RESUMO
Benzo-[a]-pyrene (B[a]P) is a family member of polycyclic aromatic hydrocarbons and a widespread environmental pollutant. It is a mammary carcinogen in rodents and contributes to the development of human breast cancer. However, the signal transduction pathways induced by B[a]P and its role in breast cancer progression have not been studied in detail. Here, we demonstrate that B[a]P induces cell migration through a lipoxygenase- and Src-dependent pathway, as well as the activation of focal adhesion kinase, Src, and the extracellular signal-regulated kinase 2 in MDA-MB-231 breast cancer cells. However, B[a]P is not able to promote migration in the mammary nontumorigenic epithelial cells MCF12A. Moreover, B[a]P promotes an increase of αvß3 integrin-cell surface levels and an increase of metalloproteinase (MMP)-2 and MMP-9 secretions. In summary, our findings demonstrate that B[a]P induces the activation of signal transduction pathways and biological processes involved in the invasion/metastasis process in MDA-MB-231 breast cancer cells.
Assuntos
Benzopirenos/farmacologia , Movimento Celular/efeitos dos fármacos , Proteína-Tirosina Quinases de Adesão Focal/metabolismo , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Quinases da Família src/metabolismo , Neoplasias da Mama/tratamento farmacológico , Linhagem Celular Tumoral , Ativação Enzimática/efeitos dos fármacos , Feminino , Proteína-Tirosina Quinases de Adesão Focal/biossíntese , Proteína-Tirosina Quinases de Adesão Focal/efeitos dos fármacos , Humanos , Integrina alfaVbeta3/biossíntese , Lipoxigenase/efeitos dos fármacos , Lipoxigenase/metabolismo , Células MCF-7 , Metaloproteinase 2 da Matriz/biossíntese , Metaloproteinase 2 da Matriz/metabolismo , Metaloproteinase 9 da Matriz/biossíntese , Metaloproteinase 9 da Matriz/metabolismo , Proteína Quinase 1 Ativada por Mitógeno/biossíntese , Proteína Quinase 1 Ativada por Mitógeno/efeitos dos fármacos , Invasividade Neoplásica , Metástase Neoplásica , Transdução de Sinais/efeitos dos fármacos , Quinases da Família src/biossíntese , Quinases da Família src/efeitos dos fármacosRESUMO
The participation of eicosanoids and second messengers in the regulation of endocytosis by the ovaries was investigated using the uptake of Rhodnius heme binding protein (RHBP) as an experimental model. The rate of RHBP uptake decreased up to 40% in the presence of BWA4C and NDGA, 5 and 12-lipoxygenase inhibitors, respectively, suggesting the involvement of lipoxygenase products in endocytosis regulation. Addition of Leukotriene B4 (LTB(4); one product of the 5 lipoxygenase pathway) increased in vitro the uptake of RHBP by 30%. The content of cAMP in the Rhodnius' ovaries were monitored after treatment with different eicosanoids and inhibitors of eicosanoids synthesis. The amount of cAMP decreased in the presence of indomethacin (by 50%), while treatment with PGE(2) induced an increase of 85% of this messenger in the ovaries. The presence of LTB(4) in the medium inhibited in 60% the content of cAMP in the ovaries, while BWA4C induced a 100% increase of this messenger in the ovaries. Addition of 1 microM DBcAMP in the medium resulted in a 30% decrease in the rate of RHBP uptake. Taken together, these data show that cyclooxygenase and lipoxygenase products participate in the control of protein internalization by modulation of cAMP levels.
Assuntos
Proteínas de Transporte/metabolismo , AMP Cíclico/metabolismo , Proteínas do Ovo/metabolismo , Endocitose/fisiologia , Hemeproteínas/metabolismo , Lipoxigenase/metabolismo , Ovário/metabolismo , Rhodnius/metabolismo , Animais , Eicosanoides/fisiologia , Inibidores Enzimáticos/farmacologia , Feminino , Proteínas Ligantes de Grupo Heme , Lipoxigenase/efeitos dos fármacos , Modelos Biológicos , Sistemas do Segundo MensageiroRESUMO
Nitric oxide (NO) affects cyclooxygenase (COX) and lipooxygenase (LOX) activities in several tissues. The aim of this study was to investigate the effect of NO on the AA metabolism in the anterior pituitary. LOX and COX products from anterior pituitaries of Wistar male rats were determined by [14C]-AA radioconversion method. Sodium nitroprusside (NP, 0.5 mM) and DETA NONOate (1 mM), NO donors, decreased 5-hydroxy-5,8,11,14-eicosatetraenoic acid (5-HETE) synthesis (P<0.05), effects that were reversed by hemoglobin. L-arginine also inhibited LOX activity. To the contrary, the inhibition of NO synthase by L-NAME (0.5 mM) or aminoguanidine (0.5 mM) increased 5-HETE production (P<0.05). COX activity was slightly stimulated by NP and L-arginine. However, DETA NONOate induced a stimulation of the synthesis of all prostanoids (P<0.05), this effect being reversed by hemoglobin. Neither NOS inhibitors nor hemoglobin modified basal prostanoids synthesis. These results indicate that NO inhibits LOX activity and stimulates COX activity in the anterior pituitary gland. The inhibition of LOX by NO may be another mechanism involved in the effects of NO on hormone release in the anterior pituitary.
Assuntos
Ácido Araquidônico/metabolismo , Óxido Nítrico/fisiologia , Adeno-Hipófise/metabolismo , Animais , Relação Dose-Resposta a Droga , Sequestradores de Radicais Livres/farmacologia , Ácidos Hidroxieicosatetraenoicos/biossíntese , Lipoxigenase/efeitos dos fármacos , Lipoxigenase/metabolismo , Masculino , Óxido Nítrico/farmacologia , Prostaglandina-Endoperóxido Sintases/efeitos dos fármacos , Prostaglandina-Endoperóxido Sintases/metabolismo , Ratos , Ratos WistarRESUMO
Recent evidence has implicated the central nervous system as a target organ for canatoxin, a toxic protein present in Canavalia ensiformis seeds. This toxin activates the lipoxygenase pathway of arachidonic acid metabolism and can thus induce the release of substances mediated by lipoxygenase products. In the present study, the circulating levels of luteinizing hormone (LH) were measured by RIA in male Wistar rats (200-240 g) after the administration of canatoxin into the lateral cerebral ventricle. Canatoxin (0.5-2 micrograms in 2 microliters daily for 3 days) caused a dose- and time-dependent increase in the plasma levels of LH. The total dose of canatoxin used is subconvulsive. At 2, 4 and 24 h after 2 micrograms of canatoxin LH levels were increased by 10%, 43% and 61%, respectively, compared to vehicle-injected animals (0.18 +/- 0.03 ng/ml). This response to 2 micrograms of canatoxin was not attenuated by pretreatment with two different lipoxygenase inhibitors, nordihydroguaiaretic acid (NDGA, 125 mg/kg) or esculetin (ECLT, 125 mg/kg), ip, 1 h before each canatoxin (CNTX) injection; % increase in LH with CNTX alone: 61%; CNTX+NDGA: 54%; CNTX+ECLT:76%; N = 5/group. These data show that intracerebral injection of CNTX in rats increases circulating levels of LH via a mechanism that is independent of the lipoxygenase pathway.
Assuntos
Lectinas/administração & dosagem , Hormônio Luteinizante/sangue , Proteínas de Plantas , Toxinas Biológicas , Animais , Relação Dose-Resposta a Droga , Injeções Intraventriculares , Lipoxigenase/efeitos dos fármacos , Hormônio Luteinizante/efeitos dos fármacos , Masculino , Ratos , Ratos Wistar , Fatores de TempoRESUMO
Recent evidence has implicated the central nervous system as a target organ for canatoxin, a toxic protein present in Canavalia ensiformis seeds. This toxin activates the lipoxygenase pathway of arachidonic acid metabolism and can thus induce the release of substances mediated by lipoxygenase products. In the present study, the circulating levels of luteinizing hormone (LH) were measured by RIA in male Wistar rats (200-240 g) after the administration of canatoxin into the lateral cerebral ventricle. Canatoxin (0.5-2 micrograms in 2 microliters daily for 3 days) caused a dose- and time-dependent increase in the plasma levels of LH. The total dose of canatoxin used is subconvulsive. At 2, 4 and 24 h after 2 micrograms of canatoxin LH levels were increased by 10 per cent , 43 per cent and 61 per cent , respectively, compared to vehicle-injected animals (0.18 +/- 0.03 ng/ml). This response to 2 micrograms of canatoxin was not attenuated by pretreatment with two different lipoxygenase inhibitors, nordihydroguaiaretic acid (NDGA, 125 mg/kg) or esculetin (ECLT, 125 mg/kg), ip, 1 h before each canatoxin (CNTX) injection; per cent increase in LH with CNTX alone: 61 per cent ; CNTX+NDGA: 54 per cent ; CNTX+ECLT:76 per cent ; N = 5/group. These data show that intracerebral injection of CNTX in rats increases circulating levels of LH via a mechanism that is independent of the lipoxygenase pathway