MiR-301b-3p promotes breast cancer development through inhibiting the expression of transforming growth factor-beta receptor 2.

Background: Breast cancer (BC) is a serious health threat to the patients. The present work explored the mechanism of miR-301b-3p and transforming growth factor-beta receptor 2 (TGFBR2 ) in affecting BC progression.

Methods: The miR-301b-3p-inhibitor and si-TGFBR2 solution were added to the DEME/F12 medium to culture the BC and normal breast epithelial cell lines to prepare negative control, miR-301b-3p-IN and miR-301b-3p-IN+si-TGFBR2 in the two types of cell lines. The relative expression of target genes and the interference effect were analyzed by quantitative real-time PCR (qRT- PCR). Cell viability was detected applying cell counting kit-8 (CCK-8) assay. Transwell and wound healing assay were conducted to evaluate the invasion and migration of BC cells after miR-301b-3p inhibition. Additionally, cell apoptosis and the expression STAT protein were measured by flow cytometry and Western blot, respectively.

Results: The qRT-PCR results showed that miR-301b-3p were high-expressed but the level of TGFBR2 was significantly inhibited in BC cells. The miR-301b-3p-inhibitor significantly downregulated the expression of miR-301b-3p and upregulated that of TGFBR2. Meanwhile, inhibition of miR-301b-3p suppressed the cell viability, invasion, and migration of BC cells, which, however, were restored by the inhibition of TGFBR2. MiR-301b-3p conferred anti-apoptosis ability to BC cells, while TGFBR2 promoted apoptosis of BC cells through producing an antagonistic effect with miR-301b-3p. We found that miR-301b-3p played a crucial role in the phosphorylation of STAT1 and STAT3 to promote BC progression.

Conclusion: The present findings demonstrated that miR-301b-3p played a crucial role in promoting BC cell growth, invasion and migration and anti-apoptosis, and that targeting TGFBR2 could inhibit the tumor-promoting effect of miR-301b-3p.