RESUMO
Maintenance of thymus homeostasis is a delicate interplay involving hormones, neurotransmitters and local microenvironmental proteins, as well as saccharides, acting on both thymocytes and stromal cells. Disturbances in these interactions may lead to alterations on thymocyte development. We previously showed that galectin-3, a ß-galactoside-binding protein, is constitutively expressed in the thymus, interacting with extracellular matrix glycoproteins and acting as a de-adhesion molecule, thus modulating thymocyte-stromal cell interactions. In this work, we aimed to investigate the participation of galectin-3 in the maintenance of thymus homeostasis, including hormonal-mediated circuits. For that, we used genetically engineered galectin-3-deficient mice. We observed that the thymus of galectin-3-deficient mice was reduced in mass and cellularity compared to wild-type controls; however, the proportions of different thymocyte subpopulations defined by CD4/CD8 expression were not changed. Considering the CD4-CD8- double-negative (DN) subpopulation, an accumulation of the most immature (DN1) stage was observed. Additionally, the proliferative capacity of thymocytes was decreased in all thymocyte subsets, whereas the percentage of apoptosis was increased, especially in the CD4+CD8+ double-positive thymocytes. As glucocorticoid hormones are known to be involved in thymus homeostasis, we evaluated serum and intrathymic corticosterone levels by radioimmunoassay, and the expression of steroidogenic machinery using real-time PCR. We detected a significant increase in corticosterone levels in both serum and thymus samples of galectin-3-deficient mice, as compared to age-matched controls. This was paralleled by an increase of gene transcription of the steroidogenic enzymes, steroidogenic acute regulatory protein (Star) and Cyp11b1 in thymus, 11ß-Hydroxysteroid Dehydrogenase (Hsd11b1) in the adrenal, and Cyp11a1 in both glands. In conclusion, our findings show that the absence of galectin-3 subverts mouse thymus homeostasis by a mechanism likely associated to intrathymic and systemic stress-related endocrine circuitries, affecting thymocyte number, proliferation and apoptosis.
RESUMO
ABSTRACT In recent years, many oncology institutions have implemented the use of molecular approaches to assess and manage cancer patients. One commonly observed type of genetic alteration in cancer is the loss of heterozygosity (LOH). In the clinical setting, this molecular genetic marker is an important tool for disease prognosis, diagnosis and treatment. For example, the loss of 1p/19q is a classical molecular marker for oligodendroglioma assessment. In addition, this marker is associated with a favorable prognosis and chemosensitivity in oligodendroglial tumors. Interpretation of the clinical significance of molecular markers requires that health professionals and biomedical scientists understand the basic theoretical fundamentals of molecular diagnostic techniques. Although there are different methodologies to assess LOH, including high-performance techniques, this review aims to describe the polymerase chain reaction (PCR)-based LOH assays and fluorescence in situ hybridization (FISH), which are the molecular techniques most used for evaluation of 1p/19q status in pathology laboratories.
RESUMO Nos últimos anos, instituições de oncologia têm implementado o uso de abordagens moleculares para avaliar e conduzir pacientes com câncer. O tipo mais comum de alteração encontrada no câncer é a perda de heterozigosidade (LOH). Na clínica, esse marcador molecular pode ter importância para o prognóstico, o diagnóstico e/ou na decisão do tratamento. Por exemplo, a perda de 1p/19q é um marcador molecular clássico para a avaliação do oligodendroglioma. Além disso, esse marcador está associado ao prognóstico favorável e à quimiossensibilidade em tumores oligodendrogliais. A interpretação do significado clínico dos marcadores moleculares exige que os profissionais da área da saúde entendam os fundamentos básicos teóricos das técnicas de diagnóstico molecular. Embora existam diferentes metodologias para avaliar a LOH, inclusive técnicas de alta performance, esta revisão tem o objetivo de descrever o ensaio de LOH com base na reação da cadeia da polimerase (PCR) e a hibridização in situ fluorescente (FISH), que são as técnicas moleculares mais usadas para avaliação do status 1p/19q em laboratórios de patologia.