Long noncoding RNA XIST suppresses tumorigenesis and enhances radiosensitivity in neuroblastoma cells through regulating miR-653-5p/HK2 axis

Abstract

Background: Abnormal expression of long noncoding RNAs (lncRNAs) was usually involved in tumorigenesis and radiosensitivity of various cancers. The aim of this study was to explore the biological function and regulatory mechanism of lncRNA X-inactive specific transcript (XIST) in tumorigenesis and radiosensitivity of neuroblastoma (NB).Methods: The expression levels of XIST, microRNA-653-5p (miR-653-5p) and hexokinase 2 (HK2) were detected by quantitative real-time polymerase chain reaction (qRT-PCR). Methylthiazolyldiphenyl tetrazolium bromide (MTT) assay, colony formation assay and transwell assay were utilized to detect cell viability, colony formation and cell invasion abilities. Glucose consumption or lactate production was measured by glucose assay kit or lactate assay kit, respectively. The mice xenograft model was established to investigate the role of XIST in vivo. The interaction between miR-653-5p and XIST or HK2 was predicted by starBase v2.0 and verified by dual-luciferase reporter, RNA Immunoprecipitation (RIP) and RNA pull-down assays. Western blot was used to measure the protein expression of HK2.Results: XIST and HK2 were highly expressed whilst miR-653-5p was lowly expressed in NB tissues and cells. XIST knockdown inhibited tumorigenesis by repressing NB cell proliferation and invasion. Meanwhile, XIST downregulation increased the radiosensitivity via inhibiting colony formation rates and glycolysis. Moreover, miR-653-5p could bind to XIST and its downregulation reversed the effects of XIST knockdown on tumorigenesis and radiosensitivity. Additionally, HK2 was a direct target of miR-653-5p and its overexpression attenuated the effects of miR-653-5p restoration on suppression of tumorigenesis and promotion of radiosensitivity. Besides, XIST functioned as a molecular sponge of miR-653-5p to regulate HK2 expression. Furthermore, XIST knockdown also suppressed tumor growth by upregulating miR-653-5p and downregulating HK2 in vivo.Conclusion: XIST interference inhibited tumorigenesis and increased radiosensitivity in NB by regulating miR-653-5p/HK2 axis, providing a novel therapeutic strategy for NB.

XIST in Brain Cancer

“…XIST is further implicated in neuroblastoma tumorigenesis by negatively affecting miR-653-5p, downregulating it and preventing it from targeting hexokinase 2 (HK2), a serine protease that is overexpressed in neuroblastoma [43]. Increased expression of HK2 attenuates the effects of miR-653-5p on the suppression of migration and proliferation.…”