RESUMO
Mantle cell lymphoma (MCL) is an aggressive B-cell non-Hodgkin's lymphoma (NHL). In cancers, tumor suppressive microRNAs may be silenced by DNA hypermethylation. By microRNA profiling of representative EBV-negative MCL cell lines before and after demethylation treatment, miR-155-3p was found significantly restored. Methylation-specific PCR, verified by pyrosequencing, showed complete methylation of miR-155-3p in one MCL cell line (REC-1). 5-aza-2'-deoxycytidine treatment of REC-1 led to demethylation and re-expression of miR-155-3p. Over-expression of miR-155-3p led to increased sub-G1 apoptotic cells and reduced cellular viability, demonstrating its tumor suppressive properties. By luciferase assay, lymphotoxin-beta (LT-ß) was validated as a miR-155-3p target. In 31 primary MCL, miR-155-3p was found hypermethylated in 6(19%) cases. To test if methylation of miR-155-3p was MCL-specific, miR-155-3p methylation was tested in an additional 191 B-cell, T-cell and NK-cell NHLs, yielding miR-155-3p methylation in 66(34.6%) including 36(27%) non-MCL B-cell, 24(53%) T-cell and 6(46%) of NK-cell lymphoma. Moreover, in 72 primary NHL samples with RNA, miR-155-3p methylation correlated with miR-155-3p downregulation (p=0.024), and LT-ß upregulation (p=0.043). Collectively, miR-155-3p is a potential tumor suppressive microRNA hypermethylated in MCL and other NHL subtypes. As miR-155-3p targets LT-ß, which is an upstream activator of the non-canonical NF-kB signaling, miR-155-3p methylation is potentially important in lymphomagenesis.
Assuntos
Linfoma de Célula do Manto/genética , Linfoma não Hodgkin/genética , MicroRNAs/metabolismo , Sequência de Bases , Linhagem Celular Tumoral , Metilação de DNA , Epigênese Genética , Humanos , Linfoma de Célula do Manto/metabolismo , Linfoma não Hodgkin/metabolismo , Linfotoxina-beta/biossíntese , Linfotoxina-beta/genética , MicroRNAs/genética , Regiões Promotoras Genéticas , Regulação para CimaRESUMO
miR-124-1 is a tumour suppressor microRNA (miR). Epigenetic deregulation of miRs is implicated in carcinogenesis. Promoter DNA methylation and histone modification of miR-124-1 was studied in 5 normal marrow controls, 4 lymphoma, 8 multiple myeloma (MM) cell lines, 230 diagnostic primary samples of acute myeloid leukaemia (AML), acute lymphoblastic leukaemia (ALL), chronic myeloid leukaemia (CML), chronic lymphocytic leukaemia (CLL), MM, and non-Hodgkin's lymphoma (NHL), and 53 MM samples at stable disease or relapse. Promoter of miR-124-1 was unmethylated in normal controls but homozygously methylated in 4 of 4 lymphoma and 4 of 8 myeloma cell lines. Treatment of 5-Aza-2'-deoxycytidine led to miR-124-1 demethylation and re-expression of mature miR-124, which also associated with emergence of euchromatic trimethyl H3K4 and consequent downregulation of CDK6 in myeloma cells harboring homozygous miR-124-1 methylation. In primary samples at diagnosis, miR-124-1 methylation was absent in CML but detected in 2% each of MM at diagnosis and relapse/progression, 5% ALL, 15% AML, 14% CLL and 58.1% of NHL (p<0.001). Amongst lymphoid malignancies, miR-124-1 was preferentially methylated in NHL than MM, CLL or ALL. In primary lymphoma samples, miR-124-1 was preferentially hypermethylated in B- or NK/T-cell lymphomas and associated with reduced miR-124 expression. In conclusion, miR-124-1 was hypermethylated in a tumour-specific manner, with a heterochromatic histone configuration. Hypomethylation led to partial restoration of euchromatic histone code and miR re-expression. Infrequent miR-124-1 methylation detected in diagnostic and relapse MM samples showed an unimportant role in MM pathogenesis, despite frequent methylation found in cell lines. Amongst haematological cancers, miR-124-1 was more frequently hypermethylated in NHL, and hence warrants further study.
Assuntos
Epigênese Genética/genética , Neoplasias Hematológicas/genética , MicroRNAs/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Antimetabólitos Antineoplásicos/farmacologia , Azacitidina/farmacologia , Western Blotting , Linhagem Celular Tumoral , Imunoprecipitação da Cromatina , Quinase 6 Dependente de Ciclina/genética , Feminino , Humanos , Leucemia Linfocítica Crônica de Células B/genética , Leucemia Mieloide Aguda/genética , Linfoma/genética , Linfoma não Hodgkin/genética , Masculino , Metilação/efeitos dos fármacos , Pessoa de Meia-Idade , Mieloma Múltiplo/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Adulto JovemRESUMO
BACKGROUND: T-cell-rich B-cell lymphoma (TCRBL) is a lymphoma of B-cell type associated with a prominent component of T cells (constituting > 50% of the cellular population). We report the first case of TCRBL diagnosed by fine needle aspiration (FNA). It was confirmed by subsequent lymph node excision biopsy. CASE: A 37-year-old woman presented with a short history of chest wall pain. Examination revealed induration, warmth and armorlike swelling of the right anterior chest wall, axilla and upper arm, with matted lymph nodes in the ipsilateral axilla and supraclavicular fossa. FNA showed a polymorphic, lymphoid aspirate, among which were many small lymphocytes, significant numbers of centroblastlike cells and a few markedly atypical lymphoid cells with convoluted nuclei. Histiocytes, freely lying karyorrhectic debris and mitotic figures were readily identified. Plasma cells, eosinophils and Reed-Sternberg cells were not seen. The cell block contained similar cells, with larger lymphoid cells scattered among smaller lymphocytes. Immunohistochemical studies showed that the larger cells were B cells. Molecular studies on the cell block confirmed an immunoglobulin gene rearrangement. CONCLUSION: TCRBL is a distinct type of lymphoma that can be accurately diagnosed by FNA.
