Establishment and Characterization of a Reliable Xenograft Model of Hodgkin Lymphoma Suitable for the Study of Tumor Origin and the Design of New Therapies.

Radhia M’Kacher,Anne-Laure Bauchet,Bruno Colicchio,Steffen Junker,Jean Bourhis,Dima Jouni,Patrice Carde,Annelise Bennaceur-Griscelli,Corina Cuceu,Luc Morat,Monika Frenzel,Claire Borie,Alain Dieterlen,Lev Stimmer,Mustafa Al Jawhari,Eric Laplagne,Thomas Mehrling,Aude Lenain,Leonhard Heidingsfelder,Jacques Bosq,T Girinsky ,Géraldine Pottier ,Éric Jeandidier ,William M Hempel ,Nathalie Déchamps ,Noufϊssa Oudrhiri ,Raphaël Boisgard

doi:10.3390/cancers10110414

Abstract

To identify the cells responsible for the initiation and maintenance of Hodgkin lymphoma (HL) cells, we have characterized a subpopulation of HL cells grown in vitro and in vivo with the aim of establishing a reliable and robust animal model for HL. To validate our model, we challenged the tumor cells in vivo by injecting the alkylating histone-deacetylase inhibitor, EDO-S101, a salvage regimen for HL patients, into xenografted mice. Methodology: Blood lymphocytes from 50 HL patients and seven HL cell lines were used. Immunohistochemistry, flow cytometry, and cytogenetics analyses were performed. The in vitro and in vivo effects of EDO-S101 were assessed. Results: We have successfully determined conditions for in vitro amplification and characterization of the HL L428-c subline, containing a higher proportion of CD30−/CD15− cells than the parental L428 cell line. This subline displayed excellent clonogenic potential and reliable reproducibility upon xenografting into immunodeficient NOD-SCID-gamma (−/−)(NSG) mice. Using cell sorting, we demonstrate that CD30−/CD15− subpopulations can gain the phenotype of the L428-c cell line in vitro. Moreover, the human cells recovered from the seventh week after injection of L428-c cells into NSG mice were small cells characterized by a high frequency of CD30−/CD15− cells. Cytogenetic analysis demonstrated that they were diploid and showed high telomere instability and telomerase activity. Accordingly, chromosomal instability emerged, as shown by the formation of dicentric chromosomes, ring chromosomes, and breakage/fusion/bridge cycles. Similarly, high telomerase activity and telomere instability were detected in circulating lymphocytes from HL patients. The beneficial effect of the histone-deacetylase inhibitor EDO-S101 as an anti-tumor drug validated our animal model. Conclusion: Our HL animal model requires only 103 cells and is characterized by a high survival/toxicity ratio and high reproducibility. Moreover, the cells that engraft in mice are characterized by a high frequency of small CD30−/CD15− cells exhibiting high telomerase activity and telomere dysfunction.

Highlights

Hodgkin lymphoma (HL) is a malignancy of the immune system, characterized by the presence of scarce malignant cells, termed Hodgkin and Reed–Sternberg cells (HRS), which in most cases are derived from germinal center B cells [1]
We demonstrate that CD30−/CD15− subpopulations can gain the phenotype of the L428 clones (L428-c) cell line in vitro
The role of CD30−/CD15− cells present in HL cell lines has been the subject of debate for several years [12,13,20]

Summary

Introduction

Hodgkin lymphoma (HL) is a malignancy of the immune system, characterized by the presence of scarce malignant cells, termed Hodgkin and Reed–Sternberg cells (HRS), which in most cases are derived from germinal center B cells [1]. HL lymph nodes and the lack of reliable HL animal models present a major obstacle for studies on molecular mechanisms of HL development and the identification of putative therapeutic targets. Such studies rely heavily on cell lines derived from malignant HRS cells [2]. Only one previous model system, based on the L540 and L540cy

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Discussion

Conclusion