Endometrial expression of the estrogen-sensitive genes MMP-26 and TIMP-4 is altered by a substitution protocol without down-regulation in IVF patients.
BACKGROUND
The aim of this study was to analyse the effects of an estradiol (E(2))-progesterone substitution protocol on the endometrial expression of estrogen-sensitive genes during the peri-implantation period.


METHODS
Peripheral blood and endometrial biopsies were obtained from 13 infertile women both in a natural cycle (NC), on days 5 and 7 after ovulation (NC5, NC7), and in an artificial (substituted) cycle (AC), on days 5 and 7 of progesterone addition (AC5, AC7). Estrogen receptor-alpha (ERalpha) and progesterone receptor (PR) were assayed by immunohistochemistry. Matrix metalloproteinase-26 (MMP-26) mRNA and tissue inhibitor of metalloproteinase-4 (TIMP-4) mRNA were semiquantitatively assessed in tissue sections using in situ hybridization (ISH) and quantified in tissue extracts using real-time PCR.


RESULTS
Levels of both E(2) and progesterone were higher in the peripheral blood in AC than in NC. Also on day AC5, expressions of ERalpha, PR and MMP-26 mRNA (focally) were increased in the epithelium and TIMP-4 mRNA in the stroma. Expression levels of these genes dropped significantly between AC5 and AC7, but not between NC5 and NC7. Abnormally high levels in AC5 samples suggest overstimulation with E(2), and the rapid decrease between AC5 and AC7 suggests overstimulation with progesterone.


CONCLUSIONS
In ACs, increased levels of E(2) in the blood exaggerate the endometrial expression of estrogen-sensitive genes, whereas higher levels of progesterone in the blood in the secretory phase exaggerate the drop in expression of these genes. Dramatic variations in the gene expression may not be optimal for the implantation process.
Pilka
R
R
Department of Obstetrics and Gynaecology, Palacky University, Olomouc, Czech Republic.
Oborna
I
I
Lichnovsky
V
V
Havelka
P
P
Fingerova
H
H
Eriksson
P
P
Hansson
S
S
Casslén
B
B
D000328:Adult; D015536:Down-Regulation; D004717:Endometrium / Q000378:metabolism*; D047628:Estrogen Receptor alpha / Q000378:metabolism; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D005307:Fertilization in Vitro; D005786:Gene Expression Regulation; D006801:Humans; D053505:Matrix Metalloproteinases, Secreted / Q000235:genetics / Q000378:metabolism*; D008597:Menstrual Cycle / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D019714:Tissue Inhibitor of Metalloproteinases / Q000235:genetics / Q000378:metabolism*; D000097792:Tissue Inhibitor of Metalloproteinase-4
D047628:Estrogen Receptor alpha; D004967:Estrogens; D053505:Matrix Metalloproteinases, Secreted; D011980:Receptors, Progesterone; D019714:Tissue Inhibitor of Metalloproteinases; D000097792:Tissue Inhibitor of Metalloproteinase-4; C410599:MMP26 protein, human