title: Roles of palmitoylation and the KIKK membrane-targeting motif in leukemogenesis by oncogenic KRAS4A.
abstract: BACKGROUND
  We have previously shown that palmitoylation is essential for NRAS leukemogenesis, suggesting that targeting RAS palmitoylation may be an effective therapy for NRAS-related cancers. For KRAS-driven cancer, although much research has been focused on the KRAS4B splice variant, which does not undergo palmitoylation, KRAS4A has recently been shown to play an essential role in the development of carcinogen-induced lung cancer in mice and to be widely expressed in human cancers. However, the role of palmitoylation in KRAS4A tumorigenesis is not clear.
  
  
  METHODS
  The expression of KRAS4A in KRAS-mutated leukemia cell lines and acute myeloid leukemia (AML) cells were checked using western blotting and reverse transcriptions-quantitative polymerase chain reaction (RT-qPCR) analysis, respectively. The leukemogenic potentials of oncogenic KRAS4A and its palmitoylation-defective mutants were examined by a mouse bone marrow transduction and transplantation model and the in vitro transformation assays. The activation of the RAS downstream signaling pathways and the membrane localizations of the KRAS4A and its mutants were analyzed via western blot analysis and confocal microscopy, respectively.
  
  
  RESULTS
  We show here that KRAS4A is expressed in human leukemia cell lines and in AML cells harboring KRAS mutations and that mutation at the palmitoylation site of oncogenic KRAS4A significantly abrogates its leukemogenic potential. However, unlike NRAS, palmitoylation-defective KRAS4A still induces leukemia in mice, albeit with a much longer latency. Using NRAS/KRAS4A chimeric constructs, we found that the KIKK motif of KRAS4A contributes to the transforming activity of KRAS4A. Mutations at both palmitoylation site and the KIKK motif abolish the ability of oncogenic KRAS4A to induce leukemia in mice.
  
  
  CONCLUSIONS
  Our studies suggest that therapies targeting RAS palmitoylation may also be effective in treating KRAS4A associated malignancies and that interfering the KIKK membrane-targeting motif would enhance the therapeutic effectiveness.
authors.affiliation: State Key Laboratory of Medical Genomics, Institute of Health Sciences, Shanghai Institutes for Biological Sciences and Graduate School, Chinese Academy of Sciences, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China. hbzhao@sibs.ac.cn.
authors.forename: Huanbin
authors.initials: H
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China. liupingjize@126.com.
authors.forename: Ping
authors.initials: P
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China. zhangruihong007@163.com.
authors.forename: Ruihong
authors.initials: R
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China. wumin806@163.com.
authors.forename: Min
authors.initials: M
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China. lidonghes@163.com.
authors.forename: Donghe
authors.initials: D
authors.lastname: Li
authors.affiliation: State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China. xuemeiyxx@163.com.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China. zhangchun84135@126.com.
authors.forename: Chun
authors.initials: C
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China. bjiao@sibs.ac.cn.
authors.forename: Bo
authors.initials: B
authors.lastname: Jiao
authors.affiliation: State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China. chenbing.rjsih@yahoo.com.
authors.forename: Bing
authors.initials: B
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Medical Genomics, Institute of Health Sciences, Shanghai Institutes for Biological Sciences and Graduate School, Chinese Academy of Sciences, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China. zchen@stn.sh.cn.|State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China. zchen@stn.sh.cn.
authors.forename: Zhu
authors.initials: Z
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Collaborative Innovation Center of Hematology, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, 200025, Shanghai, China. rbren@brandeis.edu.|Department of Biology, Brandeis University, Waltham, MA, USA. rbren@brandeis.edu.
authors.forename: Ruibao
authors.initials: R
authors.lastname: Ren
mesh_terms: D000818:Animals; D002460:Cell Line; D006801:Humans; D054878:Lipoylation / Q000502:physiology*; D008175:Lung Neoplasms / Q000209:etiology*; D008565:Membrane Proteins / Q000187:drug effects*; D051379:Mice; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism*
chemical_list: C117307:KRAS protein, human; D008565:Membrane Proteins; D016283:Proto-Oncogene Proteins p21(ras)