Structure-function studies of aromatase and its inhibitors: a progress report.
The utilization of computer modeling, site-directed mutagenesis, inhibition kinetic analysis and reaction metabolite analysis allows us to better understand the structure-function relationship between aromatase and its inhibitors. Our results have helped in determining how steroidal and nonsteriodal aromatase inhibitors bind to the active site of the enzyme. This information has also aided in the understanding of the reaction mechanism of aromatase. Furthermore, our structure-function studies of aromatase have generated important information for predicting how environmental chemicals interact with the enzyme. During the last 2 years, a new aromatase computer model based on the X-ray structure of rabbit cytochrome P450 2C5 has been generated and used to evaluate the results obtained from new aromatase mutants produced in this laboratory. In addition, we have succeeded in the expression and purification of functionally active aromatase using an Escherichia coli expression method. The catalytic properties of this recombinant aromatase are similar to those properties exhibited by the human placental aromatase preparation and the mammalian cell-expressed enzyme. The E. coli expressed aromatase will be very useful for further structure-function studies of aromatase. Our laboratory has also evaluated the growth-inhibiting activity of aromatase inhibitors in estrogen receptor-positive breast cancer using three-dimensional cell cultures of aromatase-over expressing MCF-7 and T-47D cell lines (i.e. MCF-7aro and T-47Daro). Our results demonstrate that these three-dimensional cultures are valuable approaches to assess the growth-inhibiting activity of aromatase inhibitors. Finally, we have identified several phytochemicals to be potent inhibitors of aromatase. To demonstrate the impact of the phytochemicals on estrogen formation in vivo, we showed that the intake of anti-aromatase chemicals from red wine was capable of suppressing MCF-7aro-mediated tumor formation in nude mice and aromatase-induced hyperplasia in a transgenic mouse model in which aromatase is over-expressed in the mammary tissue.
Chen
Shiuan
S
Divisions of Immunology and Informational Sciences, Beckman Research Institute of the City of Hope, Duarte, CA, USA. schen@coh.org
Zhang
Fangming
F
Sherman
Mark A
MA
Kijima
Ikuko
I
Cho
Michael
M
Yuan
Yate-Ching
YC
Toma
Yoshiro
Y
Osawa
Yoshio
Y
Zhou
Dujin
D
Eng
Elizabeth T
ET
D000818:Animals; D001141:Aromatase / Q000235:genetics / Q000378:metabolism*; D047072:Aromatase Inhibitors; D001943:Breast Neoplasms / Q000201:enzymology; D045744:Cell Line, Tumor; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D007529:Isoflavones / Q000494:pharmacology; D008958:Models, Molecular; D009376:Neoplasms, Hormone-Dependent / Q000201:enzymology; D048789:Phytoestrogens; D028321:Plant Preparations / Q000494:pharmacology; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship
D047072:Aromatase Inhibitors; D004791:Enzyme Inhibitors; D007529:Isoflavones; D048789:Phytoestrogens; D028321:Plant Preparations; D011994:Recombinant Proteins; D001141:Aromatase