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Authors
Abstract(s)
O carcinoma da bexiga é uma patologia com taxas de incidência e prevalência e
valores de morbilidade e mortalidade que continuam a preocupar a comunidade médica
e científica. Dados estatísticos revelam que a taxa de mortalidade tem vindo a diminuir
nas últimas década devido aos avanços médico-cirúrgicos,enquanto a taxa de incidência
continua a aumentar. É devido a estes factos que cada vez mais se procura perceber os
mecanismos fisiopatológicos celulares e moleculares que estão na base desta patologia.
Assim, a comunidade científica pesquisa incessantemente novos métodos e potenciais
fármacos que possam conduzir à sua prevenção e/ou regressão.
Para o estudo desta neoplasia, o modelo experimental de carcinoma da bexiga
induzido por nitrosaminas em ratos tem sido já usado por outros grupos de investigação,
com resultados satisfatórios.
O recurso a fármacos com propriedades anti-inflamatórias para a prevenção
destes tumores poderá ser uma opção válida que exige estudos mais abrangentes. Os
Celecoxibes são fármacos com acções anti-inflamatórias, analgésicas e actividades
antipiréticas em modelos animais, e que na última década têm vindo a ser testados em
carcinomas com o intuito de os prevenir. Estes fármacos actuam especificamente na
ciclooxigenase-2 (COX-2 – envolvida na produção de prostanóides), que se julga
essencial no desenvolvimento tumoral. O ácido acetilsalicílico (AAS), é igualmente um
anti-inflamatório, mas com propriedades de actuação diferentes das do Celecoxibe, pois
o AAS não é um inibidor selectivo, mas sim um inibidor das COX-1 e COX-2 (quando
aplicado em doses elevadas). Pelas características que apresentam, nomeadamente no
que diz respeito a mecanismos de acção, poderiam ser pensados como fármacos com
elevado potencial na prevenção e/ou regressão do carcinoma da bexiga
O objectivo deste trabalho compreendeu três fases: 1ª – Caracterização e
validação do modelo de carcinoma da bexiga induzido por nitrosamina em rato Wistar
macho; 2ª – Avaliação da capacidade de um Celecoxibe (Celebrex®) na
prevenção/regressão do desenvolvimento do carcinoma da bexiga; 3ª – Avaliação da
capacidade do AAS (Aspegic®) na prevenção do desenvolvimento do carcinoma da
bexiga. No sentido de cumprir os objectivos traçados, foi elaborado um protocolo
experimental que envolveu a utilização de 9 grupos de ratos: i) grupo Controlo,
administrado com sumo de laranja; ii) grupo BBN, tratado com uma nitrosamina (a
0,05%), por via oral na água de bebida; iii) grupo CEL, administrado com 10 mg/kg/dia
de Celecoxibe dissolvido em sumo de laranja; iv) grupo CEL-10 P, administrado com
10 mg/kg/dia de Celecoxibe e BBN, ambos nas primeiras oito semanas; v) grupo CEL-1
P administrado com 1 mg/kg/dia de Celecoxibe e BBN, ambos nas primeiras oito
semanas; vi) grupo CEL-10 C, administrado com BBN nas primeiras oito semanas e
com 10 mg/kg/dia de Celecoxibe nas últimas doze; vii) grupo AAS, administrado com
250 mg/kg/dia de ácido acetilsalicílico dissolvido em sumo de laranja; viii) grupo AAS-
250 P, tratado com 250 mg/kg/dia de ácido acetilsalicílico e BBN, ambos nas primeiras
oito semanas; ix) grupo AAS-25 P, administrado com 25 mg/kg/dia de ácido
acetilsalicílico e BBN, ambos nas primeiras oito semanas. Foi estabelecido o período
experimental de 20 semanas, de acordo com a literatura.
Foram efectuadas uma avaliação histomorfológica qualitativa (macroscópica e
microscópica) e uma apreciação quantitativa da percentagem de tumores por grupo,
número de tumores por rato e volume tumoral médio. Esta primeira avaliação foi
complementada com a determinação sérica de alguns marcadores tumorais (TGF-β e
TNF-α), inflamatórios (PCR e IL-1β) e de equilíbrio oxidativo (MDA, TAS e 3-NT).
Foi realizada a aferição de parâmetros hemodinâmicos, designadamente pressões
arteriais, índice glicémico, função renal, hepática, perfil lipídico e hemograma
completo, para além de indicadores de trofismos cardíaco, renal e hepático.
Os resultados obtidos no grupo BBN em relação ao Controlo demonstraram uma
elevada percentagem de tumores (65%), de um elevado volume tumoral médio (cerca de
112 mm3). Neste grupo constatou-se a presença de lesões tumorais diversas (em
médio/alto grau), nomeadamente: hiperplasia severa, displasia moderada, metaplasia
epidermóide, papilomas, atrofia do urotélio e proliferação pseudopapilar. Como
complemento destas observações, os marcadores de lesão tumoral apresentaram-se com
um aumento da concentração sérica (TGF-β e TNF-α) e os valores dos marcadores
inflamatórios (PCR e IL-1β) apresentaram o mesmo perfil.
Em relação ao segundo objectivo do estudo – avaliação da eficácia do
Celecoxibe – os resultados demonstraram uma grande eficácia (não total) na prevenção de tumores. Com efeito, verificou-se no grupo CEL-10 P uma inibição do aparecimento
de tumores em 88% dos ratos, com um número reduzido de tumores por rato (0,5), se
bem que só um rato apresentava 4 pequenas massas bem definidas (volume total 21
mm3). No grupo CEL-1 P, verificou-se igualmente um efeito positivo na inibição do
desenvolvimento tumoral (75%), e um volume tumoral muito insignificante (0,5 mm3).
A avaliação histomorfológica revelou lesões de menor incidência nas células epiteliais
(hiperplasias moderadas, atrofia do urotélio moderada e edema da mucosa moderado).
Em paralelo, constatou-se ainda uma diminuição significativa da concentração sérica de
TGF-β e de PCR. Porém, o grupo Curativo (CEL-10 C) não apresentou resultados
satisfatórios, uma vez que aumentou ligeiramente o número de ratos com tumor (78%)
em relação ao grupo BBN.
Em relação ao estudo do AAS, verificou-se que este fármaco é igualmente
benéfico na prevenção de tumores da bexiga, uma vez que a dose elevada provocou uma
baixa percentagem de tumores por rato (25%), enquanto a dose baixa teve uma
percentagem ligeiramente superior (38%). O volume tumoral foi também idêntico, com
o grupo de alta dose a ter menor volume total (0,26 mm3) que o grupo de baixa dose
(7,9 mm3).
Em suma, este trabalho confirmou a eficácia do protocolo no desenvolvimento
tumoral, revelando lesões de grau de diferenciação moderado a alto, com alguns graus
invasivos. Por seu turno, os fármacos escolhidos (um inibidor selectivo da COX-2 e um
AINE, ambos com propriedades anti-inflamatórias) foram eficazes na prevenção do
crescimento tumoral e na atenuação de marcadores de crescimento e proliferação
celular. Estes resultados sugerem que a prevenção, mas não a regressão, do processo
inflamatório é um alvo terapêutico de elevado potencial na quimioterapia do carcinoma
da bexiga.
The bladder cancer pathology has incidence and prevalence rates, as well as levels of morbidity and mortality which still concern the medical and scientific community. Statistics data shows that mortality rate has been decreasing during the last decades due to medical-chirurgical improvements, while incidence rate has yet increasing. This explains the continuous search for the cellular and molecular pathophysiological mechanisms underlying this disease. Thus, scientific communities search new methods and potential drugs able to prevent and/or reverse this condition. The experimental bladder cancer model induced by nitrosamines in rats has been used for other research groups, with satisfactory results. The drugs with anti-inflammatory properties might be valid options to prevent these tumours, deserving more complete studies. The Celecoxibs are drugs with antiinflammatory, analgesic and antipyretic actions in animal models, which, during the last decade, have been tested in cancer in order to prevent its development. These drugs act specifically in a enzyme (COX-2, which participates in the formation of prostanoids), that are thinking as essential in the progression of tumours. The acetilsalicilic acid (ASA) is also an anti-inflammatory, but with different properties the action from those of the celecoxib, since the ASA is not a selective inhibitor, but an inhibitor of COX-1 and COX-2 (when used in high doses). Due to its characteristics, namely concerning the action mechanism could be viewed as potential drugs to prevent and/or attenuate bladder cancer. The goal of this work has three distinct phases: 1st – Characterization and validation of the model of bladder cancer induced by nitrosamines in male Wistar rats; 2 nd – Evaluate the ability of a Celecoxib (the Celebrex® ) to prevent or revert bladder cancer development; 3rd – Evaluate the ability of a ASA (Aspegic® ) to prevent bladder cancer development In order to achieve the planed aims, an experimental protocol was designed, using 9 rat groups: i) control group, treated with orange juice; ii) BBN group, treated with nitrosamine (0.05% in drinking water); iii) CEL group, treated with 10 mg/kg/day of Celecoxib dissolved in orange juice; iv and v) CEL-10 P and CEL-1 P groups, which intend to evaluate the preventive effect of Celecoxib on tumour development; vi) CEL-1 C group, which intend to evaluate the cure effect of Celecoxib on tumour development; vii) AAS group, treated with 250 mg/kg/day of AAS dissolved in orange juice; viii and ix) AAS-250 P and AAS-25 P groups, which intend to evaluate the preventive effect of AAS on tumour development. A 20-week experimental period was established, according to the literature. A histological qualitative (macroscopy and microscopy) evaluation was made, as well as a quantification of percentage of tumours per group, number of tumours per rat and median tumour volume. This evaluation was complemented with the determination of serum markers of tumour (TGF-β and TNF-α), inflammation (PCR and IL-1β) and redox status (MDA, TAS and 3-NT). As supplementary evaluation hemodynamics parameters were made, namely blood pressure, glycaemia, renal and hepatic function, lipid profile and complete haemograma, as well as cardiac, renal and hepatic trophism. The obtained results in the BBN group versus the control has demonstrate an elevated percentage of tumours (65%), accompanied by an high median tumour volume (about 112 mm3 ). Moreover, in that group there were distinct tumour lesions (of moderate/high grade), namely: severe hyperplasia, urothelium atrophy and papillary proliferation. As complement for those observations, the tumour markers showed an increment of serum concentration (TGF-β and TNF-α) and the inflammatory markers (PCR and IL-1β) revealer the same profile. Concerning the second goal of the study – the evaluation of the Celecoxib efficacy – the results have demonstrated a higher efficacy (not total) in cancer prevention. Therefore, in CEL-10 P there was an inhibition of tumour development in 88% of the rats, with a reduced number of tumours per rate (0.5), despite the 4 tumours of low dimensions in the only rat which has presented tumours (total volume of 21 mm3 ). In the CEL-1 P group, there was also a positive effect on the inhibition of tumor development (75%), and a very insignificant tumour volume (0.5 mm3 ). The histological evaluation has revealed a lower incidence of epithelial cells lesions (moderate hyperplasia, urothelium atrophy and moderate mucosa oedema). Simultaneously, there was a significant decrease in serum content of TGF-β and PCR. However, the curative group (CEL-10 C) showed no satisfactory results, since a slightly increased in the number of rats with tumor (78%) compared to the BBN group. Concerning the ASA study, we found that this drug is also beneficial in the prevention of bladder tumors, since the high dose caused a small percentage of tumors per rat (25%), while the low dose had a slight high percentage (38 %). The tumor volume was also identical, with the high dose group revealed a lower total volume (0.26 mm3 ) than the low dose group (7.9 mm3 ). As summary, this work has confirmed the efficacy of the protocol for tumour development, revealing moderate and high grade lesion, with some degree of invasivity. On the other hand, the drugs tested (a selective COX-2 inhibitor and a NSAID, both with anti-inflammatory properties) were efficient in preventing tumour growth and attenuating the markers of growth and cellular differentiation. The results suggests that prevention of inflammatory process, but not reversion, is a therapeutic target of high potential in chemoprevention of bladder cancer.
The bladder cancer pathology has incidence and prevalence rates, as well as levels of morbidity and mortality which still concern the medical and scientific community. Statistics data shows that mortality rate has been decreasing during the last decades due to medical-chirurgical improvements, while incidence rate has yet increasing. This explains the continuous search for the cellular and molecular pathophysiological mechanisms underlying this disease. Thus, scientific communities search new methods and potential drugs able to prevent and/or reverse this condition. The experimental bladder cancer model induced by nitrosamines in rats has been used for other research groups, with satisfactory results. The drugs with anti-inflammatory properties might be valid options to prevent these tumours, deserving more complete studies. The Celecoxibs are drugs with antiinflammatory, analgesic and antipyretic actions in animal models, which, during the last decade, have been tested in cancer in order to prevent its development. These drugs act specifically in a enzyme (COX-2, which participates in the formation of prostanoids), that are thinking as essential in the progression of tumours. The acetilsalicilic acid (ASA) is also an anti-inflammatory, but with different properties the action from those of the celecoxib, since the ASA is not a selective inhibitor, but an inhibitor of COX-1 and COX-2 (when used in high doses). Due to its characteristics, namely concerning the action mechanism could be viewed as potential drugs to prevent and/or attenuate bladder cancer. The goal of this work has three distinct phases: 1st – Characterization and validation of the model of bladder cancer induced by nitrosamines in male Wistar rats; 2 nd – Evaluate the ability of a Celecoxib (the Celebrex® ) to prevent or revert bladder cancer development; 3rd – Evaluate the ability of a ASA (Aspegic® ) to prevent bladder cancer development In order to achieve the planed aims, an experimental protocol was designed, using 9 rat groups: i) control group, treated with orange juice; ii) BBN group, treated with nitrosamine (0.05% in drinking water); iii) CEL group, treated with 10 mg/kg/day of Celecoxib dissolved in orange juice; iv and v) CEL-10 P and CEL-1 P groups, which intend to evaluate the preventive effect of Celecoxib on tumour development; vi) CEL-1 C group, which intend to evaluate the cure effect of Celecoxib on tumour development; vii) AAS group, treated with 250 mg/kg/day of AAS dissolved in orange juice; viii and ix) AAS-250 P and AAS-25 P groups, which intend to evaluate the preventive effect of AAS on tumour development. A 20-week experimental period was established, according to the literature. A histological qualitative (macroscopy and microscopy) evaluation was made, as well as a quantification of percentage of tumours per group, number of tumours per rat and median tumour volume. This evaluation was complemented with the determination of serum markers of tumour (TGF-β and TNF-α), inflammation (PCR and IL-1β) and redox status (MDA, TAS and 3-NT). As supplementary evaluation hemodynamics parameters were made, namely blood pressure, glycaemia, renal and hepatic function, lipid profile and complete haemograma, as well as cardiac, renal and hepatic trophism. The obtained results in the BBN group versus the control has demonstrate an elevated percentage of tumours (65%), accompanied by an high median tumour volume (about 112 mm3 ). Moreover, in that group there were distinct tumour lesions (of moderate/high grade), namely: severe hyperplasia, urothelium atrophy and papillary proliferation. As complement for those observations, the tumour markers showed an increment of serum concentration (TGF-β and TNF-α) and the inflammatory markers (PCR and IL-1β) revealer the same profile. Concerning the second goal of the study – the evaluation of the Celecoxib efficacy – the results have demonstrated a higher efficacy (not total) in cancer prevention. Therefore, in CEL-10 P there was an inhibition of tumour development in 88% of the rats, with a reduced number of tumours per rate (0.5), despite the 4 tumours of low dimensions in the only rat which has presented tumours (total volume of 21 mm3 ). In the CEL-1 P group, there was also a positive effect on the inhibition of tumor development (75%), and a very insignificant tumour volume (0.5 mm3 ). The histological evaluation has revealed a lower incidence of epithelial cells lesions (moderate hyperplasia, urothelium atrophy and moderate mucosa oedema). Simultaneously, there was a significant decrease in serum content of TGF-β and PCR. However, the curative group (CEL-10 C) showed no satisfactory results, since a slightly increased in the number of rats with tumor (78%) compared to the BBN group. Concerning the ASA study, we found that this drug is also beneficial in the prevention of bladder tumors, since the high dose caused a small percentage of tumors per rat (25%), while the low dose had a slight high percentage (38 %). The tumor volume was also identical, with the high dose group revealed a lower total volume (0.26 mm3 ) than the low dose group (7.9 mm3 ). As summary, this work has confirmed the efficacy of the protocol for tumour development, revealing moderate and high grade lesion, with some degree of invasivity. On the other hand, the drugs tested (a selective COX-2 inhibitor and a NSAID, both with anti-inflammatory properties) were efficient in preventing tumour growth and attenuating the markers of growth and cellular differentiation. The results suggests that prevention of inflammatory process, but not reversion, is a therapeutic target of high potential in chemoprevention of bladder cancer.
Description
Keywords
Carcinoma da bexiga Carcinoma da bexiga - Aspirina Carcinoma da bexiga - Celecoxibe
Citation
Publisher
Universidade da Beira Interior