关键词: 环状RNA, 乳腺癌, hsa_circ_0050900, 增殖, 迁移, 凋亡, 细胞周期

Abstract: Background and purpose: Circular RNA (circRNA), a special non-coding RNA generally low-expressed in vivo, is not easy to be degraded by RNA enzyme, and its structure and expression are stable. Nowadays, with the progress of RNA sequencing, the occurrence and development of a variety of tumors are related to the expression of circRNA. However, there is no report on the relationship between the occurrence and development of breast cancer and the abnormal expression of hsa_circ_0050900. This study aimed to explore the expression of hsa_circ_0050900 in breast cancer and the effect of its abnormal expression on the function of breast cancer cells. Methods: Four cases of female breast cancer and corresponding para-cancerous tissues after clinical operation from the First Affiliated Hospital of Chongqing Medical University were selected and sequenced by RNA sequencing (RNA-seq). Real-time fluorescence quantitative polymerase chain reaction (RTFQ-PCR) was used to verify the expression of hsa_circ_0050900 in breast cancer and breast cancer cells, including 30 samples of breast cancer tissues and their adjacent tissues (also from the First Affiliated Hospital of Chongqing Medical University), normal human breast epithelial cell line MCF-10A used as control cells, and two breast cancer cell lines MCF-7 and SK-BR-3. The expression level of hsa_circ_0050900 in breast cancer cells was detected by RTFQ-PCR. The proliferation and migration function of breast cancer cells were examined by cell counting kit-8 (CCK-8) assay, 5-ethynyl-2'-deoxyuridine (EdU) assay, wound healing assay and transwell assay. Apoptosis was detected by TUNEL one-step method. Hoechst 33342 test was used to determine the state of cells by nuclear staining for the detection of apoptosis. The expression levels of cyclin D2 (CCND2) and cyclin-dependent kinase 4 (CDK4) were detected by Western blot. Results: Based on the sequencing results, the circRNA hsa_circ_0050900 with high expression in breast cancer tissues and cells was selected. The expression of hsa_circ_0050900 in breast cancer cells was decreased by the constructed si-circ plasmid significantly. The proliferation ability of the cells transfected with si-circ was decreased, apoptosis was promoted, and the expression levels of cell cycle related proteins CCND2 and CDK4 were decreased. Conclusion: The expression of circRNA hsa_circ_0050900 is significantly higher in breast cancer than in para-cancerous tissues. Knocking down hsa_circ_0050900 can regulate cell proliferation, migration, apoptosis and cell cycle.

Key words: CircRNA, Breast cancer, hsa_circ_0050900, Proliferation, Migration, Apoptosis, Cell cycle