Therapeutical interference with the epigenetic landscape of germ cell tumors: a comparative drug study and new mechanistical insights

Melanie R Müller,Gamal A Wakileh,Aaron Burmeister,Alexa Stephan,Felix Bremmer,Patrick Petzsch,Margaretha A Skowron,Peter Albers,Daniel Nettersheim,Karl Köhrer

doi:10.1186/s13148-021-01223-1

Abstract

BackgroundType II germ cell tumors (GCT) are the most common solid cancers in males of age 15 to 35 years. Treatment of these tumors includes cisplatin-based therapy achieving high cure rates, but also leading to late toxicities. As mainly young men are suffering from GCTs, late toxicities play a major role regarding life expectancy, and the development of therapy resistance emphasizes the need for alternative therapeutic options. GCTs are highly susceptible to interference with the epigenetic landscape; therefore, this study focuses on screening of drugs against epigenetic factors as a treatment option for GCTs.ResultsWe present seven different epigenetic inhibitors efficiently decreasing cell viability in GCT cell lines including cisplatin-resistant subclones at low concentrations by targeting epigenetic modifiers and interactors, like histone deacetylases (Quisinostat), histone demethylases (JIB-04), histone methyltransferases (Chaetocin), epigenetic readers (MZ-1, LP99) and polycomb-repressive complexes (PRT4165, GSK343). Mass spectrometry-based analyses of the histone modification landscape revealed effects beyond the expected mode-of-action of each drug, suggesting a wider spectrum of activity than initially assumed. Moreover, we characterized the effects of each drug on the transcriptome of GCT cells by RNA sequencing and found common deregulations in gene expression of ion transporters and DNA-binding factors. A kinase array revealed deregulations of signaling pathways, like cAMP, JAK-STAT and WNT.ConclusionOur study identified seven drugs against epigenetic modifiers to treat cisplatin-resistant GCTs. Further, we extensively analyzed off-target effects and modes-of-action, which are important for risk assessment of the individual drugs.

Highlights

Type II germ cell tumors (GCT) are the most common solid cancers in males of age 15 to 35 years
From the 127 analyzed targets, 80 were commonly and significantly expressed among the different GCT entities (Additional file 1: Fig. S1B). These 80 targets were checked for expression in GCT cell lines to allow for in vitro screening of potential drugs (Additional file 1: Fig. S1C, D) [15, 16, 20,21,22]. 33 epigenetic modulators were commonly expressed among the cell lines (SE: TCam-2; Embryonal carcinoma (EC): 2102EP, NCCIT; CC: JAR) (Additional file 1: Fig. S1C, D)
We identified 14 inhibitors against these targets, including histone deacetylase inhibitors (HDACi), histone demethylase inhibitors (HDMi), histone methyltransferase inhibitors (HMTi), inhibitors of proteins binding to acetylated histones (PAHi), polycomb-repressive complex inhibitors (PRCi) and DNA methyltransferase inhibitors (DNMTi)

Summary

Introduction

Type II germ cell tumors (GCT) are the most common solid cancers in males of age 15 to 35 years. Treatment of these tumors includes cisplatin-based therapy achieving high cure rates, and leading to late toxicities. As mainly young men are suffering from GCTs, late toxicities play a major role regarding life expectancy, and the development of therapy resistance emphasizes the need for alternative therapeutic options. One group derives from a pre-cancerous, non-invasive disease named germ cell neoplasia in situ (GCNIS), and is classified as type II GCT, which occur primarily after. New therapeutic approaches to treat cisplatin refractory GCTs and circumvent late toxicities induced by the cisplatinbased therapy are needed [6]

Methods

Results

Conclusion