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Philipp Mayer, Andreas Harjung, Marco Breinig, Lars Fischer, Volker Ehemann, Mona Malz, Hans Scherübl, Sarah Britsch, Jens Werner, Michael A Kern, Hendrik Bläker, Peter Schirmacher and Frank Bergmann

Pancreatic endocrine tumors (PET) represent a heterogenous group of neoplasms. Although surgical resection is considered a safe and effective treatment for many PET, therapeutic options for inoperable and progressive PET are limited. The expression of heat-shock protein (HSP) 90 was investigated in 120 clinically and pathomorphologically well-characterized PET from 84 patients using immunohistochemistry. In addition, in 19 snap–frozen PET and in three healthy pancreatic tissues, we performed immunoblot analyses, and in 15 snap–frozen PET and in three healthy pancreatic tissues, we investigated the expression of HSP90 isoforms by means of semiquantitative RT-PCR. Functional tests were conducted using the human pancreas carcinoid cell line BON and the mouse insulinoma cell line β-TC-3. HSP90 was expressed in 95% of the PET patients. The transcript levels of the HSP90 isoforms HSP90α, HSP90β, glucose-related protein 94, and TNF receptor-associated protein 1 were significantly increased in PET compared with non-neoplastic pancreatic tissues. The treatment of the cell lines BON and β-TC-3 with the HSP90 inhibitors 17-allylamino-17-demethoxygeldanamycin and 17-dimethylaminoethylamino-17-demethoxy-geldanamycin resulted in significant, dose-dependent reduction of cell viability, cell cycle arrest, and increased apoptosis. Furthermore, HSP90 inhibition induced the degradation and inactivation of several oncogenetic HSP90 client proteins in a time- and dose-dependent manner. HSP90 inhibitors increased the therapeutic effects of doxorubicin and 5-fluorucacil in BON and β-TC-3 cells. HSP90 is expressed in the vast majority of PET and its inhibition reveals significant treatment effects in vitro. Thus, HSP90 qualifies as a promising new target.

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Florian Bösch, Katharina Brüwer, Annelore Altendorf-Hofmann, Christoph J Auernhammer, Christine Spitzweg, C Benedikt Westphalen, Stefan Boeck, Gabriele Schubert-Fritschle, Jens Werner, Volker Heinemann, Thomas Kirchner, Martin Angele and Thomas Knösel

Cancer immunotherapy has evolved major breakthroughs in the last years. The cell-surface receptor programmed death-1 (PD-1) and its ligand, programmed death ligand-1 (PD-L1), have been detected in various cancer types. However, the analysis on gastroenteropancreatic neoplasia (GEP-NENs) is limited. Therefore, the aim of this study was to characterize GEP-NENs with regard to PD-1/PD-L1 pathway and tumor-infiltrating lymphocytes (TILs). On protein level, we examined TILs, PD-1 and PD-L1 expression in tumor tissue of 244 GEP-NENs using immunohistochemistry. Expression levels were correlated with clinicopathological parameters including long-term survival in an observational study. In total, 244 patients could be included. Most of the patients had a NEN of the small intestine (52.5%) or the pancreas (29.5%). All tumors could be graded by their morphology and Ki67 index, with 57.8% G1, 34% G2 and 8.2% G3 tumors. High TILs (19.6%) and high PD-1 (16.1%) expression showed a significant correlation with shorter patient survival (P < 0.05) and with a higher grading. Furthermore, expression of PD-L1 (8.7%) showed a trend to shorter patient survival. High TILs and PD-1 expression are significantly associated with shorter patient survival and higher grading in GEP-NENs. PD-L1 expression showed a trend to shorter patient survival. Immunotherapy might be a promising therapeutic approach in GEP-NENs especially in tumors with high TILs.