Hypoxia-driven DDIT4 deficiency suppresses autophagy and drives metabolic reprogramming to promote hepatocellular carcinoma proliferation by activating mTORC1 pathway
QIN Heyao
QIAN Meirui
SHU Taiyu
WANG Dan
DUAN Yixin
JIANG Jianli
Abstract：Objective To investigate the dynamic regulation of DNA damage-inducible transcript 4(DDIT4)in the adaptation of hepatocellular carcinoma(HCC)cells to hypoxic microenvironments and its impact on malignant behavior.Methods A hypoxic model of HCC cells was established using CoCl2 to simulate hypoxic conditions,and the expression of DDIT4 was detected.A stable DDIT4 knockdown cell line was constructed using lentivirus-mediated RNA interference.Cell proliferation and autophagy were assessed using CCK-8 and Western blotting.Transcriptomic and metabolomic sequencing were employed to analyze changes in metabolic pathways.The phosphorylation level of key mTORC1 site(Ser2448)was detected to elucidate the molecular regulatory mechanisms.Results Hypoxic treatment induced dynamic changes in DDIT4 expression in HepG2 cells,with a peak at 24 h followed by a significant decline at 48 h(P＜0.01).DDIT4 knockdown significantly enhanced cell proliferation(P＜0.01)and inhibited autophagic flux(P＜0.05).Integrated transcriptomic and metabolomic analyses further revealed that DDIT4 deficiency led to abnormalities in glycolysis and purine metabolism,along with imbalances in redox homeostasis.Mechanistically,DDIT4 deficiency significantly increased the phosphorylation activity of mTORC1(Ser2448)(P＜0.05).Conclusion Through dynamical regulation of mTORC1 pathway,DDIT4 coordinates hypoxic adaptation of HCC and relieves stress damage through upregulation in the early phase,while its later depletion triggers excessive mTORC1 activation,driving metabolic reprogramming and malignant proliferation.Analyzing the dynamic regulation of DDIT4 in different stages of hypoxia may provide novel therapeutic strategies to overcome clinical challenges in HCC,including chemoresistance and postoperative recurrence.
Keywords：hepatocellular carcinomaDDIT4autophagymetabolic reprogrammingmTORC1
Publication Date：2025-07-31
Online Publishing Date：2026-08-26(First online date of this platform, not the publication date of the document)
Pages：7( 937-943 )