UCA1 Overexpression Promotes Hypoxic Breast Cancer Cell Proliferation and Inhibits Apoptosis via HIF-1α Activation

The noncoding RNA termed urothelial carcinoma-associated 1 (UCA1) is an oncogenic lncRNA involved in promoting the growth of several tumors through various pathways. The aim of this study was to explore the expression of UCA1 in hypoxic breast cancer and its impact on tumorigenesis in low levels of oxygen. Here, we show that UCA1 is upregulated in a number of hypoxic (1% O(2)) breast cancer cells. In addition, UCA1 expression is significantly overexpressed in breast cancer tissues compared to matched normal cells. UCA1 knockdown in hypoxia inhibits breast cancer proliferation and induces apoptosis. The knockdown of hypoxia-inducible transcription factor 1α (HIF-1α) but not HIF-2α significantly decreases the expression of UCA1 in hypoxia. Overall, these findings indicate that UCA1 is a hallmark of hypoxic breast cancer and its expression is positively regulated by HIF-1α.