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Chemoresistance persists as a significant, unresolved clinical challenge in many cancer types. The tumor microenvironment, in which cancer cells reside and interact with non-cancer cells and tissue structures, has a known role in promoting every aspect of tumor progression, including chemoresistance. However, the molecular determinants of microenvironment-driven chemoresistance are mainly unknown. In this review, we propose that the TP53 tumor suppressor, found mutant in over half of human cancers, is a crucial regulator of cancer cell-microenvironment crosstalk and a prime candidate for the investigation of microenvironment-specific modulators of chemoresistance. Wild-type p53 controls the secretion of factors that inhibit the tumor microenvironment, whereas altered secretion or mutant p53 interfere with p53 function to promote chemoresistance. We highlight resistance mechanisms promoted by mutant p53 and enforced by the microenvironment, such as extracellular matrix remodeling and adaptation to hypoxia. Alterations of wild-type p53 extracellular function may create a cascade of spatial amplification loops in the tumor tissue that can influence cellular behavior far from the initial oncogenic mutation. We discuss the concept of chemoresistance as a multicellular/tissue-level process rather than intrinsically cellular. Targeting p53-dependent crosstalk mechanisms between cancer cells and components of the tumor environment might disrupt the waves of chemoresistance that spread across the tumor tissue, increasing the efficacy of chemotherapeutic agents.

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Introdução:Os kits empregados no diagnóstico do vírus da imunodeficiência humana (HIV) devem cumprir requisitos da RDC n° 36, de 26 de agosto de 2015, para registro junto à Agência Nacional de Vigilância Sanitária e da Lei n° 6.360, de 23 de setembro de 1976, para comercialização no país. Uma das etapas do registro é a análise prévia laboratorial dos produtos de maior classe de risco (classe IV), realizada pelo Laboratório de Sangue e Hemoderivados (LSH). Na análise dos produtos são utilizados painéis sorológicos constituídos de amostras verdadeiro positivas como principal ferramenta na avaliação de sensibilidade. Objetivo: Revalidar painel sorológico verdadeiro positivo para HIV, destinado à avaliação de kits de diagnóstico in vitro do HIV. Método: Foram realizadas a avaliação retrospectiva e a seleção dos resultados do painel frente aos kits recebidos para análise prévia de janeiro de 2010 a dezembro de 2011 que obtiveram resultado satisfatório. Foi utilizado como critério de revalidação a reatividade das amostras do painel em três ensaios imunoenzimáticos (ELISA), em três ensaios de quimiluminescência (CLIA), em três ensaios imunocromatográfcos (testes rápidos) e em três western blot; e reatividade em um ensaio enzimático fluorescente ligado à enzima (ELFA), além do volume igual ou superior a 1 mL. Resultados: No período foram recebidos para análise no LSH 73 kits para diagnóstico in vitro da infecção pelo HIV, sendo 47 (64,4%) satisfatórios, assim distribuídos: 43,0% (20/47) ELISA, 34,0% (16/47) ensaios imunocromatográfcos, 13,0% (06/47) western blot, 2,0% (01/47) ELFA e 8,0% (04/47) ensaios de quimiluminescência. Após a avaliação, 77,0% (34/44) das unidades foram revalidadas, sendo excluídas do painel 23,0% (10/44), pois não alcançaram os critérios estabelecidos. Conclusões: O painel revalidado atualmente é composto por 34 unidades de amostras verdadeiro positivas, com resultados consistentes, aumentando, assim, a confiabilidade e a segurança das análises realizadas e dos testes comercializados no país.

Introduction: Kits used in the diagnosis of the human immunodefciency virus (HIV) must meet the requirements of RDC No. 36, of August 26, 2015 for registration with the National Health Surveillance Agency and Law No. 6.360, of September 23 1976 for commercialization in the country. One of the registration steps corresponds to the previous laboratory analysis of the products with the highest risk class (class IV), carried out by the Laboratory of Blood and Blood Products (LSH). In the analysis of the products, serological panels consisting of true positive samples are used as the main tool in the sensitivity assessment. Objective: To revalidate a true HIV positive serological panel for the evaluation of in vitro HIV diagnostic kits. Method: A retrospective evaluation and selection of the panel results was performed against the kits that obtained satisfactory results and were received for prior analysis from January 2010 to December 2011. The reactivity of the panel samples in three immunoenzymatic assays (ELISA), in three chemiluminescence assays (CLIA), in three immunochromatographic assays (rapid tests) and in three western blots was used as revalidation criterion; and reactivity in an enzyme-linked fluorescent enzyme assay (ELFA), in addition to a volume equal to or greater than 1 mL. Results: During the period, 73 kits for in vitro diagnosis of HIV infection were received for analysis at the LSH, 47 (64.4%) of which were satisfactory, distributed as follows: 43.0% (20/47) ELISA, 34.0% (16/47) immunochromatographic assays, 13.0% (06/47) western blot, 2.0% (01/47) ELFA, 8.0% (04/47) chemiluminescence assays. After the evaluation, 77.0% (34/44) of the units were revalidated, and 23.0% (10/44) were excluded from the panel, as they did not meet the established criteria. Conclusions: The revalidated panel currently consists of 34 units of true positive samples, with consistent results, thus increasing the reliability and safety of the analyses carried out and of the tests marketed in the country.

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Colorectal cancer (CRC) ranks second in the number of cancer deaths worldwide, mainly due to late diagnoses, which restrict treatment in the potentially curable stages and decrease patient survival. The treatment of CRC involves surgery to remove the tumor tissue, in addition to radiotherapy and systemic chemotherapy sessions. However, almost half of patients are resistant to these treatments, especially in metastatic cases, where the 5-year survival rate is only 12%. This factor may be related to the intratumoral heterogeneity, tumor microenvironment (TME), and the presence of cancer stem cells (CSCs), which is impossible to resolve with the standard approaches currently available in clinical practice. CSCs are APC-deficient, and the search for alternative therapeutic agents such as small molecules from natural sources is a promising strategy, as these substances have several antitumor properties. Many of those interfere with the regulation of signaling pathways at the central core of CRC development, such as the Wnt/ß-catenin, which plays a crucial role in the cell proliferation and stemness in the tumor. This review will discuss the use of naturally occurring small molecules inhibiting the Wnt/ß-catenin pathway in experimental CRC models over the past decade, highlighting the molecular targets in the Wnt/ß-catenin pathway and the mechanisms through which these molecules perform their antitumor activities.

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Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which can infect several organs, especially impacting respiratory capacity. Among the extrapulmonary manifestations of COVID-19 is myocardial injury, which is associated with a high risk of mortality. Myocardial injury, caused directly or indirectly by SARS-CoV-2 infection, can be triggered by inflammatory processes that lead to damage to the heart tissue. Since one of the hallmarks of severe COVID-19 is the "cytokine storm", strategies to control inflammation caused by SARS-CoV-2 infection have been considered. Cannabinoids are known to have anti-inflammatory properties by negatively modulating the release of pro-inflammatory cytokines. Herein, we investigated the effects of the cannabinoid agonist WIN 55,212-2 (WIN) in human iPSC-derived cardiomyocytes (hiPSC-CMs) infected with SARS-CoV-2. WIN did not modify angiotensin-converting enzyme II protein levels, nor reduced viral infection and replication in hiPSC-CMs. On the other hand, WIN reduced the levels of interleukins six, eight, 18 and tumor necrosis factor-alpha (TNF-α) released by infected cells, and attenuated cytotoxic damage measured by the release of lactate dehydrogenase (LDH). Our findings suggest that cannabinoids should be further explored as a complementary therapeutic tool for reducing inflammation in COVID-19 patients.

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Coronavirus disease 2019 (COVID-19) was initially described as a viral infection of the respiratory tract. It is now known, however, that several other organs are affected, including the brain. Neurological manifestations such as stroke, encephalitis, and psychiatric conditions have been reported in COVID-19 patients, but the neurotropic potential of the virus is still debated. Herein, we sought to investigate SARS-CoV-2 infection in human neural cells. We demonstrated that SARS-CoV-2 infection of neural tissue is non-permissive, however, it can elicit inflammatory response and cell damage. These findings add to the hypothesis that most of the neural damage caused by SARS-CoV-2 infection is due to a systemic inflammation leading to indirect harmful effects on the central nervous system despite the absence of local viral replication.

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Coronavirus disease 2019 (COVID-19) was initially described as a viral infection of the respiratory tract. It is now known, however, that several other organs are affected, including the brain. Neurological manifestations such as stroke, encephalitis, and psychiatric conditions have been reported in COVID-19 patients, but the neurotropic potential of the virus is still debated. Herein, we sought to investigate SARS-CoV-2 infection in human neural cells. We demonstrated that SARS-CoV-2 infection of neural tissue is non-permissive, however, it can elicit inflammatory response and cell damage. These findings add to the hypothesis that most of the neural damage caused by SARS-CoV-2 infection is due to a systemic inflammation leading to indirect harmful effects on the central nervous system despite the absence of local viral replication.

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SARS-CoV-2 infects cardiac cells and causes heart dysfunction. Conditions such as myocarditis and arrhythmia have been reported in COVID-19 patients. The Sigma-1 receptor (S1R) is a ubiquitously expressed chaperone that plays a central role in cardiomyocyte function. S1R has been proposed as a therapeutic target because it may affect SARS-CoV-2 replication; however, the impact of the inhibition of S1R in human cardiomyocytes remains to be described. In this study, we investigated the consequences of S1R inhibition in iPSC-derived human cardiomyocytes (hiPSC-CM). SARS-CoV-2 infection in hiPSC-CM was productive and reduced cell survival. S1R inhibition decreased both the number of infected cells and viral particles after 48 hours. S1R inhibition also prevented the release of pro-inflammatory cytokines and cell death. Although the S1R antagonist NE-100 triggered those protective effects, it compromised cytoskeleton integrity by downregulating the expression of structural-related genes and reducing beating frequency. Our findings suggest that the detrimental effects of S1R inhibition in human cardiomyocytes' integrity may abrogate its therapeutic potential against COVID and should be carefully considered.

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Zika virus (ZIKV) has been extensively studied since it was linked to congenital malformations, and recent research has revealed that astrocytes are targets of ZIKV. However, the consequences of ZIKV infection, especially to this cell type, remain largely unknown, particularly considering integrative studies aiming to understand the crosstalk among key cellular mechanisms and fates involved in the neurotoxicity of the virus. Here, the consequences of ZIKV infection in iPSC-derived astrocytes are presented. Our results show ROS imbalance, mitochondrial defects and DNA breakage, which have been previously linked to neurological disorders. We have also detected glial reactivity, also present in mice and in post-mortem brains from infected neonates from the Northeast of Brazil. Given the role of glia in the developing brain, these findings may help to explain the observed effects in congenital Zika syndrome related to neuronal loss and motor deficit.

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The deregulation of the Wnt/ß-catenin signaling pathway is a central event in colorectal cancer progression, thus a promising target for drug development. Many natural compounds, such as flavonoids, have been described as Wnt/ß-catenin inhibitors and consequently modulate important biological processes like inflammation, redox balance, cancer promotion and progress, as well as cancer cell death. In this context, we identified the chalcone lonchocarpin isolated from Lonchocarpus sericeus as a Wnt/ß-catenin pathway inhibitor, both in vitro and in vivo. Lonchocarpin impairs ß-catenin nuclear localization and also inhibits the constitutively active form of TCF4, dnTCF4-VP16. Xenopus laevis embryology assays suggest that lonchocarpin acts at the transcriptional level. Additionally, we described lonchocarpin inhibitory effects on cell migration and cell proliferation on HCT116, SW480, and DLD-1 colorectal cancer cell lines, without any detectable effects on the non-tumoral intestinal cell line IEC-6. Moreover, lonchocarpin reduces tumor proliferation on the colorectal cancer AOM/DSS mice model. Taken together, our results support lonchocarpin as a novel Wnt/ß-catenin inhibitor compound that impairs colorectal cancer cell growth in vitro and in vivo.

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Combination chemotherapy has been a mainstay in cancer treatment for the last 60 years. Although the mechanisms of action and signaling pathways affected by most treatments with single antineoplastic agents might be relatively well understood, most combinations remain poorly understood. This review presents the most common alterations of signaling pathways in response to cytotoxic and targeted anticancer drug treatments, with a discussion of how the knowledge of signaling pathways might support and orient the development of innovative strategies for anticancer combination therapy. The ultimate goal is to highlight possible strategies of chemotherapy combinations based on the signaling pathways associated with the resistance mechanisms against anticancer drugs to maximize the selective induction of cancer cell death. We consider this review an extensive compilation of updated known information on chemotherapy resistance mechanisms to promote new combination therapies to be to discussed and tested.

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