Abstract
Breast cancer is the most frequently diagnosed malignancy in women. However, the molecular mechanisms underlying breast cancer pathogenesis are not fully understood. The present study examined the role of miR-433 in breast cancer and investigated its underlying molecular mechanisms of action. Reverse transcription-quantitative polymerase chain reaction and western blot analysis were performed to analyze the level of microRNA (miRNA/miR)/mRNA and protein expression, respectively. Additionally, MTT assay was used to determined cell proliferation and viability. Cell apoptosis was measured by flow cytometry. A dual-luciferase reporter assay was used to confirm the identity of the downstream target of miR-433. The results revealed that miR-433 was downregulated in breast cancer tissues and cell lines. Overexpression of miR-433 inhibited cell proliferation and cell viability in BT-549 cells, whereas downregulation of miR-433 increased cell proliferation and cell viability in MDA-MB-231 cells. Further flow cytometry analysis revealed that miR-433 was able to induce apoptosis and also alter the levels of proteins expression of B-cell lymphoma-2 and Bcl-associated X. Bioinformatics analysis showed that RAC-γ serine/threonine-protein kinase (AKT3) was one of the downstream targets of miR-433, and luciferase reporter assay further confirmed that AKT3 is a direct target of miR-433. The knockdown of AKT3 was able to inhibit proliferation and viability in BT-549 cells. Overexpression of AKT3 prevented the inhibitory effects of miR-433 on proliferation and viability in BT-549 cells. The level of AKT3 mRNA expression was upregulated in breast cancer tissues compared with normal tissues and was inversely correlated with miR-433 expression levels. In summary, the results of the present study results indicate that the tumor-suppressive role of miR-433 may be mediated by regulating AKT3. miR-433 may therefore serve as a potential therapeutic target for breast cancer.