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Hum Mol Genet. 2014 Oct 15;23(20):5418-28. doi: 10.1093/hmg/ddu265. Epub 2014 May 27.

mTOR pathway is activated by PKA in adrenocortical cells and participates in vivo to apoptosis resistance in primary pigmented nodular adrenocortical disease (PPNAD).

Author information

1
Génétique Reproduction et Développement (GReD), Clermont Université, Université Blaise Pascal, Clermont-Ferrand Cedex 1 63012, France, CNRS, UMR 6293, GReD, INSERM, U1103, Aubière Cedex 63171, France, GReD, INSERM, U1103, Aubière Cedex 63171, France.
2
Institut Cochin, Université Paris Descartes, INSERM U1016, CNRS UMR8104, Paris 75014, France, Department of Endocrinology and Department of Pathology, Reference Center for Rare Adrenal Diseases, Assistance Publique Hôpitaux de Paris, Hôpital Cochin, Paris 75014, France, Department of Pathology, Hôpital Pitié-Salpêtrière, Université Pierre et Marie Curie, 75013 Paris, France.
3
Génétique Reproduction et Développement (GReD), Clermont Université, Université Blaise Pascal, Clermont-Ferrand Cedex 1 63012, France, CNRS, UMR 6293, GReD, INSERM, U1103, Aubière Cedex 63171, France, GReD, INSERM, U1103, Aubière Cedex 63171, France, Service d'Endocrinologie, Centre Hospitalier Universitaire de Clermont-Ferrand, Clermont-Ferrand 63003, France and.
4
Section on Endocrinology and Genetics, PDEGEN, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
5
Institut Cochin, Université Paris Descartes, INSERM U1016, CNRS UMR8104, Paris 75014, France, Department of Endocrinology and Department of Pathology, Reference Center for Rare Adrenal Diseases, Assistance Publique Hôpitaux de Paris, Hôpital Cochin, Paris 75014, France.
6
Génétique Reproduction et Développement (GReD), Clermont Université, Université Blaise Pascal, Clermont-Ferrand Cedex 1 63012, France, CNRS, UMR 6293, GReD, INSERM, U1103, Aubière Cedex 63171, France, GReD, INSERM, U1103, Aubière Cedex 63171, France, antoine.martinez@univ-bpclermont.fr.

Abstract

Primary pigmented nodular adrenocortical disease (PPNAD) is associated with inactivating mutations of the PRKAR1A tumor suppressor gene that encodes the regulatory subunit R1α of the cAMP-dependent protein kinase (PKA). In human and mouse adrenocortical cells, these mutations lead to increased PKA activity, which results in increased resistance to apoptosis that contributes to the tumorigenic process. We used in vitro and in vivo models to investigate the possibility of a crosstalk between PKA and mammalian target of rapamycin (mTOR) pathways in adrenocortical cells and its possible involvement in apoptosis resistance. Impact of PKA signaling on activation of the mTOR pathway and apoptosis was measured in a mouse model of PPNAD (AdKO mice), in human and mouse adrenocortical cell lines in response to pharmacological inhibitors and in PPNAD tissues by immunohistochemistry. AdKO mice showed increased mTOR complex 1 (mTORC1) pathway activity. Inhibition of mTORC1 by rapamycin restored sensitivity of adrenocortical cells to apoptosis in AdKO but not in wild-type mice. In both cell lines and mouse adrenals, rapid phosphorylation of mTORC1 targets including BAD proapoptotic protein was observed in response to PKA activation. Accordingly, BAD hyperphosphorylation, which inhibits its proapoptotic activity, was increased in both AdKO mouse adrenals and human PPNAD tissues. In conclusion, mTORC1 pathway is activated by PKA signaling in human and mouse adrenocortical cells, leading to increased cell survival, which is correlated with BAD hyperphosphorylation. These alterations could be causative of tumor formation.

PMID:
24865460
PMCID:
PMC4184389
DOI:
10.1093/hmg/ddu265
[Indexed for MEDLINE]
Free PMC Article
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