Hypoxia-inducible factor-1α regulates chemokine receptor type 4 to activate AKT/mTOR pathway to promote the viability and migration of diffuse large B cell lymphoma cells

Abstract

Background To investigate the effects of hypoxia-inducible factor-1α (HIF-1α) on the viability and migration of diffuse large B cell lymphoma (DLBCL) cells and the underlying mechanisms. Methods HIF-1α overexpression and knockdown plasmids were constructed and transfected into DLBCL cells. The efficacy of HIF-1α expression was detected via real time quantitative polymerase chain reaction (RT-qPCR). Whether overexpression and knockdown HIF-1α affect the expression of chemokine receptor type 4 (CXCR4) and promote cells proliferation and migration were detected via CCK8 assay and Transwell assay. How HIF-1α works on CXCR4 was measured by double fluorescent reporter assay and chromatin immunoprecipitation (ChIP) assay. The expression level of CXCR4 and AKT/mTOR pathway-related proteins were detected via Western blot assay. Results CCK8 assay and Transwell assay showed that both hypoxic conditions and HIF-1α overexpression under normoxia promoted the viability and migration of DLBCL cells while HIF-1α knockdown showed inhibitory effects. The effects of HIF-1α on DLBCL cells were suppressed when the expression of CXCR4 was inhibited. Double fluorescent reporter enzyme assay and ChIP assay showed that HIF-1α combined with the functional site HRE1 of CXCR4 promoter to promote the transcription of CXCR4. Western blot assay demonstrated that HIF-1α promoted the expression of CXCR4 to activate the phosphorylation of AKT/mTOR pathway under hypoxia. Conclusion HIF-1α regulated CXCR4 by binding to the functional site HRE1 of CXCR4 promoter and further activate AKT / mTOR signaling pathway, thereby promoting the viability and migration of DLBCL cells under hypoxia.