RESUMO
Nuclear receptor coactivator 3 (NCoA3) is a transcriptional coactivator of NFκB and other factors, which is expressed at relatively low levels in normal cells and is amplified or overexpressed in several types of cancer, including breast tumors. NCoA3 levels have been shown to be decreased during adipogenesis; however, its role in tumorsurrounding adipose tissue (AT) remains unknown. Therefore, the present study assessed the modulation of NCoA3 in breast cancerassociated adipocytes and evaluated its association with the expression of inflammatory markers. 3T3L1 adipocytes were stimulated with conditioned medium from human breast cancer cell lines and the expression levels of NCoA3 were evaluated by reverse transcriptionquantitative (q)PCR. NFκB activation was measured by immunofluorescence, and tumor necrosis factor and monocyte chemoattractant protein 1 levels were analyzed by qPCR and dot blot assays. The results obtained from the in vitro model were supported using mammary AT (MAT) from female mice, MAT adjacent to tumors from patients with breast cancer and bioinformatics analysis. The results revealed that adipocytes expressing high levels of NCoA3 were mainly associated with a proinflammatory profile. In 3T3L1 adipocytes, NCoA3 downregulation or NFκB inhibition reversed the expression of inflammatory molecules. In addition, MAT from patients with a worse prognosis exhibited high levels of this coactivator. Notably, adipocyte NCoA3 levels could be modulated by inflammatory signals from tumors. The modulation of NCoA3 levels in synergy with NFκB activity in MAT in a tumor context could be factors required to establish breast cancerassociated inflammation. As adipocytes are involved in the development and progression of breast cancer, this signaling network deserves to be further investigated to improve future tumor treatments.
Assuntos
Neoplasias da Mama , Coativador 3 de Receptor Nuclear , Animais , Feminino , Humanos , Camundongos , Adipócitos/metabolismo , Neoplasias da Mama/patologia , NF-kappa B/genética , NF-kappa B/metabolismo , Coativador 3 de Receptor Nuclear/genética , Coativador 3 de Receptor Nuclear/metabolismo , Regulação para Cima , Células 3T3-L1RESUMO
RAC3 is a coactivator of steroid receptors and NF-κB. It is usually overexpressed in several tumors, contributes to maintain cancer stem cells and also to induce them when is overexpressed in non-tumoral cells. In this work, we investigated whether the inflammatory cytokine TNF may contribute to the transforming effects of RAC3 overexpression in the non-tumoral HEK293 cell line. The study model included the HEK293 tumoral transformed cell line constitutively overexpressing RAC3 by stable transfection and control non-tumoral cells transfected with an empty vector. The HeLa and T47D tumoral cells that naturally overexpress RAC3 were used as positive control. We found that TNF potentiated RAC3-induced mesenchymal transition, involving an increased E-Cadherin downregulation, Vimentin and SNAIL upregulation and enhanced migratory behavior. Moreover, concerning the molecular mechanisms by which TNF potentiates the RAC3 transforming action, they involve the IKK activation, which in addition induced the ß-Catenin transactivation. Our results demonstrate that although RAC3 overexpression could be a signal strong enough to induce cancer stem cells, the inflammatory microenvironment may be playing a key role contributing to the migratory and invasive phenotype required for metastasis and cancer persistence.