Triterpenes from Poria cocos are revealed as potential retinoid X receptor selective agonists based on cell and in silico evidence

Poria cocos is an edible and medicinal fungus that is widely used in Traditional Chinese Medicines as well as in modern applications. Retinoid X receptor (RXR) occupies a central place in nuclear receptor signaling, and a pharmacological RXR-dependent pathway is involved in myeloid cell function. Here, structural information for 82 triterpenes from P. cocos and 17 known RXR agonists was collected in a compound library and retrieved for a molecular docking study. Three triterpenes, 16alpha-hydroxytrametenolic acid (HTA), pachymic acid (PA), and polyporenic acid C (PPAC), were identified as novel RXR-specific agonists based on luciferase reporter assays and in silico evidence. Treatment with HTA, PA, and PPAC significantly induced differentiation of the human promyelocytic leukemia cell line HL-60 with EC50 values of 21.0 +/- 0.52, 6.7 +/- 0.37, and 9.4 +/- 0.65 muM, respectively. These effects were partly blocked by the RXR antagonist UVI3003, suggesting that an RXR-dependent pathway may play an important role in their anti-acute promyelocytic leukemia (APL) effects. Taken together, triterpenes from P. cocos are revealed as naturally occurring RXR selective agonists with the potential for anti-cancer activity. These results suggest a novel approach to the treatment or prevention of APL.