Marília Dourado

Apoptosis Deregulation Influences Chemoresistance to Azaguanine in Human Leukemic Cell Lines

The involvement of apoptosis in the cytotoxicity mediated by nucleoside analogues, namely azaguanine, and its implication in resistance are not well understood. Using human T-cell acute lymphoblastic leukemia cell lines, sensitive (CEM cells) and resistant to azaguanine (CM3 cells), we observe a decrease in the expression of proapoptotic proteins in CM3 cells, which may be related to the resistance to cell death induced by azaguanine. On the other hand, CM3 cells lack cross resistance with other anticarcinogenic drugs, suggesting that azaguanine may be used alternatively in the presence of chemoresistance. A better knowledge of the apoptotic pathways involved in leukemic cell death resistance may contribute to the development of therapeutic strategies, aimed to prevent chemotherapy resistance.

Modelos experimentais em oncologia: O contributo da cultura de células para o conhecimento da biologia do cancro

Resumo A cultura de tecidos surgiu no seculo xx (Harrison, 1907) para estudar o comportamento das celulas animais em ambiente homeostatico e em situacoes de stress. A capacidade de estudar as celulas a nivel molecular relaciona-se com a forma como as celulas podem crescer e ser manipuladas em laboratorio. A cultura de celulas in vitro permitiu estudar crescimento, diferenciacao e morte celular e efectuar manipulacoes geneticas necessarias ao perfeito conhecimento da estrutura e funcoes dos genes. A cultura de celulas estaminais humanas veio colmatar algumas limitacoes inerentes aos restantes modelos de cultura. Ao que parece, as celulas estaminais cancerigenas mantem-se quiescentes nos locais metastaticos ate serem activadas por sinais apropriados do microambiente. Varios estudos revelaram que diferentes tipos de cancros podem surgir da transformacao maligna de celulas estaminais. A eliminacao destas celulas progenitoras tumorais e essencial para o desenvolvimento de novas abordagens terapeuticas mais eficazes em cancros agressivos. Por outro lado, a utilizacao de celulas dendriticas modificadas em cultura podera contribuir para a producao de uma potencial vacina terapeutica eficaz para obter a regressao tumoral. Rev Port Pneumol 2009; XV (4): 669-682

Medição da autonomia em atividades da vida diária

Introdução: As atividades da vida diária constituem o nível mais básico de autonomia, que permitem a participação no dia-a-dia em termos de sobrevivência e bem-estar básicos. Neste trabalho, focaremos a necessidade de avaliar as atividades da vida diária em cuidados continuados e paliativos. Objetivo: Descrever e comparar instrumentos de medição de atividades da vida diária. Material e métodos: Pesquisa bibliográfica de instrumentos de medição de atividades de vida diária, em inglês e português, entre 1980 e 2017, nas bases de dados científicas reconhecidas para este efeito. Resultados: Encontraram-se seis instrumentos de medição e, para cada um, identificou-se o número de perguntas e dimensões avaliadas, as propriedades psicométricas e a existência de versão portuguesa validada. Discussão: Todos os instrumentos são preenchidos pelo profissional, por observação direta, e avaliam os autocuidados. Vestir/despir, alimentação e mobilidade são atividades comuns a todos, havendo outras específicas de apenas uma escala. Conclusão: As dimensões vestir/despir, alimentação e mobilidade são as mais avaliadas. Apenas o índice de Barthel está validado para a população portuguesa. Quanto a critérios de qualidade, uma escala apresenta fiabilidade para o acidente vascular cerebral. A maioria das escalas apresenta boa correlação com outras escalas de avaliação da autonomia.

Epithelial-mesenchymal transition and microRNAs: Challenges and future perspectives in oral cancer

Head and neck cancer is the sixth most common cancer worldwide, with oral squamous cell carcinoma (OSCC) being the most representative type. OSCC is a public health problem with high morbidity and poor survival rate. Epithelial‐mesenchymal transition is emerging as a hallmark in OSCC.

Recombinant trail: a synergistic effect in myeloid leukemias.

The tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL/Apo-2L) is a member of the TNF superfamily that trigger and activate 2 death receptors, DR4 and DR5, and 2 decoy receptors, DcR1 and DcR2. Several studies demonstrated that TRAIL in monotherapy can induces cancer cell death cells, but few have been done in leukemias in combination with conventional drugs. The aim of this work is to analyse the potential synergist effect of a recombinant TRAIL (rhTRAIL) in myeloid leukemias. For this, 2 myeloid leukemia cell lines, HL-60 (promyelocitic leukemia) and K-562 (Chronic Myeloid Leukemia) were treated with different concentrations of rhTRAIL as single agent and in combination with ATRA (all-transretinoic acid) and imatinib, respectively. The viability was measure using the trypan blue test and cell death by flow cytometry (FC) and Optical Microscopy. TRAIL and TRAIL-Rs were evaluated by FC. Our results show that rhTRAIL induced a decrease in cell viability inducing cell death, in a time, dose and cell type dependent manner. We observe an IC50 in HL-60 treated for 48h of 250 ng/mL, although in K562 cells, rhTRAIL wasn’t able to induce a significant effect. However, when we previously treated the cells with ATRA or IMATINIB a synergistic effect is observed, mainly in HL60 cells. These results may be correlated with the differential TRAIL receptors expression, namely the presence of the anti-apoptotic TRAIL receptors, in K562 cells. On the other hand, the higher percentage of pro-apoptotic TRAIL receptors may be related with the therapeutic efficacy of rhTRAIL in HL-60 cells. Our study suggests that rhTRAIL can be use as a new therapeutic aproach in APL, as single agent. However, it can potentiate the cytotoxic effect of conventional drugs.

The role of CD26 and CD40 expression in therapeutic response - experimental study in oral cancer lines.

Oral cancer (OC) is one of the 10 most diagnosed cancers in the world. It is aggressive and difficult to treat. Despite the achieved therapeutic advances, the 5 year survival rate has not changed in the past decade. Understanding the basic molecular pathogenesis of OC may give new opportunities for future treatments. Regulators of the immune system such as CD40 [1].and CD26 [2] are believed to be involved in carcinogenesis besides immunologic anti-tumour defence. The aim of this study was to evaluate the influence of CD26/DPPIV and CD40/CD40L cell expression in two OC cell lines and treatment response. For this two human OC cell lines BICR10 (in situ) and HSC3 (metastatic) were incubated with cisplatin in different concentrations. Cell morphology was evaluated by light microscopy and cell viability was estimated by alamar blue test. Cell death CD26 and CD40/CD40L expression was evaluated by flow cytometry and DPPIV by luminescent assay. Preliminary results show that BICR10 has higher CD26/DPPIV levels and lower CD40/CD40L expression than HSC3. However, after treatment with cisplatin expression of CD40/CD40L and DPPIV increases in both cell lines that could be related with apoptosis detected by morphology and cytometry. Our results suggest that CD40/CD40L and CD26/DPPIV can be involved in OC development and drug response and could constitute a new molecular target to cancer diagnosis/prognosis and treatment.

New targeted therapies in myelodysplastic syndrome: the role of farnesyltransferase and proteasome inhibitors

One of the main mechanisms responsible for MDS molecular pathogenesis involves the activation of tyrosine-kinase receptors, such as FLT3, RAS proteins, and deregulation of apoptotic pathways. Regarding this, new drugs have been developed to target pathways involved in malignancy, such as Farnesyltransferase Inhibitors (IFTs) and proteasome inhibitors (PI). This work aims to clarify the role of IFTs and PI as potential therapeutic agents in Myelodysplastic Syndrome (MDS). For this, F-36P cells, were incubated with different concentrations of α-HFPA (IFT) and MG262 (PI), as single agents and in association with the conventional therapeutic drug, Cytosine Arabinoside (Ara-C). Cell growth and viability was evaluated by Trypan Blue test. Cell death was analyzed by optic microscopy and flow cytometry (FC). Expression of proteins involved in apoptosis and cell cycle regulation was evaluated by FC. The detection of RAS and FLT3 mutations was accessed by sequentiation and PCR, respectively. Our results show that α-HFPA and MG262, in monotherapy, induce a decrease in cell growth and viability in a time and dose-dependent manner (IC50, α-HFPA 125 μM; MG262 100 nM). The antiproliferative effect of α-HFPA could be related to RAS/MAPK pathway inhibition, as we observed a decrease in cyclin D1 levels, while the cytotoxicity induced by MG262 to an increase in BAX expression. Our results show that α-HFPA is effective independently of RAS mutations, once we didn’t identify mutations in none of the isoforms studied, but we observe ITD mutations in FLT3 gene. These results suggest that IFTs and PIs may constitute a potential therapeutic approach as single agents in MDS.

Sondas de RNA ribossómico no diagnóstico da tuberculose humana

RESUMO Tendo em vista um mais rapido e especifico diagnostico laboratorial da tuberculose, os autores avaliaram esta tecnologia usando para tal 15 amostras desconhecidas, avaliaram ainda as condicoes ambientais do seu laboratorio, o que para este tipo de tecnologia e particularmente critica.