The activation of neuronal NO synthase is mediated by Gâ protein βγ subunit and the tyrosine phosphatase SHPâ 2

In CHO cells we had found that CCK positively regulated cell proliferation via the activation of a soluble guanylate cyclase. Here we demonstrate that CCK stimulated a nitric oxide synthase (NOS) activity. The production of NO was involved in the proliferative response elicited by CCK regarding the inhibitory effect of NOS inhibitors Lâ NAME and αâ guanidinoglutaric acid. We identified the NOS activated by the peptide as the neuronal isoform: the expression of the C415A neuronal NOS mutant inhibited both CCKâ induced stimulation of NOS activity and cell proliferation. These two effects were also inhibited after expression of the C459S tyrosine phosphatase SHPâ 2 mutant and the βARKl (495â 689) sequestrant peptide, indicating the requirement of activated SHPâ 2 and Gâ βγ subunit. Kinetic analysis (Western blot after coimmunoprecipitation and specific SHPâ 2 activity) revealed that in response to CCKâ treatment, SHPâ 2 associated to Gâ β1 subunit, became activated, and then dephosphorylated the neuronal NOS through a direct association. These data demonstrate that the neuronal NOS is implicated in proliferative effect evoked by CCK. A novel growth signaling pathway is described, involving the activation of neuronal NOS by dephosphorylation of tyrosyl residues.â Cordelier, P., Estève, J.â P., Rivard, N., Marletta, M., Vaysse, N., Susini, C., Buscail, L. The activation of neuronal no synthase is mediated by Gâ protein βγ subunit and the tyrosine phosphatase SHPâ 2. FASEB J. 13, 2037â 2050 (1999)Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154447/1/fsb2fasebj13142037.pd

Autocrine regulation of human prostate carcinoma cell proliferation by somatostatin through the modulation of the SH2 domain containing protein tyrosine phosphatase (SHP)-1

The present study was intended to gain additional information on the growth regulation of prostate by somatostatin\ud (SRIF) and the intracellular events involved. The humanprostate adenocarcinoma cell lines PC-3 and LNCaP produce SRIF and express subtypes 2 and 5 of SRIF receptors. The secretion\ud of SRIF is related to the proliferative status of these cells; an inverse relationship exists between cell proliferation and the amount of secreted SRIF. Moreover, the growth of PC-3 cells\ud is inhibited by SRIF overexpression and increased by blockage of endogenous SRIF. Coincident with the increase in SRIF\ud secretion, the activity and levels of theSH2domain containing protein tyrosine phosphatase (SHP)-1, present in PC-3 cells are augmented, but the effect can be partially prevented by neutralization of secreted endogenously SRIF. The activity of SHP-1 is also stimulated by the SRIF analog RC160. Overexpression of SHP-1 induces inhibition of PC-3 cell growth.\ud SHP-1 is also present in normal prostate, benign prostatic hyperplasia, prostatic intraepithelial neoplasia, and well differentiated adenocarcinoma. In contrast, no signal is detected in poorly differentiated prostate cancer. These findings demonstrate that SRIF inhibits PC-3 and LNCaP cell proliferation through an autocrine/paracrine SRIF loop. This effect could be mediated by activation of the tyrosine phosphatase SHP-1 detected in these cells as well as in human prostate and prostate cancer.Fundación para la Investigación en UrologíaMinisterio de Asuntos Exteriore

Knockout of Vdac1 activates hypoxia-inducible factor through reactive oxygen species generation and induces tumor growth by promoting metabolic reprogramming and inflammation

BACKGROUND: Mitochondria are more than just the powerhouse of cells; they dictate if a cell dies or survives. Mitochondria are dynamic organelles that constantly undergo fusion and fission in response to environmental conditions. We showed previously that mitochondria of cells in a low oxygen environment (hypoxia) hyperfuse to form enlarged or highly interconnected networks with enhanced metabolic efficacy and resistance to apoptosis. Modifications to the appearance and metabolic capacity of mitochondria have been reported in cancer. However, the precise mechanisms regulating mitochondrial dynamics and metabolism in cancer are unknown. Since hypoxia plays a role in the generation of these abnormal mitochondria, we questioned if it modulates mitochondrial function. The mitochondrial outer-membrane voltage-dependent anion channel 1 (VDAC1) is at center stage in regulating metabolism and apoptosis. We demonstrated previously that VDAC1 was post-translationally C-terminal cleaved not only in various hypoxic cancer cells but also in tumor tissues of patients with lung adenocarcinomas. Cells with enlarged mitochondria and cleaved VDAC1 were also more resistant to chemotherapy-stimulated cell death than normoxic cancer cells. RESULTS: Transcriptome analysis of mouse embryonic fibroblasts (MEF) knocked out for Vdac1 highlighted alterations in not only cancer and inflammatory pathways but also in the activation of the hypoxia-inducible factor-1 (HIF-1) signaling pathway in normoxia. HIF-1α was stable in normoxia due to accumulation of reactive oxygen species (ROS), which decreased respiration and glycolysis and maintained basal apoptosis. However, in hypoxia, activation of extracellular signal-regulated kinase (ERK) in combination with maintenance of respiration and increased glycolysis counterbalanced the deleterious effects of enhanced ROS, thereby allowing Vdac1 (-/-) MEF to proliferate better than wild-type MEF in hypoxia. Allografts of RAS-transformed Vdac1 (-/-) MEF exhibited stabilization of both HIF-1α and HIF-2α, blood vessel destabilization, and a strong inflammatory response. Moreover, expression of Cdkn2a, a HIF-1-target and tumor suppressor gene, was markedly decreased. Consequently, RAS-transformed Vdac1 (-/-) MEF tumors grew faster than wild-type MEF tumors. CONCLUSIONS: Metabolic reprogramming in cancer cells may be regulated by VDAC1 through vascular destabilization and inflammation. These findings provide new perspectives into the understanding of VDAC1 in the function of mitochondria not only in cancer but also in inflammatory diseases

Caractérisation des mécanismes moléculaires d'activation de la SHP-1 et de ses effecteurs (implication dans l'effet anti-prolifératif de la somatostatine transmis par le récepteur SST2)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Mécanismes moléculaires du signal pro-apoptotique du récepteur de somatostatine sst2

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Mécanismes moléculaires du signal anti-prolifératif transmis par le récepteur de somatostatine sst2 (implication des connexines 26 et 43)

TOULOUSE3-BU Sciences (315552104) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Implication des métabolites sphingolipidiques dans la prolifération, la survie et la réponse des cellules cancéreuses pancréatiques aux molécules chimiothérapeutiques

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF