Expression of key oestrogen-regulated genes differs substantially across the menstrual cycle in oestrogen receptor-positive primary breast cancer

Abstract

Plasma estradiol (E2) and progesterone vary markedly through the menstrual cycle. Data on whether these differences in hormone levels affect gene expression in oestrogen receptor-positive (ER+) tumours are inconsistent. We wished to determine whether there are substantial changes in the expression of oestrogen-regulated genes (ERGs) in ER+ breast cancer through the menstrual cycle. One hundred and seventy five paraffin-embedded ER+ breast carcinomas from premenopausal patients were analysed. Timing of the ovarian cycle was confirmed using serum progesterone levels. Patients were ascribed to one of three pre-defined menstrual cycle windows: 1 (days 27-35 + 1-6), 2 (days 7-16) and 3 (days 17-26). The RNA expression of ESR1, four ERGs (PGR, GREB1, TFF1 and PDZK1), and three proliferation genes (MKI67, TOP2A and CDC20) were compared between the windows. Gene expression of the four ERGs was 53-129 % higher in window 2 than window 1 (p = 0.0013, 0.0006, 0.022 and 0.066 for PGR, GREB1, TFF1 and PDZK1, respectively) and lower (9-41 %) in window 3 compared to window 2 (p = 0.079, 0.31, 0.031 and 0.065 for PGR, GREB1, TFF1 and PDZK1, respectively). Their average expression (AvERG) was 64 % higher in window 2 than window 1 (p < 0.0001) and 21 % lower in window 3 than window 2 (p = 0.0043). There were no significant differences between the windows for ESR1 and proliferation genes. In agreement with the gene expression data, progesterone receptor protein levels measured by immunohistochemistry (IHC) were 164 and 227 % higher in windows 2 and 3, respectively, compared to window 1 (30.7 and 37.9 % cells positive vs. 11.6 %; p = 0.0003 and 0.0004, respectively), while no difference in ER IHC score was observed. In conclusion, we observed significant differences in the expression of ERGs in ER+ breast tumours across the menstrual cycle. This variability may affect the interpretation of gene expression profiles incorporating ERGs and may be exploitable as an endogenous test of endocrine responsiveness.

Differential expression of progesterone receptor, FOXA1, GATA3, and p53 between pre- and postmenopausal women with estrogen receptor-positive breast cancer

“…TFF1, originally known as pS2, was the gene which correlated most significantly with plasma estradiol concentration in postmenopausal ER-positive breast cancer tissues [13]. It was also reported that expression levels of TFF1, similar to PgR, in ER-positive breast tumors differed across the menstrual cycle in premenopausal women, although expression of proliferation genes, such as Ki67, did not differ during the cycle [12].…”

“…We previously analyzed genetic and environmental predictors, endogenous hormones and growth factors, and risk of ER-positive breast cancer, and demonstrated that risk factors differed between women of different menopausal status [24]. It has been reported that plasma estradiol levels are significantly associated with estrogen-responsive gene expression of ER-positive breast cancers in both pre-and postmenopausal women [12,13].…”

“…PgR is one of the estrogen-responsive genes, and it has been reported that plasma estradiol levels are related to expression levels of estrogen-responsive genes, such as PGR and trefoil factor 1 (TFF1)/pS2, in ER-positive breast cancer in both preand postmenopausal women [12,13]. We previously showed that the incidence of ER-positive, PgR-negative breast cancer in women aged 50 years or younger and in those older than 50 years were 6% and 15%, respectively, whereas for ER-positive, PgR-positive tumors, incidences were 81% and 64%, respectively [14].…”

Dynamics of Protein Expression Reveals Primary Targets and Secondary Messengers of Estrogen Receptor Alpha Signaling in MCF-7 Breast Cancer Cells

“…Circulating levels of estradiol in blood of premenopausal women change between 100 to 700 pmol/L within a month (57), resulting in the alternating expression of estrogen-regulated proteins in tissues, blood and urine (58). Because estrogenregulated proteins are often identified as disease biomarkers (59), dynamic profile of such proteins in biological fluids may eliminate some false biomarkers (60).…”

Consideration of GREB1 as a potential therapeutic target for hormone-responsive or endocrine-resistant cancers

“…Several studies have reported that GREB1 levels in breast tumors correlate with both plasma and serum E2 levels in premenopausal women [40][41][42]. Quantitative RT-PCR showed that GREB1 and three other known ESR1-regulated genes (TFF1, PGR, PDZK1) changed throughout the menstrual cycle in ESR1+ but not ESR1-tumors [42].…”