The oncoprotein SET is frequently overexpressed in many types of tumors and contributes to malignant initiation and progression through multiple mechanisms,including the hijacking of the tumor suppressors p53 and PP2A...The oncoprotein SET is frequently overexpressed in many types of tumors and contributes to malignant initiation and progression through multiple mechanisms,including the hijacking of the tumor suppressors p53 and PP2A.Targeting aberrant SET represents a promising strategy for cancer intervention.However,the mechanism by which endogenous SET is regulated in cancer cells remains largely unknown.Here,we identified the tumor suppressor p53 as a key regulator that transcriptionally repressed the expression of SET in both normal and cancer cells.In addition,p53 stimulated PP2A phosphatase activity via p53-mediated transcriptional repression of SET,whereby SET-mediated inhibition of PP2A was alleviated.Moreover,targeting the interaction between SET and PP2A catalytic subunit(PP2Ac)with FTY720 enhanced stress-induced p53 activation via PP2A-mediated dephosphorylation of p53 on threonine 55(Thr55).Therefore,our findings uncovered a previously unknown p53-SETPP2A regulatory feedback loop.To functionally potentiate this feedback loop,we designed a combined therapeutic strategy by simultaneously administrating a p53 activator and SET antagonist in cancer cells and observed a dramatic synergistic effect on tumor suppression.Our study reveals mechanistic insight into the regulation of the oncoprotein SET and raises a potential strategy for cancer therapy by stimulating the p53-SET-PP2A feedback loop.展开更多
基金supported by Beijing Municipal Natural Science Foundation(7192126)the National Natural Science Foundation of China(81872311,82073132,82122054,and 81720108027)+1 种基金the National Key R&D Program of China(2019YFC1005200,and 2019YFC1005201)CAMS Innovation Fund for Medical Sciences(2021-I2M-1-016)。
文摘The oncoprotein SET is frequently overexpressed in many types of tumors and contributes to malignant initiation and progression through multiple mechanisms,including the hijacking of the tumor suppressors p53 and PP2A.Targeting aberrant SET represents a promising strategy for cancer intervention.However,the mechanism by which endogenous SET is regulated in cancer cells remains largely unknown.Here,we identified the tumor suppressor p53 as a key regulator that transcriptionally repressed the expression of SET in both normal and cancer cells.In addition,p53 stimulated PP2A phosphatase activity via p53-mediated transcriptional repression of SET,whereby SET-mediated inhibition of PP2A was alleviated.Moreover,targeting the interaction between SET and PP2A catalytic subunit(PP2Ac)with FTY720 enhanced stress-induced p53 activation via PP2A-mediated dephosphorylation of p53 on threonine 55(Thr55).Therefore,our findings uncovered a previously unknown p53-SETPP2A regulatory feedback loop.To functionally potentiate this feedback loop,we designed a combined therapeutic strategy by simultaneously administrating a p53 activator and SET antagonist in cancer cells and observed a dramatic synergistic effect on tumor suppression.Our study reveals mechanistic insight into the regulation of the oncoprotein SET and raises a potential strategy for cancer therapy by stimulating the p53-SET-PP2A feedback loop.
