HPV16 Enhances Radiosensitivity in Esophageal Squamous Cell Carcinoma by Promoting De Novo Fatty Acid Synthesis and Disulfidptosis

Our previous study reported that HPV16 was detected in 48.87% of ESCC patients, which was correlated with better radiotherapy response; however, the underlying mechanisms remained unclear. This study aims to elucidate how HPV16 enhances radiosensitivity through metabolic reprogramming. We overexpressed HPV16-E6/E7 in TE-1 and KYSE-410 cells to establish an in vitro model (denoted as HPV16-positive cells). CCK-8 and colony formation assays showed that HPV16-positive cells exhibited enhanced proliferation and increased radiosensitivity. Using [U-¹³C] glucose tracing, we observed increased de novo synthesis of non-essential fatty acids (C14:0, C14:1, C16:0, C16:1, C18:0, C18:1) in HPV16-positive cells compared to controls. Following 2 Gy X-ray irradiation, the percentage of de novo fatty acid synthesis level was unaffected in HPV16-positive cells, but significantly suppressed in control cells. Irradiation increased the NADP + /NADPH ratio in both cell types. However, [U-¹³C] glucose labeling results showed NADPH consumption rates for lipid acid synthesis were maintained at a high level after irradiation in HPV16-positive cells, while they were reduced significantly in control cells after irradiation. We next inhibited de novo fatty acid synthesis in HPV16-positive cells by palmitic acid (C16:0) supplement, which alleviated the irradiation-induced increase in the NADP + /NADPH ratio and decreased radiosensitivity in HPV16-positive cells. Immunofluorescence analysis revealed that radiation exposure induced F-actin collapse in LV-E6/E7-TE-1 cells, which was accompanied by cystine accumulation and NADPH depletion-disulfidptosis. HPV16 drives high de novo fatty acid synthesis in ESCC cells, which consumes NADPH and leads to disulfide stress-induced cell death, Disulfidptosis, enhancing ESCC radiosensitivity.