Banca de DEFESA: ANDRE AZEVEDO DOS SANTOS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ANDRE AZEVEDO DOS SANTOS
DATE: 30/03/2021
TIME: 14:30
LOCAL: PLATAFORMA VIRTUAL
TITLE:

IMMUNOHISTOCHEMICAL PROFILE OF TUMOR STEM CELL MARKERS IN SALIVARY GLAND TUMORS

KEY WORDS:

Salivary glands; Neoplasms; Tumor stem cells; Immunohistochemistry.

PAGES: 112
BIG AREA: Ciências da Saúde
AREA: Odontologia
SUMMARY:

Salivary gland tumors (SGTs) are characterized by complex clinicopathological features and morphological diversity, as well as different clinical behaviors and prognoses. There is strong evidence that tumor stem cells (TSCs) play important roles in the tumorigenesis of different neoplasms. However, the role of TSCs in the behavior and prognosis of SGTs has not been fully elucidated. This study aimed to describe the immunoexpression profile of biomarkers of TSCs (CD44, ALDH1, OCT4, and SOX2) in a series of cases of SGTs (20 pleomorphic adenomas [PAs], 20 adenoid cystic carcinomas [ACCs], and 20 mucoepidermoid carcinomas [MECs]). The data were analyzed with the Statistical Package for the Social Sciences, adopting a level of significance of 5% (p<0.05). Differences were observed between the parenchymal immunoexpression profiles of the biomarkers in the tumors studied. In PAs and ACCs, marked immunoexpression of ALDH1 and OCT4, respectively, was found, with preferential staining of non-luminal cells, except for ALDH1 which preferentially stained luminal cells. No difference between the immunoexpression of the biomarkers was observed in MECs, with CD44, OCT4 and SOX2 staining epidermoid and intermediate cells, while expression of ALDH1 was also detected in some mucosal cells. Regarding the immunostained subcellular compartment, CD44 was predominantly expressed on the membrane, ALDH1 in the cytoplasm, and OCT4 and SOX2 in the nucleus. Cytoplasmic staining for CD44 and OCT4 was also observed. Comparison of parenchymal immunoexpression between the groups of tumors showed higher expression of ALDH1, OCT4 and SOX2 in PAs, ACCs and MECs, respectively. However, parenchymal immunoexpression of ALDH1 was absent in ACCs and the MEC cases exhibited high parenchymal immunoexpression of SOX2 that differed from the other tumors. Furthermore, immunoexpression of all biomarkers, except for SOX2, was found in the stroma of most PAs, ACCs and MECs. Statistical analysis revealed higher parenchymal immunoexpression of ALDH1 in major SGTs (p=0.021) and of OCT4 in minor SGTs (p=0.011); higher parenchymal immunoexpression of SOX2 in tumors without myoepithelial differentiation (p<0.001) and of OCT4 in tumors with myoepithelial differentiation (p=0.009); higher parenchymal immunoexpression of ALDH1 in benign tumors (p<0.001) and of SOX2 in malignant tumors (p=0.002). CD44 was the only biomarker whose parenchymal immunoexpression was significantly associated with the clinical parameters of malignant tumors, with higher expression of this marker being associated with less aggressive tumors and with those showing a better prognosis. Stromal immunoexpression of CD44, ALDH1 and OCT4 was significantly associated with malignant tumors. Significant correlations between the immunoexpression of the biomarkers were observed in the general sample, as well as in individual analysis of the tumors. These results suggest the existence of different subpopulations of TSCs in SGTs and that these subpopulations play an important role in tumorigenesis. The results also suggest that the immunoexpression detected in the tumor stroma, characterizing the presence of mesenchymal stem cells, is directly related to the biological behavior and progression of malignant SGTs or that these cells represent TSCs that have undergone epithelial-mesenchymal transition.

BANKING MEMBERS:
Externa à Instituição - JAMILE MARINHO BEZERRA DE OLIVEIRA MOURA - UERN
Presidente - 346077 - LELIA BATISTA DE SOUZA
Interna - 350484 - ROSEANA DE ALMEIDA FREITAS