Hypoxia-inducible factor-1α contributes to the proliferation of cholesteatoma keratinocytes through regulating endothelin converting enzyme 1 expression.

Objective: Cholesteatoma is a hyperproliferative, pseudoneoplastic lesion of the middle ear characterized by aggressive growth and bone destruction. Hypoxia-inducible factor-1α (HIF-1α, also known as HIF1A) is a key transcription factor that enters the nucleus and upregulates many genes involved in cancer progression in the oxygen-free environment. This study is designed to explore the role and mechanism of HIF1A in the progression of cholesteatoma. Methods: HIF1A and endothelin converting enzyme 1 (ECE1) levels were determined using real-time quantitative polymerase chain reaction. The protein levels of HIF1A, Cyclin D1, proliferating cell nuclear antigen, and ECE1 were measured using western blot. Cell viability, proliferation, and cell cycle progression were analyzed using cell counting kit-8, Colony formation, 5-ethynyl-2'-deoxyuridine, and flow cytometry assays. Binding between HIF-1α and ECE1 promoter was predicted by Jaspar and verified using Chromatin immunoprecipitation and dual-luciferase reporter assays. Results: HIF1A and ECE1 were highly expressed in cholesteatoma patients and keratinocytes. Moreover, HIF1A knockdown might suppress the cell viability, proliferation, and cycle progression of cholesteatoma keratinocytes. Furthermore, HIF1A upregulated the transcription of ECE1 through binding to its promoter region. Conclusion: HIF1A might expedite cholesteatoma keratinocyte proliferation partly by increasing ECE1 expression, providing a possible therapeutic target for the cholesteatoma treatment.