Avaliação do efeito antiproliferativo da apocinina e diapocinina em células de osteossarcoma humano / Evaluation of the antiproliferative effect of apocynin and diapocynin on human osteosarcoma cells

O osteossarcoma (OS) é o tumor maligno primário mais comum do tecido ósseo, caracterizado pela formação de osteócitos anormais. Apesar do avanço nas terapias convencionais (quimioterapia e retirada do tumor), essas não conseguem eliminar totalmente as células tumorais e impedir a progressão da doença. Recentemente, agentes derivados de fontes naturais ganharam considerável atenção por causa de sua segurança, eficácia e disponibilidade imediata. Nesse sentido, a apocinina, inibidor do complexo NADPH-oxidase, vem sendo estudada como agente antitumoral em alguns tipos de câncer como: pâncreas, próstata, pulmão e mama. Apocinina é um pró-fármaco e sua ação parece estar relacionada à sua conversão produzindo a diapocinina, a qual se mostrou mais efetiva do que a apocinina. Portanto, o objetivo desse estudo é avaliar, in vitro, o potencial antitumoral da apocinina e diapocinina em células de osteossarcoma humano. Para isso, foram utilizados osteoblastos humanos normais (HOb) e osteossarcoma humano imortalizadas (SaOS-2) tratados ou não com apocinina e diapocinina em diversas concentrações. Foram realizados os ensaios de viabilidade celular, alterações morfológicas, apoptose celular, produção de espécies reativas de oxigênio (EROs), formação de colônias, migração, invasão e expressão do fator indutor de hipóxia-1alfa (HIF-1). Também foram conduzidos ensaios para verificar a atividade de metaloproteinase de matriz (MMP) 2 e 9. Os resultados em SaOS-2 mostraram que o tratamento com apocinina nas concentrações de 1,5 e 3 mM; e diapocinina nas concentrações de 0,75 e 1,5 mM reduziram a viabilidade; aumentaram o número de células em apoptose e diminuíram a produção de EROs; sem causar danos às células HOb. Além disso, essas mesmas concentrações inibiram a migração e invasão celular; diminuíram a expressão de HIF-1; e reduziram a atividade de MMP-2 em SaOS-2. Considerando os resultados obtidos, concluímos que a apocinina e diapocinina podem atuar como possíveis moduladores de células tumorais, sendo que a diapocinina mostrou ser mais efetiva nos parâmetros testados.(AU)

Osteosarcoma (OS) is the most common primary malignant tumor of bone tissue, characterized by the formation of abnormal osteocytes. Despite advances in conventional therapies (chemotherapy and surgery) they cannot completely eliminate tumor cells and prevent the progression of the disease. Recently, agents derived from natural sources have achieved considerable attention because of their safety, efficacy and immediate availability of therapies. In this way, apocynin, an inhibitor of the NADPH-oxidase complex, has been studied as an antitumor agent in some types of cancer, such as pancreas, prostate, lung and breast. Apocynin is a prodrug and its action indicate to be related to its conversion to diapocynin, which has been shown to be more efficient than apocynin itself. Thus, the aim of this study is to evaluate, in vitro, the antitumor potential of apocynin and diapocynin in human osteosarcoma cells. For this, normal human osteoblasts (HOb) and immortalized human osteosarcoma cells (SaOS-2) were treated or no-treated with apocynin and diapocynin in various concentrations. Cell viability assay, morphological alterations, cellular apoptosis, reactive oxygen species (ROS) production, colony formation, migration, invasion and expression of hypoxia-inducible factor-1 alpha (HIF-1) were performed. We also performed assays to verify the activity of matrix metalloproteinase (MMP) 2 and 9. The results in SaOS-2 showed that treatment with apocynin at concentrations of 1,5 e 3 mM; and diapocynin at concentrations of 0,75 e 1,5 mM reduced cell viability; increased the number of cells in apoptosis and decreased the production of ROS; without damaging HOb cells. Moreover, these same concentrations inhibited cell migration and invasion; decreased HIF-1 expression; and reduced MMP 2 activity in SaOS-2. Considering the results, we suggest that apocynin and diapocynin may act as possible modulators of tumor cells, and diapocynin has been shown to be more effective.(AU)

Rottlerin enhances IL-1beta-induced COX-2 expression through sustained p38 MAPK activation in MDA-MB-231 human breast cancer cells

Cyclooxygenase-2 (COX-2) is an important enzyme in inflammation. In this study, we investigated the underlying molecular mechanism of the synergistic effect of rottlerin on interleukin1beta (IL-1beta)-induced COX-2 expression in MDA-MB-231 human breast cancer cell line. Treatment with rottlerin enhanced IL-1beta-induced COX-2 expression at both the protein and mRNA levels. Combined treatment with rottlerin and IL-1beta significantly induced COX-2 expression, at least in part, through the enhancement of COX-2 mRNA stability. In addition, rottlerin and IL-1beta treatment drove sustained activation of p38 Mitogen-activated protein kinase (MAPK), which is involved in induced COX-2 expression. Also, a pharmacological inhibitor of p38 MAPK (SB 203580) and transient transfection with inactive p38 MAPK inhibited rottlerin and IL-1beta-induced COX-2 upregulation. However, suppression of protein kinase C delta (PKC delta) expression by siRNA or overexpression of dominant-negative PKC delta (DN-PKC-delta) did not abrogate the rottlerin plus IL-1beta-induced COX-2 expression. Furthermore, rottlerin also enhanced tumor necrosis factor-alpha (TNF-alpha), phorbol myristate acetate (PMA), and lipopolysaccharide (LPS)-induced COX-2 expression. Taken together, our results suggest that rottlerin causes IL-1beta-induced COX-2 upregulation through sustained p38 MAPK activation in MDA-MB-231 human breast cancer cells.

Prevention of TNF-induced necrotic cell death by rottlerin through a Nox1 NADPH oxidase

Previous studies have demonstrated that rottlerin, a specific PKCdelta inhibitor, potentiates death receptor- mediated apoptosis through a cytochrome c-dependent or -independent pathway. However, its ability to regulate necrotic cell death, as well as the underlying mechanism, remains unknown. We found that in murine fibrosarcoma L929 cells, treatment with rottlerin protected the cells against TNF-induced necrosis, whereas it sensitized the cells to apoptosis induced by co-treatment with Hsp90 inhibitor geldanamycin and TNF, in a manner independent of its ability to inhibit PKC-delta. TNF treatment induced rapid accumulation of mitochondrial superoxide (O2") through the Nox1 NADPH oxidase when cells undergo necrosis. Moreover, pretreatment with rottlerin failed to induce the GTP-bound form of small GTPase Rac1 by TNF treatment, and subsequently suppressed mitochondrial O2(-) production and poly(ADP-ribose) polymerase activation, thus inhibiting necrotic cell death. Therefore, our study suggests that Nox1 NADPH oxidase is a new molecular target for anti-necrotic activity of rottlerin upon death-receptor ligation.

Effects of 3,4-dihydroxyacetophenone on cytosolic calcium in pulmonary artery endothelial and smooth muscle cells during acute hypoxia / 华中科技大学学报（医学）（英德文版）

The effects of 3, 4-Dihydroxyacetophenone (3, 4-DHAP) on cytosolic free calcium [Ca2+]i in pulmonary artery endothelia (PAECs) and smooth muscle cells (PASMCs) during acute hypoxia were studied. Porcine pulmonary artery endothelial and smooth muscle cells (PASMCs) were cultured primarily, and they were divided into 4 groups: groups incubated under normoxia or hypoxia and those with or without treatment with 3,4-DHAP. The [Ca2+]i of both PAECs and PASMCs was measured by determining the fluorescence of fura 2 AM on spetrofluorometer. Our results showed that hypoxia caused significant elevation of [Ca2+]i, in both PAECs and PASMCs, 3,4-DHAP could attenuate the hypoxic elevation of [Ca2+]i only in PASMCs but not in PAECs. It is concluded that 3,4-DHAP decreases the hypoxic elevation of [Ca2+]i in PASMCs. This might contribute to its inhibitory effect on hypoxic pulmonary vasoconstriction.

Determination of the responsible molecular zone for the chalcones bacteriostatic activity

Foi estudada a bioatividade de compostos com estrutura de acetofenoma e benzadeído pela metodologia cinético-turbidimétrica. Os agentes testados näo inibiram o desenvolvimento de S. aureus ATCC 25.923, mas foram eficientes para E. coli ATCC25.992. Os resultados foram satisfatoriamente interpretados, a partir da fórmula anteriormente proposta, para estudo do mecanismo de açäo bacteriostática. Na comparaçäo de substâncias de estruturas similares, definiu-se a Eficácia Bacteriostática Percentual (Ebp) de um fármaco com Ebp = 100/CIM, em que 100 é o fator percentual arbitrário e CIM é a concentraçäo inibitória mínima do fármaco, em ug/ml. Na comparaçäo das Ebp dos pares de acetofenonas e benzaldeídos apropriados, encontra-se que: Ebp (acetofenona) + Ebp (benzaldeído) <<<< Ebp (chalcona) A maior Ebp, observada para as chalconas deve-se à presença na estrutura de chalcona da ligaçäo dupla Calfa=Cbeta, que possibilita a intensificaçäo do deslocamento eletrônico no anel B da molécula, aumentando a polarizaçäo do grupo carbonila e a oxidrila vizinha (2) é a responsável pela presença da atividade bacteriostática destas substâncias