Recent studies have indicated that the expression of ubiquitin-specific protease 51(USP51),a novel deubiquitinating enzyme(DUB)that mediates protein degradation as part of the ubiquitin‒proteasome system(UPS),is assoc...Recent studies have indicated that the expression of ubiquitin-specific protease 51(USP51),a novel deubiquitinating enzyme(DUB)that mediates protein degradation as part of the ubiquitin‒proteasome system(UPS),is associated with tumor progression and therapeutic resistance in multiple malignancies.However,the underlying mechanisms and signaling networks involved in USP51-mediated regulation of malignant phenotypes remain largely unknown.The present study provides evidence of USP51's functions as the prominent DUB in chemoresistant triple-negative breast cancer(TNBC)cells.At the molecular level,ectopic expression of USP51 stabilized the 78 kDa Glucose-Regulated Protein(GRP78)protein through deubiquitination,thereby increasing its expression and localization on the cell surface.Furthermore,the upregulation of cell surface GRP78 increased the activity of ATP binding cassette subfamily B member 1(ABCB1),the main efflux pump of doxorubicin(DOX),ultimately decreasing its accumulation in TNBC cells and promoting the development of drug resistance both in vitro and in vivo.Clinically,we found significant correlations among USP51,GRP78,and ABCB1 expression in TNBC patients with chemoresistance.Elevated USP51,GRP78,and ABCB1 levels were also strongly associated with a poor patient prognosis.Importantly,we revealed an alternative intervention for specific pharmacological targeting of USP51 for TNBC cell chemosensitization.In conclusion,these findings collectively indicate that the USP51/GRP78/ABCB1 network is a key contributor to the malignant progression and chemotherapeutic resistance of TNBC cells,underscoring the pivotal role of USP51 as a novel therapeutic target for cancer management.展开更多
Background:Programmed death ligand 1(PD-L1)has been demonstrated to facilitate tumor progression and therapeutic resistance in an immuneindependent manner.Nevertheless,the function and underlying signaling network(s)o...Background:Programmed death ligand 1(PD-L1)has been demonstrated to facilitate tumor progression and therapeutic resistance in an immuneindependent manner.Nevertheless,the function and underlying signaling network(s)of cancer cell-intrinsic PD-L1 action remain largely unknown.Herein,we sought to better understand how ubiquitin-specific peptidase 51(USP51)/PD-L1/integrin beta-1(ITGB1)signaling performs a cell-intrinsic role in mediating chemotherapeutic resistance in non-small cell lung cancer(NSCLC).Methods:Western blotting and flow cytometry were employed for PD-L1 detection in NSCLC cell lines.Coimmunoprecipitation and pulldown analyses,protein deubiquitination assay,tissue microarray,bioinformatic analysis and molecular biology methods were then used to determine the significance of PD-L1 in NSCLC chemoresistance and associated signaling pathways in several different cell lines,mouse models and patient tissue samples.Ubiquitin-7-amido-4-methylcoumarin(Ub-AMC)-based deubiquitinase activity,cellular thermal shift and surface plasmon resonance(SPR)analyses were performed to investigate the activity of USP51 inhibitors.Results:We provided evidence that cancer cell-intrinsic PD-L1 conferred the development of chemoresistance by directly binding to its membrane-bound receptor ITGB1 in NSCLC.At the molecular level,PD-L1/ITGB1 interaction subsequently activated the nuclear factor-kappa B(NF-κB)axis to elicit poor response to chemotherapy.We further determined USP51 as a bona fide deubiquitinase that targeted the deubiquitination and stabilization of the PD-L1 protein in chemoresistant NSCLC cells.Clinically,we found a significant direct relationship between the USP51,PD-L1 and ITGB1 contents in NSCLC patients with chemoresistant potency.The elevated USP51,PD-L1 and ITGB1 levels were strongly associated with worse patient prognosis.Of note,we identified that a flavonoid compound dihydromyricetin(DHM)acted as a potential USP51 inhibitor and rendered NSCLC cells more sensitive to chemotherapy by targeting USP51-dependent PD-L1 ubiquitination and degradation in vitro and in vivo.Conclusions:Together,our results demonstrated that the USP51/PD-L1/ITGB1 network potentially contributes to the malignant progression and therapeutic resistance in NSCLC.This knowledge is beneficial to the future design of advanced cancer therapy.展开更多
基金supported by grants from the International Science and Technology Cooperation Project of China(No.2022YFE0133300)the National Natural Science Foundation of China(No.82472870 and No.82172801).
文摘Recent studies have indicated that the expression of ubiquitin-specific protease 51(USP51),a novel deubiquitinating enzyme(DUB)that mediates protein degradation as part of the ubiquitin‒proteasome system(UPS),is associated with tumor progression and therapeutic resistance in multiple malignancies.However,the underlying mechanisms and signaling networks involved in USP51-mediated regulation of malignant phenotypes remain largely unknown.The present study provides evidence of USP51's functions as the prominent DUB in chemoresistant triple-negative breast cancer(TNBC)cells.At the molecular level,ectopic expression of USP51 stabilized the 78 kDa Glucose-Regulated Protein(GRP78)protein through deubiquitination,thereby increasing its expression and localization on the cell surface.Furthermore,the upregulation of cell surface GRP78 increased the activity of ATP binding cassette subfamily B member 1(ABCB1),the main efflux pump of doxorubicin(DOX),ultimately decreasing its accumulation in TNBC cells and promoting the development of drug resistance both in vitro and in vivo.Clinically,we found significant correlations among USP51,GRP78,and ABCB1 expression in TNBC patients with chemoresistance.Elevated USP51,GRP78,and ABCB1 levels were also strongly associated with a poor patient prognosis.Importantly,we revealed an alternative intervention for specific pharmacological targeting of USP51 for TNBC cell chemosensitization.In conclusion,these findings collectively indicate that the USP51/GRP78/ABCB1 network is a key contributor to the malignant progression and chemotherapeutic resistance of TNBC cells,underscoring the pivotal role of USP51 as a novel therapeutic target for cancer management.
基金International Science and Technology Cooperation Project of China,Grant/Award Number:2022YFE0133300National Natural Science Foundation of China,Grant/Award Numbers:82172801,81972454。
文摘Background:Programmed death ligand 1(PD-L1)has been demonstrated to facilitate tumor progression and therapeutic resistance in an immuneindependent manner.Nevertheless,the function and underlying signaling network(s)of cancer cell-intrinsic PD-L1 action remain largely unknown.Herein,we sought to better understand how ubiquitin-specific peptidase 51(USP51)/PD-L1/integrin beta-1(ITGB1)signaling performs a cell-intrinsic role in mediating chemotherapeutic resistance in non-small cell lung cancer(NSCLC).Methods:Western blotting and flow cytometry were employed for PD-L1 detection in NSCLC cell lines.Coimmunoprecipitation and pulldown analyses,protein deubiquitination assay,tissue microarray,bioinformatic analysis and molecular biology methods were then used to determine the significance of PD-L1 in NSCLC chemoresistance and associated signaling pathways in several different cell lines,mouse models and patient tissue samples.Ubiquitin-7-amido-4-methylcoumarin(Ub-AMC)-based deubiquitinase activity,cellular thermal shift and surface plasmon resonance(SPR)analyses were performed to investigate the activity of USP51 inhibitors.Results:We provided evidence that cancer cell-intrinsic PD-L1 conferred the development of chemoresistance by directly binding to its membrane-bound receptor ITGB1 in NSCLC.At the molecular level,PD-L1/ITGB1 interaction subsequently activated the nuclear factor-kappa B(NF-κB)axis to elicit poor response to chemotherapy.We further determined USP51 as a bona fide deubiquitinase that targeted the deubiquitination and stabilization of the PD-L1 protein in chemoresistant NSCLC cells.Clinically,we found a significant direct relationship between the USP51,PD-L1 and ITGB1 contents in NSCLC patients with chemoresistant potency.The elevated USP51,PD-L1 and ITGB1 levels were strongly associated with worse patient prognosis.Of note,we identified that a flavonoid compound dihydromyricetin(DHM)acted as a potential USP51 inhibitor and rendered NSCLC cells more sensitive to chemotherapy by targeting USP51-dependent PD-L1 ubiquitination and degradation in vitro and in vivo.Conclusions:Together,our results demonstrated that the USP51/PD-L1/ITGB1 network potentially contributes to the malignant progression and therapeutic resistance in NSCLC.This knowledge is beneficial to the future design of advanced cancer therapy.
