Abstract P6-06-14: Analysis of secreted proteome in an in vivo like human 3D model of breast cancer
Authors: Persson Emma , Gregersson Pernilla , Fitzpatrick Paul , Gustafsson Anna , Ståhlberg Anders , Landberg Göran 
Published: March 2020

Abstract
Background: Breast cancer is the most common form of cancer amongst women and affects millions worldwide each year. The tumor micro environment plays a key role in cancer progression and disease outcome of which a highly important factor is the secreted proteome which includes cytokines, chemokines and other proteins. Cancer cells influence neighboring cells by both autocrine and paracrine secretion which affects cancer cell characteristics such as stem-like properties, proliferation and metastatic capacity. Due to the importance of cancer cell signaling and cell to cell communication, when studying the cancer cell secretome in a three-dimensional environment new signaling pathways and new possible drug targets can be investigated.
Methods: To understand the complexity of breast cancer cell secretion, the human in vivo like system patient derived scaffolds (PDS) was used as a modeling system whereby patient specific extracellular matrix mediated cellular secretion in both ERα+ and ERα- cell lines were investigated. 54 human breast cancer tumors were decellularized and the PDS were repopulated with either MCF7 or MDA-MB-231 cells. Cell lines were grown on scaffolds for 21 days. At day 16 cell media was changed and at day 21 conditioned media was collected for secretome analysis. Multiplex Proximity Extension Assay (OLINK, Uppsala Sweden) was performed on conditioned media and 184 proteins were analyzed for each sample.
Results: The secretome from cells grown in PDS culture differs distinctly from the secretome from cells cultured in standard monolayer cultures, both in numbers and amount of secreted proteins. Secreted proteins from cells grown in PDS cultures were also shown to increase the cancer stem cell population compared to secretome from cells cultivated in monolayer culture. By comparing secretomic profiles from MCF7 cells grown in 54 PDSs, three clusters were created with an unsupervised clustering method. When these three clusters were correlated to clinical information about the specific tumors in each cluster, patients in one of the clusters were found to have a significantly lower chance of relapse-free survival and a higher frequency of high-grade tumors. Further, cells grown in PDS from this cluster also showed a different genetic profile with increased expression of markers related to epithelial-mesenchymal transition.
Conclusion: Breast cancer cells grown in a three-dimensional in vivo-like model have a distinct different secretomic profile compare to monolayer cultured cells and the secretion can be related to the original characteristics of the breast tumor. This highlights the importance of the tumor microenvironment induced secretion and the possibility to target secreted proteins as a therapeutic strategy.
Citation Format: Emma Persson, Pernilla Gregersson, Paul Fitzpatrick, Anna Gustafsson, Anders Ståhlberg, Göran Landberg. Analysis of secreted proteome in an in vivo like human 3D model of breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-06-14.