The Mammalian Target of Rapamycin Kinase and Tumor Growth Inhibition

Human cancer expression profiling studies highlight the important variability in gene expression patterns and signaling pathways activated within tumors of a homogenous pathological group. These observations support the need for marker and molecular signature identification to adapt appropriate treatments to the patient. Increasing evidence indicates that the mammalian target of rapamycin [mTOR; also named rapamycin-associated protein (FRAP) or rapamycin and FKBP12 target (RAFT)] signaling pathway is hyperactive in a number of cancers, suggesting that this pathway may represent an attractive target for cancer therapy. mTOR is a highly conserved, 290-kDa serine-threonine protein kinase that belongs to the phosphoinositide kinase-related kinase (PIKK) family comprising also ataxia-telangiectasia (ATM), ATM and Rad3-related protein kinase (ATR) and DNA-dependent protein kinase (DNA-PK) (Abraham 2004).