d-ring-fused and d-homo
lactone compounds in estratriene and
androstane series were synthesized using microwave-assisted reaction conditions. Microwave-irradiated synthesis methods were convenient and effective, and provided high yields with short reaction times. Their inhibition of C17,20-lyase and 17β-hydroxysteroid
dehydrogenase type 1 (17β-HSD1) activities were studied in in vitro
enzyme assays. d-ring-fused triazolyl
estrone analog 24 showed potent inhibition of
NADH-complexed 17β-HSD1, with a binding affinity similar to that of the substrate
estrone; its inhibition against
NADPH-complexed 17β-HSD1 was markedly weaker.
Compound 24 also significantly and selectively reduced proliferation of
cancer cell lines of gynecological origin. This estrane
triazole changed the cell cycle and induced apoptosis of HeLa, SiHa, and MDA-MB-231
cancer cells, measured by both increased subG1 fraction of cells and activation of
caspase-independent signaling pathways. A third mode of anti-estrogenic action of 24 saw increased
mRNA expression of the SULT1E1 gene in HeLa cells; in contrast, its 3-benzyloxy analog 23 increased
mRNA expression of the HSD17B2 gene, thus showing pronounced
pro-drug anti-estrogenic activity.
Estradiol-derived d-ring
triazole compound 24 thus acts at the
enzyme, gene expression and cellular levels to decrease the production of active
estrogen hormones, demonstrating its pharmacological potential.