Proceedings of Oncobiology Symposiums
Proceedings of XIV Oncobiology Symposium

INTRODUCTION AND OBJECTIVE: Thyroid cancer (TC) is the most common endocrine malignancy and the majority of these tumors derive from follicular cells and can vary from differentiated to undifferentiated cell phenotypes. Several gene products are aberrantly expressed in TC, including osteopontin (OPN). Total OPN is a key activator of epithelial- mesenchymal transition (EMT) and stemness potential, modulating cancer progression and related features. OPN primary transcript undergoes alternative splicing, generating OPN splice variants (OPN-SV), including OPNa, OPNb and OPNc, which are aberrantly expressed in cancer cells, presenting tumor and tissue specific roles. Our group previously demonstrated that OPNa overexpression in c643 TC cells can activate cell migration and invasion. However, the cellular and molecular mechanisms related to these events and how OPNa isoform can differently contribute to these aspects is still poorly understood. This work aimed to investigate the related transcriptional and/or protein level profiling of EMT and stemness markers that could be associated to OPNa-induced migratory properties in c643 TC cells. MATERIAL AND METHOD: c643 cell line overexpressing OPNa (c643-OPNa) and the control c643 cells containing the empty vector (c643-EV) were used to analyze the expression of EMT and stemness markers by quantitative real time PCR (RT-qPCR) and immunoblot. Thyrosphere formation assays were also performed using both cell clones, besides the evaluation of stemness transcriptional patterns by RT-qPCR. RESULTS AND CONCLUSION: c643-OPNa cells expressed both epithelial and mesenchymal markers, with N-cadherin and Twist being upregulated in relation to c643-EV control cells. Moreover, among the 4 tested stemness markers, SOX-2 and LIN-28 were upregulated. Furthermore, c643-OPNa showed increased protein expression levels of N-cadherin, besides upregulation of the stemness markers c-Myc, SOX-2, NANOG and OCT-4A. The c643-OPNa cells also rendered higher number and size of formed thyrospheres, which also expressed higher levels of stemness markers. In conclusion, these data evidenced that OPNa overexpression in c643 cells may be associated with an intermediate EMT phenotype and higher stemness features. According to observed transcriptional and protein expression patterns of EMT and stemness markers, these molecular features could be among the signals differentially activated by OPNa that may contribute the acquisition of TC cell motility and invasion profile. These assumptions may support the proposal of OPNa as a putative target aiming to inhibit TC motility and invasion properties.