HIF1α-associated circDENND4C promotes proliferation of breast cancer cells in hypoxic environment

Background: Accumulating evidence has shown that hypoxia plays a key role in regulating proliferation of breast cancer cells. However, the mechanism of how hypoxia regulates breast cancer remains unclear. We sought to investigate if hypoxia regulated proliferation through circular RNA. Materials and Methods: Western blot was used to detect hypoxia-inducible factor 1 alpha (HIF1α) levels in breast cancer cells under hypoxic conditions. Candidate circular RNAs (circRNAs) were selected and quantified by quantitative real-time polymerase chain reaction (qRT-PCR) after hypoxia induction. CCK8 assay was used to investigate the changes of proliferation after interfering circDENND4C and HIF1a. Results: In breast cancer cells, circDENND4C was increased under hypoxic conditions and decreased after knocking-down HIF1α. In addition, knocking-down circDENND4C inhibited proliferation of breast cancer cells in a hypoxic environment. Finally, tumors with a large size had higher circDENND4C expression levels than those of small size. Conclusion: CircDENND4C is a HIF1α-associated circRNA promoting the proliferation of breast cancer cells under hypoxia