Estrous cycle modulates ovarian carcinoma growth.
OBJECTIVE
The effects of reproductive hormones on ovarian cancer growth are not well understood. Here, we examined the effects of estrous cycle variation and specific reproductive hormones on ovarian cancer growth.


METHODS
We investigated the role of reproductive hormones in ovarian cancer growth using both in vivo and in vitro models of tumor growth.


RESULTS
In vivo experiments using the HeyA8 and SKOV3ip1 ovarian cancer models showed that tumor cell inoculation during proestrus significantly increased tumor burden (251-273%) compared with injection during the estrus phase. Treatment of ovariectomized mice with 17beta-estradiol resulted in a 404% to 483% increase in tumor growth compared with controls. Progestins had no significant effect, but did block estrogen-stimulated tumor growth. Tumors collected from mice sacrificed during proestrus showed increased levels of vascular endothelial growth factor (VEGF) and microvessel density compared with mice injected during estrus. HeyA8, SKOV3ip1, and mouse endothelial (MOEC) cells expressed estrogen receptor alpha and beta and progesterone receptor at the protein and mRNA levels, whereas 2774 ovarian cancer cells were estrogen receptor-negative. In vitro assays showed that 17beta-estradiol significantly increased ovarian cancer cell adhesion to collagen in estrogen receptor-positive, but not in estrogen receptor-negative cells. Additionally, 17beta-estradiol increased the migratory potential of MOEC cells, which was abrogated by the mitogen-activated protein kinase (MAPK) inhibitor, PD 09859. Treatment with 17beta-estradiol activated MAPK in MOEC cells, but not in HeyA8 or SKOV3ip1 cells.


CONCLUSIONS
Our data suggest that estrogen may promote in vivo ovarian cancer growth, both directly and indirectly, by making the tumor microenvironment more conducive for cancer growth.
Armaiz-Pena
Guillermo N
GN
Department of Gynecologic Oncology and Cancer Biology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA.
Mangala
Lingegowda S
LS
Spannuth
Whitney A
WA
Lin
Yvonne G
YG
Jennings
Nicholas B
NB
Nick
Alpa M
AM
Langley
Robert R
RR
Schmandt
Rosemarie
R
Lutgendorf
Susan K
SK
Cole
Steven W
SW
Sood
Anil K
AK
D000818:Animals; D015153:Blotting, Western; D002448:Cell Adhesion / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology*; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000378:metabolism; D004967:Estrogens / Q000494:pharmacology*; D030762:Estrous Cycle / Q000502:physiology*; D005260:Female; D020249:Hormone Replacement Therapy; D006801:Humans; D007124:Immunoenzyme Techniques; D047468:Immunoprecipitation; D051379:Mice; D008819:Mice, Nude; D055806:Microvessels / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000473:pathology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011980:Receptors, Progesterone / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
D047628:Estrogen Receptor alpha; D004967:Estrogens; D012333:RNA, Messenger; D011980:Receptors, Progesterone; D042461:Vascular Endothelial Growth Factor A; D004958:Estradiol; D020928:Mitogen-Activated Protein Kinases