SIL14, a New Quinoline-Based Pannexin-1 Channel Blocker Attenuates Development of Renal Cysts

Background: Polycystic kidney diseases (PKD) are a group of inherited nephropathies marked with the formation of fluid-filled cysts along the nephron. ADPKD (autosomal dominant PKD) is caused by a mutation in PKD1 or PKD2 genes encoding polycystins 1 and 2, whereas ARPKD (autosomal recessive PKD) is initiated due to mutations in PKHD1 gene encoding fibrocystin, a protein capable of interacting with polycystin-1/2 complex. Earlier studies demonstrate that cyst fluid contains a high level of ATP which disrupts normal purinergic signaling and promotes cyst growth. Our previous studies provide evidence that pannexin-1, a hemichannel permeable for ATP, can serve as a major transporter of ATP from the cyst-lining cells. Thus, we have shown that chronic administration of probenecid, a non-selective Panx1 blocker and gout remedy, slows cyst formation in a murine model of ADPKD (Arkhipov et al., 2023). Hypothesis: With development of a new specific class of pannexin-1 blockers (Crocetti et al, 2023), we hypothesized that one of them, SIL14, can be used in pharmacological treatment of PKD cysts. Methods: Specific inhibitory properties of SIL14 against pannexin-1 activity were tested with patch-clamp technique. Hamster ovarian cells were transfected with mPanx1 cDNA and whole-cell currents were isolated under ramp protocol 48-72 hrs later. Effect of SIL14 on the development of renal cysts was tested in mouse cortical collecting duct cell culture (mpkCCD cl4 ) grown 3 weeks in Matrigel in presence of 10 µM forskolin. Pannexin-1 expression in the mpkCCD cl4 cysts was visualized with confocal microscopy in fixed and stained specimens. Results: In PCK rats, a model of ARPKD, cysts contain a high level of ATP, most probably, released by lining epithelial cells. Acute application of SIL14 on CHO cells revealed strong inhibitory properties against pannexin-1 dependent currents. The effect was partially reversible and dose dependent with IC 50 =13µM. MpkCCD l4 cells, when seeded in Matrigel in presence of forskolin, form 3D cyst-like spheroids. Confocal miscroscopy reveals a prominent pannexin-1 staining in plasma membrane of the cells. Chronic pannexin-1 blockage with 5 or 30 µM SIL14 reduces cyst size (p=0.054 and p<0.001, respectively). Conclusion: SIL14 is a potent pannexin-1 inhibitor which can be considered as a therapeutic approach in ADPKD treatment. Further in vivo studies are required to test this drug on cyst formation in animal models of PKD, side effects and pharmacokinetics. Supported by: NIH DK123266 and DK131114. NIH DK123266 and DK131114. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.