Background:Gastric cancer(GC)is one of the most common malignancies worldwide,particularly in China.DNA damage-inducible transcript 4(DDIT4)is a mammalian target of rapamycin inhibitor and is induced by various cellul...Background:Gastric cancer(GC)is one of the most common malignancies worldwide,particularly in China.DNA damage-inducible transcript 4(DDIT4)is a mammalian target of rapamycin inhibitor and is induced by various cellular stresses;however,its critical role in GC remains poorly understood.The present study aimed to investigate the poten-tial relationship and the underlying mechanism between DDIT4 and GC development.Methods:We used western blotting,real-time polymerase chain reaction,and immunohistochemical or immunoflu-orescence to determine DDIT4 expression in GC cells and tissues.High-content screening,cell counting kit-8 assays,colony formation,and in vivo tumorigenesis assays were performed to evaluate cell proliferation.Flow cytometry was used to investigate cell apoptosis and cell cycle distribution.Results:DDIT4 was upregulated in GC cells and tissue.Furthermore,downregulating DDIT4 in GC cells inhibited proliferation both in vitro and in vivo and increased 5-fluorouracil-induced apoptosis and cell cycle arrest.In contrast,ectopic expression of DDIT4 in normal gastric epithelial cells promoted proliferation and attenuated chemosensitivity.Further analysis indicated that the mitogen-activated protein kinase and p53 signaling pathways were involved in the suppression of proliferation,and increased chemosensitivity upon DDIT4 downregulation.Conclusion:DDIT4 promotes GC proliferation and tumorigenesis,providing new insights into the role of DDIT4 in the tumorigenesis of human GC.展开更多
Persistent hepatic cellular metabolic stress and liver inflammatory stimuli are key signatures of nonalcoholic steatohepatitis(NASH).DDX3X is a vital molecule involved in cell fate decisions in both pro-survival stres...Persistent hepatic cellular metabolic stress and liver inflammatory stimuli are key signatures of nonalcoholic steatohepatitis(NASH).DDX3X is a vital molecule involved in cell fate decisions in both pro-survival stress granule(SG)and pro-death NOD-like receptor family pyrin domain containing 3(NLRP3)inflammasome assembly in response to stress signals.However,the role of DDX3X in NASH remains unclear.We characterized the cell type-specific roles of DDX3X in NASH.Human liver tissues from NASH patients and normal control subjects were collected to assess DDX3X expression and distribution.Nutritional steatohepatitis models were constructed by feeding macrophage-specific DDX3X knockout(DDX3^(XΔMφ)),hepatocyte-specific DDX3X knockout(DDX3X^(Δhep)),and wild-type control(DDX3X^(fl/fl))mice a high-fat and high-cholesterol(HFHC)diet,a methionine-and choline-deficient(MCD)diet,and a high-fat/high-iron/high-fructose/high-cholesterol,low-methionine,and choline-deficient(HFHIHFHC-MCD)diet.The study demonstrated that DDX3X was predominantly expressed in macrophages and hepatocytes in control liver tissues,and its expression was down-regulated in patients or mice with NASH.Compared to DDX3X^(fl/fl) littermates,DDX3^(XΔMφ)mice showed improved liver histology in nutritional steatohepatitis models.Loss of macrophage DDX3X inhibited NLRP3 inflammasome-mediated pyroptosis,causing anti-inflammatory M2 polarization and alleviating hepatocyte steatohepatitic changes.DDX3X^(Δhep) mice developed marked steatohepatitis in multiple nutritional steatohepatitis models compared to DDX3X^(fl/fl) littermates.DDX3X-deleted hepatocytes showed impaired SG assembly,leading to increased sensitivity and intolerance to metabolic stimulation and resultant steatohepatitis.In conclusion,DDX3X plays opposite roles in different cell types during the progression of NASH.A better understanding of the cell-specific differences in the crosstalk between SG formation and NLRP3 activation is crucial for developing prospective targeted DDX3X inhibitors for the treatment of NASH.展开更多
基金supported by the National Natural Science Foundation of China(Nos.81430072,81421003,81602641,81572929).
文摘Background:Gastric cancer(GC)is one of the most common malignancies worldwide,particularly in China.DNA damage-inducible transcript 4(DDIT4)is a mammalian target of rapamycin inhibitor and is induced by various cellular stresses;however,its critical role in GC remains poorly understood.The present study aimed to investigate the poten-tial relationship and the underlying mechanism between DDIT4 and GC development.Methods:We used western blotting,real-time polymerase chain reaction,and immunohistochemical or immunoflu-orescence to determine DDIT4 expression in GC cells and tissues.High-content screening,cell counting kit-8 assays,colony formation,and in vivo tumorigenesis assays were performed to evaluate cell proliferation.Flow cytometry was used to investigate cell apoptosis and cell cycle distribution.Results:DDIT4 was upregulated in GC cells and tissue.Furthermore,downregulating DDIT4 in GC cells inhibited proliferation both in vitro and in vivo and increased 5-fluorouracil-induced apoptosis and cell cycle arrest.In contrast,ectopic expression of DDIT4 in normal gastric epithelial cells promoted proliferation and attenuated chemosensitivity.Further analysis indicated that the mitogen-activated protein kinase and p53 signaling pathways were involved in the suppression of proliferation,and increased chemosensitivity upon DDIT4 downregulation.Conclusion:DDIT4 promotes GC proliferation and tumorigenesis,providing new insights into the role of DDIT4 in the tumorigenesis of human GC.
基金grants from the National Natural Science Foundation of China(nos.82000548,82100621,82170574,and 81402337)the Funding for Clinical Trials from the Affiliated Drum Tower Hospital,Medical School of Nanjing University(no.2021-LCYJ-PY-4)and the Natural Science Fund of Jiangsu Province(no.BK20210147).
文摘Persistent hepatic cellular metabolic stress and liver inflammatory stimuli are key signatures of nonalcoholic steatohepatitis(NASH).DDX3X is a vital molecule involved in cell fate decisions in both pro-survival stress granule(SG)and pro-death NOD-like receptor family pyrin domain containing 3(NLRP3)inflammasome assembly in response to stress signals.However,the role of DDX3X in NASH remains unclear.We characterized the cell type-specific roles of DDX3X in NASH.Human liver tissues from NASH patients and normal control subjects were collected to assess DDX3X expression and distribution.Nutritional steatohepatitis models were constructed by feeding macrophage-specific DDX3X knockout(DDX3^(XΔMφ)),hepatocyte-specific DDX3X knockout(DDX3X^(Δhep)),and wild-type control(DDX3X^(fl/fl))mice a high-fat and high-cholesterol(HFHC)diet,a methionine-and choline-deficient(MCD)diet,and a high-fat/high-iron/high-fructose/high-cholesterol,low-methionine,and choline-deficient(HFHIHFHC-MCD)diet.The study demonstrated that DDX3X was predominantly expressed in macrophages and hepatocytes in control liver tissues,and its expression was down-regulated in patients or mice with NASH.Compared to DDX3X^(fl/fl) littermates,DDX3^(XΔMφ)mice showed improved liver histology in nutritional steatohepatitis models.Loss of macrophage DDX3X inhibited NLRP3 inflammasome-mediated pyroptosis,causing anti-inflammatory M2 polarization and alleviating hepatocyte steatohepatitic changes.DDX3X^(Δhep) mice developed marked steatohepatitis in multiple nutritional steatohepatitis models compared to DDX3X^(fl/fl) littermates.DDX3X-deleted hepatocytes showed impaired SG assembly,leading to increased sensitivity and intolerance to metabolic stimulation and resultant steatohepatitis.In conclusion,DDX3X plays opposite roles in different cell types during the progression of NASH.A better understanding of the cell-specific differences in the crosstalk between SG formation and NLRP3 activation is crucial for developing prospective targeted DDX3X inhibitors for the treatment of NASH.
