title: Src kinase-mediated phosphorylation stabilizes inducible nitric-oxide synthase in normal cells and cancer cells.
abstract: Src kinases are key regulators of cellular proliferation, survival, motility, and invasiveness. They play important roles in the regulation of inflammation and cancer. Overexpression or hyperactivity of c-Src has been implicated in the development of various types of cancer, including lung cancer. Src inhibition is currently being investigated as a potential therapy for non-small cell lung cancer in Phase I and II clinical trials. The mechanisms of Src implication in cancer and inflammation are linked to the ability of activated Src to phosphorylate multiple downstream targets that mediate its cellular effector functions. In this study, we reveal that inducible nitric-oxide synthase (iNOS), an enzyme also implicated in cancer and inflammation, is a downstream mediator of activated Src. We elucidate the molecular mechanisms of the association between Src and iNOS in models of inflammation induced by lipopolysaccharide and/or cytokines and in cancer cells and tissues. We identify human iNOS residue Tyr(1055) as a target for Src-mediated phosphorylation. These results are shown in normal cells and cancer cells as well as in vivo in mice. Importantly, such posttranslational modification serves to stabilize iNOS half-life. The data also demonstrate interactions and co-localization of iNOS and activated Src under inflammatory conditions and in cancer cells. This study demonstrates that phosphorylation of iNOS by Src plays an important role in the regulation of iNOS and nitric oxide production and hence could account for some Src-related roles in inflammation and cancer.
authors.affiliation: Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: Alexey
authors.initials: A
authors.lastname: Tyryshkin
authors.forename: F Murat
authors.initials: FM
authors.lastname: Gorgun
authors.forename: Elmoataz
authors.initials: E
authors.lastname: Abdel Fattah
authors.forename: Tuhina
authors.initials: T
authors.lastname: Mazumdar
authors.forename: Lavannya
authors.initials: L
authors.lastname: Pandit
authors.forename: Shenyan
authors.initials: S
authors.lastname: Zeng
authors.forename: N Tony
authors.initials: NT
authors.lastname: Eissa
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D004789:Enzyme Activation / Q000187:drug effects; D004795:Enzyme Stability / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology; D004848:Epithelium / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D006207:Half-Life; D006801:Humans; D008168:Lung / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D051379:Mice; D008810:Mice, Inbred C57BL; D008954:Models, Biological; D009369:Neoplasms / Q000201:enzymology* / Q000473:pathology; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010768:Phosphoserine / Q000378:metabolism; D011014:Pneumonia / Q000201:enzymology / Q000473:pathology; D021381:Protein Transport / Q000187:drug effects; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D010768:Phosphoserine; D004815:Epidermal Growth Factor; D052247:Nitric Oxide Synthase Type II; D019061:src-Family Kinases