RESUMO
B-cell chronic lymphocytic leukemia (B-CLL) cells are resistant to apoptosis, and consequently accumulate to the detriment of normal B cells and patient immunity. Because current therapies fail to eradicate these apoptosis-resistant cells, it is essential to identify alternative survival pathways as novel targets for anticancer therapies. Overexpression of cell-surface G protein-coupled receptors drives cell transformation, and thus plays a critical role in malignancies. In this study, we identified neurotensin receptor 2 (NTSR2) as an essential driver of apoptosis resistance in B-CLL. NTSR2 was highly expressed in B-CLL cells, whereas expression of its natural ligand, neurotensin (NTS), was minimal in both B-CLL cells and patient plasma. Surprisingly, NTSR2 remained in a constitutively active phosphorylated state, caused not by a mutation-induced gain-of-function but rather by an interaction with the oncogenic tyrosine kinase receptor TrkB. Functional and biochemical characterization revealed that the NTSR2-TrkB interaction acts as a conditional oncogenic driver requiring the TrkB ligand brain-derived neurotrophic factor (BDNF), which unlike NTS is highly expressed in B-CLL cells. Together, NTSR2, TrkB and BDNF induce autocrine and/or paracrine survival pathways that are independent of mutation status and indolent or progressive disease course. The NTSR2-TrkB interaction activates survival signaling pathways, including the Src and AKT kinase pathways, as well as expression of the anti-apoptotic proteins Bcl-2 and Bcl-xL. When NTSR2 was downregulated, TrkB failed to protect B-CLL cells from a drastic decrease in viability via typical apoptotic cell death, reflected by DNA fragmentation and Annexin V presentation. Together, our findings demonstrate that the NTSR2-TrkB interaction plays a crucial role in B-CLL cell survival, suggesting that inhibition of NTSR2 represents a promising targeted strategy for treating B-CLL malignancy.
Assuntos
Apoptose , Biomarcadores Tumorais/metabolismo , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Leucemia Linfocítica Crônica de Células B/patologia , Glicoproteínas de Membrana/metabolismo , Receptor trkB/metabolismo , Receptores de Neurotensina/metabolismo , Biomarcadores Tumorais/genética , Fator Neurotrófico Derivado do Encéfalo/genética , Proliferação de Células , Humanos , Leucemia Linfocítica Crônica de Células B/genética , Leucemia Linfocítica Crônica de Células B/metabolismo , Glicoproteínas de Membrana/genética , Receptor trkB/genética , Receptores de Neurotensina/genética , Células Tumorais CultivadasRESUMO
In this paper, we have investigated the use of DNA hybridization as the basis for the production of new mesoscale components. AFM experimental results are studied and compared to two theoretical approaches: molecular and thermodynamic. We explain how and why DNA hybridization process can provide a good bond to self assemble components, and how molecular modelling methods allow further understanding of the physical mechanism of this process. Furthermore, the strength interaction of DNA complementary strands is measured and analyzed using statistical tools. These results are then compared to the theoretical approaches.