Abstract 864: Alternated activation of TGFβ pathway and differential expression of epithelial to mesenchymal transition transcription factors in relation to lymph node metastasis in two subtypes of breast cancer tumors

Abstract

Abstract Breast cancer is the leading cause of cancer death among women worldwide, being distant metastases the main cause of death. Epithelial to mesenchymal transition (EMT) has been implicated in promoting cancer invasion and metastasis. This process can be induced by TGFβ through the expression of transcription factors: TWIST, SNAIL, SLUG and ZEB1, which expression may be promoted by different signaling pathways such as SMAD2/SMAD3, PI3K/AKT and ERK/MAPK. The expression of EMT transcription factors has been previously studied in several cancer cell lines, although no studies have been performed in breast cancer tumors. In this study, we analyzed by immunohistochemistry the expression of the four transcription factors, and the signal transduction key proteins p-SMAD2 (ser465/467), p-SMAD2L (ser245/250/,255) and p-AKT (ser473), in 107 breast cancer tumors. We found expression of at least one transcription factor in all triple negative tumors (n=24), while only 70% luminal tumors showed expression of at least one of these proteins. Expression of ZEB1, SNAIL and SLUG was observed in tumors with metastases to lymph node, whereas the majority of tumors expressing TWIST were negative for lymph node status. All triple negative tumors with an active state of the signal transduction pathway TGFβ/SMAD showed expression of at least one transcription factor, whereas 65% of luminal tumors with an active state of the same pathway showed no expression of these transcription factors. Active state of PI3K/AKT pathway was observed only for luminal tumors as it has been described. Sixty-three percent of tumors having this pathway active showed expression of at least one transcription factor. In conclusion we found differential expression of EMT transcription factors in relation to lymph node status and a differential active state of signaling pathways in relation to tumoral subtype of breast cancer tumors. Our results suggest a different mechanism of EMT induction by TGFβ in relation to two tumor’s subtypes and lymph node metastasis. Citation Format: Victoria Ortega-Hernandez, Patricia Gajardo-Meneses, Wanda Fernandez, Pilar Carvallo. Alternated activation of TGFβ pathway and differential expression of epithelial to mesenchymal transition transcription factors in relation to lymph node metastasis in two subtypes of breast cancer tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 864. doi:10.1158/1538-7445.AM2017-864