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The mechanisms underlying MMR deficiency in immunodeficiency‐related non‐Hodgkin lymphomas are different from those in other sporadic microsatellite instable neoplasms
Author(s) -
Borie Claire,
Colas Chrystelle,
Dartigues Peggy,
Lazure Thierry,
Rince Patricia,
Buhard Olivier,
Folliot Patrick,
Chalastanis Alexandra,
Muleris Martine,
Hamelin Richard,
Mercier Dominique,
Oliveira Carla,
Seruca Raquel,
Chadburn Amy,
Leblond Véronique,
Barete Stéphane,
Gaïdano Gianluca,
Martin Antoine,
Gaulard Philippe,
Fléjou JeanFrançois,
Raphael Martine,
Duval Alex
Publication year - 2009
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.24681
Subject(s) - microsatellite instability , msh6 , msh2 , dna mismatch repair , cancer research , context (archaeology) , mlh1 , biology , immunodeficiency , pms2 , cancer , immunosuppression , lymphoma , kras , immunology , colorectal cancer , immune system , genetics , gene , allele , microsatellite , paleontology
The spectrum of tumors showing microsatellite instability (MSI) has recently been enlarged to sporadic neoplasms whose incidence is favored in the context of chronic immunosuppression. We investigated the biological, therapeutic and clinical features associated with MSI in immunodeficiency‐related non‐Hodgkin lymphomas (ID‐RL). MSI screening was performed in 275 ID‐RL. MSI ID‐RL were further analyzed for MMR gene expression and for BRAF/KRAS mutations since these genes are frequently altered in MSI cancers. We also assessed the expression of O 6 ‐methylguanine‐DNA methyltransferase (MGMT), an enzyme whose inactivation has been reported in lymphomas and may help in the selection of MMR deficient clones. Unlike other sporadic MSI neoplasms, MSI ID‐RL ( N = 17) presented with heterogeneous MMR defects and no MLH1 promoter methylation. About one third of these tumors presented with normal expression of MLH1, MSH2, MSH6 and PMS2 . They accumulated BRAF activating mutations (33%). Unlike other ID‐RL, MSI ID‐RL were primarily EBV‐negative NHL of T‐cell origin, and arose after long‐term immunosuppression in patients who received azathioprine as part of their immunosuppressive regimen ( p = 0.05) and/or who exhibited methylation‐induced loss of expression of MGMT in tumor cells ( p = 0.02). Overall, these results highlight that, in the context of deficient immune status, some MSI neoplasms arise through alternative mechanism when compared to other sporadic MSI neoplasms. They give the exact way how to make the diagnosis of MSI in these tumors and may help to define biological and clinicalrisk factors associated with their emergence in such a clinicalcontext. © 2009 UICC