Nuclear Respiratory Factor 1 Drives Hepatocellular Carcinoma Progression By Forming A Positive Feedback Loop With LPCAT1-ERK1/2-CREB Axis

Background: Liver cancer is the third leading cause of cancer related deaths worldwide and hepatocellular carcinoma(HCC)accounts for over 80% of all liver cancer cases.Although surgical treatment,radiotherapy,chemotherapy,targeted therapy,immunotherapy has made great progress,the prognosis of HCC was not improved significantly.Therefore,it’s urgent to investigate the molecular mechanism of genesis and development of HCC in order to find novel treatment target for it and improve its prognosis.Nuclear respiratory factor 1 is a transcription factor that regulates mitochondria biogenesis,but its role in HCC and the underlying mechanism is largely unknown.This study aims to explore the biological function of NRF1 in HCC and the relevant regulation mechanism.Methods: HCC transcriptome sequencing data was downloaded from The cancer Genome Atlas(TCGA)and differentially expressed gene analysis,clinicopathological parameter analysis,survival analysis,gene set enrichment analysis(GSEA)were conducted to investigate the expression level and the biological function of NRF1 in HCC preliminarily.In HCC clinical specimens and cell lines,NRF1 expression level was detected by q RT-PCR and Western Blot.After NRF1 knockdown or overexpression in HCC cell lines,CCK8 cell proliferation assay,colony formation assay,flow cytometry analysis,transwell migration or invasion assay,wound healing assay,nude mice subcutaneous tumor fornation model or tail vein injection lung metastasis tumor model were performed to analyze the effect of NRF1 on HCC cell proliferation and metastasis.q RT-PCR,Western Blot,Ch IP-PCR,dual luciferase reporter gene assay were utilized to investigate the underlying mechanism.Results: NRF1 was overexpressed and hyperactive in HCC tissue and cell lines and high expression of NRF1 was correlated with unfavorable prognosis of HCC patients.NRF1 promoted proliferation,migration and invasion of HCC cells both in vitro and in vivo.Mechanistically,NRF1 activated ERK1/2-CREB signaling pathway by transactivating lysophosphatidylcholine acyltransferase 1(LPCAT1),thus promoting cell cycle progression and epithelial mesenchymal transition(EMT)of HCC cells.Meanwhile,LPCAT1 upregulated the expression of NRF1 by activating ERK1/2-CREB signaling pathway through catalyzing the synthesis of dipalmitoyl phosphatidylcholine(DPPC),forming a positive feedback loop.Conclusions: NRF1 is overexpressed in HCC and promotes the proliferation and migration of HCC cells through NRF1-LPCAT1-ERK1/2-CREB positive feedback loop.