Folic Acid Oversupplementation Alters Global DNA Methylation and Circadian Clock Gene Expression in FaDu Head and Neck Squamous Cell Carcinoma Cells: An Exploratory Study

Background/Objectives: Folic acid (FA), the synthetic form of folate (vitamin B9), is a vitamin involved in one-carbon metabolism, DNA synthesis, and DNA methylation. Because folate metabolism influences methyl donor availability, FA availability may affect circadian clock gene regulation through methylation-related or other metabolic mechanisms in head and neck squamous cell carcinoma (HNSCC). This exploratory study aims to determine whether FA oversupplementation influences cell viability and alters global DNA methylation, as well as the expression and methylation status of circadian clock genes in HNSCC cells.