The synergistic effect of SAHA and parthenolide in MDA-MB231 breast cancer cells.

The sesquiterpene lactone Parthenolide (PN) exerted a cytotoxic effect on MDA-MB231 cells, a triple-negative breast cancer (TNBC) cell line, but its effectiveness was scarce when employed at low doses. This represents an obstacle for a therapeutic utilization of PN. In order to overcome this difficulty we associated to PN the suberoylanilide hydroxamic acid (SAHA), an histone deacetylase inhibitor. Our results show that SAHA synergistically sensitized MDA-MB231 cells to the cytotoxic effect of PN. It is noteworthy that treatment with PN alone stimulated the survival pathway Akt/mTOR and the consequent nuclear translocation of Nrf2, while treatment with SAHA alone induced autophagic activity. However, when the cells were treated with SAHA/PN combination, SAHA suppressed PN effect on Akt/mTOR/Nrf2 pathway, while PN reduced the prosurvival autophagic activity of SAHA. In addition SAHA/PN combination induced GSH depletion, fall in Δψm, release of cytochrome c, activation of caspase 3 and apoptosis. Finally we demonstrated that combined treatment maintained both hyperacetylation of histones H3 and H4 induced by SAHA and down-regulation of DNMT1 expression induced by PN. Inhibition of the DNA-binding activity of NF-kB, which is determined by PN, was also observed after combined treatment. In conclusion, combination of PN to SAHA inhibits the cytoprotective responses induced by the single compounds, but does not alter the mechanisms leading to the cytotoxic effects. Taken together our results suggest that this combination could be a candidate for TNBC therapy.

The oxygen radicals involved in the toxicity induced by parthenolide in MDA-MB-231 cells.

It has been shown that the sesquiterpene lactone parthenolide lowers the viability of MDA-MB-231 breast cancer cells, in correlation with oxidative stress. The present report examined the different radical species produced during parthenolide treatment and their possible role in the toxicity caused by the drug. Time course experiments showed that in the first phase of treatment (0-8 h), and in particular in the first 3 h, parthenolide induced dichlorofluorescein (DCF) signal in a large percentage of cells, while dihydroethidium (DHE) signal was not stimulated. Since the effect on DCF signal was suppressed by apocynin and diphenyleneiodonium (DPI), two inhibitors of NADPH oxidase (NOX), we suggest that parthenolide rapidly stimulated NOX activity with production of superoxide anion (O2•-), which was converted by superoxide dismutase 1 (SOD1) into hydrogen peroxide (H2O2). In the second phase of treatment (8-16 h), parthenolide increased the number of positive cells to DHE signal. Since this event was not prevented by apocynin and DPI and was associated with positivity of cells to MitoSox Red, a fluorochrome used to detect mitochondrial production of O2•-, we suggest that parthenolide induced production of O2•- at the mitochondrial level independently by NOX activity in the second phase of treatment. Finally, in this phase, most cells became positive to hydroxyphenyl fluorescein (HPF) signal, a fluorescent probe to detect highly reactive oxygen species (hROS), such as hydroxyl radical and peroxynitrite. Therefore, parthenolide between 8-16 h of treatment induced generation of O2•- and hROS, in close correlation with a marked reduction in cell viability.

Trombose da artéria renal e síndrome do anticorpo antifosfolípide: relato de caso / Renal arterial thrombosis and the antiphospholipid antibody syndrome: case report

Objetivo: descrever um caso clínico raro na infância, com achados clínicos da síndrome do anticorpo antifosfolípide.Descrição: criança, sexo masculino, com 2 anos e 6 meses de idade, com insuficiência renal, trombose da artéria renal e diagnóstico de síndrome do anticorpo antifosfolípide, foi internada com dor abdominal, palidez, letargia e anúria há 36 horas. Ao exame físico, apresentava-se desnutrida, com hipertensão arterial severa, edema moderado e dor em hipocôndrio. Os achados laboratoriais incluíram: uréia=112mg/dl; creatinina plasmática=4,5 mg/dl; pH sangüíneo=7,47; bicarbonato sangUíneo=12,8 mmol/L; K=7,2 mEq/L. A diálise peritoneal foi iniciada e mantida por 11 dias. Após 7 semanas de evolução, o paciente ainda necessitava de droga anti-hipertensiva e a função renal estava anormal. A biópsia renal revelou infarto renal anêmico; ultra-sonografia renal com doppler, fluxo sangüíneo renal ausente no lado direito, e a arteriografia mostrou oclusão total da artéria renal direita. A pesquisa de doenças do colágeno foi negativa. Foi realizada nefrectomia à direita obtendo-se normalização da pressão arterial. Aos 5 anos e 8 meses, foi novamente hospitalizada com quadro de crises de ausência e dores abdominais e precordiais. A dosagem do anticorpo anticardiolipina foi positiva. Atualmente aos 7 anos, está em seguimento ambulatorial, assintomática e com dosagens negativas do anticorpo anticardiolipina.Comentários: as observações deste caso mostram que crianças com quadro de trombose arterial, mesmo na ausência de doenças do colágeno, devem ser investigadas para uma possível associação com a síndrome do anticorpo antifosfolípide