Abstract 3341: Chronic TNFα treatment enhances cancer stem cell-like phenotype via Notch1 activation in oral squamous cell carcinoma cells

Although there is an increasing evidence of chronic inflammation-associated tumorigenesis, the molecular and cellular mechanisms linking chronic inflammation to tumorigenesis have not yet been fully understood. Recent studies have uncovered and validated the pathophysiological role of self-renewing cells, named cancer stem cells (CSC; also called tumor-initiating cells), in long-term sustenance of cancers. In this study, we investigated the effect of chronic inflammation on CSC phenotype of oral squamous cell carcinoma cells (OSCC). We treated OSCC cell lines with tumor necrosis factor alpha (TNFα), a major proinflammatory cytokine, for extended periods and examined the effect of chronic TNFα on CSC characteristics, i.e., undifferentiated tumor sphere forming ability, stem cell-associated genes expression and chemo-radioresistance. Chronic treatment of OSCC with TNFα enhanced CSC phenotype, which is shown by increased tumor sphere forming ability, greatly increased tumorigenicity and chemo-radioresistance, and increased expression of stemness-related genes. Moreover, activation of Notch1 signaling was detected in the TNFα treated cell, and suppression of Notch1 signaling inhibited CSC phenotype. Furthermore, we demonstrated that inhibition of Hes-1, the downstream target of Notch1, led to suppression of CSC phenotype. Taken together, the data suggest that proinflammatory cytokine exposure can generate or/and enrich OSCC CSC population, in part, by activation of the Notch1 signaling pathway. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3341. doi:1538-7445.AM2012-3341