RESUMO
Whilst the survival rates of childhood acute lymphoblastic leukemia (ALL) have increased remarkably over the last decades, the therapy resistance and toxicity are still the major causes of treatment failure. It was shown that overexpression of heme oxygenase-1 (HO-1) promotes proliferation and chemoresistance of cancer cells. In humans, the HO-1 gene (HMOX1) expression is modulated by two polymorphisms in the promoter region: (GT)n-length polymorphism and single-nucleotide polymorphism (SNP) A(-413)T, with short GT repeat sequences and 413-A variants linked to an increased HO-1 inducibility. We found that the short alleles are significantly more frequent in ALL patients in comparison to the control group, and that their presence may be associated with a higher risk of treatment failure, reflecting the role of HO-1 in chemoresistance. We also observed that the presence of short alleles may predispose to develop chemotherapy-induced neutropenia. In case of SNP, the 413-T variant co-segregated with short or long alleles, while 413-A almost selectively co-segregated with long alleles, hence it is not possible to determine if SNPs are actually of phenotypic significance. Our results suggest that HO-1 can be a potential target to overcome the treatment failure in ALL patients.
Assuntos
Neutropenia Febril Induzida por Quimioterapia/genética , Resistencia a Medicamentos Antineoplásicos/genética , Heme Oxigenase-1/genética , Polimorfismo de Nucleotídeo Único , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Células Cultivadas , Neutropenia Febril Induzida por Quimioterapia/etiologia , Criança , Humanos , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Regiões Promotoras GenéticasRESUMO
The extracellular matrix (ECM) is a dynamic environment involved in the regulation of haematopoiesis. A crucial role of this structure is the promotion of proliferation, maturation, and differentiation of haematopoietic stem cells (HSC), and adhesion and migration of HSC in bone marrow. In the present study the effect of ECM proteins (fibronectin, collagens, laminin, thrombospondin, and vitronectin) on proliferation and apoptosis of acute lymphoblastic leukaemia cells isolated from acute lymphoblastic leukaemia (ALL) patients (in vitro) was assessed. The leukaemia cells were obtained as interphase on Ficoll/Isopaque (Pancoll human, PAN-Biotech) density gradient and, after washing, counted in a chamber. Subsequently, cells were used for culture and apoptosis assay. Presence of fibronectin, collagen type IV, and laminin was associated with inhibition of lymphoblastic leukaemia cell proliferation. Analysis of the culture of lymphoblastic leukaemia cells in the presence of ECM showed fibronectin as the most active protein.
