17alpha-estradiol inhibits LAPC-4 prostatic tumor cell proliferation in cell cultures and tumor growth in xenograft animals.
BACKGROUND
Blockade of androgen activity is a major effective therapy for advanced prostate cancer. Estrogen analogs have been used for prostate cancer therapy for years presumably by inhibiting testosterone biosyntheses, but with considerable adverse events due to their classic estrogenic activity. With the discovery of the estrogen receptor (ER) beta and its presence in prostate tumor cells, evaluation of estrogen analogs with less classic estrogenic activity in prostate cancer therapy is emerging.


METHODS
The effects of 17alpha-estradiol (alphaE2), a stereo-isomer of 17beta-estradiol (betaE2), on dihydrotestosterone (DHT)-induced cell growth and gene expressions were examined in androgen-dependent LAPC-4 prostatic tumor cells and in LAPC-4 xenograft animals, and compared to those of betaE2.


RESULTS
Both alphaE2 and betaE2 attenuated DHT induction of PSA gene expression, cell proliferation, and cell growth in cultured LAPC-4 cells. The inhibition of cell proliferation was associated with a blockade of DHT-induced cyclin A and cyclin D1 expression by alphaE2 and betaE2. In LAPC-4 xenograft mice, alphaE2 significantly inhibited tumor growth without altering the plasma testosterone level, while betaE2 failed to inhibit tumor growth even though it significantly inhibited PSA gene expression.


CONCLUSIONS
alphaE2 is an effective agent for inhibition of DHT-induced PSA, cyclin A, cyclin D1 gene expression, and cell proliferation in LAPC-4 cells, and tumor growth in LAPC-4 xenograft mice.
Qiao
Yaming
Y
Department of Medicine/Endocrinology, Weill Medical College of Cornell University, New York, New York 10021, USA.
Zhang
Zhi-Kai
ZK
Cai
Li-Qun
LQ
Tan
Chen
C
Imperato-McGinley
Julianne L
JL
Zhu
Yuan-Shan
YS
D000818:Animals; D015153:Blotting, Western; D048708:Cell Growth Processes / Q000187:drug effects; D045744:Cell Line, Tumor; D019925:Cyclin A / Q000096:biosynthesis / Q000235:genetics; D019938:Cyclin D1 / Q000096:biosynthesis / Q000235:genetics; D013196:Dihydrotestosterone / Q000037:antagonists & inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D008297:Male; D051379:Mice; D016513:Mice, SCID; D009376:Neoplasms, Hormone-Dependent / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D017430:Prostate-Specific Antigen / Q000096:biosynthesis / Q000235:genetics; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D011897:Random Allocation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013237:Stereoisomerism; D023041:Xenograft Model Antitumor Assays
D019925:Cyclin A; D012333:RNA, Messenger; D013196:Dihydrotestosterone; D019938:Cyclin D1; D004958:Estradiol; D017430:Prostate-Specific Antigen