Approximately 40,000 cases of oral squamous cell carcinoma (OSCC) are diagnosed each year in the United States. Surgery, chemotherapy, and radiation are the mainstays of treatment for advanced OSCC, but frequently result in disfigurement and adverse cytotoxicities. Recurrent disease, leading to death, is associated with development of chemotherapy and/or radiation resistance. Efforts to combat OSCC have been severely hindered by an incomplete understanding of the mechanisms of disease progression and a lack of molecular markers that can be used to predict responsiveness to chemotherapy and radiation. Our long-term goal is to determine the role that gene mutations play in OSCC, to apply this knowledge towards risk stratification in patients, and to develop therapeutic strategies to overcome the negative consequences of these mutations. We and others have reported the mutational landscape of OSCC, identifying the procaspase-8 gene as one of the most commonly mutated genes in this disease. Mutations in the coding region for procaspase-8 zymogen were identified in 8 percent of patient tumors, a finding confirmed by analysis of 302 OSCC tumors by The Cancer Genome Atlas (TCGA). Wild-type caspase-8 is known to mediate death receptor-mediated apoptosis. In functional studies of four OSCC-associated, procaspase-8 mutants, we determined that the mutant proteins potently inhibit death receptor-mediated apoptosis, and a representative mutant interfered with formation of the death inducing signaling complex (DISC). The procaspase-8 mutants also conferred enhanced resistance to cisplatin and radiation. Inhibition of the DNA damage response proteins ATR and ATM reversed cisplatin and radiation resistance, respectively, in cells with mutant procaspase-8. We hypothesize that OSCC- associated procaspase-8 mutations promote resistance to death ligands, chemotherapy, and radiation, while defining a substantial subpopulation of patients who may benefit from treatment with ATR or ATM inhibitors. To test this hypothesis, we propose three Specific Aims.
Aim 1 will utilize innovative OSCC models to investigate the impact of a broad panel of OSCC-associated procaspase-8 mutant proteins on DISC formation, apoptosis, and necroptosis following death receptor activation.
Aim 2 will determine whether the mutant proteins confer resistance to cisplatin or radiation in vitro and in vivo, and will compare clinical outcomes of OSCC patients harboring wild-type versus mutant procaspase-8 using specimens from an ongoing Phase II clinical trial incorporating concurrent cisplatin/radiation treatment.
In Aim 3, i vitro and in vivo studies will determine the potential of ATR/ATM inhibition as a strategy for reversing chemotherapy and radiation resistance. Results from our studies will determine the significance and consequences of frequent procaspase-8 mutation on OSCC responsiveness to death receptor agonists, chemotherapy, and radiation, and the mechanisms responsible for these effects. We also expect that our findings will lay the foundation for biomarker-driven clinical trials evaluating the value of ATR or ATM inhibition in patients with procaspase-8 mutations.

Public Health Relevance

We have identified a gene (procaspase-8 gene) that is commonly mutated in oral squamous cell carcinoma (OSCC), a deadly form of cancer that frequently develops resistance to conventional chemotherapy drugs and radiation. We will use cell line and preclinical tumor models, as well as OSCC patient-derived specimens, to determine the role of procaspase-8 mutations in conferring chemotherapy and radiation resistance in this disease. Moreover, we will utilize molecular targeting of cellular kinases (ATR and ATM) involved in repair of DNA damage in an effort to reverse chemotherapy and radiation resistance in OSCC cells and tumors harboring procaspase-8 mutations.

National Institute of Health (NIH)
National Institute of Dental & Craniofacial Research (NIDCR)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-BMCT-C (01))
Program Officer
Venkatachalam, Sundaresan
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Pittsburgh
Internal Medicine/Medicine
Schools of Medicine
United States
Zip Code
Kemmer, J D; Johnson, D E; Grandis, J R (2018) Leveraging Genomics for Head and Neck Cancer Treatment. J Dent Res 97:603-613
Leonard, Brandon C; Johnson, Daniel E (2018) Signaling by cell surface death receptors: Alterations in head and neck cancer. Adv Biol Regul 67:170-178
Lee, David S; O'Keefe, Rachel A; Ha, Patrick K et al. (2018) Biochemical Properties of a Decoy Oligodeoxynucleotide Inhibitor of STAT3 Transcription Factor. Int J Mol Sci 19:
Cho, Janice; Johnson, Daniel E; Grandis, Jennifer R (2018) Therapeutic Implications of the Genetic Landscape of Head and Neck Cancer. Semin Radiat Oncol 28:2-11
Johnson, Daniel E; O'Keefe, Rachel A; Grandis, Jennifer R (2018) Targeting the IL-6/JAK/STAT3 signalling axis in cancer. Nat Rev Clin Oncol 15:234-248
Xu, Mary Jue; Johnson, Daniel E; Grandis, Jennifer R (2017) EGFR-targeted therapies in the post-genomic era. Cancer Metastasis Rev 36:463-473