Objective To investigate the effects of X-ray dose on the expressions of microRNA-221 （miR-221） and phosphatase and a tensin homolog deleted from chromosome10 （PTEN） in human colorectal carcinoma （CRC） cells. Methods Human CRC-derived cell line， Caco2， was cultured conventionally. The cells were divided into five groups and exposed to different doses of X-ray （0， 2， 4， 6， and 8 Gy） respectively. The total RNA and protein of the Caco2 cells were extracted after irradiation， and the miR-221 and PTEN mRNA expressions were detected by real-time RT-PCR.Moreover， the protein alteration of PTEN in Caco2 cells was detected by Western-blot analysis. Results The radiation dose of X-ray significantly affected the expressions of miR-221 and PTEN protein in human Caco2 cells in a dose-depen-dent manner. Moreover， the miR-221 expression level was up-regulated gradually with the increase of irradiation dose， on the contrary， the PTEN protein expression level was down-regulated gradually （P＜0.01）. Conclusion The radiation dose can affect the miR-221 and PTEN protein expression pattern in CRC cells.
ObjectiveTo study the expressions of microRNA-221 (miR-221) and the protein of phosphatase and tension protein homologue (PTEN) in the proximal and distal stumps after sciatic nerve injury in rats and their correlation with the repair of peripheral nerve injury, so as to provide a new target for clinical diagnosis of peripheral nerve injury.MethodsNinety-six male Sprague-Dawley rats of SPF grade were selected to establish sciatic nerve injury models. Twenty-four rats were sacrificed at 0 (immediately after operation), 1, 4, and 7 days after operation. The proximal and distal sciatic nerve fragments were taken under aseptic conditions. The expression of miR-221 was detected by real-time fluorescent quantitative PCR, and the expression of PTEN protein was detected by Western blot and immunofluorescent staining. The relationship between miR-221 and PTEN was verified by dual-luciferase reporter gene. At the same time, the ultrastructure of nerve stump was observed by transmission electron microscopy.ResultsThe results of real-time fluorescent quantitative PCR, Western blot, and immunofluorescence staining showed that the relative expression of miR-221 in the proximal and distal stumps increased gradually with time, and the relative expression of PTEN protein decreased gradually, and the differences between different time points after operation were significant (P<0.05). At 1, 4, and 7 days after operation, the relative expression of miR-221 in proximal stump was significantly higher than that in distal stump, and the relative expression of PTEN protein in proximal stump was significantly lower than that in distal stump (P<0.05). Dual-luciferase reporter gene suggested that PTEN was the target for miR-221. Transmission electron microscopy observation showed that the normal morphological structure was observed at 0 day after operation, and the proliferation of Schwann cells and degeneration of axons and myelin sheaths gradually increased with time. There was no significant difference between proximal and distal stumps at 1 day after operation. At 4 and 7 days, Schwann cells proliferated more in proximal stump than in distal stump, and the degeneration of axons and myelin sheaths was less.ConclusionAfter sciatic nerve injury in rats, the up-regulation of the miR-221 expression targets the down-regulation of PTEN expression, which results in the difference of expression levels of miR-221 and PTEN in proximal and distal stumps. This phenomenon may play a role in promoting nerve repair after peripheral nerve injury.