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.

[1]  K. Lim,et al.  Oncogenic Ras-induced secretion of IL6 is required for tumorigenesis. , 2007, Genes & development.

[2]  M. Shipitsin,et al.  Activation of RalA is critical for Ras-induced tumorigenesis of human cells. , 2005, Cancer cell.

[3]  J. Blenis,et al.  Identification of the tuberous sclerosis complex-2 tumor suppressor gene product tuberin as a target of the phosphoinositide 3-kinase/akt pathway. , 2002, Molecular cell.

[4]  C. Marshall,et al.  Plasma membrane-targeted ras GTPase-activating protein is a potent suppressor of p21ras function , 1993, Molecular and cellular biology.

[5]  R. Kucherlapati,et al.  K-ras is an essential gene in the mouse with partial functional overlap with N-ras. , 1997, Genes & development.

[6]  A. Balmain,et al.  Carcinogen-specific mutation and amplification of Ha-ras during mouse skin carcinogenesis , 1986, Nature.

[7]  D. Goeddel,et al.  Identification and Characterization of an IκB Kinase , 1997, Cell.

[8]  H. S. Kim,et al.  Elevated blood pressures in mice lacking endothelial nitric oxide synthase. , 1996, Proceedings of the National Academy of Sciences of the United States of America.

[9]  F. Real,et al.  Genetic profile of 22 pancreatic carcinoma cell lines , 2001, Virchows Archiv.

[10]  L. Cantley,et al.  Targeting the PI3K-Akt pathway in human cancer: rationale and promise. , 2003, Cancer cell.

[11]  Marshall W. Anderson,et al.  LOH of chromosome 12p correlates with Kras2 mutation in non-small cell lung cancer , 2003, Oncogene.

[12]  Ryuji Kobayashi,et al.  IκB Kinase Promotes Tumorigenesis through Inhibition of Forkhead FOXO3a , 2004, Cell.

[13]  S. Adam,et al.  Divergent Roles for RalA and RalB in Malignant Growth of Human Pancreatic Carcinoma Cells , 2006, Current Biology.

[14]  K. Lim,et al.  Reduction in the requirement of oncogenic Ras signaling to activation of PI3K/AKT pathway during tumor maintenance. , 2005, Cancer cell.

[15]  Mike Rothe,et al.  IκB Kinase-β: NF-κB Activation and Complex Formation with IκB Kinase-α and NIK , 1997 .

[16]  Paul Tempst,et al.  Protein S-nitrosylation: a physiological signal for neuronal nitric oxide , 2001, Nature Cell Biology.

[17]  W. Sessa,et al.  Regulation of endothelium-derived nitric oxide production by the protein kinase Akt , 1999, Nature.

[18]  M. Malumbres,et al.  Targeted Genomic Disruption of H-ras and N-ras, Individually or in Combination, Reveals the Dispensability of Both Loci for Mouse Growth and Development , 2001, Molecular and Cellular Biology.

[19]  R. Busse,et al.  Activation of nitric oxide synthase in endothelial cells by Akt-dependent phosphorylation , 1999, Nature.

[20]  Loss of heterozygosity of Kras2 gene on 12p12-13 in Chinese colon carcinoma patients. , 2006, World journal of gastroenterology.

[21]  C. Shachaf,et al.  Conditional animal models: a strategy to define when oncogenes will be effective targets to treat cancer. , 2004, Seminars in cancer biology.

[22]  A. Watanabe,et al.  Growth inhibition of human pancreatic cancer cell lines by anti‐sense oligonucleotides specific to mutated K‐ras genes , 1999, International journal of cancer.

[23]  H. E. Marshall,et al.  Protein S-nitrosylation: purview and parameters , 2005, Nature Reviews Molecular Cell Biology.

[24]  C. Counter,et al.  A genetically defined normal human somatic cell system to study ras oncogenesis in vivo and in vitro. , 2006, Methods in enzymology.

[25]  R. Jain,et al.  The role of nitric oxide in tumour progression , 2006, Nature Reviews Cancer.

[26]  J. Downward.  Targeting RAS signalling pathways in cancer therapy , 2003, Nature Reviews Cancer.

[27]  J. E. Griffiths,et al.  The Akt kinase signals directly to endothelial nitric oxide synthase , 1999, Current Biology.

[28]  M. Greenberg,et al.  Akt Promotes Cell Survival by Phosphorylating and Inhibiting a Forkhead Transcription Factor , 1999, Cell.

[29]  M. Ewen,et al.  Wild-Type NRas and KRas Perform Distinct Functions during Transformation , 2007, Molecular and Cellular Biology.

[30]  R. Groszmann,et al.  Selective inhibition of tumor microvascular permeability by cavtratin blocks tumor progression in mice. , 2003, Cancer cell.

[31]  R. Ren,et al.  Oncogenic NRAS, KRAS, and HRAS exhibit different leukemogenic potentials in mice. , 2007, Cancer research.

[32]  A. Wolfman,et al.  Ha-ras and N-ras regulate MAPK activity by distinct mechanisms in vivo , 1998, Oncogene.

[33]  B. Chait,et al.  Redox regulation of cell signalling , 1996, Nature.

[34]  J. Bos,et al.  Minimal Ras-binding domain of Raf1 can be used as an activation-specific probe for Ras , 1997, Oncogene.