Characterization of preneoplastic and neoplastic rat mesothelial cell lines: the involvement of TETs, DNMTs, and 5-hydroxymethylcytosine.

Daniel L Pouliquen,Charly Liddell,Philippe Hulin,Marie-Noëlle Guilly,Jean-François Fonteneau,Marc Grégoire,David Roulois,Christophe Blanquart,Vanessa Le Martelot,Myriam Robard,Amal Ouacher,Sophie Deshayes,Joëlle S Nader

doi:10.18632/oncotarget.8970

Abstract

Malignant mesothelioma (MM) is one of the worst cancers in terms of clinical outcome, urging the need to establish and characterize new preclinical tools for investigation of the tumorigenic process, improvement of early diagnosis and evaluation of new therapeutic strategies. For these purposes, we characterized a collection of 27 cell lines established from F344 rats, after 136 to 415 days of induction with crocidolite asbestos administered intraperitoneally. Four mesotheliomas were distinguished from 23 preneoplastic mesothelial cell lines (PN) according to their propensity to generate tumors after orthotopic transplantation into syngeneic rats, their growth pattern, and the expression profile of three genes. PN cell lines were further discriminated into groups / subgroups according to morphology in culture and the expression profiles of 14 additional genes. This approach was completed by analysis of positive and negative immunohistochemical MM markers in the four tumors, of karyotype alterations in the most aggressive MM cell line in comparison with a PN epithelioid cell line, and of human normal mesothelial and mesothelioma cells and a tissue array. Our results showed that both the rat and human MM cell lines shared in common a dramatic decrease in the relative expression of Cdkn2a and of epigenetic regulators, in comparison with PN and normal human mesothelial cells, respectively. In particular, we identified the involvement of the relative expression of the Ten-Eleven Translocation (TET) family of dioxygenases and Dnmt3a in relation to the 5-hydroxymethylcytosine level in malignant transformation and the acquisition of metastatic potential.

Highlights

Malignant mesothelioma (MM) is a rare, aggressive cancer mainly related to asbestos exposure [1], the long latency time between exposure and occurrence of clinical symptoms limiting the efficacy of therapeutic interventions
Our results showed that both the rat and human MM cell lines shared in common a dramatic decrease in the relative expression of Cdkn2a and of epigenetic regulators, in comparison with preneoplastic mesothelial cell lines (PN) and normal human mesothelial cells, respectively
Downregulation of E-cadherin was observed in the preneoplastic lesions of a rat model of lung carcinogenesis, which preceded the occurrence of the epithelial-to-mesenchymal transition (EMT) [5], a key feature of the process of evading growth suppressors

Summary

Introduction

Malignant mesothelioma (MM) is a rare, aggressive cancer mainly related to asbestos exposure [1], the long latency time between exposure and occurrence of clinical symptoms limiting the efficacy of therapeutic interventions. Cell lines are universal model systems in cancer research and their characterization has provided crucial insights into the mechanisms leading to malignant transformation. Preneoplastic cells represent crucial elements in understanding the timing and sequence of events that lead to neoplastic transformation. Among the new hallmarks identified during the last decade [6], deregulation of cellular energetics, such as local hyperinsulinism, has been identified to lead to the development of preneoplastic lesions [7], while other reports have demonstrated links between glucose metabolism and epigenetic regulator function [8]

Methods

Results

Conclusion