Elevated FBXL6 activates both wild-type KRAS and mutant KRAS^(G12D)and drives HCC tumorigenesis via the ERK/mTOR/PRELID2/ROS axis in mice  

作　　者：Hao-Jun Xiong Hong-Qiang Yu Jie Zhang Lei Fang Di Wu Xiao-Tong Lin Chuan-Ming Xie 

机构地区：[1]Key Laboratory of Hepatobiliary and Pancreatic Surgery,Institute of Hepatobiliary Surgery,Southwest Hospital,Army Medical University,Chongqing 400038,China

出　　处：《Military Medical Research》2024年第6期818-838,共21页军事医学研究(英文版)

基　　金：supported by the National Natural Science Foundation of China(82370631);the Talent Foundations from Army Medical University(4174C6),the Chongqing Government(CQYC20220303727)to Xie CM;the National Natural Science Foundation of China(31900449)to Xiong HJ.

摘　　要：Background:Kirsten rat sarcoma(KRAS)and mutant KRAS^(G12D)have been implicated in human cancers,but it remains unclear whether their activation requires ubiquitination.This study aimed to investigate whether and how F-box and leucine-rich repeat 6(FBXL6)regulates KRAS and KRAS^(G12D)activity in hepatocellular carcinoma(HCC).Methods:We constructed transgenic mouse strains LC(LSL-Fbxl6^(KI/+);Alb-Cre,n=13),KC(LSL-Kras^(G12D/+);Alb-Cre,n=10)and KLC(LSL-Kras^(G12D/+);LSL-Fbxl6^(KI/+);Alb-Cre,n=12)mice,and then monitored HCC for 320 d.Multiomics approaches and pharmacological inhibitors were used to determine oncogenic signaling in the context of elevated FBXL6 and KRAS activation.Co-immunoprecipitation(Co-IP),Western blotting,ubiquitination assay,and RAS activity detection assay were employed to investigate the underlying molecular mechanism by which FBXL6 activates KRAS.The pathological relevance of the FBXL6/KRAS/extracellular signal-regulated kinase(ERK)/mammalian target of rapamycin(mTOR)/proteins of relevant evolutionary and lymphoid interest domain 2(PRELID2)axis was evaluated in 129 paired samples from HCC patients.Results:FBXL6 is highly expressed in HCC as well as other human cancers(P<0.001).Interestingly,FBXL6 drives HCC in transgenic mice.Mechanistically,elevated FBXL6 promotes the polyubiquitination of both wild-type KRAS and KRAS^(G12D)at lysine 128,leading to the activation of both KRAS and KRAS^(G12D)and promoting their binding to the serine/threonine-protein kinase RAF,which is followed by the activation of mitogen-activated protein kinase kinase(MEK)/ERK/mTOR signaling.The oncogenic activity of the MEK/ERK/mTOR axis relies on PRELID2,which induces reactive oxygen species(ROS)generation.Furthermore,hepatic FBXL6 upregulation facilitates KRAS^(G12D)to induce more severe hepatocarcinogenesis and lung metastasis via the MEK/ERK/mTOR/PRELID2/ROS axis.Dual inhibition of MEK and mTOR effectively suppresses tumor growth and metastasis in this subtype of cancer in vivo.In clinical samples,FBXL6 expression po

关 键 词：UBIQUITINATION Kirsten rat sarcoma(KRAS) F-box and leucine-rich repeat 6(FBXL6) PRELID2 Reactive oxygen species Extracellular signal-regulated kinase(ERK) Mammalian target of rapamycin 

分 类 号：R73[医药卫生—肿瘤]