RESUMO
PURPOSE: Epigenetic changes such as DNA methylation play a key role in the development and progression of multiple myeloma. Our aim in the present study was to use genomic screening to identify genes targeted for epigenetic inactivation in multiple myeloma and assess their role in the development of resistance to dexamethasone. EXPERIMENTAL DESIGN: Gene expression was examined using microarray screening, reverse transcription-PCR, and real-time quantitative PCR. DNA methylation was examined using bisulfite PCR, bisulfite sequencing, and bisulfite pyrosequencing in 14 multiple myeloma cell lines, 87 multiple myeloma specimens, and 12 control bone marrow samples. WST-8 assays were used to assess cell viability after treatment with 5-aza-2'-deoxycytidine and/or dexamethasone. RESULTS: Microarray analysis was done to screen for genes up-regulated by 5-aza-2'-deoxycytidine. In RPMI8226 cells, 128 genes were up-regulated, whereas 83 genes were up-regulated in KMS12PE cells. Methylation of 22 genes with CpG islands in their 5' regions, including RASD1, was confirmed. Methylation of RASD1 was associated with its inactivation, which correlated with resistance to dexamethasone. Treating multiple myeloma cells with 5-aza-2'-deoxycytidine restored sensitivity to dexamethasone. Methylation of RASD1 was also detected in a subset of primary multiple myeloma specimens, and the levels of methylation were increased after repeated antitumor treatments. Gene signature analysis revealed various genes to be synergistically induced by treatment with a combination of 5-aza-2'-deoxycytidine plus dexamethasone. CONCLUSION: Our findings indicate that epigenetic inactivation of genes, including RASD1, plays a key role in the development of dexamethasone resistance in multiple myeloma. Moreover, they show the utility of demethylation therapy in cases of advanced multiple myeloma.
Assuntos
Metilação de DNA/fisiologia , Dexametasona/uso terapêutico , Resistencia a Medicamentos Antineoplásicos/genética , Mieloma Múltiplo/tratamento farmacológico , Mieloma Múltiplo/genética , Proteínas ras/genética , Antineoplásicos/uso terapêutico , Azacitidina/administração & dosagem , Azacitidina/análogos & derivados , Azacitidina/farmacologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Decitabina , Avaliação Pré-Clínica de Medicamentos , Sinergismo Farmacológico , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Inativação Gênica/fisiologia , Testes Genéticos , Humanos , Modelos Biológicos , Análise de Sequência com Séries de Oligonucleotídeos , Proteínas ras/fisiologiaRESUMO
A 44-year-old man was admitted to hospital because of respiratory distress and progressive edema in the lower extremities. He was diagnosed as having congestive heart failure, but his condition improved following intensive care. Echocardiogram revealed a thickened interventricular septum, insufficient diastolic function, and granular sparkling pattern in the ventricular wall. Pathological examination of a myocardial biopsy specimen showed the deposition of AL amyloid, resulting in a diagnosis of AL amyloidosis. He was then referred to our hospital for treatment. After a course of high-dose dexamethasone therapy, peripheral blood stem cells induced by the administration of granulocyte colony stimulating factor were harvested. He then received high-dose melphalan (HDM) with autologous peripheral blood stem cell transplantation (auto-PBSCT) support, leading to complete remission. He has been well for more than three years after the transplantation and enjoys the same daily life as before the onset of symptoms. HDM/auto-PBSCT for AL amyloidosis confers a higher response rate and longer survival than conventional chemotherapies; however, treatment-related toxicity is also high. Refinements of treatment strategies are urgently needed. This case provides insights into appropriate strategies for HDM/auto-PBSCT for AL amyloidosis with regard to patient selection, the best induction therapy, and the risk-adjusted melphalan conditioning dose; all of which should be confirmed by randomized controlled trials.
Assuntos
Amiloidose/terapia , Insuficiência Cardíaca/complicações , Transplante de Células-Tronco de Sangue Periférico , Adulto , Amiloidose/complicações , Humanos , Masculino , Indução de Remissão , Transplante AutólogoRESUMO
Epigenetic gene inactivation plays a key role in the development of various types of cancer. Using methylated CpG island amplification coupled with representational difference analysis to identify genes inactivated by DNA methylation in gastric cancer, we identified seven DNA fragments corresponding to the 5' CpG islands of the affected genes. One of the clones recovered was identical to the 5' flanking region of DFNA5, a gene previously shown to be associated with deafness and induced by DNA damage. Further analysis revealed that DFNA5 is expressed in normal tissues but is down-regulated in gastric cancer cell lines due to methylation of the region around its transcription start site. Treating gastric cancer cells that lacked DFNA5 expression with a methyltransferase inhibitor, 5-aza-2'-deoxycytidine, restored the gene's expression. Methylation of DFNA5 was detected in 50% of primary gastric tumors, and was correlated with positivity for Epstein-Barr virus and the absence of metastasis. Moreover, introduction of exogenous DFNA5 into silenced cells suppressed colony formation. Taken together, these data suggest that the silencing of DFNA5 occurs frequently in gastric cancer and may play a key role in development and progression of the disease.