Estrogen-regulated gene expression predicts response to endocrine therapy in patients with ovarian cancer
Introduction
Epithelial ovarian cancer is the leading cause of death from gynecological malignancy in the western world and the fourth leading cause of cancer death in women worldwide [1]. This is due to the fact that the disease is relatively asymptomatic in its early disease stages with approximately 70% of patients presenting with advanced disease at diagnosis. Primary treatment of ovarian cancer remains surgical debulking of tumor followed by combination chemotherapy. The response rates of relapsed patients especially those with platinum resistance may be low and its associated toxicity impacts on the remainder of the patient's quality of life [2].
Endocrine therapies have proven effective in other hormonally sensitive cancers with relatively little toxicity. Many ovarian cancers express high levels of estrogen receptor alpha (ERα) and experimental studies using preclinical models have demonstrated that ovarian cancer cells that express high levels of ERα are growth responsive to both estrogens and anti-estrogens [3], [4], [5], [6]. This raises the possibility of a therapeutic potential in targeting the ERα in this disease. The anti-estrogen tamoxifen has been used to treat chemo-resistant ovarian cancer [7], [8] and recently, we and others have shown that the aromatase inhibitor Letrozole, which by inhibiting estrogen synthesis reduces the levels of estrogen available to ERα, confers clinical benefit in a sub-group of ovarian cancer patients [9], [10].
In a phase II trial we had recruited ovarian cancer patients (previously treated with chemotherapy) to receive 2.5 mg/day of Letrozole at the time of CA125 relapse of their disease [9]. CA125 responses were evaluable in 54 of these patients with a response being demonstrated in 5 patients and stabilization of CA125 (< 50% increase) in a further 14 patients. Therefore a total of 32% of patients receiving Letrozole achieved clinical benefit. Formalin fixed paraffin-embedded tissues from primary ovarian cancers from these patients were analyzed in the current study.
To further characterize this group of estrogen responsive patients we evaluated the expression of estrogen-regulated genes to see if they might act as predictive markers of response to Letrozole. Candidate genes were identified from a microarray analysis of ER-positive ovarian cancer cells treated with 17β-estradiol (E2) [6] and from studies previously published of genes identified as being modulated by Letrozole in breast cancer clinical trials [11], [12].
Having confirmed the estrogen regulation of candidate genes in an ER-positive, estrogen-sensitive ovarian cancer cell line by RT-PCR, immunohistochemical analysis was undertaken for a subset of these genes to determine whether gene expression levels in histological samples obtained at the time of primary debulking surgery are related to subsequent clinical response to Letrozole.
Section snippets
Cell culture
The PEO4 cell line was developed at the Edinburgh Cancer Research Centre [13]. Cells were routinely cultured at 37 °C, 90% humidity and 5% CO2 in RPMI 1640 (Life Technologies, Paisley, UK) containing 10% heat-inactivated FCS, 100 μg/ml streptomycin, and 100 iu/ml penicillin. Where specified, cells were treated with E2 (Sigma), tamoxifen (Sigma), ERα agonist (propylpyrazole triol (PPT), Tocris, Avonmouth, UK) [14] or ERβ-specific agonist (diarylpropionitrile (DPN), Tocris, Avonmouth, UK) [15] at
Modulation of selected genes by estrogen in estrogen-responsive ovarian and breast cancer cell lines in vitro
To investigate which candidate genes were under estrogen regulation and potentially associated with growth changes, we first investigated a series of genes identified from two sources—microarray analysis and literature selection of breast cancer studies. We have previously reported a microarray analysis of estrogen-regulated genes in an ovarian cancer model [6], and in the present study we have selected those genes showing the most marked changes after estrogen exposure and investigated them
Discussion
In the present study we have identified a series of genes predictive of response to Letrozole in ovarian cancer patients. These had first been validated in an ER-positive estrogen growth responsive ovarian cancer cell line model. The initial group of genes studied had been identified in a microarray analysis and the estrogen sensitivity of these changes was confirmed here by use of QRT-PCR. While TFF1, TRAP1, TFAP4, MYC, CTSD and IL17BR were significantly up-regulated by E2, PLAU, VIM, BIGH3,
Acknowledgment
This work was supported by Cancer Research UK.
References (28)
- et al.
Growth inhibition of oestrogen receptor-positive human ovarian carcinoma by anti-oestrogens in vitro and in a xenograft model
Eur. J. Cancer
(1994) - et al.
The regulation of growth and protein expression by estrogen in vitro: a study of 8 human ovarian carcinoma cell lines
J. Steroid Biochem. Mol. Biol.
(1994) - et al.
A two-gene expression ratio predicts clinical outcome in breast cancer patients treated with tamoxifen
Cancer Cell
(2004) - et al.
Aromatase expression in ovarian epithelial cancers
J. Steroid Biochem. Mol. Biol.
(2005) - et al.
Cancer statistics CA 2000
CA: Cancer J. Clin.
(2000) - et al.
Quality of life and mood in women receiving extensive chemotherapy for gynaecologic cancer
Cancer
(2000) - et al.
Oestrogen receptor expression and the effects of oestrogen and tamoxifen on the growth of human ovarian carcinoma cell lines
Br. J. Cancer
(1990) - et al.
Estrogen receptor α mediates gene expression changes and growth response in ovarian cancer cells exposed to estrogen
Endocr.-Relat Cancer
(2005) - et al.
Responsiveness of patients with relapsed ovarian cancer to tamoxifen
Cancer
(1991) - et al.
Hormonal palliation of chemoresistant ovarian cancer: three consecutive Phase II trials of the Mid-Atlantic Oncology Program
J. Clin. Oncol.
(1993)
CA125 response is associated with estrogen receptor expression in a Phase II trial of Letrozole in ovarian cancer: identification of an “endocrine-sensitive” subgroup
Clin. Cancer Res.
Hormonal therapy with letrozole for relapsed epithelial ovarian cancer. Long-term results of a phase II study
Oncology
Microarray analysis of sequential tumour biopsies from patients receiving neoadjuvant therapy is able to distinguish sub-populations of breast cancers with differential responser to the aromatase inhibitor letrozole
Breast Cancer Res. Treat.
Molecular determinants of aromatase sensitivity in primary breast cancers
Breast Cancer Res. Treat.
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