ABSTRACT
Objective: To investigate the effects of silencing the regulator of ribosome synthesis 1 (RRS1) gene expression on proliferation, apoptosis, migration and invasion abilities of breast cancer BT549 cells, and to explore the possible mechanism. Methods: The expression levels of RRS1 mRNA and protein in breast cancer BT549 cells and normal mammary gland HMEC cells were detected by real-time fluorescent quantitative PCR and Western blotting, respectively. The lentivirus expression vector carrying RRS1-shRNA was constructed and transfected into BT549 cells, while the empty vector was used as the control. The silencing efficiency of RRS1 gene was identified by real-time fluorescent quantitative PCR and Western blotting, respectively. Then the proliferation, cell cycle, apoptosis, migration and invasion abilities of BT549 cells transfected with RRS1-shRNA were detected by MTT, FCM, DAPI staining and Transwell chamber assay, respectively. The expression levels of apoptosis-related proteins p53 and mouse double minute 2 homolog (MDM2) in BT549 cells transfected with RRS1-shRNA were detected by Western blotting. Results: The expression levels of RRS1 mRNA and protein in BT549 cells were significantly higher than those in the normal mammary gland HMEC cells (both P < 0.01). After transfection with RRS1-shRNA, the expression levels of RRS1 mRNA and protein in BT549 cells were significantly down-regulated as compared with the control group (both P < 0.01). After RRS1 gene silencing, the cell viability was significantly decreased (P < 0.01), the cell cycle was arrested at G2 phase (P < 0.01), the early apoptosis rate was significantly increased (P < 0.05), while the migration and invasion abilities were significantly decreased (both P < 0.05). The expression level of apoptosis-associated p53 protein was significantly up-regulated (P < 0.05), but the expression level of MDM2 protein was significantly down-regulated (P < 0.05) in BT549 cells after transfection with RRS1-shRNA. Conclusion: The RRS1 gene was highly expressed in breast cancer BT549 cells. RRS1, as a novel breast cancer related gene, maybe play an important role in the proliferation, apoptosis, migration and invasion of breast cancer cells.