Immunoexpression of cleaved caspase-3 shows lower apoptotic area indices in lip carcinomas than in intraoral cancer

ABSTRACT Objective This study aimed to evaluate apoptosis by assessing cleaved caspase-3 immunoexpression in hyperplastic, potentially malignant disorder (PMD), and malignant tumors in intraoral and lower lip sites. Material and Methods A retrospective study using paraffin blocks with tissues from patients with inflammatory fibrous hyperplasia (IFH), actinic cheilitis, oral leukoplakia, lower lip and intraoral squamous cell carcinoma (SCC) was performed. The tissues were evaluated by immunohistochemical analysis with anti-cleaved caspase-3 antibody. Apoptotic area index was then correlated with lesion type. Results From 120 lesions assessed, 55 (46%) were cleaved caspase-3-positive. The SCC samples (n=40) had the highest apoptotic area indices (n=35; 87.5%). Significant differences were detected between SCCs and PMDs (p=0.0003), as well as SCCs and IFHs (p=0.001), regarding caspase-3 immunopositivity. Carcinomas of the lower lip had lower apoptotic area indices than intraoral cancer (p=0.0015). Conclusions Cleaved caspase-3 immunoexpression showed differences in oral SCCs and PMDs and demonstrated a distinct role of apoptosis in carcinogenesis of intraoral and lower lip cancer. In future, the expression of cleaved caspase-3 with other target molecules in oral cancer may be helpful in delineating the prognosis and treatment of these tumors.

Análise comparativa da imunoexpressão da proteína p53 (clones DO-7 e PAb-240) em carcinomas de células escamosas intrabucais e labiais / Comparative analysis of p53 protein immunostaining (antibodies DO-7 and PAb-240) in oral cavity and lip squamous cell carcinomas

INTRODUÇÃO: A carcinogênese caracteriza-se como um processo multifatorial, e a inativação da proteína p53 é uma alteração genética comumente observada nos carcinomas de células escamosas de boca (CCEB). OBJETIVO: Analisar e comparar a imunoexpressão da proteína p53, por meio dos clones DO-7 e PAb-240, em CCEB com localização intrabucal e em lábio inferior. MATERIAL E MÉTODOS: Foram selecionados 40 casos de CCEB, sendo 20 de localização intrabucal e 20 em lábio inferior. Foi realizado um estudo imuno-histoquímico utilizando os anticorpos anti-p53 clone DO-7 e PAb-240. A imunoquantificação foi realizada por meio de análise digital de imagem, e os resultados, submetidos a tratamentos estatísticos. RESULTADOS: A imunoexpressão da proteína p53 foi verificada com o anticorpo DO-7 em 13 casos (65 por cento) de carcinoma intrabucal e em 19 (95 por cento) de carcinoma de lábio inferior. Imunorreatividade para o anticorpo PAb-240 foi observada em 9 casos (45 por cento) de lesões intrabucais e em 15 (75 por cento) localizados em lábio inferior. Não foram observadas, segundo o teste de Mann-Whitney, diferenças estatisticamente significativas (p > 0,05) na expressão da proteína p53 entre as duas localizações estudadas, independentemente do anticorpo avaliado. Foram identificadas, pelo teste de Wilcoxon, diferenças estatisticamente significativas entre a expressão dos clones DO-7 e PAb-240 em cada um dos grupos analisados (valor p = 0,013 - lábio inferior; valor p = 0,016 - intrabucal). CONCLUSÕES: A expressão da proteína p53 observada nos CCEB, com localizações intrabucais e labiais, sugere a ocorrência de mutações no gene TP53. As diferenças quantitativas obtidas entre os anticorpos estudados, independentemente da localização das lesões, refletem uma especificidade distinta entre os clones DO-7 e PAb-240. O desenvolvimento de mais estudos será fundamental para estabelecer o anticorpo mais adequado para proteína p53 em CCEB.

BACKGROUND: Carcinogenesis is a multifactorial process and inactivation of p53 protein is a genetic change commonly observed in oral squamous cell carcinomas (OSCC). OBJECTIVES: To analyze and compare the expression of p53 protein through antibodies DO-7 and PAb-240 in OSCC samples located in the oral cavity and lower lip. MATERIAL AND METHODS: Forty cases of OSCC were selected and divided into oral cavity and lower lip groups (20 cases each). Immunohistochemical technique was performed using antibodies DO-7 and PAb-240. Quantification of the cases was performed through digital image analysis and underwent specific statistical treatments. RESULTS: Expression of p53 protein was verified with DO-7 antibody in 13 cases (65 percent) of oral cavity carcinomas and in 19 cases (95 percent) of lower lip carcinoma. PAb-240 positivity was detected in 9 cases (45 percent) of oral cavity lesions and in 15 cases (75 percent) located in the lower lip. According to Mann-Whitney test, there were no statistically significant differences between the expressions of p53 protein in both groups, regardless of the antibody used. According to Wilcoxon test, there were statistically significant differences between the expression of DO-7 antibody and PAb-240 in each of the analyzed groups (p-value = 0.013; lower lip p-value = 0.016 - oral cavity). CONCLUSIONS: The expression of p53 protein was observed both in the oral cavity and lip OSCC, which suggests the occurrence of mutations in TP53 gene. The quantitative differences between the antibodies studied, regardless of the site of the lesions, reflect different specificity between clones DO-7 and PAb-240. Further studies are required to establish the best antibody for p53 protein in oral squamous cell carcinomas.