JAK2 inactivating mutations promotes endometrial cancer progression by targeting HIF-1α.

Objective: Endometrial cancer (EC) is the ninth most common malignancy among women. While mutations in JAK2 are frequently observed in EC, the specific biological functions of JAK2 in endometrial cancer are poorly understood.

Methods: The genetic alterations of JAK2 in different cancer types were explored using sequencing dataset deposited at TCGA database. JAK2 mutations were detected in EC formalin-fixed paraffin-embedded (FFPE) samples using Sanger sequencing. The expression levels of JAK2 was accessed using the TCGA database and immunohistochemistry. Furthermore, the relationships between JAK2 expression and staging and prognosis of EC patients were investigated using the TCGA database. Down-regulation of JAK2 were achieved by transient transfection with short hairpin RNAs (shRNAs). Effects of JAK2 on cancer cells proliferation and migration were evaluated by CCK8, colony formation, and transwell assay. The potential biological functions of JAK2 in EC were identified based on bioinformatics analysis. Effects of JAK2 on expression levels of target genes were detected by RT-qPCR and western blotting. Co-immunoprecipitation (co-IP) assays was used to detect the physical association between JAK2 and HIF-1α.

Results: Frequent mutations and down-regulation of JAK2 were found in EC. Loss-of-function (LOF) assays suggested that JAK2 silencing in endometrial cancer cells promoted cell proliferation and migration, which were partially dependent on HIF-1α signaling pathway. Furthermore, our findings demonstrated that JAK2 interacted with HIF-1α and reduced HIF1α protein expression under hypoxia.

Conclusion: These findings revealed novel molecular mechanisms underlying JAK2 LOF mutations-driven endometrial tumorigenesis and revealed that the HIF-1α pathway may be a potential therapeutic target in JAK2-mutated endometrial cancer.