Morphological changes in the lingual papillae and their connective tissue cores on the 7,12-dimethylbenz[alpha]anthracene (DMBA) stimulated rat experimental model

Effects of low-intensity ultrasound combined with low-dose carboplatin in an orthotopic hamster model of tongue cancer: A preclinical study

Low-intensity ultrasound (LIUS) combined with chemotherapy is an innovative modality for cancer treatment, but its effect on orthotopic carcinoma remains unknown. Our previous study revealed that LIUS enhanced the growth inhibitory effects of several chemotherapeutic drugs in nude mice with transplanted tumors. In the present study, we used 7,12-dimethylbenz(alpha)anthracene to induce orthotopic tongue carcinogenesis in hamsters. We used the first-line chemotherapy drug for tongue cancer, carboplatin (CBP) in combination with LIUS to investigate the synergistic effect. The results revealed that LIUS combined with low-dose CBP enhanced the inhibitory effects of CBP on tumor growth, prolonged survival, and did not increase the incidence of side-effects. It also enhanced the inherent DNA damage caused by CBP, suppressed the expression of the DNA repair proteins O⁶-methylguanine DNA methyltransferase (MGMT) and Chk1, and increased the expression of DNA damage-inducible protein GADD45α. Furthermore, compared with CBP alone, LIUS combined with CBP reduced the expression of cyclin D1 and cyclin B1, induced the expression of caspase-3, cleaved caspase-3, caspase-8, Bax, and Bak, and inhibited the expression of Bcl-2. Examination of clinical samples revealed that MGMT, Chk1, and Gadd45α were higher in OTSCC than in adjacent normal tissue. Hence, our results indicated that LIUS enhanced the ability of low-dose CBP to damage DNA in an orthotopic hamster model of tongue cancer, induced apoptosis, inhibited tumor growth and progression, while it did not increase the toxic side-effects of the drug, suggesting additional clinical benefits for patients treated with the combination of CBP with LIUS.

Expression of Ki-67 and P16 INK4a in chemically-induced perioral squamous cell carcinomas in mice

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.

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.