Oxazolinyl derivatives of androst-16-ene as inhibitors of CYP17A1 activity and prostate carcinoma cells proliferation: Effects of substituents in oxazolinyl moiety.

Steroid derivatives modified with nitrogen containing heterocycles are known to inhibit activity of steroidogenic enzymes, decrease proliferation of cancer cells and attract attention as promising anticancer agents. Specifically, 2'-(3β-hydroxyandrosta-5,16-dien-17-yl)-4',5'-dihydro-1',3'-oxazole 1a potently inhibited proliferation of prostate carcinoma cells. In this study we synthesized and investigated five new derivatives of 3β-hydroxyandrosta-5,16-diene comprising 4'-methyl or 4'-phenyl substituted oxazolinyl cycle 1 (b-f). Docking of compounds 1 (a-f) to CYP17A1 active site revealed that the presence of substitutents at C4' atom in oxazoline cycle, as well as C4' atom configuration, significantly affect docking poses of compounds in the complexes with enzyme. Testing of compounds 1 (a-f) as CYP17A1 inhibitors revealed that the only compound 1a, comprising unsubstituted oxazolinyl moiety, demonstrated strong inhibitory activity, while other compounds 1 (b-f) were slightly active or non active. Compounds 1 (a-f) efficiently decreased growth and proliferation of prostate carcinoma LNCaP and PC-3 cells at 96 h incubation; the effect of compound 1a was the most powerful. Compound 1a efficiently stimulated apoptosis and caused PC-3 cells death, that was demonstrated by a direct comparison of pro-apoptotic effects of compound 1a and abiraterone.