KRT6A Impairs Radiosensitivity in Cervical Squamous Cell Carcinoma by Enhancing Fatty Acid Synthesis

Cervical squamous cell carcinoma (CESC), a subtype of cervical cancer, is an aggressive cancer. Radiotherapy is a key treatment for locally advanced cases, but its success is often limited by radioresistance. Therefore, this study explores whether the intermediate filament protein KRT6A increases the radioresistance of CESC cells by regulating lipid metabolism. The expression profile of KRT6A was analyzed using the Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) datasets via the University of California Santa Clara UCSC Xena platform, while associated signaling pathways were identified through gene set enrichment analysis (GSEA) based on the GSE44001 dataset. Radioresistant SiHa cells (SiHa-R) were developed from the parental human CESC SiHa cell line. KRT6A mRNA levels were measured by qRT-PCR. Protein expression of KRT6A, γH2AX, and key lipogenic enzymes fatty acid synthase (FASN) and acetyl-CoA carboxylase (ACC1) was detected through Western blotting. Cell viability and proliferation were assessed using CCK-8 and colony formation assays, respectively. Apoptosis was evaluated with Annexin V-FITC/PI staining. Lipogenesis was examined by BODIPY staining and Acetyl-CoA measurement. Fatty acid composition was analyzed using liquid chromatography-mass spectrometry (LC-MS). KRT6A was found to be upregulated in CESC tissues compared to normal tissues and was further increased in radioresistant cells compared to radiosensitive cells. Its knockdown in radioresistant SiHa cells reduced cell viability and proliferation, increased apoptosis, and enhanced radiation-induced DNA damage. GSEA indicated KRT6A's involvement in fatty acid metabolism. LC-MS analysis showed that reducing KRT6A expression led to the overall decrease in multiple fatty acids. Overexpression of KRT6A increased FASN and ACC1 levels, promoted lipid droplet formation, and decreased radiation damage. These resistance effects were effectively reversed by the lipogenesis inhibitor C75. Therefore, KRT6A promotes radioresistance in CESC by activating lipogenesis.