Structure-activity relationship analyses of glycyrrhetinic acid derivatives as anticancer agents.

Cancer cell resistance to kinase inhibitors and targeted agents, acquisition of a multidrug-resistant (MDR) phenotype and/or intrinsic resistance to apoptosis prevent effective treatment in about 50% of solid cancers in adults, and the percentage is even higher in children. Glycyrrhetinic acid (GA) and some of its derivatives may offer hope in combating cancer types associated with poor prognoses. Some GA derivatives are indeed able to target both the proteasome and peroxisome proliferator-activated receptors (PPARs), two proteins that play major roles in cancer cell biology but are not related to MDR and/or apoptosis-related resistance phenotypes.