RENATA DE FREITAS SAITO
Projetos de Pesquisa
Unidades Organizacionais
Instituto do Câncer do Estado de São Paulo, Hospital das Clínicas, Faculdade de Medicina
LIM/24 - Laboratório de Oncologia Experimental, Hospital das Clínicas, Faculdade de Medicina
LIM/24 - Laboratório de Oncologia Experimental, Hospital das Clínicas, Faculdade de Medicina
24 resultados
Resultados de Busca
Agora exibindo 1 - 10 de 24
- Amblyomin-X induces ER stress, mitochondrial dysfunction, and caspase activation in human melanoma and pancreatic tumor cell(2016) MORAIS, Katia L. P.; PACHECO, Mario Thiego Fernandes; BERRA, Carolina Maria; BOSCH, Rosemary V.; SCIANI, Juliana Mozer; CHAMMAS, Roger; SAITO, Renata de Freitas; IQBAL, Asif; CHUDZINSKI-TAVASSI, Ana MarisaDuring the last two decades, new insights into proteasome function and its role in several human diseases made it a potential therapeutic target. In this context, Amblyomin-X is a Kunitz-type FXa inhibitor similar to endogenous tissue factor pathway inhibitor (TFPI) and is a novel proteasome inhibitor. Herein, we have demonstrated Amblyomin-X cytotoxicity to different tumor cells lines such as pancreatic (Panc1, AsPC1BxPC3) and melanoma (SK-MEL-5 and SK-MEL-28). Of note, Amblyomin-X was not cytotoxic to normal human fibroblast cells. In addition, Amblyomin-X promoted accumulation of ER stress markers (GRP78 and GADD153) in sensitive (SK-MEL-28) and bortezomib-resistant (Mia-PaCa-2) tumor cells. The intracellular calcium concentration [Ca2+] (i) was slightly modulated in human tumor cells (SK-MEL-28 and Mia-PaCa-2) after 24 h of Amblyomin-X treatment. Furthermore, Amblyomin-X induced mitochondrial dysfunction, cytochrome-c release, PARP cleavage, and activation of caspase cascade in both human tumor (SK-MEL-28 and Mia-PaCa-2) cells. These investigations might help in further understanding of the antitumor properties of Amblyomin-X.
- Effective Synergy of Sorafenib and Nutrient Shortage in Inducing Melanoma Cell Death through Energy Stress(2020) ANTUNES, Fernanda; PEREIRA, Gustavo J. S.; SAITO, Renata F.; V, Marcus Buri; GAGLIARDI, Mara; BINCOLETTO, Claudia; CHAMMAS, Roger; FIMIA, Gian Maria; PIACENTINI, Mauro; CORAZZARI, Marco; SMAILI, Soraya SoubhiSkin melanoma is one of the most aggressive and difficult-to-treat human malignancies, characterized by poor survival rates, thus requiring urgent novel therapeutic approaches. Although metabolic reprogramming has represented so far, a cancer hallmark, accumulating data indicate a high plasticity of cancer cells in modulating cellular metabolism to adapt to a heterogeneous and continuously changing microenvironment, suggesting a novel therapeutic approach for dietary manipulation in cancer therapy. To this aim, we exposed melanoma cells to combined nutrient-restriction/sorafenib. Results indicate that cell death was efficiently induced, with apoptosis representing the prominent feature. In contrast, autophagy was blocked in the final stage by this treatment, similarly to chloroquine, which also enhanced melanoma cell sensitization to combined treatment. Energy stress was evidenced by associated treatment with mitochondrial dysfunction and glycolysis impairment, suggesting metabolic stress determining melanoma cell death. A reduction of tumor growth after cycles of intermittent fasting together with sorafenib treatment was also observed in vivo, reinforcing that the nutrient shortage can potentiate anti-melanoma therapy. Our findings showed that the restriction of nutrients by intermittent fasting potentiates the effects of sorafenib due to the modulation of cellular metabolism, suggesting that it is possible to harness the energy of cancer cells for the treatment of melanoma.
- Phosphatidylcholine-Derived Lipid Mediators: The Crosstalk Between Cancer Cells and Immune Cells(2022) SAITO, Renata de Freitas; ANDRADE, Luciana Nogueira de Sousa; BUSTOS, Silvina Odete; CHAMMAS, RogerTo become resistant, cancer cells need to activate and maintain molecular defense mechanisms that depend on an energy trade-off between resistance and essential functions. Metabolic reprogramming has been shown to fuel cell growth and contribute to cancer drug resistance. Recently, changes in lipid metabolism have emerged as an important driver of resistance to anticancer agents. In this review, we highlight the role of choline metabolism with a focus on the phosphatidylcholine cycle in the regulation of resistance to therapy. We analyze the contribution of phosphatidylcholine and its metabolites to intracellular processes of cancer cells, both as the major cell membrane constituents and source of energy. We further extended our discussion about the role of phosphatidylcholine-derived lipid mediators in cellular communication between cancer and immune cells within the tumor microenvironment, as well as their pivotal role in the immune regulation of therapeutic failure. Changes in phosphatidylcholine metabolism are part of an adaptive program activated in response to stress conditions that contribute to cancer therapy resistance and open therapeutic opportunities for treating drug-resistant cancers.
- Galectin-3 sensitized melanoma cell lines to vemurafenib (PLX4032) induced cell death through prevention of autophagy(2018) BUSTOS, S. O.; PEREIRA, G. J. S.; SAITO, R. F.; GIL, C. D.; ZANATTA, D. B.; SMAILI, S. S.; CHAMMAS, R.Melanoma is a current worldwide problem, as its incidence is increasing. In the last years, several studies have shown that melanoma cells display high levels of autophagy, a self-degradative process that can promote survival leading to drug resistance. Consequently, autophagy regulation represents a challenge for cancer therapy. Herein, we showed that galectin-3 (Gal-3), a β-galactoside binding lectin which is often lost along melanoma progression, is a negative regulator of autophagy in melanoma cells. Our data demonstrated that Gal-3low/negative cells were more resistant to the inhibition of the activity of the cancer driver gene BRAFV600E by vemurafenib (PLX4032). Interestingly, in these cells, starvation caused further LC3-II accumulation in cells exposed to chloroquine, which inhibits the degradative step in autophagy. In addition, Gal-3 low/negative tumor cells accumulated more LC3-II than Gal-3 high tumor cells in vivo. Resistance of Gal-3low/negative cells was associated with increased production of superoxide and activation of the Endoplasmic Reticulum (ER) stress response, as evaluated by accumulation of GRP78. Pharmacological inhibition of autophagy with bafilomycin A reversed the relative resistance of Gal-3low/negative cells to vemurafenib treatment. Taken together, these results show that the autophagic flux is dependent on Gal-3 levels, which attenuate the prosurvival role of autophagy. © Bustos et al.
- Expression of PAFR as Part of a Prosurvival Response to Chemotherapy: A Novel Target for Combination Therapy in Melanoma(2012) ONUCHIC, Ana Claudia; MACHADO, Camila M. L.; SAITO, Renata F.; RIOS, Francisco J.; JANCAR, Sonia; CHAMMAS, RogerMelanoma cells express the platelet-activating factor receptor (PAFR) and, thus, respond to PAF, a bioactive lipid produced by both tumour cells and those in the tumour microenvironment such as macrophages. Here, we show that treatment of a human melanoma SKmel37 cell line with cisplatin led to increased expression of PAFR and its accumulation. In the presence of exogenous PAF, melanoma cells were significantly more resistant to cisplatin-induced cell death. Inhibition of PAFR-dependent signalling pathways by a PAFR antagonist (WEB2086) showed chemosensitisation of melanoma cells in vitro. Nude mice were inoculated with SKmel37 cells and treated with cisplatin and WEB2086. Animals treated with both agents showed significantly decreased tumour growth compared to the control group and groups treated with only one agent. PAFR accumulation and signalling are part of a prosurvival program of melanoma cells, therefore constituting a promising target for combination therapy for melanomas.
- Emerging targets for combination therapy in melanomas(2015) SAITO, Renata de Freitas; TORTELLI JR., Tharcisio Citrangulo; JACOMASSI, Mayara D'Auria; OTAKE, Andreia Hanada; CHAMMAS, RogerCutaneous melanomas are often difficult to treat when diagnosed in advanced stages. Melanoma cells adapt to survive in extreme environmental conditions and are among the tumors with larger genomic instability. Here we discuss some intrinsic and extrinsic mechanisms of resistance of melanoma cells to both conventional and target therapies, such as autophagy, adaptation to endoplasmic reticulum stress, metabolic reprogramming, mechanisms of tumor repopulation and the role of extracellular vesicles in this later phenomenon. These biological processes are potentially targetable and thus provide a platform for research and discovery of new drugs for combination therapy to manage melanoma patient treatment.
- Analysis of the insulin-like growth factor 1 receptor gene in children born small for gestational age: in vitro characterization of a novel mutation (p.Arg511Trp)(2013) LEAL, Andrea C.; MONTENEGRO, Luciana R.; SAITO, Renata F.; RIBEIRO, Tamaya C.; COUTINHO, Debora C.; MENDONCA, Berenice B.; ARNHOLD, Ivo J. P.; JORGE, Alexander A. L.Background Insulin-like growth factor 1 insensitivity caused by IGF1R mutations has been previously identified as one of the causes of growth impairment in children born small for gestational age (SGA). Objective To analyse the IGF1R in children born SGA. Subjects From an initial cohort of 54 sequential children born SGA, without catch-up growth, 25 children were selected for this IGF1R study due to the presence of serum IGF-1 values above the mean for their age and sex. Methods The proximal IGF1R promoter region, the entire coding region and the exonintron boundaries were directly sequenced, and multiplex ligation-dependent probe amplification analysis was performed. Fibroblast cultures were developed from one patient with a mutation for the in vitro characterization of IGF-1 insensitivity. Results The copy number variation analysis did not identify deletions involving the IGF1R gene. We identified two children carrying heterozygous nucleotide substitutions in IGF1R: c.16G>A/p.Gly6Arg and c.1531C>T/p.Arg511Trp. The first variant (p.Gly6Arg) was identified in control subjects (0 center dot 3%) and in a relative with normal growth; thus, it was considered to be a rare benign allelic variation. The second variant (p.Arg511Trp) was not found in 306 alleles from control subjects, and it segregated with the growth impairment phenotype in the patient's family. Fibroblasts obtained from this patient had a significantly reduced proliferative response and AKT phosphorylation after IGF-1 stimulation compared with control fibroblasts. Conclusion The identification of an inactivating IGF1R mutation in the present cohort should encourage further studies of larger series to establish the precise frequency of this molecular defect in children with growth impairment of a prenatal onset.
- Eeyarestatin I sensitizes melanoma cells to cisplatin-induced cell death(2018) SAITO, Renata de Freitas; OTAKE, Andreia Hanada; CORTEZ, Margarita M.; GILLIES, Robbert J.; CHAMMAS, Roger
bookPart Morte celular(2022) CONCEIçãO, Mércia Patrícia Ferreira; SAITO, Renata de Freitas; BUSTOS, Silvina Odete- Endoplasmic reticulum stress conditioned melanoma cell lines to chemotherapy-induced cell death.(2013) SAITO, Renata F.; OTAKE, Andreia H.; CORTES, Margarita M.; CHAMMAS, Roger
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