IADR Abstract Archives
Tertiary Chemoprevention Strategies for Oral Squamous Cell Carcinoma (OSCC)
Objectives: Despite microscopically confirmed complete excision, approximately 1/3 of OSCCs locally recur often with fatal consequences. As a result of their chemoresistance, growth advantage, and ability to generate rapidly proliferating transient amplifying cells, cancer stem cells (CSCs) are the recognized drivers of OSCC recurrence. ZEB1 and YAP work in conjunction to reactivate epithelial-mesenchymal-transition and enhance cell survival, effectively pairing cell mobility with CSC phenotype. Objective: Isolate OSCC CSCs to:1) investigate ZEB1 and YAP’s contributions to CSC motility, 2) identify a CSC-selective chemopreventive.
Methods: Recently isolated OSCC cell line (JSCC1) and a highly-tumorigenic OSCC cell line (2095sc) were evaluated to determine: 1) Paclitaxel sensitivity on tumorsphere-enriched (growth on low-attachment flasks) and non-enriched cells, 2) activity of a key stem cell enzyme (ALDH) in Paclitaxel-selected relative to treatment-naïve cells , 3) siRNA ZEB1 and/or YAP translation- inhibition on directed migration.
Results: Paclitaxel challenge showed: tumorsphere-enriched cells exhibited greater chemoresistance across all time points (24h, 48h, and 72h) and doses (2nM, 5nM, 10nM) relative to non-enriched cells. Preliminary ALDH activity (sera-free medium 108h, 5 nM Paclitaxel last 96h) showed: 1) No activity in treatment-naïve OSCC cells 2) ALDH activity increased over time 48h (2095sc only) and 96h (2095sc and JSCC1). 2095sc and JSCC1 cells transfected with siRNA (ZEB1 and/or YAP) showed similar directed migration responses: 1) YAP siRNA significantly inhibited scratch wound closure (p<0.01, n=6), 2) ZEB1 siRNA significantly inhibited closure but less than YAP (p<0.01, n=6), YAP+ZEB1 siRNA showed comparable inhibition as ZEB1 siRNA (p<0.01, n=6) [Kruskal Wallis, Dunn’s Multiple comparison post hoc test].
Conclusions: Effective tertiary chemoprevention needs to control not only transient amplifying and post mitotic tumor cells, but also chemoresistant CSCs. Previous studies from our lab have shown freeze-dried black raspberries plus Fenretinide significantly suppress OSCC tumorsphere formation, directed migration and invasion. Studies are ongoing to identify CSC-specific, complementary chemopreventive.
Methods: Recently isolated OSCC cell line (JSCC1) and a highly-tumorigenic OSCC cell line (2095sc) were evaluated to determine: 1) Paclitaxel sensitivity on tumorsphere-enriched (growth on low-attachment flasks) and non-enriched cells, 2) activity of a key stem cell enzyme (ALDH) in Paclitaxel-selected relative to treatment-naïve cells , 3) siRNA ZEB1 and/or YAP translation- inhibition on directed migration.
Results: Paclitaxel challenge showed: tumorsphere-enriched cells exhibited greater chemoresistance across all time points (24h, 48h, and 72h) and doses (2nM, 5nM, 10nM) relative to non-enriched cells. Preliminary ALDH activity (sera-free medium 108h, 5 nM Paclitaxel last 96h) showed: 1) No activity in treatment-naïve OSCC cells 2) ALDH activity increased over time 48h (2095sc only) and 96h (2095sc and JSCC1). 2095sc and JSCC1 cells transfected with siRNA (ZEB1 and/or YAP) showed similar directed migration responses: 1) YAP siRNA significantly inhibited scratch wound closure (p<0.01, n=6), 2) ZEB1 siRNA significantly inhibited closure but less than YAP (p<0.01, n=6), YAP+ZEB1 siRNA showed comparable inhibition as ZEB1 siRNA (p<0.01, n=6) [Kruskal Wallis, Dunn’s Multiple comparison post hoc test].
Conclusions: Effective tertiary chemoprevention needs to control not only transient amplifying and post mitotic tumor cells, but also chemoresistant CSCs. Previous studies from our lab have shown freeze-dried black raspberries plus Fenretinide significantly suppress OSCC tumorsphere formation, directed migration and invasion. Studies are ongoing to identify CSC-specific, complementary chemopreventive.