ABSTRACT Objective: To investigate the expression and mechanism of microRNA (miRNA)-613 in breast cancer. Methods: A total of 91 specimens of breast cancer tissue were collected from Nanchong Central Hospital between May 2017 and May 2018. Quantitative real-time PCR (qRT-PCR) was used to estimate miRNA-613 expression levels in breast cancer and adjacent tissues and breast cancer ( cells MDA-MB-231, MDA-MB-468, and MCF-7) and normal breast epithelial (HBL-100) cell lines. Based on these data, the relationship between miRNA-613 expression and clinicopathological characteristics and prognosis in breast cancer patients were analyzed using the cancer genome atlas (TCGA) database. A dual-luciferase reporter assay was used to detect the binding of miRNA-613 to the 3'UTR of SOX9. Effects on cell proliferation and cell invasion and migration upon transfection of MDA-MB-231 cells with miRNA-613 mimics were detected by the CCK-8 assay and Transwell invasion and migration assays, respectively. In addition, Western blot was used to estimate the expression levels of SOX9, β-catenin, E-cadherin, and Vimentin in the transfected cells. Results: The expression of miRNA-613 in breast cancer tissues was significantly lower than that in adjacent tissues (P<0.05) and was found to be closely related to TNM stage and lymph node metastasis (P<0.05). TCGA survival data showed that miRNA-613 expression was not related to the overall survival rate of breast cancer patients (P>0.05 ). The expression of miRNA-613 in breast cancer cell lines was significantly lower than that in the normal breast epithelial cell line (P<0.05). Similarly, the expression of miRNA-613 in highly invasive metastatic breast cancer cell lines (MDA-MB-231 and MDA-MB-468) was significantly lower than that in the metastatic breast cancer cell line MCF-7 with lower invasion ability (P<0.05). The dual-luciferase reporter assay showed that miRNA-613 could specifically bind to the 3'UTR of SOX9. Upregulation of miRNA-613 expression could inhibit the proliferation, invasion, and migration of MDA-MB-231 cells (P<0.05). This was associated with the downregulated expression of SOX9, β-catenin, and Vimentin (P<0.05) and upregulation of E-Cadherin expression (P<0.05). Conclusions: The expression of miRNA-613 was decreased in breast cancer tissues and cell lines. MiRNA-613 may inhibit the proliferation, invasion, and metastasis of breast cancer cells and epithelial-mesenchymal transition by regulating the SOX9 and Wnt/β-catenin signaling pathways.

Objective:To explore the application and practice of "flipped classroom" in the teaching of general surgery interns.Methods:A total of 20 internship groups (3 to 5 people in each group) were randomly selected from the general surgery practice group in the Department of General Surgery of the Second Clinical Medical College of North Sichuan Medical College. They were randomly divided into the flipped group (45 people) and the traditional group (40 people), with 10 subgroups in each group. The flipped group adopted the flipped classroom teaching mode (students' self-study by handing out materials before class, students and teachers' discussion in class, and students and teachers' evaluation after class), while the control group adopted the current conventional teaching mode (students' preview before class, teachers' explanation in class, and teachers' question answering after class). At the end of the teaching, a questionnaire was used to evaluate the participation and completion of each student. The teaching effect was evaluated by medical history collection and case analysis. The participation, completion, and teaching effect between the two groups were compared and analyzed. SPSS 23.0 software was used for t-test and Chi-square test. Results:The participation of the flipped group was better than that of the traditional group [(17.45±1.83) vs. (15.57±1.52)], and the difference was statistically significant ( P < 0.05). There was no statistically significant difference between the flipped group and the traditional group. There was no significant difference in medical history collection scores between the two groups. The case analysis of the flipped group was better than that of the traditional group [(87.30±6.06) vs. (81.50±5.88), P < 0.05]. The questionnaire shows that about 90% of the students think that flipped classroom can improve their interest in learning [96% (43/45)], improve their autonomous learning ability [89% (40/45)], and have better learning effect. At the same time, 78% (35/45) of students think that learning time is too long. Conclusion:The flipped classroom teaching model can improve the teaching participation of general surgery students, improve students' interest in learning, improve their self-learning ability, and improve students' thinking ability of medical record analysis.