Screening for selective TGF-βⅠinhibitors and structure-activity relationship analysis / 国际药学研究杂志

ABSTRACT

Objective To screen for selective transforming growth factor β(TGF-β)inhibitors from the compound library, and analyze their structure-activity relationship. Methods The inhibiting activities of 170 compounds to TGF-βpathway were evaluat-ed by the SMAD3 luciferase reporter system;the positive hits were examined for their selectivity towards activin receptor like kinase (ALK)4、ALK5 or ALK7 by a molecule based screening system composed of SMAD3,ATP and the purified kinase domain for ALK4, ALK5 or ALK7;the EGFP-SMAD2 fusion protein redistribution assay was used to confirm the inhibiting effects of positive hits. The structure-activity relationship was analyzed by comparing the docking module of SB431542 with ALK5 kinase domain. Results Fif-teen compounds were found capable of inhibiting luciferase expression downstream of SMAD3 with≥25%inhibitory rate;several of them showed different selectivity towards ALK4,ALK5 and ALK7. Compound 63 selectively inhibited the activity of ALK4 and ALK7 with IC500.234 and 0.370μmol/L,respectively,while compound 64 showed inhibiting activity towards all three kinases with the IC50 values 10,6 and 85 nmol/L for ALK4、ALK5 and ALK7,respectively. In addition,compounds 63 and 64 further inhibited the TGF-β1 induced EGFP-SMAD2 nuclear translocation,with the IC50 values of 0.45 and 6.30μmol/L,respectively. The MTT anti-proliferative assay indicated that compounds 63 and 64 exerted these activities at non-toxic concentrations. The analysis of structure-activity rela-tionship indicated that the compounds sharing a core structure,the 1,2,4-triarylimizazole or 1,3,5-triarylpyrazoline,with the 3,4 methyoenedioxyphenyl,6-methylpyridine and 4-aminocarboxyl substitution groups tended to exhibit better activities. Conclusion The two potent TGF-βpathway inhibitors,63 and 64 are identified through this screening project,of which,63 selectively inhibited the ALK4 and ALK7 activity,while 64 showed inhibiting activity towards all three tested types of ALKs.