THE EFFECTS OF MIRNA-628-3P ON BREAST CANCER CELL PROLIFERATION AND ITS MECHANISM OF ACTION

Liqiang Qi^{1, *}, Bo Sun², Beibei Yang², Su Lu²

¹Department of Breast Surgical Oncology, Cancer Institute and Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, PR China - ²The 2nd Department of Breast Cancer Tianjin Medical University Cancer Institute and Hospital, Tianjin 300060, PR China

Objective: This study mainly explored the effects miRNA-628-3p on breast cancer cell proliferation and its mechanism of action in this context. 

Methods: Well-growing cells were seeded in a 12-well plate at 3-5 × 10⁴/ml and a lentivirus was used to infect the breast cancer cells. 48 hours after the cells were infected with lentivirus, when the cells were fused to 90%, fresh culture medium containing the lowest selected concentration of puromycin was added to screen the breast cancer cell lines. Cells in the logarithmic growth phase were transferred to a 6 cm petri dish, 20-50 μl of DEPC water was added, and the samples were incubated in a water bath at 60 °C for 5 min. The RNA samples were stored at -70 °C until further processing. After a 100-fold dilution of the RNA samples, a UV spectrophotometer was used to calculate the RNA concentration. The adherent cells were digested with trypsin and the cell clumps were collected into Eppendorf tubes by centrifugation. After centrifugation, the supernatant was carefully aspirated and transferred to a new tube, and about 5 μl was retained for protein concentration determination. 

Results: After methylation-specific PCR detection, the positive rates of miRNA-628-3p gene methylation in cancer tissues and adjacent tissues were 60% (6/10) and 4% (4/10), respectively. The difference between the two groups was statistically significant (p<0.05). 

Conclusion: The results show that miRNA-628-3p acts as a tumour suppressor gene in breast cancer cells. Increased expression of miRNA-628-3p is a relatively specific molecular marker for a good prognosis in patients with luminal (ER-positive) breast cancer.