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

Abstract

Objective: to evaluate the influence of INK4a 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 INK4a 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 P16 INK4a expression.Keywords: Carcinogenesis. 9,10-Dimetil-1,2-benzanthracene. Immunohistochemistry. Ki-67 Antigen. Genes, p16. MTSI, CDK4I or CDKN2) located on chromosome 9p, locus 21, involved in cell cycle progression blocking process. It is inactive in a wide range human malignancies. The loss of p16 INK4a immunoexpression has been observed in the early stages of oral carcinogenesis and has been considered a molecular event of significant value in the prognostic analysis of such tumors 9,10 . This study evaluated the influence of Ki-67 and p16 proteins immunohistochemical expression on morphological parameters (mean tumor volume and histological malignancy grade) of DMBA-induced perioral SCC in mice. In addition, it sought to verify the existence of correlation between the immunoreactivity of p16 and Ki-67 proteins. METHODSThe development of the study had the approval of the Ethics in Research Committee of the Universidade Tiradentes -Aracaju / SE, with protocol number 191208. Animals and chemical carcinogenesis induction procedureWe used ten Swiss mice without distinction between gender, from the vivarium of the Universidade Tiradentes, with a body mass of about 150 ± 30g (Average age 100 days).We induced the oral lesions in the mice left oral commissure by the topical application of 9,10-dimethyl-1,2-benzanthracene (DMBA), diluted to 0.5% in acetone, on a weekly basis in three alternate days for 20 weeks 11 . After this period, the animals were kept under observation for six weeks, and we duly regis...

Immunoexpression of Ki67, P16 and Beta-catenin in precursor lesions of cutaneous squamous cell carcinoma

“…In our study, we also observed statistically significant positive linear correlations between P16 and Ki67 immunoexpression, and negative linear correlation between the membrane expression of Beta-catenin and Ki67, respectively with P16 immunoexpression. Contrary to our results, other studies showed that in carcinogenesis, tumor progression was associated with tumor proliferative fraction (Ki67-positive cells) and tumor differentiation, but without correlation with P16 expression [ 24 ].…”

Development of a murine model of oral carcinogenesis: an accelerated tool for biomarker and anti-tumour drug discovery

“…In the carcinogenesis model described herein, the average time for onset of lesions was 12.08 weeks, which is in contrast to a previous study where the lesions developed in 21.1 ± 2.13 weeks [23]. The plausible reason for this difference could be the weight and age of mice.…”

Polypodium leucotomos targets multiple aspects of oral carcinogenesis and it is a potential antitumor phytotherapy against tongue cancer growth

“…Tongue lesion tissue samples from mice not treated with PL showed remarkable Ki-67 staining. In fact, in the 4NQO-induced oral carcinogenesis experimental model, tumor progression was associated with the proliferative fraction of the tumor (cycling cells Ki-67 positive) and tumor differentiation ( Alves et al, 2016 ) (Ref). Other studies have also shown that immunohistochemical expression of the ki-67 protein is correlated with the potential proliferation of malignant oral tumors ( Warnakulasuriya, 2010 ; Alves et al, 2016 ).…”

“…In fact, in the 4NQO-induced oral carcinogenesis experimental model, tumor progression was associated with the proliferative fraction of the tumor (cycling cells Ki-67 positive) and tumor differentiation ( Alves et al, 2016 ) (Ref). Other studies have also shown that immunohistochemical expression of the ki-67 protein is correlated with the potential proliferation of malignant oral tumors ( Warnakulasuriya, 2010 ; Alves et al, 2016 ). Notably, we observed a trend towards a decrease in the survival of mice not treated with PL (data not shown), which had more severe lesions, probably caused by the weakness of these animals already at an advanced age, the toxicity of the chemical carcinogen administered, and the progressive evolution of the disease due to the absence of the phytotherapeutic that appears to inhibit the progression of more severe lesions, compared to the animals treated with PL.…”