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

ABSTRACT 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.