Usnic Acid Reduces Colon Cancer Cell Viability and Colony Formation by Affecting Cancer Cell Metabolism

Today, some natural and plant-based products are of great interest, at least as supplements, in cancer prevention and treatment due to their anti-cancer properties. One of them is usnic acid, which is a secondary metabolite synthesized by the polyketide pathway in Usnea lichen species and is a promising agent for cancer treatment. In this study, the effects of usnic acid on cell proliferation, colony formation, and cancer metabolism-related Sirtuin 2 (SIRT2) and lactate dehydrogenase (LDH) enzymes in COLO-205, a colon cancer cell line, were investigated. COLO-205 cells were exposed to three different doses of usnic acid: 15 mu M, 30 mu M, and 60 mu M for 24 h. Usnic acid treatment reduced colon cancer cell viability at a dose dependent manner. The highest dose of usnic acid treatment (60 mu M) decreased cell viability by about 40%. It has been determined that a 15 mu M dose of usnic acid reduces cell viability by about half, and a dose as low as 1 mu M reduces the colony-forming abilities of cancer cells by about half. It has been determined that usnic acid reduces the anti-cancer effect seen in this cell line, at least in part, by altering SIRT2 and LDH protein expressions, thus affecting cancer metabolism.