The Significance And Mechanism Of MicroRNA-206 In ER-positive Breast Cancer Cells

ObjectiveWe established lentivirus-mediated over-expression/low-expression of microRNA-206 in estrogen receptor-positive breast cancer cell line MCF-7 to study biological distinctions in these two cells and the control group MCF-7 in vitro. The study aims to investigate the function of microRNA-206 involved in cell proliferation and migration and whether 4-OH TAM effects three groups of cells’biological behaviors and sensitivity to endocrine therapy.Methods1. Lentivirus-mediated over-expression/low-expression of microRNA-206 in estrogen receptor-positive breast cancer cell line MCF-7.2. Quantitative real-time PCR was used to evaluate the expression of microRNA-206 in established cell lines and MCF-7.3. For the cell proliferation assay, tumor cells of each group were harvested and seeded at a density of 5000 cells/100 μL in triplicate respectively. Wound-healing assay was used to study cell migration. Flow cytometry was employed to distinguish cell apoptosis in each group.4. CCK-8 was used to detect the effects of 5μM 4-OH TAM on growth of three groups of cells after 48 hours, western blot was employed to detect the expression of interested proteins, and FCM was used to detect cell apoptosis.ResultsWe established MCF-7 with high/low-expressed miR-206 by lentiviral transduction. The level of miR-206 was highest in MCF-7 with high-expressed miR-206 among the three groups of cells (P< 0.05). MCF-7 with high-expressed miR-206 had a poorer ability of proliferation than the other two groups of cells. The migration ability of three groups of cells showed no significant difference in experimental group or control group after 48 or 72 hours. Flow cytometric results showed that MCF-7 and MCF-7 with high-expressed miR-206 had more proporation of apoptosis than MCF-7 with low-expressed miR-206 after TAM. MCF-7 with low-expressed miR-206 might be less sensitive than the other groups of cells. The expression of p21 incresed after treatment in MCF-7 and miR-206 high-expressed MCF-7 while the expression had no significant difference in MCF-7 with low-expressed miR-206 after administered TAM. In MCF-7 with high-expressed miR-206 and low-expressed miR-206 treated with TAM, the expression of bcl-2 was lower than the control groups; however, we didn’t discover the phenomena in MCF-7. The expression of ERα、NRP1、PKCε was lower in MCF-7 with high-expressed miR-206 than the other two groups of cells.ConclusionMicroRNA-206 might be involved in the regulation of ERa and apoptosis in ERa-positive breast cancer. MicroRNA-206 may be associated with sensitivity to endocrine therapy in ERa-positive breast cancer. NRP1 and PKCε may be downstream genes of microRNA-206. Further study is required to learn about these genes’effect on breast cancer cells.ObjectiveHost milieu during the perioperative period mayinfluence biological characteristics of micrometastatic foci and promote cancer migration and recurrence. It is controversial whether surgical intervention during different phases of menstrual cycle (a kind of host milieu) is associated with the prognosis of premenopausal breast cancer patients.MethodsWe performed a retrospective study of 554 premenopausal women with last menstrual period (LMP) records. Survival outcomes were compared between patients receiving surgery performed during the follicular phase (cycle days 1-14) and those during the luteal phase (days 15-31). Univariate survival analyses were performed by the Kaplan-Meier method and compared using the Log-rank test, while multivariate survival analyses were performed by Cox regression. A range of cutoff days from day 10 to 22 was used toobserve the risk trend and to exclude the possibility that different cutoff days might affect clinical outcomes.ResultsThe Cox proportional hazards regression analysis showed that the follicular phase was associated with a more favorable prognosis than the luteal phase in DFS (HR= 0.318,95% CI:0.10-0.99, P= 0.049) and in OS (HR=0.260,95% CI:0.07-0.92, P= 0.036). The follicular phase was associated with better prognosis when the cutoff day was set at day 14,18 and 19 in DFS and day 11,13 and 14 in OS. A low HR flat fluctuation was observed from cutoff day 10 to 22, and went up thereafter for both DFS and OS.ConclusionsSurgery performed during the follicular phase provides a more favorable prognosis when compared with the luteal phase. Individual timing of surgical treatment might be taken into account for tailored treatments of breast cancer patients.