The prognostic effect of PTEN expression status in colorectal cancer development and evaluation of factors affecting it: MiR-21 and promoter methylation

Background: pten is a tumor suppressor gene which is involved in cellular proliferation,differentiation,and apoptosis. loss or down-regulation of pten plays an important role in human cancers development. in this study,we investigated the effect of mir-21 and promoter methylation on the pten expression status in crc tissues and analyzed association of the pten expression status with clinicopathological features in patients with crc. results: the pten expression was positively detected in 67.2 % crc tissues and all adjacent non-cancerous samples. pten mrna level was negatively correlated with mir-21 level (r = -0.595,p < 0.001). pten expression was also correlated directly with the pten mrna level (r = 0.583,p < 0.001) and conversely with mir-21 level (r = -0.632,p < 0.001). pten promoter methylation was significantly associated with pten expression status (p = 0.013). pten expression was negatively associated with tumor size (p = 0.007) and advanced tumor stage (p = 0.011). multivariate analysis indicated that tumor stage,tumor differentiation and pten expression status were independent prognostic factors for overall carcinoma in crc patients (p < 0.05). the kaplan-meier curve indicated a negative correlation between pten expression levels and survival of crc patients (p = 0.013). conclusions: this study suggests a high frequency of mir-21 overexpression and aberrant promoter methylation in down-regulation of pten expression in colorectal carcinoma. loss of pten may be a prognostic factor for patients with crc. © 2016 yazdani et al.