RESUMO
Recent evidence has shown that deregulated expression of members of the microRNA-29 (miR-29) family may play a critical role in human cancer, including hematological malignancies. However, the roles of miR-29 in the molecular pathophysiology of T-cell acute lymphoblastic leukemia (T-ALL) has not been investigated. Here, we show that lower levels of miR-29a were significantly associated with higher blast counts in the bone marrow and with increased disease-free survival in T-ALL patients. Furthermore, miR-29a levels are extremely reduced in T-ALL cells compared to normal T cells. Microarray analysis following introduction of synthetic miR-29a mimics into Jurkat cells revealed the downregulation of several predicted targets (CDK6, PXDN, MCL1, PIK3R1, and CXXC6), including targets with roles in active and passive DNA demethylation (such as DNMT3a, DNMT3b, and members of the TET family and TDG). Restoring miR-29a levels in Jurkat and Molt-4 T-ALL cells led to the demethylation of many genes commonly methylated in T-ALL. Overall, our results suggest that reduced miR-29a levels may contribute to the altered epigenetic status of T-ALL, highlighting its relevance in the physiopathology of this disease.
Assuntos
Metilação de DNA/genética , Epigênese Genética/genética , Regulação Leucêmica da Expressão Gênica/genética , MicroRNAs/genética , Leucemia-Linfoma Linfoblástico de Células T Precursoras/genética , Antígenos de Neoplasias/biossíntese , Apoptose/genética , Linhagem Celular Tumoral , Proliferação de Células/genética , Classe Ia de Fosfatidilinositol 3-Quinase , Quinase 6 Dependente de Ciclina/biossíntese , DNA (Citosina-5-)-Metiltransferases/genética , DNA Metiltransferase 3A , Proteínas de Ligação a DNA/biossíntese , Daunorrubicina/farmacologia , Intervalo Livre de Doença , Resistencia a Medicamentos Antineoplásicos/genética , Humanos , Células Jurkat , Oxigenases de Função Mista , Proteína de Sequência 1 de Leucemia de Células Mieloides/biossíntese , Análise de Sequência com Séries de Oligonucleotídeos , Peroxidases , Fosfatidilinositol 3-Quinases/biossíntese , Proteínas Proto-Oncogênicas/biossíntese , Receptores de Interleucina-1/biossíntese , DNA Metiltransferase 3BRESUMO
The myeloid differentiation factor 88 (MyD88) plays a pivotal role in Toll-like receptor (TLR)- and interleukin-1 receptor (IL-1R)-induced osteoclastogenesis. We examined the role of MyD88 on p38 mitogen-activated protein kinase (MAPK) and nuclear factor kappa-light-chain-enhancer of activated B cell (NF-κB) activation and nucleotide-binding oligomerization domain (Nod) induction by lipopolysaccharide (LPS) and IL-1 beta, and their effect on receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) production in bone marrow stromal cell (BMSC). RANKL, Nod1, Nod2, NF-κB, and p38 protein levels were determined by Western blot. Nod2 was stimulated with muramyl dipeptide (MDP) prior to TLR4 stimulation with LPS. MyD88 deficiency markedly inhibited RANKL expression after LPS stimulation and increased OPG messenger RNA (mRNA) production. Also, MyD88 was necessary for NF-κB and p38 MAPK activation. MDP alone did not induce RANKL and OPG expressions; however, when combined with LPS, their expressions were significantly increased (p < 0.05). Our results support that MyD88 signaling has a pivotal role in osteoclastogenesis thought NF-κB and p38 activation. Nod2 and especially Nod1 levels were influenced by MyD88.