Objectives:The eukaryotic initiation factor 4F(eIF4F)translation initiation complex inhibitors(eIF4Fi)were recently found to hyperactivate extracellular signal-regulated kinases 1/2(ERK1/2)signals,which contribute to ...Objectives:The eukaryotic initiation factor 4F(eIF4F)translation initiation complex inhibitors(eIF4Fi)were recently found to hyperactivate extracellular signal-regulated kinases 1/2(ERK1/2)signals,which contribute to acquired resistance to BRAF(B-Raf proto-oncogene,serine/threonine kinase)inhibitors in melanoma.This present study aims to elucidate how to overcome the resistance of the eIF4Fi in BRAFV600E mutant melanoma cells and explore the underlying mechanisms.Methods:Melanoma A375(vemurafenib[VEM]-sensitive)and A375R(VEM-resistant)cells were exposed to eIF4Fi RocA at varying doses and durations in vitro.We investigated the impact of RocA on the activity of ERK1/2,AKT serine/threonine kinase 1(AKT1),eIF4E,and enhancer of zeste homolog 2(EZH2).We then examined the impact of RocA on pro-apoptotic BH3-only proteins and proliferative proteins.We subsequently determined the effect of combined eIF4Fi,AKT1 inhibitor,EZH2 inhibitor or VEM on tumor growth in vitro and in vivo.Results:RocA inhibited proliferation and induced apoptosis in A375 cells,but inhibited proliferation in A375R cells.RocA rapidly reactivated ERK1/2 at 3 h and returned to baseline levels at 48 h.However,eIF4E and AKT1 activation began at 12 h and peaked at 48 h.ERK1/2 positively regulated EZH2 and EZH2-dependent expression of c-Fos and EGR1,while AKT1 negatively regulated c-Myc,c-Jun,and BMF,but positively regulated eIF4E.RocA downregulated ERK1/2(or EZH2,AKT1,and eIF4E)independent bcl-2 and Mcl-1 expression.AKT1i enhanced RocA-induced cell apoptosis,while EZH2i reduced RocA-induced cell proliferation.Combined CR-1-31-B,EZH2i,and AKT1i effectively overcame resistance to RocA and VEM resistance both in vitro and in vivo.Conclusion:The eIF4F complex inhibitor reactivates ERK1/2-EZH2 and AKT1 signaling pathways,resulting in resistance to both eIF4Fi and VEM.Combined administration of an eIF4Fi with EZH2 and AKT1 inhibitors effectively enhances sensitivity to both eIF4F complex and BRAF inhibitors.展开更多
Zinc finger protein 36(ZFP36)was found to be downregulated in osteosarcoma(OS)tumor tissues.We aimed to investigate the roles and mechanisms of ZFP36 in ferroptosis regulation during OS development.Two Gene Expression...Zinc finger protein 36(ZFP36)was found to be downregulated in osteosarcoma(OS)tumor tissues.We aimed to investigate the roles and mechanisms of ZFP36 in ferroptosis regulation during OS development.Two Gene Expression Omnibus(GEO)datasets showed that ZFP36 was a differentially expressed gene(DEG)in OS.Western blot and immunohistochemistry results showed that ZFP36 was downregulated in OS tumors and cell lines.ZFP36 overexpression plasmids and small interfering RNAs(siRNAs)were respectively transfected into OS cells.ZFP36 overexpression restrained proliferation,migration,and invasion in MG63 and U2OS cells,while ZFP36 knockdown displayed the opposite results.Moreover,ZFP36 overexpression increased the levels of intracellular Fe2t,reactive oxygen species(ROS),and malondialdehyde(MDA),and decreased the levels of glutathione(GSH),glutathione peroxidase 4(GPX4),and solute carrier family 7 member 11(SLC7A11).ZFP36 overexpression disturbed mitochondrial membrane potential(MMP)and mitochondrial morphology in OS cells.However,ZFP36 knockdown had the opposite results.Mechanistic studies indicated that ZFP36 promoted E2F transcription factor 1(E2F1)messenger RNA(mRNA)degradation by binding to the AU-rich elements(AREs)within E2F130 untranslated region(30UTR)in OS cells.E2F1 overexpression abrogated the effects of ZFP36 overexpression on malignant progression,ferroptosis,and mitochondrial dysfunction in OS cells.Furthermore,E2F1 promoted the transcription activation of activating transcription factor 4(ATF4)by binding to ATF4 promoter.E2F1 knockdown inhibited malignant progression,and promoted ferroptosis and mitochondrial dysfunction in OS cells,which was abrogated by ATF4 overexpression.Additionally,MG63 cells transfected with lentivirus ZFP36 overexpression vector(Lv-ZFP36)were injected into nude mice and tumor growth was monitored.ZFP36 overexpression significantly suppressed OS tumor growth under in vivo settings.In conclusion,ZFP36 overexpression promoted ferroptosis and mitochondrial dysfunction and inhibited malignant progression in OS by regulating the E2F1/ATF4 axis.We may provide the promising ZFP36 target for OS treatment.展开更多
文摘Objectives:The eukaryotic initiation factor 4F(eIF4F)translation initiation complex inhibitors(eIF4Fi)were recently found to hyperactivate extracellular signal-regulated kinases 1/2(ERK1/2)signals,which contribute to acquired resistance to BRAF(B-Raf proto-oncogene,serine/threonine kinase)inhibitors in melanoma.This present study aims to elucidate how to overcome the resistance of the eIF4Fi in BRAFV600E mutant melanoma cells and explore the underlying mechanisms.Methods:Melanoma A375(vemurafenib[VEM]-sensitive)and A375R(VEM-resistant)cells were exposed to eIF4Fi RocA at varying doses and durations in vitro.We investigated the impact of RocA on the activity of ERK1/2,AKT serine/threonine kinase 1(AKT1),eIF4E,and enhancer of zeste homolog 2(EZH2).We then examined the impact of RocA on pro-apoptotic BH3-only proteins and proliferative proteins.We subsequently determined the effect of combined eIF4Fi,AKT1 inhibitor,EZH2 inhibitor or VEM on tumor growth in vitro and in vivo.Results:RocA inhibited proliferation and induced apoptosis in A375 cells,but inhibited proliferation in A375R cells.RocA rapidly reactivated ERK1/2 at 3 h and returned to baseline levels at 48 h.However,eIF4E and AKT1 activation began at 12 h and peaked at 48 h.ERK1/2 positively regulated EZH2 and EZH2-dependent expression of c-Fos and EGR1,while AKT1 negatively regulated c-Myc,c-Jun,and BMF,but positively regulated eIF4E.RocA downregulated ERK1/2(or EZH2,AKT1,and eIF4E)independent bcl-2 and Mcl-1 expression.AKT1i enhanced RocA-induced cell apoptosis,while EZH2i reduced RocA-induced cell proliferation.Combined CR-1-31-B,EZH2i,and AKT1i effectively overcame resistance to RocA and VEM resistance both in vitro and in vivo.Conclusion:The eIF4F complex inhibitor reactivates ERK1/2-EZH2 and AKT1 signaling pathways,resulting in resistance to both eIF4Fi and VEM.Combined administration of an eIF4Fi with EZH2 and AKT1 inhibitors effectively enhances sensitivity to both eIF4F complex and BRAF inhibitors.
基金funding support from the hospital-level project of Taizhou People's Hospital(Project No.:ZL201944).
文摘Zinc finger protein 36(ZFP36)was found to be downregulated in osteosarcoma(OS)tumor tissues.We aimed to investigate the roles and mechanisms of ZFP36 in ferroptosis regulation during OS development.Two Gene Expression Omnibus(GEO)datasets showed that ZFP36 was a differentially expressed gene(DEG)in OS.Western blot and immunohistochemistry results showed that ZFP36 was downregulated in OS tumors and cell lines.ZFP36 overexpression plasmids and small interfering RNAs(siRNAs)were respectively transfected into OS cells.ZFP36 overexpression restrained proliferation,migration,and invasion in MG63 and U2OS cells,while ZFP36 knockdown displayed the opposite results.Moreover,ZFP36 overexpression increased the levels of intracellular Fe2t,reactive oxygen species(ROS),and malondialdehyde(MDA),and decreased the levels of glutathione(GSH),glutathione peroxidase 4(GPX4),and solute carrier family 7 member 11(SLC7A11).ZFP36 overexpression disturbed mitochondrial membrane potential(MMP)and mitochondrial morphology in OS cells.However,ZFP36 knockdown had the opposite results.Mechanistic studies indicated that ZFP36 promoted E2F transcription factor 1(E2F1)messenger RNA(mRNA)degradation by binding to the AU-rich elements(AREs)within E2F130 untranslated region(30UTR)in OS cells.E2F1 overexpression abrogated the effects of ZFP36 overexpression on malignant progression,ferroptosis,and mitochondrial dysfunction in OS cells.Furthermore,E2F1 promoted the transcription activation of activating transcription factor 4(ATF4)by binding to ATF4 promoter.E2F1 knockdown inhibited malignant progression,and promoted ferroptosis and mitochondrial dysfunction in OS cells,which was abrogated by ATF4 overexpression.Additionally,MG63 cells transfected with lentivirus ZFP36 overexpression vector(Lv-ZFP36)were injected into nude mice and tumor growth was monitored.ZFP36 overexpression significantly suppressed OS tumor growth under in vivo settings.In conclusion,ZFP36 overexpression promoted ferroptosis and mitochondrial dysfunction and inhibited malignant progression in OS by regulating the E2F1/ATF4 axis.We may provide the promising ZFP36 target for OS treatment.
