Tumour maintenance is mediated by eNOS.
Tumour cells become addicted to the expression of initiating oncogenes like Ras, such that loss of oncogene expression in established tumours leads to tumour regression. HRas, NRas or KRas are mutated to remain in the active GTP-bound oncogenic state in many cancers. Although Ras activates several proteins to initiate human tumour growth, only PI3K, through activation of protein kinase B (PKB; also known as AKT), must remain activated by oncogenic Ras to maintain this growth. Here we show that blocking phosphorylation of the AKT substrate, endothelial nitric oxide synthase (eNOS or NOS3), inhibits tumour initiation and maintenance. Moreover, eNOS enhances the nitrosylation and activation of endogenous wild-type Ras proteins, which are required throughout tumorigenesis. We suggest that activation of the PI3K-AKT-eNOS-(wild-type) Ras pathway by oncogenic Ras in cancer cells is required to initiate and maintain tumour growth.
Lim
Kian-Huat
KH
Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Ancrile
Brooke B
BB
Kashatus
David F
DF
Counter
Christopher M
CM
D016475:3T3 Cells; D000818:Animals; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic; D006801:Humans; D051379:Mice; D009369:Neoplasms / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology*; D052250:Nitric Oxide Synthase Type III / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D018631:ras Proteins / Q000378:metabolism
D052250:Nitric Oxide Synthase Type III; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D018631:ras Proteins