Abstract: Objective     To explore the effect of miR-133-3p on the growth of thyroid cancer SW579 cells and transplanted tumors in vivo.     Methods     Thyroid cancer SW579 cells were divided into a control group, a miR-NC group, a miR-133-3p mimic group, and transfected with miR-NC and miR-133-3p mimic according to groups. qRT-PCR was used to detect the expression of miR-133-3p in thyroid cancer tissues and adjacent tissues and transfected cells, and clone formation. EDU staining were employed to detect cell proliferation, flow cytometry was performed to detect cell apoptosis and mitochondrial membrane potential changes. The protein expression of Survivin and caspase-3 were detected by Western blot. The kits were commended to detect the content of SOD and MDA in the cell supernatant. SW579 cells transfected with miR-133-3p mimic or miR-NC were subcutaneously injected into nude mice, and the expression of miR-133-3p was detected by qRT-PCR, the volume of tumor tissue was observed and recorded. TUNEL was employed to detected tumor tissue apoptosis, and immunohistochemistry was used to detect the expression of Survivin and caspase-3 in tumor tissue.    Results    The expression of miR-133-3p in thyroid cancer tissues was decreased. Compared with the control group, the expression of miR-133-3p in the miR-133-3p group was significantly increased (P<0.05). The rate of cell colony formation, the rate of EDU positive cells and the expression of Survivin protein were significantly reduced (P<0.05). The apoptosis rate and the expression of caspase-3 were significantly increased (P<0.05). The mitochondrial membrane potential and the SOD content were significantly decreased, and the MDA content was increased (P<0.05) in the cell supernatant. Compared with the control group, the size of transplanted tumors in the miR-133-3p group was significantly reduced (P<0.05), the expression of miR-133-3p, the rate of TUNEL positive cells and the rate of caspae3 positive cells were significantly increased in tumor tissues (P<0.05), and the rate of Survivin-positive cells was significantly reduced (P<0.05).    Conclusions    miR-133-3p can inhibit the proliferation of thyroid cancer SW579 cells, induce apoptosis and mitochondrial oxidative damage, thereby inhibiting the growth of subcutaneous transplanted tumors in nude mice, which is expected to become a target for gene therapy of thyroid cancer.

Key words:  Thyroid cancer; ,  ,  miR-133-3p; ,  ,  Cell proliferation; ,  ,  SOD; ,  ,  Cell apoptosis