Birinapant and Radiation in HNSCC

Comparison of tumors from The Cancer Genome Atlas (TCGA) reveals that head and neck squamous cell carcinomas (HNSCC) harbor the most frequent genomic amplifications of Fas-associated death domain (FADD), with or without Baculovirus inhibitor of apoptosis repeat containing BIRC2 (cIAP1), affecting about 30% of patients in association with worse prognosis. Here, we identified HNSCC cell lines harboring FADD/BIRC2 amplifications and overexpression by exome sequencing, RT-PCR, and Western blotting. In vitro, FADD or BIRC2 siRNA knockdown inhibited HNSCC displaying amplification and increased expression of these genes, supporting their functional importance in promoting proliferation. Birinapant, a novel SMAC mimetic, sensitized multiple HNSCC lines to cell death by agonists TNFα or TRAIL and inhibited cIAP1>XIAP>IAP2. Combination of birinapant and TNFα induced sub-G0 DNA fragmentation in sensitive lines and birinapant alone also induced significant G2–M cell-cycle arrest and cell death in UM-SCC-46 cells. Gene transfer and expression of FADD sensitized resistant UM-SCC-38 cells lacking FADD amplification to birinapant and TNFα, supporting a role for FADD in sensitization to IAP inhibitor and death ligands. HNSCC varied in mechanisms of cell death, as indicated by reversal by inhibitors or protein markers of caspase-dependent apoptosis and/or RIPK1/MLKL-mediated necroptosis. In vivo, birinapant inhibited tumor growth and enhanced radiation-induced TNFα, tumor responses, and ...

Source: Cancer Research - September 14, 2016 Category: Cancer & Oncology Authors: Eytan, D. F., Snow, G. E., Carlson, S., Derakhshan, A., Saleh, A., Schiltz, S., Cheng, H., Mohan, S., Cornelius, S., Coupar, J., Sowers, A. L., Hernandez, L., Mitchell, J. B., Annunziata, C. M., Chen, Z., Van Waes, C. Tags: Therapeutics, Targets, and Chemical Biology Source Type: research