A biotinylated analog of the anti-proliferative prostaglandin A1 allows assessment of PPAR-independent effects and identification of novel cellular targets for covalent modification

The cyclopentenone prostaglandin (cyPG) PGA1 displays potent anti-proliferative and anti-inflammatory effects. Therefore, PGA1 derivatives are being studied as therapeutic agents. One major mechanism for cyPG action is the modification of protein cysteine residues, the nature of the modified proteins being highly dependent on the structure of the cyPG. Biotinylated cyPGs may aid in the proteomic identification of cyPG targets of therapeutic interest. However, for the identified targets to be relevant it is critical to assess whether biotinylated cyPGs retain the desired biological activity. Here we have explored the anti-inflammatory, anti-proliferative and cell stress-inducing effects of a biotinylated analog of PGA1 (PGA1-biotinamide, PGA1-B), to establish its validity to identify cyPG-protein interactions of potential therapeutic interest. PGA1 and PGA1-B displayed similar effects on cell viability, Hsp70 and heme oxygenase-1 induction and pro-inflammatory gene inhibition. Remarkably, PGA1-B did not activate PPAR. Therefore, this biotinylated analog can be useful to identify PPAR-independent effects of cyPGs. Protein modification and subcellular distribution of PGA1-B targets were cell-type-dependent. Through proteomic and biochemical approaches we have identified a novel set of PGA1-B targets including proteins involved in stress response, protein synthesis, cytoskeletal regulation and carbohydrate metabolism. Moreover, the modification of several of the targets identified could be reproduced in vitro. These results unveil novel interactions of PGA1 that will contribute to delineate the mechanisms for the anti-proliferative and metabolic actions of this cyPG.