Hormone Response In Breast Cancer Research Articles

Intrinsic and Extrinsic Factors Governing the Transcriptional Regulation of ESR1.

Transcriptional regulation of ESR1, the gene that encodes for estrogen receptor α (ER), is critical for regulating the downstream effects of the estrogen signaling pathway in breast cancer such as cell growth. ESR1 is a large and complex gene that is regulated by multiple regulatory elements, which has complicated our understanding of how ESR1 expression is controlled in the context of breast cancer. Early studies characterized the genomic structure of ESR1 with subsequent studies focused on identifying intrinsic (chromatin environment, transcription factors, signaling pathways) and extrinsic (tumor microenvironment, secreted factors) mechanisms that impact ESR1 gene expression. Currently, the introduction of genomic sequencing platforms and additional genome-wide technologies has provided additional insight on how chromatin structures may coordinate with these intrinsic and extrinsic mechanisms to regulate ESR1 expression. Understanding these interactions will allow us to have a clearer understanding of how ESR1 expression is regulated and eventually provide clues on how to influence its regulation with potential treatments. In this review, we highlight key studies concerning the genomic structure of ESR1, mechanisms that affect the dynamics of ESR1 expression, and considerations towards affecting ESR1 expression and hormone responsiveness in breast cancer.

Abstract P6-06-08: Impact of initial surgical treatment delay on survival according to hormone responsiveness in breast cancer

Abstract Previous studies on the issue of the prognostic importance of treatment delay in breast cancer have shown inconsistent results. Furthermore, the association between the impact of treatment delay and molecular characteristics of tumors has not been adequately addressed. The purpose of this study is to examine the prognostic impact of initial surgical treatment delay after biopsy-proven cancer diagnosis in breast cancer patients. A total of 1,393 consecutive invasive breast cancer patients, treated in Seoul National University Hospital, Seoul, Korea, between July 2006 and June 2008, were included in this study. Patients with in situ or metastatic carcinoma at the time of diagnosis and patients in whom the dates of the initial pathologic diagnosis were unknown were excluded. The median time from biopsy-confirmed cancer diagnosis to initial surgical treatment was 25 days (range 0-134). When the patients were classified according to their treatment delay days (0 to 29, 30 to 59, and ≥60days), there was no difference in survival between ‘0-29days’ group and ‘30-59days’ group. However, for patients who experienced more than 60 days of initial delay in surgical treatment, the survival was significantly worse when compared to other groups (p = 0.034). The association between the treatment delay and poor outcome was only seen in patients with ER and PR negative tumors (p = 0.018) while patients with hormone-responsive tumors showed no such association. Patients with ER and PR negative tumors developed more recurrence and had shorter disease-free survival if they had treatment delay of more than 60 days. The prognostic importance of treatment delay of more than 60 days remained significant in predicting disease-free survival after adjusting for other known prognostic factors such as age, tumor size, nodal status, cancer stage, nuclear grade and Ki-67 expression (HR 5.127; 95% CI, 1.350 to 19.472; p = 0.016). Our results suggest that having treatment delay of more than 60 days is associated with poor treatment outcome in patients with ER and PR negative breast cancer. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-06-08.

Nkx3-1 and LEF-1 Function as Transcriptional Inhibitors of Estrogen Receptor Activity

Estrogen receptor (ER)-associated cofactors and cooperating transcription factors are one of the primary components determining transcriptional activity of estrogen target genes and may constitute potential therapeutic targets. Recent mapping of ER-binding sites on a genome-wide scale has provided insight into novel cooperating factors based on the enrichment of transcription factor motifs within the ER-binding sites. We have used the ER-binding sites in combination with sequence conservation to identify the statistical enrichment of Nkx and LEF motifs. We find that Nkx3-1 and LEF-1 bind to several ER cis-regulatory elements in vivo, but they both function as transcriptional repressors of estrogen signaling. We show that Nkx3-1 and LEF-1 can inhibit ER binding to chromatin, suggesting competition for common chromatin-binding regions. These data provide insight into the role of Nkx3-1 and LEF-1 as potential regulators of the hormone response in breast cancer.

Host-Related Factors in Breast Cancer: An Underappreciated Piece of the Puzzle?

Host-Related Factors in Breast Cancer: An Underappreciated Piece of the Puzzle?

Association of oestrogen receptor beta 2 (ERβ2/ERβcx) with outcome of adjuvant endocrine treatment for primary breast cancer – a retrospective study

BackgroundOestrogen receptor beta (ERβ) modulates ERα activity; wild type ERβ (ERβ1) and its splice variants may therefore impact on hormone responsiveness of breast cancer. ERβ2/ERβcx acts as a dominant negative inhibitor of ERα and expression of ERβ2 mRNA has been proposed as a candidate marker for outcome in primary breast cancer following adjuvant endocrine therapy. We therefore now assess ERβ2 protein by immunostaining and mRNA by quantitative RT-PCR in relation to treatment outcome.MethodsERβ2-specific immunostaining was quantified in 141 primary breast cancer cases receiving adjuvant endocrine therapy, but no neoadjuvant therapy or adjuvant chemotherapy. The expression of mRNA for ERβ2/ERβcx was measured in 100 cases by quantitative RT-PCR. Statistical analysis of breast cancer relapse and breast cancer survival was performed using Kaplan Meier log-rank tests and Cox's univariate and multivariate survival analysis.ResultsHigh ERβ2 immunostaining (Allred score >5) and high ERβ2 mRNA levels were independently associated with significantly better outcome across the whole cohort, including both ERα positive and negative cases (Log-Rank P < 0.05). However, only ERβ2 mRNA levels were significantly associated with better outcome in the ERα + subgroup (Log-Rank P = 0.01) and this was independent of grade, size, nodal status and progesterone receptor status (Cox hazard ratio 0.31 P = 0.02 for relapse; 0.17 P = 0.01 for survival). High ERβ2 mRNA was also associated with better outcome in node negative cases (Log Rank P < 0.001).ERβ2 protein levels were greater in ERα positive cases (T-test P = 0.00001), possibly explaining the association with better outcome. Levels of ERβ2 protein did not correlate ERβ2 mRNA levels, but 34% of cases had both high mRNA and protein and had a significantly better outcome (Log-Rank relapse P < 0.005).ConclusionHigh ERβ2 protein levels were associated with ERα expression. Although most cases with high ERβ2 mRNA had strong ERβ2 immunostaining, mRNA levels but not protein levels were independently predictive of outcome in tamoxifen-treated ERα + tumours. Post-transcriptional control needs to be considered when assessing the biological or clinical importance of ERβ proteins.

GATA-3 Expression as a Predictor of Hormone Response in Breast Cancer

GATA-3 Expression as a Predictor of Hormone Response in Breast Cancer

O-3. Prediction of hormone response in breast cancer by microarray analysis of sequential tumour biopsies from patients receiving neoadjuvant therapy with Letrozole

O-3. Prediction of hormone response in breast cancer by microarray analysis of sequential tumour biopsies from patients receiving neoadjuvant therapy with Letrozole

Prediction of hormone response in breast cancer by microarray analysis of sequential tumour biopsies from patients receiving neoadjuvant therapy with letrozole

3025 Background: Changes in tumour gene expression may be monitored in sequential biopsies of individual tumours taken during neoadjuvant therapy and analysed by microarray analysis. In the present study, the changes occurring within 10–14 days have been related to clinical and pathological response status assessed after 3 months of treatment. Methods: 69 postmenopausal women with large operable ER-rich breast cancers were treated for 3 months with neoadjuvant letrozole. Clinical response was based on clinical and ultrasound changes; pathological response on histological changes. Cancers were sampled at diagnosis, 10–14 days and 3 months; RNA was extracted and hybridized on Affymetrix HG U133A GeneChips. Results: 43 cases were assessable for response; 33 (77%) responded (>50% reduction in tumour volume) and 30 (70%) had a pathological response. No gene changed with treatment in all cases; however consistent up-regulation of 3 genes and down-regulation of 65 genes occurred in 50 cases. Clustering techniques identified changes in gene expression with treatment and produced groups with distinct patterns of molecular changes. Significant differences were detected between non-responders and responders in 125 genes. Combination of gene changes increased discrimination. Conclusions: Changes in pattern of gene expression can be detected in biopsies taken before and after 14 days treatment with neoadjuvant letrozole. These may elucidate the mechanisms of tumour response and allow early recognition of response/resistance. No significant financial relationships to disclose.

GATA-3 Expression as a Predictor of Hormone Response in Breast Cancer

Expression of estrogen receptor-alpha (ERalpha) as determined by immunohistochemistry of tumor tissue is currently the most clinically useful test to predict hormone responsiveness of breast cancer. Thirty percent of ERalpha-positive breast cancers do not respond to hormonal therapy. GATA-3 is a transcription factor that is expressed in association with ERalpha and there is evidence that GATA factors influence response to estrogen. In this pilot study, we investigated whether GATA-3 expression is associated with hormone response in breast cancer. Breast cancer tissue was stained for GATA-3 expression by immunohistochemistry in ERalpha-positive cancers from 28 patients, 14 of whom were defined as hormone unresponsive (cases) and 14 of whom were age-matched controls with hormone-responsive, ERalpha-positive cancers (controls). Comparing cases and controls, there were no differences in expression of ERalpha; progesterone receptor, ErbB2; or tumor grade. Using 20% nuclear staining to characterize tumors as GATA-3 positive or GATA-3 negative, 6 of 14 (43%) cancers in the hormone-unresponsive group and none of the controls were classified as GATA-3 negative (odds ratio, 8.2; 95% confidence interval, 1.2-infinity; p = 0.031). Using different cut points to characterize GATA-3 positivity yielded very similar results, indicating a positive association between lack of GATA-3 expression and lack of response to hormonal therapy. The study suggests that analyzing ERalpha-positive breast tumors for GATA-3 using immunohistochemistry might improve prediction of hormone responsiveness. The association between GATA-3 expression and hormone response suggests that GATA-3 may play a role in mechanisms controlling response to estrogen.

Prognostic value of maspin mRNA expression in ER alpha-positive postmenopausal breast carcinomas.

Maspin, a member of the serpin family, has a role in cell migration, angiogenesis and apoptosis. Little is known of the clinical significance of maspin gene expression in human cancers. We developed a real-time quantitative RT–PCR assay to quantify the full range of maspin mRNA copy numbers in a series of 10 ERα-positive and 10 ERα-negative breast tumours. We observed a statistical link between low maspin mRNA levels and positive oestrogen status (P=0.0012). In consequence, to better assess the prognostic value of maspin gene expression in breast cancer, we then quantified maspin mRNA content in an additional independent well-defined cohort of 105 ERα-positive postmenopausal breast cancer patients treated with primary surgery followed by adjuvant tamoxifen alone. Maspin expression varied widely in tumour tissues (by nearly four orders of magnitude), being underexpressed in 33 out of 105 tumours (31.4%) and overexpressed in 24 out of 105 tumours (22.9%) relative to normal breast tissues. Immunohistochemical studies demonstrated that maspin protein was strictly expressed in myoepithelial cells of normal breast tissue and in tumour epithelial cells, exclusively in maspin-overexpressing tumours. Patients with tumours overexpressing the maspin gene had significantly shorter relapse-free survival after surgery than patients whose tumours normally expressed or underexpressed maspin (P=0.0011). The prognostic significance of maspin overexpression persisted in Cox multivariate regression analysis (P=0.0024). These findings show that the maspin mRNA level can have important prognostic significance in human breast cancer, and point to the maspin gene as a putative molecular predictor of hormone responsiveness in breast cancer.

Relative effects of immunohistochemical expressions of c-erbB-2, p53, and bcl-2 oncoproteins on the survival of advanced breast cancer patients after endocrine therapy

c-erbB-2, p53, and bcl-2 oncoproteins were detected immunohistochemically in 92 recurrent or advanced breast cancer tumors just before an endocrine therapy, adreno-oophorectomy. Estrogen receptors (ER) and partly progesterone receptors were concomitantly assayed in the same tumor tissues. Twenty-eight percent (26/92) of c-erbB-2, 16% (15/92) of p53, and 11% (10/92) of bcl-2 expressions were shown to be positive. There were no significant correlations of these oncoproteins with clinical background characteristics of the patients, except the inverse relation between p53 expression and ER status (p=0.0033). Of these covariates, ER status was shown to be the only predictor of response to endocrine therapy. In the absence of ER measurement, p53 expression was a significant predictor of the response. Kaplan-Meier curves showed that ER had a significant and p53 expression had a marginal effect on the overall survival length of the patients, c-erB-2 or bcl-2 were indifferent to survival or response. It is concluded that p53 immunohistochemical expression might be a supplementary predictor next to ER status of the overall survival as well as response of advanced breast cancer patients treated with endocrine therapy, and that p53 alteration might modify the ER dependent hormone-responsiveness of breast cancer.

Determination of oestrogen responsiveness of breast cancer by competitive reverse transcription-polymerase chain reaction

Competitive polymerase chain reaction assays have been developed for the quantitation of oestrogen receptor mRNA and two oestrogen-regulated mRNAs (progesterone receptor and pNR-2/pS2) in breast cancer cells. These assays are more sensitive than traditional hybridisation techniques, do not require the use of radioisotopes, measure absolute amounts of messenger RNAs and can be used to measure the expression of mRNAs in small numbers of tumour cells obtained by fine-needle aspiration (FNA). These assays should prove useful for predicting the hormone responsiveness of breast cancer from tumour cells obtained by FNA at diagnosis and could be particularly useful in the management of elderly/frail patients who receive primary tamoxifen, or in other patients for whom tumour tissue for standard biochemical measurements is not available.

Tamoxifen treatment increases the concentration of 52K-cathepsin D and its precursor in breast cancer tissue.

The pro-cathepsin D of Mr 52,000 is regulated by estrogens via the estrogen receptor (RE) and is secreted by breast cancer cells in vitro. In an attempt to predict the hormone responsiveness of breast cancer in vivo, we have assayed total 52K cathepsin D and its precursor in the primary breast cancer cytosol of 36 patients treated before surgery with 30 mg of tamoxifen daily for 1 to 5 weeks (average, 3 weeks). Compared to a similar control population, total 52K cathepsin D was increased by tamoxifen (P = 0.02) but less so than its precursor (P less than 0.001). Furthermore, 45% of the RE-positive tumors from tamoxifen-treated patients had a higher cathepsin D precursor concentration than the same type of tumor from control patients, or than RE-negative tumors from tamoxifen-treated patients. This 3-week challenge test was probably too short to avoid partial estrogenic activity of tamoxifen (flare) and the authors infer that longer time of treatment would decrease rather than increase the concentration of cathepsin D in the RE-responsive tumors. However, two cancers from patients with relapses after prolonged tamoxifen treatment (greater than 6 months) also had high concentrations of 52K cathepsin D and its precursor. The authors conclude that the concentration of cathepsin D and its precursor in breast cancer cytosol can be increased by short-term tamoxifen treatment, suggesting that these tumors are estrogen responsive.

Cytochemistry of sex steroid receptors: a critique.

A number of histochemical methods for sex steroid receptors, especially estrogen receptors, have been proposed to replace standard biochemical receptor methods used to predict hormone responsiveness in breast cancer. This discussion addresses a number of serious concerns as to whether these histochemical procedures do in fact adequately detect receptors in situ, and concludes that most of the observed results can be explained by Type II and Type III non-receptor binding. Until further studies are performed, it is not valid to consider the histochemical localization of binding in cancer specimens as indicating the presence of steroid receptor proteins.