A method for treating and preventing autoimmune diseases and cancer can include administering to a subject in need thereof a therapeutically effective amount of a pharmaceutical composition comprising an Arid5a inhibitor and a pharmaceutically acceptable carrier. A screening method can include identifying candidate Arid5a inhibitors through in silico predicted binding to Arid5a target domains (Pocket X) and confirming Arid5a inhibition through in vitro by binding and luciferase assays.