Abstract 3462: Proteomic Profiling Reveals Novel Targets for Combination Treatment with Lanreotide in Neuroendocrine Tumors

Abstract Somatostatin analogues (SSAs) are well established in the treatment of neuroendocrine tumors (NETs), including small intestinal NET (SI-NET) due to their tumor growth arrest and symptom relieving characteristics. Here we determined the direct effects of lanreotide treatment on NET cell lines and a primary SI-NET culture. The cell lines HC45 and H727 were treated with a pharmacological concentration of 10 nM lanreotide for different time periods and the proteome, analyzed by in-depth HiRIEF LC-MS/MS, was compared with the proteome of non-treated cells. We quantified 6 451 and 7 801 proteins in HC45 and H727. Differential expression of the candidate proteins APC, BIRC5/survivin, BMPER, C14orf142, FYN, INSM1 and SPAG16 was confirmed by Western blotting. The possible direct anti-proliferative effect of lanreotide was evaluated in the primary SI-NET culture and the HC45, H727 and BON1 cell lines, which showed only a slight inhibition of proliferation. However, based on proteomics driven pathway analysis a significant synergy in anti-proliferative effect of lanreotide was observed when the small molecule IGF1R inhibitor, NVP-AEW541, was combined with lanreotide .This effective combination also represents an indirect model of suppressed IGF1 activity in the NET patients treated with SSA. Targeting of survivin with the small molecule YM155 dramatically reduced the proliferation of HC45. We also studied the effect of lanreotide alone or in combination with IGF-1R inhibitor on signaling pathways PI3K/Akt, Erk1/2 and P38. P38, Erk1/2 and GSK3β phosphorylation was equally increased by lanreotide and/or NVP-AEW541, however, lanreotide-induced AktS473 dephosphorylation was reversed after6 hours, unlike consistent AktS473 dephosphorylation after treating with NVP-AEW451 alone or in combination. In conclusion, we report growth inhibitory and potential feedback pro-growth signaling of the SSA lanreotide on NET cells, highlighting the role of SSAs in modulation of IGF1 in NET cell growth arrest and propose combination treatment candidate targets for improved efficacy of this agent. Citation Format: Omid Fotouhi, Hanna Kjellin, Jamileh Hashemi, Ming Lu, Christofer Juhlin, Anders Höög, Jan Zedenius, Catharina Larsson, Janne Lehtiö, Magnus Kjellman. Proteomic profiling reveals novel targets for combination treatment with lanreotide in neuroendocrine tumors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3462. doi:10.1158/1538-7445.AM2015-3462