The lncRNA HOXA11-AS acts as a tumor promoter in breast cancer through regulation of the miR-125a-5p/TMPRSS4 axis.

BACKGROUND

Long non-coding RNAs (lncRNAs) play vital roles in tumorigenesis. Here, we explored how lncRNA HOXA11-AS functions in the progression of breast cancer (BC).

METHODS

HOXA11-AS and miR-125a-5p levels were measured by a quantitative real-time polymerase chain reaction, whereas western blotting determined TMPRSS4 levels in BC tumor tissues, adjacent normal tissues and BC cell lines. The roles of HOXA11-AS, miR-125a-5p and TMPRSS4 in BC proliferation were investigated using cell counting kit-8, colony formation and flow cytometry assays, whereas scratch and transwell assays were used to measure metastasis. RNA pull-down assays and dual-luciferase assays assessed direct interactions between HOXA11-AS and miR-125a-5p. The effects of HOXA11-AS in vivo were investigated in a BC xenograft model.

RESULTS

HOXA11-AS was upregulated in tumor tissues of 56 BC patients compared to adjacent non-tumor tissues, with high levels being associated with worse overall survival. Silencing of HOXA11-AS inhibited the proliferation and metastasis of BC cells, leading to cell cycle arrest in G0/G1 and induction of apoptosis. We identified miR-125a-5p as a target of HOXA11-AS, with miR-125a-5p inhibitors partially restoring the reduction of cell proliferation and metastasis induced by HOXA11-AS silencing. We also determined that miR-125a-5p targeted TMPRSS4 mRNA, with HOXA11-AS knockdown and miR-125a-5p mimics suppressing TMPRSS4. Overexpression of TMPRSS4 partially compensated for the reduction of cell proliferation and metastasis induced by HOXA11-AS silencing. Finally, we confirmed the mechanism of HOXA11-AS in the regulation of tumorigenesis in the mouse model.

CONCLUSIONS

HOXA11-AS regulates the tumorigenic ability of BC via the miR-125a-5p/TMPRSS4 axis. This provides insights for regulatory mechanisms involved in BC progression, and may enable new treatment strategies in the clinical setting.