Cdc42 and Rac1 activity is reduced in human pheochromocytoma and correlates with FARP1 and ARHGEF1 expression.
Fiche publication
Date publication
avril 2016
Journal
Endocrine-related cancer
Auteurs
Membres identifiés du Cancéropôle Est :
Dr GASMAN Stéphane, Mme LOMAZZI Sandra, Dr TOTH Petra, Dr ORY Stéphane
Tous les auteurs :
Croisé P, Houy S, Gand M, Lanoix J, Calco V, Tóth P, Brunaud L, Lomazzi S, Paramithiotis E, Chelsky D, Ory S, Gasman S
Lien Pubmed
Résumé
Among small GTPases from the Rho family, Cdc42, RAC, and Rho are well known to mediate a large variety of cellular processes linked with cancer biology through their ability to cycle between an inactive (GDP-bound) and an active (GTP-bound) state. Guanine nucleotide exchange factors (GEFs) stimulate the exchange of GDP for GTP to generate the activated form, whereas the GTPase-activating proteins (GAPs) catalyze GTP hydrolysis, leading to the inactivated form. Modulation of Rho GTPase activity following altered expression of RHO-GEFs and/or RHO-GAPs has already been reported in various human tumors. However, nothing is known about the Rho GTPase activity or the expression of their regulators in human pheochromocytomas, a neuroendocrine tumor (NET) arising from chromaffin cells of the adrenal medulla. In this study, we demonstrate, through an ELISA-based activity assay, that Rac1 and Cdc42 activities decrease in human pheochromocytomas (PCCs) compared with the matched adjacent non-tumor tissue. Furthermore, through quantitative mass spectrometry (MS) approaches, we show that the expression of two RHO-GEF proteins, namely ARHGEF1 and FARP1, is significantly reduced in tumors compared with matched non-tumor tissue, whereas ARHGAP36 expression is increased. Moreover, siRNA-based knockdown of ARHGEF1 and FARP1 in PC12 cells leads to a significant inhibition of Rac1 and Cdc42 activities, respectively. Finally, a principal component analysis (PCA) of our dataset was able to discriminate PCC from non-tumor tissue and indicates a close correlation between Cdc42/Rac1 activity and FARP1/ARHGEF1 expression. Altogether, our findings reveal for the first time the importance of modulation of Rho GTPase activities and expression of their regulators in human PCCs.
Mots clés
Adrenal Gland Neoplasms, metabolism, Animals, Humans, PC12 Cells, Pheochromocytoma, metabolism, RNA, Small Interfering, genetics, Rats, Rho Guanine Nucleotide Exchange Factors, genetics, cdc42 GTP-Binding Protein, metabolism, rac1 GTP-Binding Protein, metabolism
Référence
Endocr. Relat. Cancer. 2016 Apr;23(4):281-93