Effects of lactone derivatives on aromatase (CYP19) activity in H295R human adrenocortical and (anti)androgenicity in transfected LNCaP human prostate cancer cells.
Certain lactone-containing secondary plant metabolites display potent biological effects, including anti-tumor activities. This is of particular interest as these compounds appear effective against hormone-dependent cancers, such as those of breast and prostate, of which the incidence is on the rise. The mechanisms of anti-tumor action of these compounds are largely unknown. Thirteen synthetic lactone derivatives were evaluated for effects on aromatase activity and mRNA expression in H295R human adrenocortical carcinoma cells. Aromatase (CYP19) is a key enzyme in the synthesis of estrogens from androgens. Over-expression has been associated with increased risk of developing estrogen-dependent mammary tumors, and aromatase inhibitors are effective in their treatment. The androgen receptor is implicated in mediating hormone-dependent prostate tumor growth, and androgen antagonists are effective in the treatment of these cancers. Thus the (anti)androgenic effects of the lactones were also assessed in LNCaP human prostate cancer cells transfected with human androgen receptor and an androgen receptor-responsive luciferase reporter gene. Cells were exposed to lactones (0.1-100 microM) dissolved in dimethyl sulfoxide (0.1% in medium) for 24 h prior to measurement of aromatase activity using a tritiated water-release assay. Three (competitive) inhibitors of aromatase activity were identified (potencies in decreasing order): 3-(3,4-dimethoxy-phenyl)-4-(4-methoxy-phenyl)-5H-furan-2-one (CRI-7; IC(50)=1 microM; K(i)=1.0 microM), 3,4-bis-(3,4-dimethoxy-phenyl)-5H-furan-2-one (CRI-8; IC(50)=2 microM; K(i)=1.2 microM) and 3-(3,4-dimethoxy-phenyl)-4-(3,4,5-trimethoxy-phenyl)-5H-furan-2-one (CRI-9; IC(50)=3 microM; K(i)=6.8 microM). Several concentration-dependent inducers of aromatase (>2fold) were also identified (CRI-1, CRI-4 or Vioxx, CRI-11 and CRI-13). These lactones also induced pII promoter-specific CYP19 transcripts. In transfected LNCaP cells, the three aromatase inhibitors CRI-7, 8 and 9 demonstrated concentration-dependent anti-androgenicity above 0.1 microM in the presence of either 0.1 nM of dihydrotestosterone or the synthetic androgen R1881. The other lactones showed no consistent pro- or anti-androgenic effects in these LNCaP cells. Lactone moiety-containing molecules may form the structural basis for the development of potent drugs effective against hormone-dependent cancers.
Sanderson
Thomas
T
INRS-Institut Armand-Frappier, 531 boulevard des Prairies, Laval, QC, Canada. thomas.sanderson@iaf.inrs.ca
Renaud
Martin
M
Scholten
Deborah
D
Nijmeijer
Sandra
S
van den Berg
Martin
M
Cowell
Simon
S
Guns
Emma
E
Nelson
Colleen
C
Mutarapat
Thumnoon
T
Ruchirawat
Somsak
S
D000306:Adrenal Cortex Neoplasms / Q000378:metabolism*; D059002:Androgen Receptor Antagonists; D000728:Androgens / Q000096:biosynthesis*; D047072:Aromatase Inhibitors; D045744:Cell Line, Tumor; D000242:Cyclic AMP / Q000378:metabolism; D003627:Data Interpretation, Statistical; D017930:Genes, Reporter; D006801:Humans; D007783:Lactones / Q000494:pharmacology*; D008156:Luciferases / Q000235:genetics; D008297:Male; D011471:Prostatic Neoplasms / Q000378:metabolism*; D012334:RNA, Neoplasm / Q000096:biosynthesis / Q000235:genetics; D013778:Tetrazolium Salts; D013844:Thiazoles; D014162:Transfection
D059002:Androgen Receptor Antagonists; D000728:Androgens; D047072:Aromatase Inhibitors; D007783:Lactones; D012334:RNA, Neoplasm; D013778:Tetrazolium Salts; D013844:Thiazoles; D000242:Cyclic AMP; D008156:Luciferases; C022616:thiazolyl blue