levels between colonic and para-cancerous tissues was also observed (CC = 0.523, P < 0.001). Furthermore, the expression of miR-106b was not significantly correlated with clinic-pathological parameters, including gender, age, histological grade, tumor size, pT stage, pN stage, pM stage and pTNM stage of the patients. Histological grade was positively correlated with pT stage (P = 0.011), pN stage (P = 0.036) and pTNM stage (P = 0.009). Patients expressing high levels of miR-106b both in colonic cancer tissues and para-cancerous ones have a relatively longer survival time but the difference is not statistically significant (P = 0.16).

Conclusions: The expression difference of miR-106b levels between colonic tissues and para-cancerous tissues is statistically significant, but the miR-106b levels were not quite correlated with clinic-pathological characteristics and overall survival times of patients with colonic cancer. Lower levels of miR-106b may be connected with neoplastic effects due to interference with TGF-β signaling, providing evidence that down-regulation of miR-106b might also play an important role in the progression of the disease. The study results are consistent with the literature and support the notion that miR-106b is an oncogenic microRNA.