Cotargeting survival signaling pathways in cancer.
Mammalian target of rapamycin (mTOR) is a component of a signaling pathway (PTEN/PI3K/AKT) that is frequently dysregulated in cancer. However, its precise relationship to the MAPK cascade (Ras/Raf/MEK/ERK), another pathway often implicated in tumorigenesis, has not been well defined. Recent evidence from tissue specimens obtained from patients who have received mTOR inhibitors suggests that ERK may be activated in response to mTOR interruption. In this issue of the JCI, Waugh Kinkade et al. and Carracedo et al. examine the relationship between these pathways in prostate and breast cancer cell model systems (see the related articles beginning on pages 3051 and 3065, respectively). Their findings suggest a link between inhibition of mTOR and ERK activation, possibly reflecting interruption of a novel negative S6K1-dependent feedback loop. Significantly, both groups observed that simultaneous inhibition of MEK/ERK and mTOR resulted in substantially enhanced antitumor effects both in vitro and in vivo. Together, these findings suggest that concurrent interruption of complementary signaling pathways warrants further investigation in cancer therapy.
Grant
Steven
S
Department of Medicine and Biochemistry, Massey Cancer Center and the Institute for Molecular Medicine, Virginia Commonwealth University Health Science Center, Richmond, Virginia, USA. stgrant@vcu.edu
D000818:Animals; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008954:Models, Biological; D009369:Neoplasms / Q000188:drug therapy* / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases
D036341:Intercellular Signaling Peptides and Proteins; D011494:Protein Kinases; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D048049:Extracellular Signal-Regulated MAP Kinases