Análise da relação entre a expressão de marcadores de células tronco tumorais (ALDH-1 e SOX-2) e as características clinico patológicas de neoplasias de glândulas salivares

Abstract

The molecular and cellular mechanisms that are associated with pathogenesis, poor treatment response, recurrence, and death in salivary gland tumors are not fully known. In this matter, stem cells (SC) within a tumor (TSC) are related to tumorigenicity and progress in human neoplasms. As such, the aim of this study was to evaluate the expression of SC-related markers (ALDH-1 and SOX-2) in salivary gland neoplasms and their possible association with clinicopathological data and patient outcomes. We selected 103 cases of malignant neoplasms (25 mucoepidermoid carcinoma; 15 acinic cell carcinoma; 13 adenoid cystic carcinoma; 10 polymorphous adenocarcinoma; 13 adenocarcinoma NOS; 8 epithelial-myoepithelial carcinoma; 7 carcinoma ex pleomorphic adenoma; 5 salivary duct carcinoma; 4 basal cell adenocarcinoma; 3 clear cell carcinoma) and 51 cases of benign neoplasms (25 pleomorphic adenoma; 9 myoepithelioma; 7 Warthin tumor; 5 canalicular adenoma; 5 basal cell adenoma). Data were analyzed in Statistical Package for Social Science, GraphPad Prism and STATA softwares. A significance level of 5% was adopted for the statistical tests (p<0.05). Most patients were male, with a mean age of 52 years, and the parotid was the most common anatomical site. Most malignant neoplasms were classified as T1-T2, N0 and M0. Protein expression assessed by immunohistochemistry and confirmed by western blot showed similar results that were statistically correlated for both SOX-2 (p<0.001) and ALDH-1 (p=0.039). Regarding the expression of SOX-2, most benign tumors were negative (n=39; 76.5%), and expression was only observed in tumors without myoepithelial differentiation (p<0.0001). In the other hand, most of the malignant tumors were positive for SOX-2 (n=54; 52.4%), being statistically significant (p=0.002). The expression occurred in cases without myoepithelial differentiation (p=0.006) mainly in mucoepidermoid carcinoma and clear cell carcinoma. No association was found between SOX-2 expression and clinical parameters. ALDH-1 was frequently expressed in the parenchyma of malignant (n=88; 85.6%) and benign (100%) neoplasms. Overall, the presence of ALDH-1 in the parenchyma was not associated with clinical data of malignant neoplasms; nevertheless, the cases of mucoepidermoid carcinoma with high expression in the parenchyma were associated with advanced clinical stage (p=0.047). The expression of ALDH-1 in tumor stroma cells occurred mainly in malignant neoplasms (n=67; 65.0%), being associated with lymph node metastasis (p=0.032), advanced clinical stage (p=0.008), recurrence (p=0.006) and death (p=0.013). Overall survival and Diseasefree survival at 5 and 10 years were lower in patients diagnosed with adenoid cystic carcinoma, advanced clinical stage, recurrence and stromal expression of ALDH-1. Multivariate analysis showed advanced clinical stage and stromal expression of ALDH1 were independent prognostic factors for disease-free survival. Based on the results, the profile of TSC presents variations in different salivary gland tumors. The differential expression of SOX-2 and ALDH-1 in these neoplasms suggests that there are different subtypes of TSC that can be activated by distinct molecular pathways. Also, the presence of ALDH-1 stromal expression characterizes cells with mesenchymal CT profile that may be directly related to the biological behavior and progress of malignant tumors in the salivary gland.