EZH2 Inhibition as New Epigenetic Treatment Option for Pancreatic Neuroendocrine Neoplasms (PanNENs)

Abstract

Pancreatic neuroendocrine neoplasms are epigenetically driven tumors, but therapies against underlying epigenetic drivers are currently not available in the clinical practice. We aimed to investigate EZH2 (Enhancer of Zest homolog) expression in PanNEN and the impact of EZH2 inhibition in three different PanNEN preclinical models. EZH2 expression in PanNEN patient samples (n = 172) was assessed by immunohistochemistry and correlated with clinico-pathological data. Viability of PanNEN cell lines treated with EZH2 inhibitor (GSK126) was determined in vitro. Lentiviral transduction of shRNA targeting EZH2 was performed in QGP1 cells, and cell proliferation was measured. Rip1TAG2 mice underwent GSK126 treatment for three weeks starting from week 10 of age. Primary cells isolated from PanNEN patients (n = 6) were cultivated in 3D as islet-like tumoroids and monitored for 10 consecutive days upon GSK126 treatment. Viability was measured continuously for the whole duration of the treatment. We found that high EZH2 expression correlated with higher tumor grade (p < 0.001), presence of distant metastases (p < 0.001), and shorter disease-free survival (p < 0.001) in PanNEN patients. Inhibition of EZH2 in vitro in PanNEN cell lines and in patient-derived islet-like tumoroids reduced cell viability and impaired cell proliferation, while inhibition of EZH2 in vivo in Rip1TAG2 mice reduced tumor burden. Our results show that EZH2 is highly expressed in high-grade PanNENs, and during disease progression it may contribute to aberrations in the epigenetic cellular landscape. Targeting EZH2 may represent a valuable epigenetic treatment option for patients with PanNEN.

IGF2BP1 Promotes Proliferation of Neuroendocrine Neoplasms by Post-Transcriptional Enhancement of EZH2

“…These cell type-specific differences might be explained by the fact that DZNep affects global, not EZH2-specific histone methylation by inhibiting the S-adenosyl-homocysteine hydrolase, which leads to the accumulation of the inhibitory S-adenosyl-homocysteine with broad effects on different cellular pathways [ 69 , 73 ]. In line with our findings, a recent report using a different EZH2 inhibitor, GSK126, showed significant antitumoral effects induced by EZH2 inhibition both in vitro and in a murine model of pancreatic neuroendocrine tumorigenesis [ 74 ].…”

Patient-derived tumoroids of advanced high-grade neuroendocrine neoplasms mimic patient chemotherapy responses and guide the design of personalized combination therapies

“…For primary cell isolation, micro-cell block manufacture, and quantification, we followed the workflow described previously. 14 In this study of high-grade GEP-NENs and in our earlier studies of lower-grade PanNENs 14,17 , our definition of "culture success" for patient-derived tumoroids was based on six factors that support translational application of patient-derived GEP-NEN tumoroids: 1) Successfully isolating and culturing viable tumor cells; 2) retaining ± 70% of the isolated cells before drug screening; 3) passing quality controls, including cytological, morphological, and histopathological examinations of clinically applied neuroendocrine marker expression in micro-cellblocks; 4) attaining sufficient technical replicates (n≥4) in drug screenings; 5) attaining stable RTG baseline and cell growth; 6) and extending culture life spans of up to 12 days ex vivo.…”

Enhancer of Zeste Homolog 2 (EZH2) Is a Marker of High-Grade Neuroendocrine Neoplasia in Gastroenteropancreatic and Pulmonary Tract and Predicts Poor Prognosis

“…The development of neuroendocrine prostate cancer seems to be mediated by EZH2 [ 50 , 51 ]. Furthermore, several preclinical studies have demonstrated that direct or indirect targeting of EZH2 is a potential new therapeutic strategy for NEN of the pancreas and small intestine [ 32 , 52 , 53 ].…”

“…Nevertheless, PRC2-independent functions of EZH2, e.g., the modification of protein activity by methylation or direct binding, have also been described in different cancer entities [ 25 , 26 , 27 , 28 , 29 , 30 ]. EZH2-mediated gene-silencing and other epigenetic mechanisms in cancer development and progression have gained increasing interest and offer new treatment options [ 19 , 31 , 32 ]. In most cancer entities (e.g., pancreatic cancer, breast cancer, prostate cancer, lung cancer), EZH2 is clearly associated with pro-tumorigenic and tumor-progressive characteristics [ 33 , 34 , 35 , 36 , 37 , 38 , 39 ].…”