Survivin in Insulin-Like Growth Factor-Induced Resistance to Lapatinib in Head and Neck Squamous Carcinoma Cells

Epidermal growth factor receptor (EGFR) inhibitors have limited efficacy in head and neck squamous cell carcinoma (HNSCC) due to various resistance mechanisms, such as activation of the insulin-like growth factor-1 receptor (IGF1R), which initiates pro-survival signaling. Survivin, a member of the inhibitor of apoptosis proteins family, is expressed at relatively high levels in malignant tissues and plays a role in cell division. Expression of survivin in tumors has been shown to correlate with poor prognosis due to chemotherapy resistance and anti-apoptotic behavior. We previously demonstrated that activation of the IGF1R reduces sensitivity to EGFR-tyrosine kinase inhibitors (TKIs) via reduced apoptosis suggesting a role of survivin in this process. This study evaluates the role of survivin in IGF1R-mediated lapatinib resistance. Using HNSCC cell lines FaDu and SCC25, survivin expression increased and lapatinib sensitivity decreased with IGF1R activation. Further, these effects were reversed by the survivin inhibitor YM-155. Conversely, survivin expression and lapatinib sensitivity were unchanged with IGF1R activation in UNC10 cells. YM-155 enhanced the inhibitory effect of lapatinib on UNC10 cells, regardless of activation of the IGF1R. These results demonstrate that enhanced survivin expression correlates with IGF1R-mediated lapatinib resistance in HNSCC cells and suggest that regulation of survivin expression may be a key mechanistic element in IGF1R-based therapeutic resistance. Combinatorial treatment with survivin antagonists and EGFR-TKIs warrants further investigation.