Abstract 3316: CD44High head and neck cancer cells demonstrate increased cell growth and chemotherapeutic resistance

Abstract

Abstract Background: Head and Neck Squamous Cell Carcinoma (HNSCC) is a tumor made up of a heterogeneous population of cancer cells. Differences in individual cell phenotype may extrapolate to clinical behavior at the tumor level. CD44 is a cell surface marker highly expressed in putative cancer stem cells. Here, we demonstrate that fluorescence activated cell sorting (FACS) for the CD44 cell surface marker isolates a population of HNSCC cells with increased growth rate, colony forming ability, and chemoresistance. Methods: FACS was used to isolate CD44High and CD44Low cells from the HNSCC cell line SCC1. CD44High, CD44Low and unsorted cells were compared with respect to cell growth using the MTT assay for 8 days. They were also seeded into agar and grown for 6 weeks to determine colony forming potential. Sorted and unsorted cells were also compared for their sensitivity to cisplatin (20 µM). Live cells were measured using the MTT assay and compared to untreated cells at the same time point in order to calculate relative growth rates. Additionally, SCC1 cells were analyzed using FACS with and without cisplatin to determine changes in the population of CD44High cells. Primary tumor specimens and normal controls were analyzed for various cancer stem cell markers via immunohistochemistry. Results: CD44High SCC1 cells grew the fastest in culture with CD44Low cells growing significantly slower. Unsorted cells had a similar growth rate to CD44High cells, which is not surprising given that CD44High cells made up roughly 60% of the total population. CD44High cells in soft agar developed significantly more colonies with a larger average colony size after 6 weeks in culture compared to unsorted and CD44Low cells. CD44High SCC1 cells also were less sensitive to cisplatin with no difference in cell growth between treated and untreated cells. Using FACS to analyze unsorted cells after treatment with cisplatin, we observed enrichment in the CD44High cell population. Control non-cancer specimens demonstrated expression of p16 with low levels of BMI and CD44 on immunohistochemical analysis. Poorly differentiated HNSCC tumors demonstrated absence of p16, high BMI, and high CD44. Conclusion: The cell surface marker CD44 is expressed in a subset of HNSCC cells that have higher growth rates, tumorogenicity, and resistance to chemotherapy. These HNSCC stem cells may be the reason for resistance and recurrence. Understanding the mechanism behind their specific phenotype will be valuable in advancing treatments for HNSCC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3316.