Expression of Ki-67 and P16 INK4a in chemically-induced perioral squamous cell carcinomas in mice / Expressão KI-67 e P16 INK4a em carcinomas espinocelulares periorais quimicamente induzidos em camundongos

ABSTRACT Objective: to evaluate the influence of Ki-67 and P16INK4a proteins immunohistochemical expressions on the clinical and morphological parameters of perioral squamous cell carcinoma induced with 9,10-dimethyl-1,2-benzanthracene (DMBA) in mice. Methods: we topically induced the lesions in the oral commissure of ten Swiss mice for 20 weeks, determining the time to tumors onset and the average tumor volume up to 26 weeks. In histopathological analysis, the variables studied were histological malignancy grade and the immunohistochemical expression of Ki-67 and P16INK4a proteins. The correlation between variables was determined by application of the Spearman correlation test. Results: the mean time to onset of perioral lesions was 21.1 ± 2.13 weeks; mean tumor volume was 555.91 ± 205.52 mm3. Of the induced tumors, 80% were classified as low score and 20% high score. There was diffuse positivity for Ki-67 in 100% of lesions - Proliferation Index (PI) of 50.1 ± 18.0. There was a strong direct correlation between Ki-67 immunoreactivity and tumor volume (R = 0.702) and a low correlation with the malignancy score (R = 0.486). The P16INK4a protein expression was heterogeneous, showing a weak correlation with tumor volume (R = 0.334). There was no correlation between the immunohistochemical expression of the two proteins studied. Conclusion: in an experimental model of DMBA-induced perioral carcinogenesis, tumor progression was associated with the tumor proliferative fraction (Ki-67 positive cells) and with tumor histological grading, but not with P16INK4a expression.

RESUMO Objetivo: avaliar a influência da expressão imuno-histoquímica das proteínas Ki-67 e p16INK4a sobre parâmetros clínico-morfológicos em carcinomas espinocelulares periorais quimicamente induzidos com 9,10-dimetil-1,2-benzantraceno (DMBA) em modelo murino. Métodos: as lesões foram induzidas topicamente na comissura labial de dez camundongos Swiss durante 20 semanas, sendo determinado o momento de surgimento dos tumores e volume tumoral médio até 26 semanas. Na análise histopatológica, as variáveis estudadas foram gradação histológica de malignidade tumoral e expressão imuno-histoquímica das proteínas Ki-67 e p16INK4a. A correlação entre as variáveis estudadas foi determinada pela aplicação do teste de correlação de Spearman. Resultados: o tempo médio de surgimento das lesões periorais foi 21,1±2,13 semanas. Volume tumoral médio foi de 555,91±205,52mm3. Dos tumores produzidos, 80% foram classificados como de baixo escore e 20%, alto escore. Evidenciou-se positividade difusa para Ki-67 em 100% das lesões - índice de marcação (PI) de 50,1±18,0. Verificou-se correlação direta forte entre a imunoexpressão do Ki-67 e o volume tumoral (R=0,702) e fraca correlação com o escore de malignidade (R=0,486). A expressão da proteína p16INK4a foi heterogênea, mostrando fraca correlação com o volume tumoral (R=0,334). Não houve correlação entre a expressão imuno-histoquímica das duas proteínas estudadas. Conclusão: Em modelo experimental de carcinogênese perioral DMBA-induzida, a progressão tumoral está associada à fração proliferativa do tumor (células ki-67 positivas) e com a gradação histológica tumoral, porém não com a expressão da p16INK4a.

Chemopreventive effect of Brazilian green propolis on experimental dermal carcinogenesis in murine model / Efecto quimiopreventivo del propóleos verde brasileño sobre la carcinogénesis cutánea en el modelo murino experimental

The aim of this study was to assess the effect of oral administration of Hydroalcoholic Extract of Green Propolis (HEGP) on dermal carcinogenesis in rodent model. For the biological assay, we used 36 mice, assigned into 6 groups (n=6): CTR (treated with 100 mg/kg HEGP and no tumor induction), TUM (treated with water and tumor induction), GP10 (treated with 10 mg/kg HEGP and tumor induction), GP50 (treated with 50 mg/kg HEGP and tumor induction) and GP100 (treated with 100 mg/kg HEGP and tumor induction). Cancer induction was performed in the back of the mice by topical application of DMBA. After 16 weeks, mice were euthanized and their backs were submitted to post-mortem histological analysis. The mean number of lesions developed in TUM (4.14±0.89) was significantly higher than in GP10 (2.05±1.02), GP50 (1.8±1.92) and GP100 (2.5±1.73) (p<0.05). The tumors formed in HEGP-treated groups were histologically more differentiated, but only in PV100 in situ lesions were evidenced. Infiltration of anatomical noble structures was less frequent in HEGP-treated groups (p<0.05). Our data suggest that oral administration of HEGP provided partial inhibition of DMBA-induced dermal carcinogenesis, as well as appeared to modulate the differentiation and infiltrative potential of the carcinomas in rodent model.

El objetivo de este estudio fue evaluar el efecto de la administración oral de extracto hidroalcohólico del propóleos verde (HEGP) sobre la carcinogénesis dérmica en modelo de roedores. Para el ensayo biológico, se utilizaron 36 ratones asignados en 6 grupos (n = 6): CTR (tratado con 100 mg/kg HEGP y sin inducción de tumores), TUM (tratada con agua e inducción de tumores), GP10 (tratado con 10 mg/kg HEGP e inducción de tumores), GP50 (tratado con 50 mg/kg HEGP e inducción de tumores) y GP100 (tratado con 100 mg/kg HEGP e inducción de tumores). La inducción de cáncer se llevó a cabo en la región dorsal de los ratones por aplicación tópica de DMBA. Después de 16 semanas, los ratones fueron sacrificados y sus dorsos fueron sometidos a análisis histológico post-mortem. El número medio de lesiones desarrolladas en TUM (4,14±0,89) fue significativamente mayor que GP10 (2,05±1,02), GP50 (1,8±1,92) y gp100 (2,5±1,73) (p<0,05). Los tumores formados en grupos tratados con HEGP fueron histológicamente más diferenciados, pero sólo en PV100 las lesiones in situ fueron manifiestas. La infiltración de las estructuras anatómicas blanco fue menos frecuente en los grupos tratados con HEGP (p<0,05). Nuestros datos sugieren que la administración oral de HEGP proporciona una inhibición parcial de la carcinogénesis dérmica inducida por DMBA, así como pareció modular la diferenciación y potencial infiltrante de los carcinomas en el modelo animal.

Modulatory activity of brazilian red propolis on chemically induced dermal carcinogenesis

To evaluate modulatory effects of a hydroalcoholic extract of Brazilian red propolis (HERP) on dermal carcinogenesis using a murine model. METHODS: The HERP was used at concentrations of 10, 50 and 100 mg/kg (PROP10, PROP50 and PROP100, respectively) to modulate dermal carcinogenesis induced by the application of 9,10-dimetil-1,2-benzatraceno (DMBA) on the backs of animals. RESULTS: The chemical compounds identified in HERP included propyl gallate, catechin, epicatechin and formononetin. PROP100 treatment resulted in significantly decreased tumor multiplicity throughout the five weeks of tumor promotion (p<0.05), and this concentration also resulted in the highest frequency of verrucous tumors (p<0.05). All of the tumors that developed in DMBA-treated animals were regarded as squamous cell carcinomas and were either diagnosed as non-invasive verrucous carcinomas or invasive squamous cell carcinomas (SCCs). The average score for malignancy was significantly lower in the PROP100-treated group than the non-treated group (p<0.05), but there was no difference between the other groups (p>0.05). CONCLUSION: The oral administration of hydroalcoholic extract of Brazilian red propolis at a dose of 100 mg/kg had a significant modulatory effect on the formation, differentiation and progression of chemically induced squamous cell carcinoma in a murine experimental model.