Abstract B32: Impact of cancer-associated fibroblasts on head and neck cancer stem cells

Abstract

Abstract Background: The tumor microenvironment (TME) is made up of epithelial cancer cells and mesenchymal stromal cells including tumor-infiltrating lymphocytes, cancer-associated fibroblasts (CAFs) and endothelial cells. Within the cancer cell population are cancer stem cells (CSC), a subpopulation of cells defined as having the capacity for self-renewal, tumorigenesis, and the ability to recapitulate a heterogeneous tumor. The interaction of the TME with cancer cells remains of interest. The focus of this study is to investigate the effect of patient-derived CAFs on head and neck CSC and tumor activity. Methods: Patient-derived head and neck cancer cell lines and patient-derived fibroblasts lines have previously been established by our group. Tumor cells were grown alone or in combination with patient-matched fibroblasts in a coculture chamber system, allowing for mixture of media but not cells. Scratch tests were performed and closure rates were compared between the two conditions (tumor cells alone and coculture). Tumor cells were then grown alone or in direct contact with matched fibroblasts for one week. Cancer cells were selected for based on epithelial cell adhesion molecule (EpCAM) status and in vitro tumor growth and stem cells percentages (defined as proportion of CD44-high and ALDH-positive cells) were calculated. Results: Patient-derived cancer cells cocultured with matched fibroblasts showed a significant increase in closure rates compared with tumor cells alone at three defined time points (p=0.03-0.002). Coculture conditions resulted in greater in vitro tumor growth after one week (6.4-fold vs. 3.7-fold increase) and an increased proportion of CD44-high tumor cells (9% vs. 5%). The effect of coculture on ALDH-positive percentages was variable. Conclusion: CAFs have previously been shown to potentiate tumorigenesis and metastases. We validated these findings with matched patient derived tumor cells and CAFs. We were then able to demonstrate that CAFs increase the proportion of head and neck CSC, suggesting the mechanism for CAF-associated increased tumor activity may be mediated through CSC. Further studies investigating the relationship between CAFs and CSC are warranted. Citation Format: Molly E. Heft Neal, John Henry J. Owen, Matthew E. Spector, Thomas E. Carey, Mark E.P. Prince, Steven B. Chinn. Impact of cancer-associated fibroblasts on head and neck cancer stem cells [abstract]. In: Proceedings of the AACR-AHNS Head and Neck Cancer Conference: Optimizing Survival and Quality of Life through Basic, Clinical, and Translational Research; 2019 Apr 29-30; Austin, TX. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_2):Abstract nr B32.