Abstract 3703: Multimodal metabolic imaging and proteomics of radiation resistance in head and neck squamous cell carcinoma

Abstract Radiation resistance can halt a well-curated treatment plan in its tracks, but it may take weeks to realize this lack of efficacy resulting in lost time and unnecessary side effects. In this study, we sought to elucidate novel biomarkers of radiation resistance to predict treatment response in head and neck squamous cell carcinoma (HNSCC) at much earlier timepoints. We grew tumor xenografts from radiation-resistant UM-SCC-47 (n=25) and -sensitive UM-SCC-22B (n=37) cells in nude athymic mice. Each group was randomly divided into treatment and control groups, which were further subdivided into four timepoints for tumor excision: pre-treatment baseline, 1-, 24-, and 48-hours post-treatment. Prior to excision, we injected pimonidazole to quantify tumor hypoxia. We determined the two-photon excited fluorescence intensity and lifetime of NADH and FAD and quantified the optical redox ratio, ratio of free to bound NADH, and mean NADH lifetime of frozen sections of each tumor. We observed spatial and temporal heterogeneity in these high-resolution optical maps that indicated different metabolic programs in radiation-resistant and -sensitive tumors. A histogram-based heterogeneity analysis revealed time dependent shifts toward glycolysis in the radiation-resistant UM-SCC-47 treatment group, while the sensitive UM-SCC-22B treatment group showed the opposite trend. Proteomics performed on both cell lines identified multiple dysregulated proteins that are often implicated in HNSCC and associated with metabolic reprogramming — specifically, EGFR and SMAD4. We also found elevated levels of hypoxia and HIF-1 in the UM-SCC-47 tumors compared with the UM-SCC-22B tumors prior to and post-radiation. Using spatially co-registered optical imaging and immunohistochemical maps of the same field of view, we will present correlations between our optical markers and EGFR, SMAD4, and HIF-1. These studies will provide evidence of how protein dysregulation causes changes to optical metabolic imaging markers. Citation Format: Jesse D. Ivers, Sina Dadgar, Narasimhan Rajaram. Multimodal metabolic imaging and proteomics of radiation resistance in head and neck squamous cell carcinoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3703.