Decreased expression of stem cell markers by simvastatin in 7,12-dimethylbenz(a)anthracene (DMBA)-induced breast cancer.

Simvastatin, a competitive inhibitor of HMG-CoA reductase widely used in the treatment and prevention of hyperlipidemia-related diseases, has recently been associated to in vitro anticancer stem cell (CSC) actions. However, these effects have not been confirmed in vivo. To assess in vivo anti-CSC effects of simvastatin, female Sprague-Dawley rats with 7,12-dimethyl-benz(a)anthracene (DMBA)-induced mammary cancer and control animals were treated for 14 days with either simvastatin (20 or 40 mg/kg/day) or soybean oil (N = 60). Tumors and normal breast tissues were removed for pathologic examination and immunodetection of CSC markers. At 40 mg/kg/day, simvastatin significantly reduced tumor growth and the expression of most CSC markers. The reduction in tumor growth (80%) could not be explained solely by the decrease in CSCs, since the latter accounted for less than 10% of the neoplasia (differentiated cancer cells were also affected). Stem cells in normal, nonneoplastic breast tissues were not affected by simvastatin. Simvastatin was also associated with a significant decrease in proliferative activity but no increase in cell death. In conclusion, this is the first study to confirm simvastatin anti-CSC actions in vivo, further demonstrating that this effect is specific for neoplastic cells, but not restricted to CSCs, and most likely due to inhibition of cell proliferation.

BJ-PI2, a non-hemorrhagic metalloproteinase from Bothrops jararaca snake venom.

BACKGROUND: Envenoming by Bothrops jararaca can result in local pain, edema, hemorrhage and necrosis, partially mediated by snake venom metalloproteinases (SVMPs). Here, we describe the characterization of BJ-PI2, a P-I class SVMP from B. jararaca venom, and its local tissue actions. METHODS: BJ-PI2 was purified by a combination of gel filtration, anion-exchange chromatography and reverse phase HPLC, and identified by mass spectrometry. Clotting and fibrin(ogen)olytic activities were assayed using conventional methods. Hemorrhagic activity and changes in vascular permeability were examined in rat dorsal skin. Myonecrosis and inflammatory activity were examined in mouse gastrocnemius muscle. RESULTS: BJ-PI2 was a 23.08kDa single-chain polypeptide. Tryptic fragments showed highest homology with SVMP insularinase A from Bothrops insularis, but also with B. jararaca SVMP bothrojaractivase; less similarity was observed with B. jararaca SVMPs BJ-PI and jararafibrases II and IV. BJ-PI2 did not clot fibrinogen or rat citrated plasma but had α- and ß-fibrinogenolytic activity (inhibited by EDTA and 1,10-phenanthroline but not by PMSF) and attenuated coagulation after plasma recalcification. BJ-PI2 had fibrinolytic activity. BJ-PI2 increased the vascular permeability of rat dorsal skin (inhibited by 1,10-phenanthroline). BJ-PI2 was not hemorrhagic or myonecrotic but caused migration of inflammatory cells. In contrast, venom was strongly hemorrhagic and myonecrotic but caused less infiltration of inflammatory cells. CONCLUSIONS: BJ-PI2 is a non-hemorrhagic, non-myonecrotic, non-coagulant P-I class SVMP that may enhance vascular permeability and inflammatory cell migration in vivo. GENERAL SIGNIFICANCE: BJ-PI2 contributes to enhanced vascular permeability and inflammatory cell migration after envenoming, but not to venom-induced hemorrhage and necrosis.

Estudo da superposição de mecanismos fisiopatológicos como modelo de hipertensão arterial com repercussões cardíacas graves / Study of overlap of pathophysiologicalmechanisms as a model of hypertensionwith severe cardiac effects

Fundamento: Acredita-se que o rato espontaneamente hipertenso (SHR) mimetize a hipertensão arterial (HA) essencial em humanos. Lesões em órgãos-alvo nesses animais não são devidas unicamente ao aumento da pressão arterial. Outros mecanismos fisiopatológicos superajuntados talvez representem melhor o complexo dano cardiovascular observado também em humanos. Objetivo: avaliar, comparativamente, as alterações cardíacas em ratos SHR nos quais mecanismos outros de HA (renovascular, hipervolemia, disfunção endotelial) sejam superpostos. Materiais e Métodos: cinco grupos foram estudados: Controle (C,n=11); SHR (n=11); SHR + L-NAME (SHR + L-NAME, n=11); SHR com estenose cirúrgica de artéria renal (SHR + 2R-1C, n=11); SHR+ deoxicorticosterona e cloreto de sódio 0,9% (SHR+DOCA-SALT, n = 11). Foram avaliados pressão arterial caudal (PAC), hipertrofia do ventrículo esquerdo (VE) e alterações histológicas miocárdicas. Resultados: Após oito semanas, os grupos SHR + L-NAME, SHR + 2R-1C e SHR + DOCA-SALT mantiveram PAC semelhante e mais elevada que os animais SHR (159,9 ± 8,3; 162,7± 16,7 e 166,3 ± 6,7 versus 138±7,8, respectivamente), bem como a espessura relativa da parede do VE (SHR + L-NAME = 0,64 ± 0,06; SHR+DOCA-SALT=0,63 ± 0,07 versus SHR=0,57±0,03) (p < 0,05). Amassa relativa do VE dogrupo SHR+ L-NAME (4,2±1,15) foi maior que nos demais grupos (SHR=2,8±0,5; SHR + 2R-1C=3,2±0,5; SHR + DOCA-SALT = 3,1 ± 0,2) (p <0,05). O desarranjo de fibras, fibrose intersticial, espessura médio-intimal aumentada foram mais frequentes nos ratos SHR + L-NAME. Conclusão: O modelo SHR + L-NAME mostrou repercussões cardíacas mais evidentes que os demais modelos de HA, fato não explicado apenas pelos níveis de PA elevados. Tal modelo pode ser utilizado em estudos futuros como representativo de maior comprometimento cardíaco na HA grave ou em estados avançados da doença.

Background: Spontaneously hypertensive rats (SHR) are believed to mimic arterial hypertension (HA) essential in humans. The injuries on targeted organs on these animals are not due only to increased blood pressure. Other pathophysiological mechanisms may represent better the superimposed complex cardiovascular damage observed on humans as well. Objective: comparatively evaluate the cardiac abnormalities in SHR in which other mechanisms of hypertension (renovascular, fluid overload and endothelial dysfunction) are superimposed. Materials and Methods: 5 groups were studied: Control (C, n=11); SHR (n = 11); SHR + L-NAME (SHR + L-NAME, n= 11), SHR with surgical stenosis of renal artery (SHR+ 2K-1C, n = 11), SHR + deoxycorticosterone and sodium chloride 0.9% (SHR + DOCA-SALT, n = 11). The blood pressure flow (PAC), left ventricular hypertrophy (VE) (echocardiography) and myocardial histological changes were evaluated. Results:After 8 weeks, the SHR + L-NAME, SHR + 2K-1C and SHR + DOCA-SALT groups maintained similar and higher PAC than SHR (159.9 ± 8.3, 162.7 ± 16.7 and 166.3 ± 6.7 versus 138± 7.8, respectively) as well as the relative thickness of the VE wall (SHR + L-NAME = 0.64 ± 0.06, SHR + DOCA-SALT= 0, 63 ± 0.07 versus SHR = 0.57 ±0.03;) (p < 0.05). The relative LV mass (MRVE, mg/g) of the group SHR + L-NAME (4.2 ± 1.15) was higher than in other groups (SHR = 2.8 ± 0.5, SHR + 2K-1C = 3.2±0.5, SHR + DOCA-SALT = 3.1 ± 0.2) (p < 0.05). Fiber disarray, interstitial fibrosis and the increased of intima-media thickness were more frequent in SHR + L-NAME. Conclusion: SHR + L-NAME showed cardiac effects more evident than the other models of hypertension, which was not explained only by high levels of PA. This model can be used in future studies as representative of greater cardiac involvement in hypertension or severe stages of the disease.