title: Design and synthesis of tag-free photoprobes for the identification of the molecular target for CCG-1423, a novel inhibitor of the Rho/MKL1/SRF signaling pathway.
abstract: CCG-1423 and related analogues represent a new class of inhibitors of Rho/MKL1/SRF-mediated gene transcription, a pathway that has been implicated in both cancer and fibrosis. The molecular target for these compounds is unknown. To facilitate its identification, a series of tag-free photoaffinity probes was designed and synthesized, each one containing a photoactivatable group and an acetylenic end group for subsequent attachment to a fluorescent tag using click chemistry. All were confirmed to maintain biological activity in a cell-based assay for inhibition of SRE-Luc expression. The functional activity of the most potent probe 24 was further confirmed in an assay for PC-3 cell migration. Photolysis of 24 in intact PC-3 cells followed by cell lysis, click ligation of a fluorescent dye, and gel electrophoresis revealed specific labeling of a single 24 kDa band that could be blocked with an active competitor. Future work will focus on identifying the labeled protein(s).
authors.affiliation: Vahlteich Medicinal Chemistry Core, Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, USA.
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Bell
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Haak
authors.forename: Susan M
authors.initials: SM
authors.lastname: Wade
authors.forename: Yihan
authors.initials: Y
authors.lastname: Sun
authors.forename: Richard R
authors.initials: RR
authors.lastname: Neubig
authors.forename: Scott D
authors.initials: SD
authors.lastname: Larsen
keywords: CCG-1423; Rho pathway inhibitor; click ligation; photoaffinity labeling; tag-free photoprobe; target identification