Browsing by Author "Silva, Liliana"
Now showing 1 - 10 of 11
Results Per Page
Sort Options
- Adipocyte secretome increases radioresistance of malignant melanocytes by improving cell survival and decreasing oxidative statusPublication . Coelho, Pedro; Silva, Liliana; Faria, Isabel; Vieira, Mónica; Monteiro, Armanda; Pinto, Gabriela; Prudêncio, Cristina; Fernandes, Rúben; Soares, RaquelRadiotherapy is a treatment option for the majority of malignancies. However, because melanoma is known to be radioresistant, the use of ionizing radiation as an adjuvant therapy in cutaneous melanoma patients is ineffective. Obesity has now been recognized as a risk factor for melanoma. High adiposity is generally associated with a more pro-oxidative status. Oxidative stress is a major player in radiation therapy and also a common link between obesity and cancer. Several adipocyte-released proteins are known to have a role in controlling cellular growth and pro-survival signaling. For that reason, we investigated the influence of 3T3-L1 mature adipocyte secretome in B16-F10 malignant melanocyte radiosensitivity. We evaluated B16-F10 cell survival and redox homeostasis when exposed to four daily doses of ionizing radiation (2 Gy per day) up to a total of 8 Gy in a medical linear accelerator. B16-F10 melanocytes exhibited slight alterations in survival, catalase activity, nitrative stress and total oxidant concentration after the first 2 Gy irradiation. The motility of the melanocytes was also delayed by ionizing radiation. Subsequent irradiations of the malignant melanocytes led to more prominent reductions in overall survival. Remarkably, 3T3-L1 adipocyte-secreted molecules were able to increase the viability and migration of melanocytes, as well as lessen the pro-oxidant burden induced by both the single and cumulative X-ray doses. In vitro adipocyte-released factors protected B16-F10 malignant melanocytes from both oxidative stress and loss of viability triggered by radiation, enhancing the radioresistant phenoyype of these cells with a concomitant activation of the AKT signaling pathway These results both help to elucidate how obesity influences melanoma radioresistance and support the usage of conventional medical linear accelerators as a valid model for the in vitro radiobiological study of tumor cell lines.
- Assessment of guanylin peptides system in type 2 diabetesPublication . Silva, Liliana; Maia, Maria Benedita SampaioOs doentes com diabetes mellitus tipo 2 apresentam predisposição para a retenção de sódio e são frequentemente hipertensos. No entanto, os mecanismos implicados na dificuldade do rim diabético em mobilizar o sódio são, ainda, pouco compreendidos. Os peptídeos da família das guanilinas estão envolvidos na regulação do transporte de electrólitos e água nos epitélios intestinal e renal, através da activação do receptor guanilato ciclase-C (GC-C) e subsequente libertação intracelular de GMPc. O objectivo do presente estudo foi a avaliação da actividade do sistema dos peptídeos das guanilinas (SPG) e do seu papel na regulação do balanço de sódio num modelo animal de diabetes tipo 2. Ratinhos machos C57BL/6 foram submetidos a uma dieta com alto teor de gordura e rica em hidratos de carbono simples (ratinhos diabéticos) ou a uma dieta normal (ratinhos controlo). A expressão renal e intestinal da guanilina (GN), uroguanilina (UGN) e do receptor GC-C assim como os níveis de GMPc na urina e plasma foram avaliados nos ratinhos controlo e diabéticos, durante a ingestão de dietas normo (NS) e hiper-salina (HS). Nos ratinhos diabéticos, durante a dieta NS verificou-se um aumento significativo da pressão arterial que foi acompanhado de redução da expressão do ARNm da GN, UGN e do GC-C no intestino e de aumento da expressão de ARNm da UGN no rim. A dieta HS induziu um aumento da expressão do ARNm da UGN no jejuno dos ratinhos controlo mas não nos diabéticos. Os ratinhos diabéticos apresentaram níveis urinários de GMPc inferiores aos controlos, em condições de dieta NS. Em conclusão, os nossos resultados sugerem que na diabetes tipo 2 ocorre uma redução da actividade intestinal do SPG que é acompanhada por um aumento compensatório da actividade renal do SPG. A diminuição da actividade do SPG intestinal na diabetes tipo 2 deve-se não só a uma redução da expressão dos peptídeos GN e UGN, mas também a uma redução da expressão do seu receptor, GC-C. Estes resultados sugerem que o SPG pode contribuir para a sensibilidade ao sódio na diabetes.
- Biomolecules in the relationship of cancer and obesityPublication . Almeida, Joana; Coelho, Pedro; Prudêncio, Cristina; Vieira, Mónica; Fernandes, Rúben; Fonseca, Magda; Soares, Raquel; Silva, Liliana; Faria, Isabel; Monteiro, Armanda; Pinto, Gabriela; Cea, V.; Galesio, M.; Noronha, J. P.; Diniz, M. S.; Sala, C.Obesity has been associated with various major causes of death and morbidity including malignant neoplasms. This increased prevalence has been accompanied by a worldwide increase in cutaneous melanoma incidence rates during the last decades, as well as gliomas, the most common primary malignant brain tumors in adults (Almeida et al., 2019). Although obesity aetiology is established, the implicated mechanisms remain unclear (Coelho et al., 2016). Melanoma is refractory to conventional therapies, and radiotherapy usage as an adjuvant therapy in cutaneous melanoma patients is ineffective, so it is extremely important to understand the antioxidant modulation of melanoma under an environment of obesity (Coelho et al., 2017; Oliveira et al., 2016). Moreover, the metastatic potential of some types of cancer is reduced or inhibited by obesity, which drives major concerns on the prognosis of metastasized patients (Fonseca et al., 2021). All of the studies disclose interesting models for the study of these tumors’ biology under an obese environment, that can be explored for the search of biomarkers, prognostic markers and therapeutic approaches.
- Evaluation of quinoxaline-1,4-dioxide and derivatives biological activity in normal and tumour cellPublication . Silva, Liliana; Coelho, Pedro; Soares, Raquel; Prudêncio, Cristina; Vieira, MónicaQuinoxaline derivatives are synthetic heterocyclic compounds with multiples pharmacological applications and biological effects. Previous studies of our group about the biological activity in eukaryotic and prokaryotic microbial models with quinoxaline-1,4-dioxide (QNX) derivatives concluded a selective antimicrobial activity in gram negative strains. To further evaluate these compounds’ potential, we investigated the biologic activity in vitro of this chemical structures in normal and tumour cells lines.
- Impacto da Radioterapia no stress oxidativo em modelos celulares radiorresistentes em contexto de obesidadePublication . Silva, Liliana; Fernandes, Rúben; Faria, Isabel Maria; Almeida, JoanaIntrodução: Estudos anteriores em modelos tumorais de glioma e melanoma, tumores radiorresistentes, indicaram que a obesidade pode estar relacionada com um aumento do status oxidativo e com a diminuição da resistência à radiação. Como a Radioterapia é o tratamento frequentemente utilizado para esta patologia, propomo-nos, desta forma, a explorar a influência da obesidade em células de glioma, as BC3H1, e melanoma, B16F10, submetidas a Radioterapia, na presença de agentes oxidantes e antioxidantes, para o estudo da sua influência ao nível da viabilidade celular e do impacto do stress oxidativo. Métodos: As células BC3H1 e B16F10 foram tratadas com t-BOOH (150μM e 50 μM, respetivamente), TUDCA (25μM e 1μM, respetivamente) e com a mistura de t-BOOH+TUDCA em meio DMEM sem soro e meio condicionado (CM), a partir de adipócitos 3T3-L1. Em seguida, parte das células foram irradiadas com uma dose total de 2Gy. Posteriormente avaliou-se a viabilidade celular (teste MTT) e o stress oxidativo (teste TBARS, atividade da catalase, concentração da GSH, e status antioxidante total), às 4h e 12h. Resultados: Observou-se um aumento da capacidade antioxidante total das células irradiadas, comparativamente com as células não irradiadas. O meio condicionado reduziu o stress oxidativo nas BC3H1, ao mesmo tempo que reduziu a sua viabilidade celular. O TUDCA nas células incubadas com MC e submetidas a radioterapia, tendencialmente diminuiu a viabilidade celular, nas concertações em estudo. Discussão/Conclusão: O meio condicionado e a radioterapia, por si só, aumentam a resposta antioxidante total na célula, às 4h e às 12h. O TUDCA nas células incubadas com meio condicionado e submetidas a radioterapia, teve um comportamento citotóxico para as BC3H1, nas concentrações testadas. Revelando a necessidade de aprofundar os estudos da ação deste composto como agente radiossensibilizador, neste e noutros modelos celulares de carcinogénese.
- Individual placement and support (IPS): how to address employment needs of people with mental health poblems in PortoPublication . Campos, Carlos; Silva, Liliana; Pereira, Luísa; Marques, António; Queirós, CristinaEmployment is one of the main concerns of patients with mental illness. Several international guidelines state that Individual Placement and Support (IPS) is the most effective intervention to address these needs. It is based on several principles such as focus on competitive employment, attention to client preferences, rapid job search, individualized job supports and eligibility based on client choice.
- Oral hygiene and health education: implications for public healthPublication . Magro, Cátia; Silva, Liliana; Louçano, Marta; Brito, Paula; Teixeira, Ricardo J.; Prudêncio, CristinaDental caries, a progressive infection caused by microorganisms, remain one of the most common diseases throughout the world. The mouth is an ideal environment for bacteria, and one of the best-known for being responsible for dental caries is the Streptococcus mutans.
- Oxidative Stress Modulation and Radiosensitizing Effect of Quinoxaline-1,4-Dioxides DerivativesPublication . Silva, Liliana; Coelho, Pedro; Teixeira, Dulce; Monteiro, Armanda; Pinto, Gabriela; Soares, Raquel; Prudêncio, Cristina; Vieira, MónicaQuinoxaline-1,4-dioxide (QNX) derivatives are synthetic heterocyclic compounds with multiple biological and pharmacological effects. In this study, we investigated the oxidative status of quinoxaline-1,4-dioxides derivatives in modulating melanoma and glioma cell lines, based on previous results from the research group and their capability to promote cell damage by the production of Reactive Oxygen Species (ROS).
- Potentional radiosensitizer effect of TUDCA in a obesity model of brain tumor cellsPublication . Silva, Liliana; Almeida, Joana; Coelho, Pedro; Faria, Isabel; Monteiro, Armanda; Soares, Raquel; Vieira, Mónica; Prudêncio, Cristina; Fernandes, RúbenObesity may play an important role in the biology of seve ral types of cancer, but the correlation with glioma Is still not very well defined. Former studies indicated that obesity may be related with an decreased resistance to radiation and increased redox status in brain tumors. Since radiothetapy is the most commonly treatment modality used in this type of tumor, we creale a new model of experiments to determinate the influence of obesity in glioma cells [n the presence of radiation with an imbalance of redox status, BC3H1 glioma cells were treated with t-BOOH (150~M), TUDCA (25~M) and a mix of t-BOOH and TUOCA{150~M and 25~M respectively) in serum-free OMEM or conditioned media (CM) from differentiated 3T3-L 1 adj pocytes. Afterwards the cells were irradiated with a total dose of 2 Gy. Subsequently BC3H1 viability was evaluated, by MTT assay, after 4 and 12 hours. We observed an increase in viability In all cells treated solely with 3T3-L 1 eM. Interestingly, in the presence of CM plus TUDCA or t-BOOH, the viability of 6C3H1 was inferior of TUOCA or t~BOOH treatments alone, this effect was independent of irradia tion. After 12 hours the I/iability of the glioma cells was significantly higher on irradiated ceUs treated only with eM, this effect was not yet observed at the 4 hours time point But, in the presence of mix of t~BOOH and TUDCA, with eM and irradiation the cells viability decrea se significanUy. The 3T3-L 1 Me increase (he cell viabrlity in the presence of radiation or not, after 12 hours expose" But in the presence of oxidatIve inducer and, In specially, with the antioxidant TUDCA, the BC3Hi viability significantly decrease. So, we observed a potential radiosensitfzer effect of TUDCA in BC3H1 in the presence of 3T3-L1 adipocytes.
- Quinoxaline-1, 4-dioxide derivatives inhibitory action in melanoma and brain tumor cellsPublication . Silva, Liliana; Coelho, Pedro; Soares, Raquel; Prudêncio, Cristina; Vieira, MónicaQuinoxaline-1,4-dioxide derivatives are synthetic heterocyclic compounds with multiple biological and pharmacological effects. In this study, we investigated the bioactivity of five quinoxaline-1,4-di-N-oxides derivatives in different animal cell lines.