PI3K/Akt/mTOR pathway involvement in regulating growth hormone secretion in a rat pituitary adenoma cell line
- 178 Downloads
Insulin-like growth factor 1 (IGF1) controls growth hormone (GH) secretion via a negative feed-back loop that may disclose novel mechanisms possibly useful to control GH hyper-secretion. Our aim was to understand whether PI3K/Akt/mTOR pathway is involved in IGF1 negative feedback on GH secretion.
Cell viability, GH secretion, Akt, and Erk 1/2 phosphorylation levels in the rat GH3 cell line were assessed under treatment with IGF1 and/or everolimus, an mTOR inhitior.
We found that IGF1 improves rat GH3 somatotroph cell viability via the PI3K/Akt/mTOR pathway and confirmed that IGF1 exerts a negative feedback on GH secretion by a transcriptional mechanism. We demonstrated that the negative IGF1 loop on GH secretion requires Akt activation that seems to play a pivotal role in the control of GH secretion. Furthermore, Akt activation is independent of PI3K and probably mediated by mTORC2. In addition, we found that Erk 1/2 is not involved in GH3 cell viability regulation, but may have a role in controlling GH secretion, independently of IGF1.
Our data confirm that mTOR inhibitors may be useful to reduce pituitary adenoma cell viability, while Erk 1/2 pathway may be considered as a useful therapeutic target to control GH secretion. Our results open the field for further studies searching for effective drugs to control GH hyper-secretion.
KeywordsGrowth hormone Insulin-like growth factor 1 PI3K/Akt/mTOR pathway MAPK pathway
We thank Novartis for providing Everolimus and NVP-BEZ235 pure substances.
This work was supported by grants from the Italian Ministry of Education, Research and University (FIRB RBAP11884M, RBAP1153LS), and Associazione Italiana per la Ricerca sul Cancro (AIRC) in collaboration with Laboratorio in rete del Tecnopolo “Tecnologie delle terapie avanzate” (LTTA) of the University of Ferrara. The funding sources had no involvement in study design, in the collection, analysis and interpretation of data, in the writing of the report and in the decision to submit the article for publication
Compliance with ethical standards
Conflict of interest
MCZ has received consultant fees from Novartis and Genzyme. EdU has received consultant fees from Novartis and grant support from Sanofi. The remaining authors declare that they have no competing interests.
- 2.M.D. Gahete, J. Córdoba-Chacón, Q. Lin, J.C. Brüning, C.R. Kahn, J.P. Castaño, H. Christian, R.M. Luque, R.D. Kineman, Insulin and IGF-I inhibit GH synthesis and release in vitro and in vivo by separate mechanisms. Endocrinology 154, 2410–2420 (2013). https://doi.org/10.1210/en.2013-1261 CrossRefPubMedPubMedCentralGoogle Scholar
- 11.M. Fernández, F. Sánchez-Franco, N. Palacios, I. Sánchez, G. Villuendas, L. Cacicedo, Involvement of vasoactive intestinal peptide on insulin-like growth factor I-induced proliferation of rat pituitary lactotropes in primary culture: evidence for an autocrine and/or paracrine regulatory system. Neuroendocrinology 77, 341–352 (2003)CrossRefPubMedGoogle Scholar
- 13.H. Rubinfeld, A. Kammer, O. Cohen, A. Gorshtein, Z.R. Cohen, M. Hadani, H. Werner, I. Shimon, IGF1 induces cell proliferation in human pituitary tumors—functional blockade of IGF1 receptor as a novel therapeutic approach in non-functioning tumors. Mol. Cell. Endocrinol. 390, 93–101 (2014). https://doi.org/10.1016/j.mce.2014.04.007 CrossRefPubMedGoogle Scholar
- 14.D. Romano, M. Pertuit, R. Rasolonjanahary, J.V. Barnier, K. Magalon, A. Enjalbert, C. Gerard, Regulation of the RAP1/RAF-1/extracellularly regulated kinase-1/2 cascade and prolactin release by the phosphoinositide 3-kinase/AKT pathway in pituitary cells. Endocrinology 147, 6036–6045 (2006)CrossRefPubMedGoogle Scholar
- 17.M. Musat, M. Korbonits, B. Kola, N. Borboli, M.R. Hanson, A.M. Nanzer, J. Grigson, S. Jordan, D.G. Morris, M. Gueorguiev, M. Coculescu, S. Basuand, A.B. Grossman, Enhanced protein kinase B/Akt signaling in pituitary tumors. Endocr. Relat. Cancer 12, 423–433 (2005). https://doi.org/10.1677/erc.1.00949 CrossRefPubMedGoogle Scholar
- 18.D. Dworakowska, E. Wlodek, C.A. Leontiou, S. Igreja, M. Cakir, M. Teng, M.I. Prodromou, N. Góth, S. Grozinsky-Glasberg, M. Gueorguiev, B. Kola, M. Korbonits, A.B. Grossman, Activation of RAF/MEK/ERK and PI3K/AKT/mTOR pathways in pituitary adenomas and their effects on downstream effectors. Endocr. Relat. Cancer. 16, 1329–1338 (2009)CrossRefPubMedGoogle Scholar
- 19.A. Gorshtein, H. Rubinfeld, E. Kendler, M. Theodoropoulou, V. Cerovac, G.K. Stalla, Z.R. Cohen, M. Hadani, I. Shimon, Mammalian target of rapamycin inhibitors rapamycin and RAD001 (everolimus) induce anti-proliferative effects in GH-secreting pituitary tumor cells in vitro. Endocr. Relat. Cancer 16, 1017–1027 (2009). https://doi.org/10.1677/ERC-08-0269 CrossRefPubMedGoogle Scholar
- 20.E.A. Sajjad, G. Zieliński, M. Maksymowicz, Ł. Hutnik, T. Bednarczuk, P. Włodarski, mTOR is frequently active in GH-secreting pituitary adenomas without influencing their morphopathological features. Endocr. Pathol. 24, 11–19 (2013). https://doi.org/10.1007/s12022-012-9230-y CrossRefPubMedGoogle Scholar
- 21.M.C. Zatelli, M. Minoia, C. Filieri, F. Tagliati, M. Buratto, M.R. Ambrosio, M. Lapparelli, M. Scanarini, E.C. degli Uberti, Effect of everolimus on cell viability in nonfunctioning pituitary adenomas. J. Clin. Endocrinol. Metab. 95, 968–976 (2010). https://doi.org/10.1210/jc.2009-1641 CrossRefPubMedGoogle Scholar
- 22.E. Gentilin, C. Di Pasquale, M. Rossi, F. Tagliati, T. Gagliano, R. Rossi, M. Pelizzo, I. Merante Boschin, E.C. degli Uberti, M.C. Zatelli, Igf-I influences everolimus activity in medullary thyroid carcinoma. Front. Endocrinol 6, 63 (2015). https://doi.org/10.3389/fendo.2015.00063 CrossRefGoogle Scholar
- 23.T. Gagliano, M. Bellio, E. Gentilin, D. Molè, F. Tagliati, M. Schiavon, N.G. Cavallesco, L.G. Andriolo, M.R. Ambrosio, F. Rea, E. degli Uberti, M.C. Zatelli, mTOR, p70S6K, AKT, and ERK1/2 levels predict sensitivity to mTOR and PI3K/mTOR inhibitors in human bronchial carcinoids. Endocr. Relat. Cancer 20, 463–475 (2013). https://doi.org/10.1530/ERC-13-0042 CrossRefPubMedGoogle Scholar
- 24.F. Tagliati, T. Gagliano, E. Gentilin, M. Minoia, D. Molè, E.C. degli Uberti, M.C. Zatelli, Magmas overexpression inhibits staurosporine induced apoptosis in rat pituitary adenoma cell lines. PLoS One 8, e75194 (2013). https://doi.org/10.1371/annotation/3af6faef-d942-4221-8d1a-47ce279e462b CrossRefPubMedPubMedCentralGoogle Scholar
- 25.E. Gentilin, D. Molè, T. Gagliano, M. Minoia, M.R. Ambrosio, E.C. degli Uberti, M.C. Zatelli, Inhibitory effects of mitotane on viability and secretory activity in mouse gonadotroph cell lines. Reprod. Toxicol. 45, 71–76 (2014). https://doi.org/10.1016/j.reprotox.2014.01.008 CrossRefPubMedGoogle Scholar
- 26.E. Gentilin, F. Tagliati, M. Terzolo, M. Zoli, M. Lapparelli, M. Minoia, M.R. Ambrosio, E.C. degli Uberti, M.C. Zatelli, Mitotane reduces human and mouse ACTH-secreting pituitary cell viability and function. J. Endocrinol. 218, 275–285 (2013). https://doi.org/10.1530/JOE-13-0210 CrossRefPubMedGoogle Scholar
- 27.M.C. Zatelli, D. Piccin, C. Vignali, F. Tagliati, M.R. Ambrosio, M. Bondanelli, V. Cimino, A. Bianchi, H.A. Schmid, M. Scanarini, A. Pontecorvi, L. De Marinis, G. Maira, E.C. degli Uberti, Pasireotide, a multiple somatostatin receptor subtypes ligand, reduces cell viability in non-functioning pituitary adenomas by inhibiting vascular endothelial growth factor secretion. Endocr. Relat. Cancer 14, 91–102 (2007)CrossRefPubMedGoogle Scholar
- 28.M.W. Pfaffl, A new mathematical model for relative quantification in real-time RT-PCR. Nucleic Acids Res. 623, 29 e45 (2001)Google Scholar
- 29.E. Gentilin, C. Di Pasquale, T. Gagliano, F. Tagliati, K. Benfini, M.R. Ambrosio, M. Bondanelli, E.C. degli Uberti, M.C. Zatelli, Protein Kinase C Delta restrains growth in ACTH-secreting pituitary adenoma cells. Mol. Cell. Endocrinol. 419, 252–258 (2016). https://doi.org/10.1016/j.mce.2015.10.025 CrossRefPubMedGoogle Scholar
- 30.T. Gagliano, E. Gentilin, K. Benfini, C. Di Pasquale, M. Tassinari, S. Falletta, C. Feo, F. Tagliati, E. degli Uberti, M.C. Zatelli, Mitotane enhances doxorubicin cytotoxic activity by inhibiting P-gp in human adrenocortical carcinoma cells. Endocrine 47, 943–951 (2014). https://doi.org/10.1007/s12020-014-0374-z CrossRefPubMedGoogle Scholar
- 31.T. Gagliano, E. Gentilin, F. Tagliati, K. Benfini, C. Di Pasquale, C. Feo, S. Falletta, E. Riva, E. degli Uberti, M.C. Zatelli, Inhibition of epithelial growth factor receptor can play an important role in reducing cell growth and survival in adrenocortical tumors. Biochem. Pharmacol. 98, 639–648 (2015). https://doi.org/10.1016/j.bcp.2015.10.012 CrossRefPubMedGoogle Scholar
- 32.C.J. Romero, E. Pine-Twaddell, D.I. Sima, R.S. Miller, L. He, F. Wondisford, S. Radovick, Insulin-like growth factor 1 mediates negative feedback to somatotroph GH expression via POU1F1/CREB binding protein interactions. Mol. Cell. Biol. 32, 4258–4269 (2012). https://doi.org/10.1128/MCB.00171-12 CrossRefPubMedPubMedCentralGoogle Scholar
- 33.M.C. Zatelli, M. Minoia, C. Martini, F. Tagliati, M.R. Ambrosio, M. Schiavon, M. Buratto, F. Calabrese, E. Gentilin, G. Cavallesco, L. Berdondini, F. Rea, E.C. degli Uberti, Everolimus as a new potential antiproliferative agent in aggressive human bronchial carcinoids. Endocr. Relat. Cancer 17, 719–729 (2010). https://doi.org/10.1677/ERC-10-0097 CrossRefPubMedGoogle Scholar
- 35.A. Carracedo, L. Ma, J. Teruya-Feldstein, F. Rojo, L. Salmena, A. Alimonti, A. Egia, A.T. Sasaki, G. Thomas, S.C. Kozma, A. Papa, C. Nardella, L.C. Cantley, J. Baselga, P.P. Pandolfi, Inhibition of mTORC1 leads to MAPK pathway activation through a PI3K-dependent feedback loop in human cancer. J. Clin. Invest. 118, 3065–3074 (2008). https://doi.org/10.1172/JCI34739 PubMedPubMedCentralGoogle Scholar
- 36.S.L. Atkin, A.M. Landolt, R.V. Jeffreys, L. Hipkin, J. Radcliffe, C.R. Squire, M.C. White, Differential effects of insulin-like growth factor 1 on the hormonal product and proliferation of glycoprotein-secreting human pituitary adenomas. J. Clin. Endocrinol. Metab. 77, 1059–1066 (1993)PubMedGoogle Scholar
- 37.V. Cerovac, J. Monteserin-Garcia, H. Rubinfeld, M. Buchfelder, M. Losa, T. Florio, M. Paez-Pereda, G.K. Stalla, M. Theodoropoulou, The somatostatin analog octreotide confers sensitivity to rapamycin treatment on pituitary tumor cell. Cancer Res. 70, 666–674 (2010). https://doi.org/10.1158/0008-5472.CAN-09-2951 CrossRefPubMedGoogle Scholar
- 38.B. Kola, M. Korbonits, S. Diaz-Cano, G. Kaltsas, D.G. Morris, S. Jordan, L. Metherell, M. Powell, S. Czirják, G. Arnaldi, S. Bustin, M. Boscaro, F. Mantero, A.B. Grossman, Reduced expression of the growth hormone and type 1 insulin-like growth factor receptors in human somatotroph tumors and an analysis of possible mutations of the growth hormone receptor. Clin. Endocrinol. 59, 328–338 (2003)CrossRefGoogle Scholar