Cytotoxicity of lipophilic statins depends on their combined actions on HIF-1α expression and redox status in B16.F10 melanoma cells

Abstract

Statins, as inhibitors of de-novo synthesis of cholesterol, exert cytotoxic actions on tumor cells. Despite the increasing data on the antitumoral activities of statins, their complete mechanisms of action still remain obscure. Therefore, the present study aims to investigate the mechanisms of lipophilic statin-induced cytotoxicity on B16.F10 murine melanoma cells in vitro. In-vitro effects of two lipophilic statins, simvastatin and lovastatin, and a hydrophilic statin, pravastatin, were investigated with respect to B16.F10 murine melanoma cell proliferation and viability. Our results show that only lipophilic statins exerted strong cytotoxic effects on B16.F10 melanoma cells. To gain further evidence on the pleiotropic effects of statins responsible for their cytotoxicity in B16.F10 cells, we have assessed their proapoptotic effects by Annexin V-fluorescein isothiocyanate/propidium iodide staining and measured tumor cell production of the hypoxia-inducible factor 1α by western blot analysis, nonenzymatic antioxidant levels by an antioxidant colorimetric assay, and superoxide dismutase activity through an indirect method on the basis of inhibition of xanthine oxidase activity. Protein array was also used to assess angiogenic/inflammatory protein production in B16.F10 cells. Our results pointed out that the cytotoxic actions exerted by lipophilic statins were mainly based on the suppressive actions of these drugs on hypoxia-inducible factor 1α expression and nonenzymatic antioxidant levels, as well as because of the inhibition of superoxide dismutase activity in B16.F10 melanoma cells. In addition, the reduction in the angiogenic/inflammatory capacity of tumor cells induced by lipophilic statins can strengthen and support their cytotoxicity.

HIF-1α acts as a molecular target for simvastatin cytotoxicity in B16.F10 melanoma cells cultured under chemically induced hypoxia

“…The present study provides a follow-up of our earlier observations that inhibition of the constitutive expression of HIF-1α in B16.F10 murine melanoma cells is one of the main reasons behind the cytotoxicity caused by lipophilic statins on these cancer cells (1). Therefore, the present study evaluated whether this finding could be expanded under hypoxic conditions, when the constitutive production of HIF-1α in B16.F10 melanoma cells is accompanied by its induced expression as a result of CoCl 2 -mediated transcription factor stabilization and activation (28).…”

“…3B). Our previous results have shown that SIM inhibited strongly the constitutive expression of HIF-1α in B16.F10 murine melanoma cells at a concentration 10-fold higher than that used in the present study (1). Regarding the production of NF-κB, SIM treatment did not affect the expression levels of this transcription factor under normoxic or hypoxic conditions (Fig.…”

“…The range of statin concentrations was selected based on our previous study regarding the statin effects on B16.F10 cells (1). The cytotoxicity of the ethanol concentrations used for the preparation of the different SIM solutions was also assessed.…”

“…Our previous studies demonstrated that one of the main mechanisms of simvastatin (SIM) cytotoxic effects on B16.F10 murine melanoma cells under normoxic conditions is associated with the suppression of the constitutive tumor cell production of the α subunit of hypoxia inducible factor (HIF)-1 (1). The normoxic expression of HIF-1 via the constitutive activation of the Ras-Raf-mitogen-activated protein kinase kinase-extracellular signal-regulated kinase 1/2 and phosphatidylinositol-4,5-bisphosphate 3-kinase-AKT signaling pathways ensures the maintenance of the malignant phenotype of highly metastatic melanoma cells (2)(3)(4).…”

É possível determinar a maturidade fisiológica das sementes de milho (<i>Zea mays</i>) utilizando o sal de tetrazólio?

“…Dessa forma, o sal de tetrazólio poderá ser utilizado como um indicador bioquímico da maturidade fisiológica da semente. É essencial destacar que em outras áreas da ciência, o sal de tetrazólio é utilizado para avaliar a viabilidade de células vegetais e animais e para acompanhar o desenvolvimento das células, em várias pesquisas das áreas de medicina e de microbiologia (ALUPEI et al, 2014;JUNILLON;FLANDROIS, 2014;WANG et al, 2014 Lakon (1940Lakon ( , 1942; no entanto, seu trabalho só foi conhecido na América após a II Guerra Mundial, quando foram entrevistados cientistas alemães (DELOUCHE et al, 1976 Além dessas duas enzimas, existem inúmeras proteínas que atuam em diversos ciclos para permitir a funcionalidade e o pleno desenvolvimento dos tecidos meristemáticos e os tecidos de reserva. Por isso que é necessário conhecer o exato momento em que a semente chega a sua plena maturidade findando o ciclo de formação e entrando no estágio de quiescência e se preparando para germinar no momento oportuno.…”