In vitro assessment of cytotoxic, genotoxic and mutagenic effects of antimalarial drugs artemisinin and artemether in human lymphocytes.

Artemisinin is a substance extracted from the Chinese plant Artemisia annua L. widely used in natural medicine for the treatment of various diseases. Artemether is a substance synthesized from artemisinin, and both drugs are commonly administered in the treatment of malaria. Although considered effective antimalarial drugs, very little is known about the genotoxic, cytotoxic and mutagenic effects of these drugs. Therefore, in the present study, we evaluated the genotoxic, mutagenic and cytotoxic effects of artemisinin (12.5, 25 and 50 µg/mL) and artemether (7.46; 14.92 and 29.84 µg/mL) in cultured human lymphocytes using the comet assay, the micronucleus test and the cytotoxicity assay for detection of necrosis and apoptosis by acridine orange/ethidium bromide staining. Our results showed a significant increase (p < 0.05) in the rate of DNA damage measured by comet assay and in the micronucleus frequency after treatment with both drugs. It was also observed that only artemisinin induced a statistically significant increase (p < 0.05) in the number of lymphocytes with death by necrosis 48 h after treatment. The results demonstrated that these two drugs induce mutagenic, genotoxic and cytotoxic effects in cultured human lymphocytes. Our data indicate the need for caution in the use of such drugs, since genotoxic/mutagenic effects may increase the risk of carcinogenesis.

Effect of diterpenoid kaurenoic acid on genotoxicity and cell cycle progression in gastric cancer cell lines.

The goal of our study was to evaluate the effect of kaurenoic acid, obtained from copaiba oil resin, in gastric cancer (GC) and a normal mucosa of stomach (MNP01) cell lines. The compound was tested at concentrations of 2.5, 5, 10, 30 and 60µg/mL. Comet and micronucleus assays were used to access its potential genotoxicity in vitro. Moreover, we evaluated the effect of kaurenoic acid in cell cycle progression and in the transcription of genes involved in the control of the cell cycle: MYC, CCND1, BCL2, CASP3, ATM, CHK2 and TP53. Kaurenoic acid induced an increase on cell DNA damage or micronucleus frequencies on GC cell lines in a dose-dependent manner. The GC and MNP01 cell lines entering DNA synthesis and mitosis decreased significantly with kaurenoic acid treatment, and had an increased growth phase compared with non-treated cells. The treatment induced apoptosis (or necrosis) even at a concentration of 2.5µg/mL in relation to non-treated cells. GC cell lines presented reduced MYC, CCND1, BCL2 and CASP3 transcription while ATM, CHK2 and TP53 increased in transcription in relation to non-treated cells, especially at a concentration above 10µg/mL. The gene transcription in the MNP01 (non-treated non-cancer cell line) was designated as a calibrator for all the GC cell lines. In conclusion, our results showed that kaurenoic acid obtained from Copaifera induces DNA damage and increases the micronuclei frequency in a dose-dependent manner in GC cells, with a significant genotoxicity observed above the concentration of 5µg/mL. Moreover, this compound seems to be able to induce cell cycle arrest and apoptosis in GC cells.

In vitro assessment of anticytotoxic and antigenotoxic effects of CANOVA(®).

BACKGROUND: CANOVA(®) (CA) is a homeopathic immunomodulator. It contains several homeopathic medicines prepares according to the Brazilian Pharmacopoeia. CA is indicated in clinical conditions in which the immune system is impaired and against tumors. N-methyl-N-nitrosourea (NMU) is an N-nitroso compound, with genotoxic/mutagenic properties. Although several studies have shown promising results in the use of CA, there are no studies reporting possible antigenotoxic effects. METHOD: This study evaluated the in vitro antigenotoxic and anticytotoxic effects of CA in human lymphocytes exposed to NMU. Samples of human lymphocytes that were subjected to different concentrations of a mixture containing CA and NMU were used. The genotoxicity/antigenotoxicity of CA was evaluated by the comet assay, anticytotoxicity was assessed by quantification of apoptosis and necrosis using acridine orange/ethidium bromide. RESULTS: CA significantly reduced DNA damage induced by NMU and reduced significantly the frequency of NMU-induced apoptosis after 24 h of treatment. CONCLUSION: CA has an important cytoprotective effect significantly reducing the DNA damage and apoptosis induced by the carcinogen NMU.

In vitro evaluation of the cytotoxic and genotoxic effects of artemether, an antimalarial drug, in a gastric cancer cell line (PG100).

Artemisinin is a sesquiterpene lactone endoperoxide, obtained from Artemisia annua, and extensively used as an antimalarial drug. Many studies have reported the genotoxic and cytotoxic effects of artemisinins; however, there are no studies that compare such effects between cancer cell lines and normal human cells after treatment with artemether, an artemisinin derivative. Gastric cancer is the fourth most frequent type of cancer and the second highest cause of cancer mortality worldwide. Thus, the aim of this study was to evaluate the in vitro genotoxic and cytotoxic effects induced by artemether in gastric cancer cell line (PG100) and compare them with the results obtained in human lymphocytes exposed to the same conditions. We used MTT (3-(4,5-methylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide) assay, comet assay and ethidium bromide/acridine orange viability staining to evaluate the cytotoxic and genotoxic effects of artemether in PG100. MTT assay showed a decrease in the survival percentages for both cell types treated with different concentrations of artemether (P < 0.05). PG100 also showed a significant dose-dependent increase in DNA damage index at concentrations of 119.4 and 238.8 µg ml(-1) (P < 0.05). Our results showed that artemether induced necrosis in PG100 at concentrations of 238.8 and 477.6 µg ml(-1), for all the tested harvest times (P < 0.05). In lymphocytes, artemether induced both apoptosis and necrosis at concentrations of 238.8 and 477.6 µg ml(-1), for all the tested harvest times (P < 0.05). In conclusion, human lymphocytes were more sensitive to the cytotoxic effects of the antimalarial drug than the gastric cancer cell line PG100.

Cytogenetic biomonitoring of inhabitants of a large uranium mineralization area: the municipalities of Monte Alegre, Prainha, and Alenquer, in the State of Pará, Brazil.

Uranium is a natural radioactive metallic element; its effect on the organism is cumulative, and chronic exposure to this element can induce carcinogenesis. Three cities of the Amazon region-Monte Alegre, Prainha, and Alenquer-in North Brazil, are located in one of the largest uranium mineralization areas of the world. Radon is a radioactive gas, part of uranium decay series and readily diffuses through rock. In Monte Alegre, most of the houses are built of rocks removed from the Earth's crust in the forest, where the uranium reserves lie. The objective of the present work is to determine the presence or absence of genotoxicity and risk of carcinogenesis induced by natural exposure to uranium and radon in the populations of these three cities. The frequency of micronuclei (MN) and chromosomal aberrations (CA) showed no statistically significant differences between the control population and the three study populations (P > 0.05). MN was also analyzed using the fluorescence in situ hybridization (FISH) technique, with a centromere-specific probe. No clastogenic and/or aneugenic effects were found in the populations. Using FISH analysis, other carcinogenesis biomarkers were analyzed, but neither the presence of the IGH/BCL2 translocation nor an amplification of the MYC gene and 22q21 region was detected. Clastogenicity and DNA damage were also not found in the populations analyzed using the alkaline comet assay. The mitotic index showed no cytotoxicity in the analyzed individuals' lymphocytes. Once we do not have data concerning radiation doses from other sources, such as cosmic rays, potassium, thorium, or anthropogenic sources, it is hard to determine if uranium emissions in this geographic region where our study population lives are too low to cause significant DNA damage. Regardless, genetic analyses suggest that the radiation in our study area is not high enough to induce DNA alterations or to interfere with mitotic apparatus formation. It is also possible that damages caused by radiation doses undergo cellular repair.

Genotoxic effects of white fluorescent light on human lymphocytes in vitro.

Sources of light beams such as white fluorescent light, are present in our daily life to meet the needs of life in the modern world. This study was conducted with the objective of determining the possible genotoxic, cytotoxic and aneugenic effects caused by this agent in different stages of the cell cycle (G0/early G1, S, and late G2), using different cytogenetic parameters (sister chromatid exchanges--SCE, chromosome aberrations--CA, and detection of aneugenic effects) in lymphocytes from temporary cultures of human peripheral blood. WFL showed a genotoxic effect in vitro, expressed by an increase in the frequency of SCE's, regardless of the cell cycle stage. However, no increase in the frequency of CAs was observed. In addition, disturbances in cell cycle kinetics and chromosomal segregation were also observed. Taken together, such data may contribute to a better understanding and a different management in the use of phototherapy for some pathological conditions.

Cytogenetics in pediatric medulloblastomas

A meduloblastoma é um tipo de tumor frequentemente encontrada na infância e adolescência. É geralmente encontrada na fossa posterior (também conhecida como o compartilhamento infratentorial) e afeta, principalmente, o cerebelo. Embora um progresso significativo tenha sido alcançado no tratamento destes pacientes, muitos aspectos do comportamento biológico deste tumor ainda estão incertos. Portanto o estudo dos eventos genéticos envolvidos nestas neoplasias poderia ser considerado uma ferramenta útil na compreensão destes tumores, desde que, o comportamento biológico de um tumor passou a ser determinado pelas suas alterações genéticas. Em meduloblastoma, a alteração observada com maior frequência é um isocromossomo 17, mas sozinha esta aberração não constitui um fator prognóstico; apenas reflete uma proliferação celular desenfreada. Vários genes (por exemplo, TP53, ABR e HIC-1) parecem estar relacionados à gênese destes tumores, mas estudos mais aprofundados são necessários para esclarecer o assunto. Os avanços no campo de citogenética molecular tem permitido a gênese de processos de proliferação. Portanto, o objetivo desta revisão é apresentar uma revisão atualizada da literatura sobre meduloblastoma.

Review article: chromosomal diagnosis in rhabdomyosarcoma

Os rabdomiossarcomas (RMS) são considerados tumores clinicamente agressivos com origem a partir de células mesenquimais imaturas e que se caracterizam pela presença de células com diferenciação pouco definida. O emprego das técnicas citogenéticas convencionais em RMS vem contribuindo consideravelmente para a diferenciação entre os rabdomiossarcomas alveolares e os outros tumores de células pequenas e redondas, além de fornecer informações prognósticas importantes referente ao rabdomiossarcoma do tipo alveolar. Assim, este trabalho visa a realizar uma revisão das alterações citogenéticas observadas nos diferentes subtipos histológicos de RMS, enfocando não só os trabalhos de citogenética convencional, mas também novas abordagens utilizadas para o estudo de neoplasias tais como FISH, CGH, SKY e M-FISH. Tais metodologias vêm contribuindo de maneira significativa para a melhor compreensão da heterogeneidade cariotípica observada nos RMS.

Síndromes mielodisplásicas: revisão dos esquemas de classificação / Myelodysplastic syndromes: classification schemes review

Introdução: As síndromes mielodisplásicas (SMD) são doenças clonais das células-tronco hematopoiéticas caracterizadas por hematopoiese ineficiente e freqüente evolução para leucemia mielóide aguda. Em 1982, o Grupo Franco-Americano-Britânico (FAB) propôs classificação para as SMD, baseada em características morfológicas no sangue periférico e medula óssea. Recentemente a organização Mundial de Saúde (OMS) publicou uma classificação revisada das SMD, baseada em modificações significantes da proposta FAB. Objetivo: Enfocar as principais diferenças entre os dois esquemas referidos de classificação. Método: Material pesquisado no banco de dados da Biblioteca Nacional de Medicina e do Centro Nacional para Informação em Biotecnologia dos Estados Unidos, com os termos: "síndromes "mielodisplásicas", "câncer", "classificação", "prognóstico", "revisão", "FAB", "OMS". Foram selecionados apenas artigos publicados em in-ês entre 1976 e 2004. Considerações Finais: A classificação da OMS das SMD foi construí da a partir do bem sucedido esquema FAB, da qual clínicos e patologistas estão familiarizados, e suas mudanças incluem dados citogenéticos e o refinamento dos critérios de diagnóstico. Contudo, como todos os esquemas de classificação, proposta da OMS deve ser considerada um trabalho em progressão e, à medida que forem acumuladas evidências sobre o significado de lesões genéticas específicas e características clínicas, revisões serão necessárias

Evaluation of the mutagenic activity of hydroxyurea on the G1-S-G2 phases of the cell cycle: an in vitro study.

Hydroxyurea is considered an antineoplastic drug, which also plays an important role in the treatment of sickle cell anemia patients. We evaluated and compared the clastogenic and cytotoxic effects of hydroxyurea, using chromosomal aberrations and mitotic index, respectively, as endpoints. In vitro short-term cultures of lymphocytes were exposed to several concentrations of this drug, at various cell cycle phases. There was a significant increase in the cytotoxicity of hydroxyurea at G1 and G1/S as well in the G2 phase of the cell cycle. Hydroxyurea did not significantly increase chromosome aberrations. There was an S-dependent cytotoxic effect of hydroxyurea, which is expected based on the known activity of hydroxyurea as an inhibitor of ribonucleotide reductase.

Genes e câncer: revisão / Genes and cancer: a revieww

Introdução: Nos dias atuais o câncer ocupa uma posição de destaque, contribuindo de maneira significativa para o alto índice de mortalidade na população mundial, chegando a assumir características de problema de saúde pública. Para tentar compreender o processo carcinogênico, e planejar formas racionais de tratamento, é necessário entender a biologia da célula e suas interações nos tecidos principalmente no que tange aos eventos genéticos envolvidos. Objetivo: Discutir os elementos ( oncogenes, genes supressores de tumor, genes de reparo e fatores de crescimento) e mecanismos genéticos que atuam na gênese do câncer: Método: Realizada revisão bibliográfica utilizando os mais recentes trabalho a respeito do assunto. Considerações Finais: O melhor entendimento do processo carcinogênico fornecerá um maior embasamento para a descoberta de novos tratamentos na prevenção ou cura do câncer

Efeitos biológicos do mercúrio e seus derivados em seres humanos: uma revisão bibliográfica / Biological effects of mercury and its compounds in human being: a mini-review

Introdução: O mercúrio e seus derivados são considerados poluentes ambientais originados de várias fontes. A preocupação maior a respeito da poluição mercurial é decorrente dos efeitos à saúde relacionados à exposição ao mercúrio metilado (metilmercúrio) encontrado na água e alimentos aquáticos. O sistema nervoso central é o alvo principal do metilmercúrio. Este metal também é reconhecidamente um agente teratogênico. No entanto, seus efeitos genotóxicos(ação no DNA) são de difícil interpretação e contraditórios. Objetivo: Este trabalho tem por objetivo realizar uma revisão bibliográfica enfocando os efeitos biológicos deste metal e seus derivados em humanos, visando uma melhor compreensão sobre seu variado modo de ação na saúde dos indivíduos. Método: Foi realizado um levantamento bibliográfico com trabalhos pertinentes, enfatizando-se a produção mais recente a respeito do assunto. Considerações Finais: Os efeitos biológicos do mercúrio e seus derivados são extremamentes variados, apresentado, no entanto, consequências suficientemente graves que justificam a realização cada vez maior de estudos suplementares, que servirão como modelos para manter a integridade da saúde de pessoas expostas