The pro-apoptotic Ras effector Nore1 may serve as a Ras-regulated tumor suppressor in the lung.
Ras oncoproteins mediate multiple biological effects by activating multiple effectors. Classically, Ras activation has been associated with enhanced cellular growth and transformation. However, activated forms of Ras may also inhibit growth by inducing senescence, apoptosis, and differentiation. Induction of apoptosis by Ras may be mediated by its effector RASSF1, which appears to function as a tumor suppressor. We now show that the Ras effector Nore1, which is structurally related to RASSF1, can also mediate a Ras-dependent apoptosis. Moreover, an analysis of Nore1 protein expression showed that it is frequently down-regulated in lung tumor cell lines and primary lung tumors. Like RASSF1, this correlates with methylation of the Nore1 promoter rather than gene deletion. Finally, re-introduction of Nore1, driven by its own promoter, impairs the growth in soft agar of a human lung tumor cell line. Consequently, we propose that the Ras effector Nore1 is a member of a family of Ras effector/tumor suppressors that includes RASSF1.
Vos
Michele D
MD
Department of Cell and Cancer Biology, National Cancer Institute, National Institutes of Health, 9610 Medical Center Drive, Rockville, MD 20850-3300, USA.
Martinez
Alfredo
A
Ellis
Chad A
CA
Vallecorsa
Teresa
T
Clark
Geoffrey J
GJ
D016475:3T3 Cells; D048868:Adaptor Proteins, Signal Transducing; D000230:Adenocarcinoma / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D015139:Blotting, Southern; D019556:COS Cells; D002352:Carrier Proteins / Q000502:physiology*; D002454:Cell Differentiation; D002455:Cell Division; D002460:Cell Line; D016922:Cellular Senescence; D003001:Cloning, Molecular; D015536:Down-Regulation; D017353:Gene Deletion; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D007150:Immunohistochemistry; D008168:Lung / Q000473:pathology*; D008745:Methylation; D051379:Mice; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins / Q000502:physiology*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017386:Sequence Homology, Amino Acid; D013997:Time Factors; D014018:Tissue Distribution; D014407:Tumor Cells, Cultured; D018631:ras Proteins / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins; D006877:Hydroxamic Acids; C454042:RASSF5 protein, human; D012333:RNA, Messenger; C455831:Rassf5 protein, mouse; C012589:trichostatin A; D020559:Monomeric GTP-Binding Proteins; D018631:ras Proteins