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).
CCG-1423及其相关类似物代表了一类新的抑制Rho/MKL1/SRF介导的基因转录的抑制剂,这条途径已被证实与癌症和纤维化有关。这些化合物的分子靶标尚不清楚。为了促进其鉴定,设计并合成了一系列无标记的光亲和探针,每个探针都含有一个光活化基团和一个乙炔末端基团,以便后续使用点击化学将其连接到荧光标记上。所有这些探针都经过确认,在细胞基于SRE-Luc表达抑制的活性测定中保持生物活性。最有效的探针24的功能活性在PC-3细胞迁移的测定中进一步得到确认。在完整的PC-3细胞中光解24,随后细胞裂解,点击连接荧光染料,凝胶电泳显示特异性标记了一个24 kDa的蛋白带,可以用活性竞争物阻断。未来的工作将集中在识别被标记的蛋白质。