Investigação do fator de transcrição SOX2 na transição epitélio-mesênquima e na progressão tumoral em modelos de estudo de melanoma

Abstract

Melanoma, an extremely aggressive skin cancer mainly due to its high invasive and migratory capacity, has a neoplastic progression that can be associated with processes that are hallmarks of cancers: resistance to apoptosis, epithelial-mesenchymal transition (EMT), exacerbated disorder and cellular dedifferentiation. Other markers involved in cell maturation and commonly deregulated in carcinogenesis are genes that encode transcription factors, where we highlight SOX family proteins, including SOX2. SOX2 is involved in promoting tumorigenesis, mainly because it is associated with an undifferentiated phenotype of cells, however, its influence on the later stages of carcinogenesis is not yet well programmed. Therefore, we aimed to investigate, in an in vitro model of A375, SK-MEL-28 and 888-MEL cells and a spontaneous model of canine melanoma, the involvement of SOX2 in the regulation of TEM and tumor progression. Melanoma cell lines were silenced for SOX2 through the lentivirus/shRNA complex and evaluated by flow cytometry to confirm knockdown. Silenced cells and their controls were also investigated for cell regulation and migration and gene expression of target markers in TEM. In canine melanomas, histopathological parameters were evaluated and immunohistochemistry was performed to measure planetary (Ki67), apoptosis (Caspase-3), TEM (E-cadherin and N-cadherin) and the transcription factor SOX2. Our results demonstrated that cells with SOX2 knockdown had a significant reduction in both safety and migratory potential. Furthermore, the decrease in SOX2 expression influenced important markers of TEM, generating a significant increase in the expression of E-cadherin, a decrease in the expression of Vimentin and a distinct modulation in the transcription factors Snail, SLUG, ZEB1 and ZEB2, ranging from according to cell lineage. In canine melanoma lesions, we observed that positive cases for SOX2 were associated with the presence of neoplastic emboli and a higher apoptotic index (represented by Caspase-3 expression). Cutaneous melanomas, when evaluated separately, showed a lower proliferative index and positive brightness between Ki67 and cytoplasmic SOX2. Collectively, our results demonstrate the influence of SOX2 directly on important processes of carcinogenesis, even in stages considered a little later, such as TEM, a finding initiated in the literature until then. Therefore, better elucidation of the mechanism of action of SOX2 in these pathways can contribute to the understanding of tumor development, as well as making this protein a prognostic marker and even a therapeutic target.