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. (c) 2013 Wiley Periodicals, Inc.