Abstract 5098: Cues from extracellular matrix produced by fibroblasts prime lung cancer cells for distant dissemination
Authors: Pollaci Giuliana , Giovinazzo Francesca , Rondinone Ornella , Bruccoleri Antonina , Facchinetti Federica , Tortoreto Monica , Pastorino Ugo , Bertolini Giulia , Sozzi Gabriella , Roz Luca 
Published: September 2020

Abstract
Extracellular matrix (ECM) plays a crucial role in the regulation of tumor growth and progression. In the lungs, fibroblasts are involved in ECM homeostasis and are therefore crucial in lung tissue repair and remodeling. These activities are exploited by cancer cells during tumor growth by reprogramming fibroblast towards a tumor supportive phenotype including regulation of ECM-related proteins. We previously identified the nuclear transported XPO1 as a master regulator of fibroblast metabolic reprogramming. How cues from ECM can regulate the fate of cells disseminating from primary tumors is however poorly understood.
To investigate the relevance of ECM remodeling during tumor development, primary lung fibroblasts were treated with TGF-β to mimic signals in the tumor microenvironment and Real-Time PCR was then performed to evaluate expression levels of ECM-related genes. Co-cultures and experiments with fibroblast conditioned medium or fibroblast-derived decellularized extracellular matrix (dECM) were performed with lung cancer cells and modulation of stemness phenotype evaluated by increase of CD133+ cancer stem cells. dECM from patient-derived fibroblast cultures was used in subcutaneous co-injections experiments with lung cancer cell lines in immunocompromised mice and dissemination to the lungs evaluated by flow-cytometry.
Treatment with TGF-β induced over-expression of ECM-related genes (including COL1A and SPARC) which could be prevented by pharmacological inhibition of XPO1. Primary tumor growth was increased by dECM obtained from cultures of cancer associated fibroblasts. Interestingly analysis of tumors obtained by co-injection with different ECMs showed acquisition of specific phenotypes at late time points including relative content of CD133+ cancer stem cells and regulation of ECM-related genes in both cancer cells and stromal cells. Primary tumor microenvironments with high content of COL1A and COL6A3 were conductive to dissemination to distant sites which was associated by a local reduction of NK cells and an increase in macrophages. In vitro XPO1 inhibition prevented the ability of activated fibroblasts to stimulate migration of lung cancer cell lines and to increase the frequency of CD133+ cancer stem cells thereby reducing their pro-tumorigenic activity in vivo.
Taken together these results reveal the activity of lung fibroblasts in dictating the metastatic phenotype by an ECM-regulated niche at the primary tumor site and suggest potential therapeutic value of pharmacological interventions blocking tumor-stroma interactions.
Citation Format: Giuliana Pollaci, Francesca Giovinazzo, Ornella Rondinone, Antonina Bruccoleri, Federica Facchinetti, Monica Tortoreto, Ugo Pastorino, Giulia Bertolini, Gabriella Sozzi, Luca Roz. Cues from extracellular matrix produced by fibroblasts prime lung cancer cells for distant dissemination [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5098.