关键词: miR-143-3p, 甲状腺癌, 促炎因子, 活性氧, 八聚体结合蛋白 , 4

Abstract: Objective To explore the effect of overexpression of miR-143-3p on thyroid cancer ( TC) cells and its mechanism. Method The expression of miR-143-3p in normal thyroid epithelial cells and different TC cells was analyzed by Real-time PCR. Targetscan website and dual luciferase reporter system verified the targeting relationship between miR-143-3p and TGIF2 3′ UTR; the overexpression efficiency of miR-143-3p and TGIF2 mRNA was detected by Real-time PCR. After successful overexpression, CAL-62 cells were divided into the control group, miR-143-3p mimic group, pcDNA-TGIF2 group and miR-143-3p +TGIF2 group, the contents of inducible nitric oxide synthase ( iNOS) , interleukin ( IL) -1β and IL-6 in cell supernatant were detected by ELISA. The level of superoxide dismutase ( SOD) was detected by the kit, and the production of reactive oxygen species ( ROS) was detected by immunofluorescence. Micro-observation of stem cells into spheroids, and the expressions of TGIF2, p-P65, leucine-rich repeat-containing G protein-coupled receptor 5 ( LGR5 ) and octamer-binding transcription factor 4 ( OCT4) were detected by Western blot. The effect of miR-143-3p overexpression on tumor growth in nude mice was detected. Result The expression of miR-143-3p in TC cells was significantly lower than that in normal TC cells ( P < 0. 05 ) . Targetscan website and dual luciferase reporter system confirmed that miR-143-3p was targeted to TGIF2. In the miR-143-3p mimic group, the expression of miR-143-3p was up-regulated ( P <0. 05) , the expression of TGIF2 mRNA and protein was down-regulated ( P<0. 05) , the contents of iNOS, IL-1β and IL-6 were significantly decreased ( P<0. 05) , the antioxidant capacity and the sphere-forming ability of stem cells were significantly decreased ( P<0. 05) , and the protein expression levels of p-P65, LGR5 and OCT4 were significantly decreased ( P < 0. 05 ) . The results of pcDNA-TGIF2 group were opposite. Overexpression of miR-143-3p can significantly inhibit the pro-cancer effect of pcDNA-TGIF2. The xenograft tumor model in nude mice showed that overexpression of miR-143-3p could reduce tumor weight and volume, and down-regulate the expression of TGIF2 and OCT4 in tumor tissues ( P < 0. 05) . Conclusion miR-143-3p overexpression can inhibit the levels of proinflammatory factors, antioxidant capacity and stem cell-like characteristics of TC cells by down-regulating the expression of TGIF2, and inhibit the formation of tumors in nude mice.

Key words: miR-143-3p, thyroid cancer, pro-inflammatory factors, reactive oxygen species, OCT4