Porphyrin Derivatives Inhibit the Interaction between Receptor Activator of NF‐κB and Its Ligand

Abstract

Receptor activator of NF-κB (RANK), a member of the TNF-receptor superfamily, plays an important role in bone resorption and stimulates immune and epithelial cell activation. Denosumab, a human monoclonal antibody that blocks the RANK ligand (RANKL), is approved for the treatment of osteoporosis and bone metastasis. However, a small molecule that inhibits the RANK-RANKL interaction would be beneficial to decrease cost and to facilitate treatments with orally available therapeutic agents. Herein we report the discovery of the first nonpeptidic inhibitors of RANK-RANKL interactions. In screening a chemical library by competitive ELISA, the porphyrin verteporfin was identified as a hit. Derivatives were screened, and the chlorin-macrocycle-containing pheophorbide A and purpurin 18 were found to bind recombinant RANKL, to inhibit RANK-RANKL interactions in the ELISA, and to suppress the RANKL-dependent activation of model cells and the differentiation of RANK-expressing precursors into osteoclasts. This discovery of a family of small molecules that inhibit RANK activation presents an initial basis for further development of nonpeptidic therapeutic agents targeting the interaction between RANK and RANKL.

Structural insights into the binding of zoledronic acid with RANKL via computational simulations

“…The interaction between ZOL and RANKL belongs to the type of small molecule-protein interaction. In the present study, the detected equilibrium dissociation constant was in the range of protein-small molecule binding and showed the moderate strength of intermolecular binding between ZOL and RANKL, which was similar to the interaction between RANKL and Pheophorbide A (K D = 40 μM), of the same order of magnitude ( Chypre et al, 2017 ; Porkolab et al, 2020 ). Furthermore, we detected that the binding interaction operated in a concentration-dependent manner.…”

Mechanistic advances in osteoporosis and anti‐osteoporosis therapies

“…Orally, Y1693 demonstrates good tolerability and efficacy in OVX mice and could also suppress the expression of osteoclast marker genes 200 . In addition, another verteporfin analog shows a dose‐dependent inhibition of RANK–RANKL interaction in a competitive ELISA 201 . However, its specificity has not been tested, and there is a lack of in vivo data 201 …”

“…In addition, another verteporfin analog shows a dose‐dependent inhibition of RANK–RANKL interaction in a competitive ELISA 201 . However, its specificity has not been tested, and there is a lack of in vivo data 201 …”

“…201 However, its specificity has not been tested, and there is a lack of in vivo data. 201 SPD304 was first reported to promote the dissociation of RANKL trimer (Figure 4B), but it is interrupted due to the high toxicity. 202 Rinotas et al 203 developed several analogs of SPD-304 with improved toxicity profiles, which can selectively inhibit RANKL-induced osteoclastogenesis, without affecting TNF activity or osteoblast differentiation.…”

“…200 In addition, another verteporfin analog shows a dose-dependent inhibition of RANK-RANKL interaction in a competitive ELISA. 201 However, its specificity has not been tested, and there is a lack of in vivo data. 201 SPD304 was first reported to promote the dissociation of RANKL trimer (Figure 4B), but it is interrupted due to the high toxicity.…”