Targeted analysis of salicylate binding partners in renal epithelial cells reveals major AMPK dependency

Autosomal dominant polycystic kidney disease (ADPKD) is the most prevalent genetic kidney disease and is characterized by the formation and growth of fluid-filled renal cysts. With the current treatment tolvaptan not suited for the majority of patients, an urgent need remains for novel therapeutics. We have shown before that activation of adenosine monophosphate activated protein kinase (AMPK) with salsalate ameliorates disease progression in vivo to a similar extent as tolvaptan. Salsalate achieves this by affecting multiple disease mechanisms known to be involved in ADPKD pathogenesis, such as metabolic reprogramming, cell proliferation and inflammation. However, it is unclear to which extent these effects are dependent on AMPK activation or result from secondary target activation. Therefore, we investigated whether salsalate's active compound, salicylate, modulates these processes in Pkd1^-/- renal epithelial cell lines, and whether salicylate effects are regulated by AMPK. Our findings indicate that for a large part, the effects of salicylate on targets related to cellular metabolism, cell proliferation and inflammation are dependent on its activation of AMPK. However, we also observed that salicylate induces mitochondrial uncoupling and inhibition of heme synthesis, while other AMPK activators do not, revealing AMPK-independent effects of salicylate in cystic disease. These results provide us with further insights into the working mechanisms of salsalate/salicylate and offer a solid basis for the future development of salsalate as a potential therapeutic for ADPKD.