The relationship between and clinical significance of MicroRNA-32 and phosphatase and tensin homologue expression in colorectal cancer

MicroRNAs (miRNAs, miRs) are suspected to play important roles in carcinogenesis. MiR‐32 has altered expression in colorectal cancer (CRC); however, the clinical significance of miR‐32 expression in the process of carcinogenesis is poorly understood. In this study, we determined the levels of, the correlation between, and the clinical significance of the expression of miR‐32 and phosphatase and tensin homologue (PTEN), a tumor suppressor targeted by miR‐32, in CRC. The levels of miR‐32 and PTEN gene expression in 35 colorectal carcinoma samples, 35 corresponding cancer‐adjacent tissue samples, 27 colorectal adenoma samples, and 16 normal tissue samples were quantified using real‐time quantitative reverse transcriptase‐polymerase chain reaction. PTEN protein expression was determined using western blot and immunohistochemistry (IHC). The relationship between the miR‐32 and PTEN protein expression and clinicopathological factors was analyzed. Significant upregulation of miR‐32 expression and reduction of PTEN were identified in CRC tissues. High miR‐32 levels were significantly associated with lymph node and distant metastasis, and Kaplan–Meier analysis indicated that patients with high miR‐32 expression had a poor overall survival. Low PTEN protein expression was also significantly correlated with distant metastasis. An inverse relationship between miR‐32 and PTEN protein expression was identified. In addition, IHC analysis revealed weak or indiscernible PTEN staining in tumor tissue. MiR‐32 overexpression was correlated with specific CRC clinicopathological features and may be a marker of poor prognosis in CRC patients. MiR‐32 and PTEN expression were inversely correlated, and miR‐32 may be associated with the development of CRC. © 2013 Wiley Periodicals, Inc.