Background/Aims: While the range of therapeutic options for well-differentiated gastroenteropancreatic neuroendocrine tumors has recently increased with the emergence of targeted therapies, such as mTOR inhibitors, there is no recent progress in the treatment of poorly differentiated neuroendocrine carcinomas (PDNECs). Since PDNECs have been shown to strongly express mTOR pathway components, the aim of the present study was to assess the antitumor effect of the mTOR inhibitor everolimus in preclinical models of PDNECs. Methods: The expression of mTOR pathway components and their response to everolimus were assessed in two neuroendocrine cell lines: STC-1 and GluTag. A xenograft model of intrahepatic dissemination in the nude mouse, based on the intrasplenic injection of either STC-1 and GluTag tumor cells, was used. Animals were started on everolimus treatment 3 days after injection. The effects of treatment on tumor growth, proliferative capacities, apoptosis and in situ expression of mTOR pathway components were assessed. Results: The expression of mTOR pathway components was comparable in STC-1 and GluTag cells and in human PDNECs and could be inhibited in vitro by everolimus. In vivo, the tumor volume of STC-1 and GluTag xenografts was significantly reduced in treated animals (6.05 ± 1.84% as compared to 21.76 ± 3.88% in controls). Everolimus treatment also induced a significant decrease in Ki67 index and in the phosphorylation levels of the two major effectors of mTOR, p70S6K and 4E-BP1. Conclusion: Our experimental data suggest that mTOR inhibition could be considered a therapeutic option for high-grade gastroenteropancreatic neuroendocrine tumors.

1.
Yao JC, Hassan M, Phan A, Dagohoy C, Leary C, Mares JE, Abdalla EK, Fleming JB, Vauthey J-N, Rashid A, Evans DB: One hundred years after ‘carcinoid': epidemiology of and prognostic factors for neuroendocrine tumors in 35,825 cases in the United States. J Clin Oncol 2008;26:3063-3072.
[PubMed]
2.
Rindi G, Klimstra DS, Arnold R, Klöppel G, Bosman FT, Komminoth P, Perren A. Nomenclature and classification of neuroendocrine neoplasms of the digestive system; in Bosman FT, Carneiro F, Hruban RH, Theise ND (eds): WHO Classification of Tumours of the Digestive System. Lyon, IARC, 2012, pp 13-14.
3.
Yao JC, Shah MH, Ito T, Bohas CL, Wolin EM, Van Cutsem E, Hobday TJ, Okusaka T, Capdevila J, de Vries EGE, Tomassetti P, Pavel ME, Hoosen S, Haas T, Lincy J, Lebwohl D, Öberg K: Everolimus for advanced pancreatic neuroendocrine tumors. N Engl J Med 2011;364:514-523.
[PubMed]
4.
Raymond E, Dahan L, Raoul J-L, Bang Y-J, Borbath I, Lombard-Bohas C, Valle J, Metrakos P, Smith D, Vinik A, Chen J-S, Hörsch D, Hammel P, Wiedenmann B, Van Cutsem E, Patyna S, Lu DR, Blanckmeister C, Chao R, Ruszniewski P: Sunitinib malate for the treatment of pancreatic neuroendocrine tumors. N Engl J Med 2011;364:501-513.
[PubMed]
5.
Moertel CG, Kvols LK, O'Connell MJ, Rubin J: Treatment of neuroendocrine carcinomas with combined etoposide and cisplatin. Evidence of major therapeutic activity in the anaplastic variants of these neoplasms. Cancer 1991;68:227-232.
[PubMed]
6.
Mitry E, Baudin E, Ducreux M, Sabourin JC, Rufié P, Aparicio T, Aparicio T, Lasser P, Elias D, Duvillard P, Schlumberger M, Rougier P: Treatment of poorly differentiated neuroendocrine tumours with etoposide and cisplatin. Br J Cancer 1999;81:1351-1355.
[PubMed]
7.
Lindholm DP, Eriksson B, Granberg D: Response to temozolomide and bevacizumab in a patient with poorly differentiated neuroendocrine carcinoma. Med Oncol 2012;29:301-303.
[PubMed]
8.
Motzer RJ, Escudier B, Oudard S, Hutson TE, Porta C, Bracarda S, Grünwald V, Thompson JA, Figlin RA, Hollaender N, Urbanowitz G, Berg WJ, Kay A, Lebwohl D, Ravaud A: Efficacy of everolimus in advanced renal cell carcinoma: a double-blind, randomised, placebo-controlled phase III trial. Lancet 2008;372:449-456.
[PubMed]
9.
Kasajima A, Pavel M, Darb-Esfahani S, Noske A, Stenzinger A, Sasano H, Dietel M, Denkert C, Röcken C, Wiedenmann B, Weichert W: mTOR expression and activity patterns in gastroenteropancreatic neuroendocrine tumours. Endocr Relat Cancer 2011;18:181-192.
[PubMed]
10.
Missiaglia E, Dalai I, Barbi S, Beghelli S, Falconi M, della Peruta M, Piemonti L, Capurso G, Di Florio A, delle Fave G, Pederzoli P, Croce CM, Scarpa A: Pancreatic endocrine tumors: expression profiling evidences a role for AKT-mTOR pathway. J Clin Oncol 2010;28:245-255.
[PubMed]
11.
Jiao Y, Shi C, Edil BH, de Wilde RF, Klimstra DS, Maitra A, Schulick RD, Tang LH, Wolfgang CL, Choti MA, Velculescu VE, Diaz LA Jr, Vogelstein B, Kinzler KW, Hruban RH, Papadopoulos N: DAXX/ATRX, MEN1, and mTOR pathway genes are frequently altered in pancreatic neuroendocrine tumors. Science 2011;331:1199-1203.
[PubMed]
12.
Meric-Bernstam F, Akcakanat A, Chen H, Do K-A, Sangai T, Adkins F, Gonzalez-Angulo AM, Rashid A, Crosby K, Dong M, Phan AT, Wolff RA, Gupta S, Mills GB, Yao J: PIK3CA/PTEN mutations and Akt activation as markers of sensitivity to allosteric mTOR inhibitors. Clin Cancer Res 2012;18:1777-1789.
[PubMed]
13.
Pavel ME, Hainsworth JD, Baudin E, Peeters M, Hörsch D, Winkler RE, Klimovsky J, Lebwohl D, Jehl V, Wolin EM, Oberg K, Van Cutsem E, Yao JC: Everolimus plus octreotide long-acting repeatable for the treatment of advanced neuroendocrine tumours associated with carcinoid syndrome (RADIANT-2): a randomised, placebo-controlled, phase 3 study. Lancet 2011;378:2005-2012.
[PubMed]
14.
Shida T, Kishimoto T, Furuya M, Nikaido T, Koda K, Takano S, Kimura F, Shimizu H, Yoshidome H, Ohtsuka M, Tanizawa T, Nakatani Y, Miyazaki M: Expression of an activated mammalian target of rapamycin (mTOR) in gastroenteropancreatic neuroendocrine tumors. Cancer Chemother Pharmacol 2010;65:889-893.
[PubMed]
15.
Catena L, Bajetta E, Milione M, Ducceschi M, Valente M, Dominoni F, Colonna V: Mammalian target of rapamycin expression in poorly differentiated endocrine carcinoma: clinical and therapeutic future challenges. Target Oncol 2011;6:65-68.
[PubMed]
16.
Rindi G, Grant SG, Yiangou Y, Ghatei MA, Bloom SR, Bautch VL, Solcia E, Polak JM: Development of neuroendocrine tumors in the gastrointestinal tract of transgenic mice. Heterogeneity of hormone expression. Am J Pathol 1990;136:1349-1363.
[PubMed]
17.
Drucker DJ, Jin T, Asa SL, Young TA, Brubaker PL: Activation of proglucagon gene transcription by protein kinase-A in a novel mouse enteroendocrine cell line. Mol Endocrinol 1994;8:1646-1655.
[PubMed]
18.
Pourreyron C, Poncet G, Roche C, Gouysse G, Nejjari M, Walter T, Villaume K, Jacquier M-F, Bernard C, Dumortier J, Chayvialle J-A, Bachelot T, Scoazec J-Y: The role of angiogenesis in endocrine liver metastases: an experimental study. J Surg Res 2008;144:64-73.
[PubMed]
19.
Couderc C, Poncet G, Villaume K, Blanc M, Gadot N, Walter T, Lepinasse F, Hervieu V, Cordier-Bussat M, Scoazec J-Y, Roche C: Targeting the PI3K/mTOR pathway in murine endocrine cell lines: in vitro and in vivo effects on tumor cell growth. Am J Pathol 2011;178:336-344.
[PubMed]
20.
Rindi G, Bordi C: Endocrine tumours of the gastrointestinal tract: aetiology, molecular pathogenesis and genetics. Best Pract Res Clin Gastroenterol 2005;19:519-534.
[PubMed]
21.
Duran I, Kortmansky J, Singh D, Hirte H, Kocha W, Goss G, Le L, Oza A, Nicklee T, Ho J, Birle D, Pond GR, Arboine D, Dancey J, Aviel-Ronen S, Tsao M-S, Hedley D, Siu LL: A phase II clinical and pharmacodynamic study of temsirolimus in advanced neuroendocrine carcinomas. Br J Cancer 2006;95:1148-1154.
[PubMed]
22.
Inui A: Cancer anorexia-cachexia syndrome. Are neuropeptides the key? Cancer Res 1999;59:4493-4501.
[PubMed]
23.
Albert S, Serova M, Dreyer C, Sablin M-P, Faivre S, Raymond E: New inhibitors of the mammalian target of rapamycin signaling pathway for cancer. Expert Opin Investig Drugs 2010;19:919-930.
[PubMed]
24.
Laplante M, Sabatini DM: mTOR signaling in growth control and disease. Cell 2012;149:274-293.
[PubMed]
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