MiR-466 as a poor prognostic predictor suppresses cell proliferation and EMT in breast cancer cells by targeting PSMA7.

OBJECTIVE

MiR-466 has been reported to exert a tumor-suppressive role in several cancers, including colorectal cancer and osteosarcoma, but its clinical significance and functional mechanisms in breast cancer (BC) pathogenesis still remain elusive.

PATIENTS AND METHODS

The expression of miR-466 was determined using reverse transcription quantitative PCR. The clinical significance of miR-466 in BC patients was assessed by Chi-square test, Kaplan-Meier method and Cox regression analyses. Functional experiments, including CCK-8 and transwell assays, were performed to analyze cell proliferation, migration and invasion ability. The association between miR-466 and proteasome subunit α7 (PSMA7) was confirmed by Luciferase reporter assay.

RESULTS

Here, we first observed that the expression of miR-466 was significantly downregulated in BC tissues and cell lines. The decreased miR-466 expression was significantly associated with tumor size (p = 0.003), lymph node metastasis (p = 0.008), TNM stage (p = 0.032) and poor survival rate. In addition, miR-466 was identified as an independent prognostic factor for BC patients. We further found that the overexpression of miR-466 significantly inhibited cell proliferation, migration and invasion. Mechanistically, PSMA7 was a potential target gene of miR-466 and negatively regulated miR-466 in BC cells. Oncomine database and Kaplan-Meier overall survival analysis indicated that upregulation of PSMA7 was associated with poor prognosis of BC patients. The rescue experiments demonstrated that PSMA7 overexpression reversed the effects of miR-466 on cell proliferation, migration, invasion and EMT transcription factors (E-cadherin, N-cadherin, and vimentin).

CONCLUSIONS

Collectively, these results suggest that the miR-466/PSMA7 axis might have potential as a therapeutic target for BC treatment.