RESUMO
Multiple myeloma (MM) is a plasma cell cancer with poor survival, characterized by the expansion of multiple myeloma cells (MMCs) in the bone marrow. Using a microarray-based genome-wide screen for genes responding to DNA methyltransferases (DNMT) inhibition in MM cells, we identified RECQ1 among the most downregulated genes. RecQ helicases are DNA unwinding enzymes involved in the maintenance of chromosome stability. Here we show that RECQ1 is significantly overexpressed in MMCs compared to normal plasma cells and that increased RECQ1 expression is associated with poor prognosis in three independent cohorts of patients. Interestingly, RECQ1 knockdown inhibits cells growth and induces apoptosis in MMCs. Moreover, RECQ1 depletion promotes the development of DNA double-strand breaks, as evidenced by the formation of 53BP1 foci and the phosphorylation of ataxia-telangiectasia mutated (ATM) and histone variant H2A.X (H2AX). In contrast, RECQ1 overexpression protects MMCs from melphalan and bortezomib cytotoxicity. RECQ1 interacts with PARP1 in MMCs exposed to treatment and RECQ1 depletion sensitizes MMCs to poly(ADP-ribose) polymerase (PARP) inhibitor. DNMT inhibitor treatment results in RECQ1 downregulation through miR-203 deregulation in MMC. Altogether, these data suggest that association of DNA damaging agents and/or PARP inhibitors with DNMT inhibitors may represent a therapeutic approach in patients with high RECQ1 expression associated with a poor prognosis.
Assuntos
DNA de Neoplasias/genética , Resistencia a Medicamentos Antineoplásicos/fisiologia , Mieloma Múltiplo/enzimologia , Proteínas de Neoplasias/fisiologia , RecQ Helicases/fisiologia , Bortezomib/farmacologia , Ciclo Celular/efeitos dos fármacos , Quebras de DNA de Cadeia Dupla , Dano ao DNA , Metilação de DNA/efeitos dos fármacos , Replicação do DNA/efeitos dos fármacos , DNA de Neoplasias/metabolismo , DNA-Citosina Metilases/antagonistas & inibidores , Indução Enzimática , Inibidores Enzimáticos/farmacologia , Inibidores Enzimáticos/uso terapêutico , Regulação Neoplásica da Expressão Gênica , Humanos , Melfalan/farmacologia , MicroRNAs/genética , Terapia de Alvo Molecular , Mieloma Múltiplo/tratamento farmacológico , Mieloma Múltiplo/genética , Mieloma Múltiplo/patologia , Proteínas de Neoplasias/antagonistas & inibidores , Proteínas de Neoplasias/genética , Células-Tronco Neoplásicas/efeitos dos fármacos , Células-Tronco Neoplásicas/enzimologia , Plasmócitos/efeitos dos fármacos , Plasmócitos/enzimologia , Poli(ADP-Ribose) Polimerase-1/metabolismo , Interferência de RNA , RNA Interferente Pequeno/genética , RecQ Helicases/antagonistas & inibidores , RecQ Helicases/genética , Células Tumorais CultivadasRESUMO
A lot of genes deregulated in malignant plasma cells (PCs) involved in multiple myeloma have been reported these last years. The expression of some of these genes is associated with poor survival. A critical step is to elucidate the biological mechanisms triggered by these gene products. Such studies are hampered by the difficulty to obtain malignant PCs and to genetically modify them. Usual lentiviral vectors (LVs) pseudotyped with vesicular stomatitis virus envelope glycoprotein poorly transduced healthy and malignant PCs. Here, we report that LVs pseudotyped with the hemagglutinin and fusion glycoproteins from the measles Edmonston strain (H/F-LVs) can efficiently and stably transduce healthy and primary malignant PCs, without modifying their main phenotypic characteristics. Both LV pseudotypes efficiently transduced human myeloma cell lines. Importantly, both healthy and malignant PCs expressed CD46 and SLAMF1/CD150 membrane proteins, which are critical receptors for binding and productive genetic modification by H/F-LVs. The ability to efficiently introduce and express a given gene into PCs opens the possibility to study in detail PC biology.
