Distribution of estrogen and progesterone receptors in healthy tissue adjacent to breast lesions at various stages--immunohistochemical study of 107 cases

Morphological Features and Immunohistochemical Profiling of Male Breast Gynaecomastia; A Large Tissue Microarray Study

Introduction

Gynaecomastia is the commonest male breast condition accounting for approximately 85% of male breast lesions. There is minimal information on the immunohistochemical profile of gynaecomastia. We aimed to comprehensively profile a large series of gynaecomastia samples for putative mammary diagnostic, predictive and prognostic markers.

Methods

A total of 156 samples, were histologically reviewed, assembled onto tissue microarrays, and stained for oestrogen receptors (ERα, ERβ1, ERß2), progesterone receptors (total PR, PRα), androgen receptor (AR), basal & luminal cytokeratins (CK5/6, CK14, CK8/18) and the proliferation marker Ki67. Relevant cut offs for marker positivity were defined based on existing literature: AR (10%), ERα and PR (Allred score >3/8), ERß (10% and 20%), cytokeratins (10%) and Ki67 (10% and 20%).

Results

108 samples from 86 patients aged 13-75 years were available for immunohistochemical assessment. 73.1% of the lesions were AR positive, compared to 99% for ERα and 100% for both ERß1 and ERß2. 98% of samples were positive for total PR and 97.1% for PRα. 69.8% expressed CK5/6 whilst 57% were CK14 positive. A tri-layered pattern of cytokeratin expression was also observed. Ki67 positivity was low with 17.1% and 6.7% classified as Ki67 positive using 10% and 20% cut off values respectively. A significant negative correlation was found between ERα expression and patient age (rs = -0.221, p=0.023). Bivariate correlations were produced, and comparisons made with previously published data regarding the immunohistochemical status in normal female breast tissue, proliferative and neoplastic breast diseases of the female and male breast.

Conclusions

Hormone receptors, including oestrogen receptor α and ß isoforms as well as androgen receptors were abundantly expressed within the intraductal luminal hyperplastic epithelium in gynaecomastia supporting the hormonal role in the pathogenesis and treatment. ERα, ERβ1 and ERβ2 were expressed in a higher proportion of cells compared with their expression in the female breast benign lesions which further characterises gynaecomastia biology. The identification of a low Ki67 proliferative index and the mixed cytokeratin profile in gynaecomastia differentiates this benign condition from male breast cancer. Therefore, Ki67 and cytokeratins can help in the differential diagnosis from histological mimics in the routine diagnostic work up.

Investigating the Factors Associated with the Level of Expression of Estrogen and Progesterone Receptors in Patients Suffering from Colorectal Cancer

Background

The present study was performed to investigate the factors related to the expression level of estrogen and progesterone receptor in patients with colorectal cancer. Material and Methods. This crosssectional study was performed on 54 patients suffering from colorectal cancer referring to Imam Reza Hospital in Birjand during 2018-2019. After the biopsy performed during surgery, the specimen was sent for immunohistochemistry, and the status of receptors was determined. Eventually, the data were analyzed by SPSS 22.

Results

Out of the 54 patients studied, 64.8% were male. The mean age of the patients was 62.28 ± 14.03 years. The level of expression of beta-estrogen receptors and progesterone receptors had a significant relationship with age, consuming drugs of abuse, and familial history (P = 0.001). Also, the level of expression of estrogen and progesterone receptors of patients with a more advanced stage of cancer was significantly lower (P = 0.001).

Conclusion

The extent of expression of estrogen and progesterone receptors affects the progression and prognosis of disease. Thus, through hormone therapy, a step can be taken to reduce the progression and even to treat colorectal cancer.

What to Expect From the New ASCO/CAP Guideline Recommendations for Hormone Receptor Testing in Breast Cancer: A National Reference Laboratory Experience

The new ASCO/CAP guidelines on hormone receptor testing in breast cancer recommends standard operating procedures (SOPs) established to confirm or adjudicate estrogen receptor (ER) results with weak or ≤10% staining, and the status of internal controls (ICs) reported for cases with 0% to 10% staining. The aim of this study is to determine the frequency of ER testing with weak or ≤10% staining that may require additional steps following SOPs and to identify any correlation between hormone receptor status of the tumor and the likelihood of finding IC. Breast cancer cases between January 2014 and April 2019 were included to identify negative, low-positive and weak-positive cases. The presence/absence of IC was correlated to tumor type. Following ASCO/CAP guidelines, 29.8% of cases (374/1261) will need additional steps to confirm/adjudicate results due to negative, low, or weak positive ER status. The probability of finding IC is ~50% lower in cases of ER and progesterone receptor (PgR) negative tumors. Repeat testing may be warranted in 13.1% (92/700) of all cases due to lack of IC. In conclusion, the new ASCO/CAP guidelines recommend laboratories to establish and follow SOP to confirm or adjudicate ER results for about 30% of the cases before reporting hormone receptors status. Over 40% of cases with <10% tumor ER positivity lacked IC that may need a comment per the guidelines indicating a repeat testing may be warranted. However, the presence/absence of IC may be related to the subtype of breast cancer and should not necessarily bring into question the validity of the test.

Protein arginine N-methyltransferase 2 reverses tamoxifen resistance in breast cancer cells through suppression of ER-α36

Breast cancer is one of the most common malignancies in females, and 17β-estradiol (E2)/estrogen receptor α (ERα) signaling plays an important role in the initiation and progression of breast cancer. The role of the ER-α subtype and its co-regulator in the initiation of breast cancer and the occurrence of tamoxifen resistance remains to be further elucidated. In our previous studies, protein arginine N-methyltransferase 2 (PRMT2), a co-regulator of estrogen receptor-α (ER-α), was confirmed to interact with ER-α66 and has the ability to inhibit cell proliferation in breast cancer cells. In the present study, we found that tamoxifen treatment induced a decrease in PRMT2 and an increase in ER-α36 as well as ER-α36-mediated non-genomic effect in MDA-MB-231 cells, which were relatively resistant to tamoxifen by contrast to MCF-7 cells. Moreover, PRMT2 was able to interact with ER-α36 directly, suppress ER-α36 and downstream PI3K/Akt and MAPK/ERK signaling, reversing the tamoxifen resistance of breast cancer cells. The present study may be meaningful for understanding the role of PRMT2 in breast cancer progression and for developing a new endocrine therapeutic strategy for breast cancer patients with tamoxifen resistance.

Estrogen and progesterone signalling in the normal breast and its implications for cancer development

The ovarian hormones estrogen and progesterone are master regulators of the development and function of a broad spectrum of human tissues, including the breast, reproductive and cardiovascular systems, brain and bone. Acting through the nuclear estrogen (ER) and progesterone receptors (PR), both play complex and essential coordinated roles in the extensive development of the lobular alveolar epithelial structures of the normal breast during puberty, the normal menstrual cycle and pregnancy. The past decade has seen major advances in understanding the mechanisms of action of estrogen and progesterone in the normal breast and in the delineation of the complex hierarchy of cell types regulated by ovarian hormones in this tissue. There is evidence for a role for both ER and PR in driving breast cancer, and both are favourable prognostic markers with respect to outcome. In this review, we summarize current knowledge of the mechanisms of action of ER and PR in the normal breast, and implications for the development and management of breast cancer.

Breast cancer risk factors in relation to estrogen receptor, progesterone receptor, insulin-like growth factor-1 receptor, and Ki67 expression in normal breast tissue

Studies have suggested that hormone receptor and Ki67 expression in normal breast tissue are associated with subsequent breast cancer risk. We examined the associations of breast cancer risk factors with estrogen receptor (ER), progesterone receptor (PR), insulin-like growth factor-1 receptor (IGF-1R), and Ki67 expression in normal breast tissue. This analysis included 388 women with benign breast disease (ages 17–67 years) in the Nurses’ Health Studies. Immunohistochemical staining was performed on tissue microarrays constructed from benign biopsies containing normal breast epithelium and scored as the percentage of epithelial cells that were positively stained. Ordinal logistic regression (outcomes in tertiles), adjusting for age and potential confounders, was performed to estimate odds ratios (OR) and 95% confidence intervals (CI) for the associations with risk factors. Alcohol consumption was positively associated (≥2.5 vs.<0.4 drink/wk: OR = 2.69, 95% CI = 1.26–5.75, p-trend = 0.008) and breastfeeding was inversely associated (≥6 months vs. never: OR = 0.11, 95% CI = 0.04–0.35, p-trend = 0.0003) with ER expression. Height (≥66 vs.<64 inches: OR = 2.50, 95% CI = 1.34–4.67, p-trend = 0.005) and BMI at age 18 (≥22 vs.<20 kg/m²: OR = 2.33, 95% CI = 1.18–4.62, p-trend = 0.01) were positively associated with PR expression. Body size at age 5–10 years was inversely associated with Ki67 (Level ≥ 2.5 vs. 1: OR = 0.55, 95% CI = 0.30–1.01, p-trend = 0.03). Premenopausal BMI (≥25 vs.<20 kg/m²) was positively associated with cytoplasmic IGF-1R (OR = 5.06, 95% CI = 1.17–21.8, p-trend = 0.04). Our data suggest that anthropometrics, breastfeeding, and alcohol intake may influence the molecular characteristics of normal breast tissue, elucidating the mechanisms by which these risk factors operate. However, larger studies are required to confirm these results.

Body size, alcohol intake and breastfeeding may affect the molecular features of normal breast tissue to influence cancer risk. A team led by Hannah Oh from the Harvard T. H. Chan School of Public Health in Boston, USA, examined the link between behavioral and physiological risk factors for breast cancer and the expression levels of certain proteins (such as hormone receptors) that also promote cancer formation. By examining healthy breast tissue biopsied from 388 women diagnosed with benign breast diseases, the researchers showed that alcohol consumption, height and body mass index were all positively associated with the expression of various breast tissue markers, while breastfeeding and early-life body size were inversely associated. The findings point to a connection between lifestyle and breast tissue-specific molecular characteristics that underpin cancer risk.

Genomic Changes in Normal Breast Tissue in Women at Normal Risk or at High Risk for Breast Cancer

Sporadic breast cancer develops through the accumulation of molecular abnormalities in normal breast tissue, resulting from exposure to estrogens and other carcinogens beginning at adolescence and continuing throughout life. These molecular changes may take a variety of forms, including numerical and structural chromosomal abnormalities, epigenetic changes, and gene expression alterations. To characterize these abnormalities, a review of the literature has been conducted to define the molecular changes in each of the above major genomic categories in normal breast tissue considered to be either at normal risk or at high risk for sporadic breast cancer. This review indicates that normal risk breast tissues (such as reduction mammoplasty) contain evidence of early breast carcinogenesis including loss of heterozygosity, DNA methylation of tumor suppressor and other genes, and telomere shortening. In normal tissues at high risk for breast cancer (such as normal breast tissue adjacent to breast cancer or the contralateral breast), these changes persist, and are increased and accompanied by aneuploidy, increased genomic instability, a wide range of gene expression differences, development of large cancerized fields, and increased proliferation. These changes are consistent with early and long-standing exposure to carcinogens, especially estrogens. A model for the breast carcinogenic pathway in normal risk and high-risk breast tissues is proposed. These findings should clarify our understanding of breast carcinogenesis in normal breast tissue and promote development of improved methods for risk assessment and breast cancer prevention in women.

Histopathological Features of Non-Neoplastic Breast Parenchyma Do Not Predict BRCA Mutation Status of Patients with Invasive Breast Cancer

BACKGROUND

Several studies have evaluated histologic features of non-neoplastic breast parenchyma in patients with BRCA1/2 mutations, but the results are conflicting. The limited data suggest a much higher prevalence of high-risk precursor lesions in BRCA carriers. Therefore, we designed this study to compare the clinicopathological characteristics of peritumoral benign breast tissue in patients with and without deleterious BRCA mutations.

METHODS

Women with breast cancer (BC) who were referred for genetic counseling and underwent BRCA genetic testing in 2010 and 2011 were included in the study.

RESULTS

Of the six benign histological features analyzed in this study, only stromal fibrosis grade 2/3 was found to be statistically different, with more BRCA noncarriers having stromal fibrosis grade 2/3 than BRCA1/2 carriers (P = 0.04).

CONCLUSION

There is no significant association between mutation risk and the presence of benign histologic features of peritumoral breast parenchyma.

Systems level-based RNAi screening by high content analysis identifies UBR5 as a regulator of estrogen receptor-α protein levels and activity

Estrogen receptor-α (ERα) is a central transcription factor that regulates mammary gland physiology and a key driver in breast cancer. In the present study, we aimed to identify novel modulators of ERα-mediated transcriptional regulation via a custom-built siRNA library screen. This screen was directed against a variety of coregulators, transcription modifiers, signaling molecules and DNA damage response proteins. By utilizing a microscopy-based, multi-end point, estrogen responsive biosensor cell line platform, the primary screen identified a wide range of factors that altered ERα protein levels, chromatin remodeling and mRNA output. We then focused on UBR5, a ubiquitin ligase and known oncogene that modulates ERα protein levels and transcriptional output. Finally, we demonstrated that UBR5 also affects endogenous ERα target genes and E2-mediated cell proliferation in breast cancer cells. In conclusion, our multi-end point RNAi screen identified novel modulators of ERα levels and activity, and provided a robust systems level view of factors involved in mechanisms of nuclear receptor action and pathophysiology. Utilizing a high throughput RNAi screening approach we identified UBR5, a protein commonly amplified in breast cancer, as a novel regulator of ERα protein levels and transcriptional activity.

Cross-talk between estradiol receptor and EGFR/IGF-IR signaling pathways in estrogen-responsive breast cancers: focus on the role and impact of proteoglycans

In hormone-dependent breast cancer, estrogen receptors are the principal signaling molecules that regulate several cell functions either by the genomic pathway acting directly as transcription factors in the nucleus or by the non-genomic pathway interacting with other receptors and their adjacent pathways like EGFR/IGFR. It is well established in literature that EGFR and IGFR signaling pathways promote cell proliferation and differentiation. Moreover, recent data indicate the cross-talk between ERs and EGFR/IGFR signaling pathways causing a transformation of cell functions as well as deregulation on normal expression pattern of matrix molecules. Specifically, proteoglycans, a major category of extracellular matrix (ECM) and cell surface macromolecules, are modified during malignancy and cause alterations in cancer cell signaling, affecting eventually functional cell properties such as proliferation, adhesion and migration. The on-going strategies to block only one of the above signaling effectors result cancer cells to overcome such inactivation using alternative signaling pathways. In this article, we therefore review the underlying mechanisms in respect to the role of ERs and the involvement of cross-talk between ERs, IGFR and EGFR in breast cancer cell properties and expression of extracellular secreted and cell bound proteoglycans involved in cancer progression. Understanding such signaling pathways may help to establish new potential pharmacological targets in terms of using ECM molecules to design novel anticancer therapies.

Does mammographic density reflect the expression of breast cancer markers?

Mammographic density reflects variation in breast tissue composition as detected on mammogram. It is associated with a number of well-known breast cancer risk factors and itself is considered one of the strongest risk factors for breast cancer. If the expression of several proteins and genes within the breast tissue influences mammographic density in the same way as it influences breast cancer risk, then mammographic density might serve as an intermediate biomarker in future epidemiological studies on breast cancer. This has the potential to provide a quick means for predicting the effect of changes in the breast microenvironment on breast cancer risk without having to wait for an eventual development of breast cancer. In this review, the expression of several proteins and genes (growth factors, enzymes, proteoglycans and pro-inflammatory markers) within the breast tissue is shown to be associated with mammographic density. These proteins and genes are suspected to play a role in breast carcinogenesis. More studies assessing differential expression of proteins and genes in mammary epithelium and stroma and their association with mammographic density among premenopausal and postmenopausal women are required. Identification of proteins and genes influencing mammographic density may provide further insight on the molecular causes of breast cancer.

Model of tumor-associated epigenetic changes of HER2, ER, and PgR expression in invasive breast cancer phenotypes

This theoretic paper is an attempt to apply the epigenetic progenitor model of human cancer origin, proposed by Feinberg et al. (Nat Rev Genet 7:21-33, 2006), to the reported phenotype features of invasive breast cancer. The model is based on the idea that expression of estrogen receptors (ER), progesterone receptors (PgR), and HER2 molecules in breast tumors is either remnants of the tissue stem cell from which the tumor has developed or a newly acquired tumor-associated epigenetic feature. HER2 overexpression is considered as an example of the tumor-associated epigenetic changes. The model makes a simple distinction regarding the possible types of ER and PgR expression: the "functional" steroid hormone receptors are inherited from pretumoral tissue stem cells, while the "dysfunctional" steroid hormone receptors are acquired during tumorigenesis from initially ER-PgR-negative cells. In the former, estrogen binding increases the PgR expression while progesterone binding decreases the expression of ER and PgR. Since the estrogen-dependent PgR expression works only in cells with functional ERs, the expected share of tumors with functional ER and PgR receptors is in the model calculated as the squared probability of expressing the PgRs. Reported data from various trials are pooled together to find out phenotype shares (ER+PgR+ makes 62.03 %, ER+PgR- 16.43 %, ER-PgR+ 3.06, and ER-PgR- 18.48 %). By applying the model on these shares, the proposed share of tumors with the functional ER+PgR+ phenotype was 38.48 %, while the share of tumors with the dysfunctional ER+PgR+ was 23.55 %. The presented model suggests that both luminal A and luminal B tumor types are heterogeneous regarding the steroid receptor expression. Some tumors have functional and some have dysfunctional steroid receptors. If these predicted subgroups exist, their detection in the clinical practice might substantially improve treatment options, particularly in the premenopausal setting.

Progesterone and estrogen receptors segregate into different cell subpopulations in the normal human breast

Progesterone is critical in normal breast development and its synthetic derivatives are emerging as major drivers of breast cancer risk. The recent demonstration that progesterone regulates the stem cell compartment in the murine mammary gland, despite the absence of progesterone receptor (PR) in mammary stem cells, highlights the fact that PR distribution in progenitor cell subsets in the human breast remains to be conclusively shown. By utilising two independent cell sorting strategies to fractionate cells into distinct subpopulations enriched for different cell lineage characteristics, we have demonstrated a consistent enrichment of PR transcripts, relative to estrogen receptor transcripts, in the bipotent progenitor subfraction in the normal human breast. We have also shown co-expression of both steroid hormone receptors with basal markers in a subset of human breast cells, and finally we have demonstrated that PR+ bipotent progenitor cells are estrogen-insensitive, and that estrogen regulates PR in mature luminal cells only.

Lowering oral contraceptive norethindrone dose increases estrogen and progesterone receptor levels with no reduction in proliferation of breast epithelium: a randomized trial

BACKGROUND

This study was conducted to compare breast epithelial-cell proliferation and estrogen and progesterone receptor levels in women taking one of two oral contraceptives (OCs) containing the same dose of estrogen but different doses of the progestin norethindrone (NET).

STUDY DESIGN

Thirty-three women were randomly assigned 1:1 to one of two OCs with 35-mcg ethinylestradiol (EE2) but different doses of NET - 1 or 0.4 mg. At the end of the active pill phase of the third OC cycle, a breast biopsy was performed and the percentages of epithelial cells of the terminal duct lobular units were measured for Ki67 (MIB1), progesterone receptors A and B (PRA and PRB, respectively), and estrogen receptor α (ERα).

RESULTS

The biopsies from 27 women had sufficient epithelium for analysis. The percentages of cells positive for PRA, PRB and ERα were approximately double with the lower progestin dose (PRA: p=.041; PRB: p=.030; ERα: p=.056). The Ki67 percentage was not reduced with the lower progestin dose (12.5% for 0.4-mg NET vs. 7.8% for 1.0-mg NET).

CONCLUSIONS

The increase in PRA-, PRB- and ERα-positive cells with the 60% lower progestin dose OC appears likely to account for its failure to decrease breast-cell proliferation. This breast-cell proliferation result is contrary to that predicted from the results of lowering the medroxyprogesterone acetate dose in menopausal hormone therapy.

Anti-tumor effects of retinoids combined with trastuzumab or tamoxifen in breast cancer cells: induction of apoptosis by retinoid/trastuzumab combinations

INTRODUCTION

HER2 and estrogen receptor (ER) are important in breast cancer and are therapeutic targets of trastuzumab (Herceptin) and tamoxifen, respectively. Retinoids inhibit breast cancer growth, and modulate signaling by HER2 and ER. We hypothesized that treatment with retinoids and simultaneous targeting of HER2 and/or ER may have enhanced anti-tumor effects.

METHODS

The effects of retinoids combined with trastuzumab or tamoxifen were examined in two human breast cancer cell lines in culture, BT474 and SKBR3. Assays of proliferation, apoptosis, differentiation, cell cycle distribution, and receptor signaling were performed.

RESULTS

In HER2-overexpressing/ER-positive BT474 cells, combining all-trans retinoic acid (atRA) with tamoxifen or trastuzumab synergistically inhibited cell growth, and altered cell differentiation and cell cycle. Only atRA/trastuzumab-containing combinations induced apoptosis. BT474 and HER2-overexpressing/ER-negative SKBR3 cells were treated with a panel of retinoids (atRA, 9-cis-retinoic acid, 13-cis-retinoic acid, or N-(4-hydroxyphenyl) retinamide (fenretinide) (4-HPR)) combined with trastuzumab. In BT474 cells, none of the single agents except 4-HPR induced apoptosis, but again combinations of each retinoid with trastuzumab did induce apoptosis. In contrast, the single retinoid agents did cause apoptosis in SKBR3 cells; this was only modestly enhanced by addition of trastuzumab. The retinoid drug combinations altered signaling by HER2 and ER. Retinoids were inactive in trastuzumab-resistant BT474 cells.

CONCLUSIONS

Combining retinoids with trastuzumab maximally inhibits cell growth and induces apoptosis in trastuzumab-sensitive cells. Treatment with such combinations may have benefit for breast cancer patients.

The pro-metastatic protein anterior gradient-2 predicts poor prognosis in tamoxifen-treated breast cancers

Transcriptomic screens in breast cancer cell lines have identified a protein named anterior gradient-2 (AGR2) as a potentially novel oncogene overexpressed in estrogen receptor (ER) positive tumours. As targeting the ER is responsible for major improvements in cure rates and prevention of breast cancers, we have evaluated the pro-oncogenic function of AGR2 in anti-hormone therapeutic responses. We show that AGR2 expression promotes cancer cell survival in clonogenic assays and increases cell proliferation and viability in a range of cancer cell lines. Chromatin immunoprecipitation and reporter assays indicate that AGR2 is transcriptionally activated by estrogen through ERalpha. However, we also found that AGR2 expression is elevated rather than inhibited in response to tamoxifen, thus identifying a novel mechanism to account for an agonistic effect of the drug on a specific pro-oncogenic pathway. Consistent with these data, clinical analysis indicates that AGR2 expression is related to treatment failure in ERalpha-positive breast cancers treated with tamoxifen. In contrast, AGR2 is one of the most highly suppressed genes in cancers of responding patients treated with the anti-hormonal drug letrozole. These data indicate that the AGR2 pathway represents a novel pro-oncogenic pathway for evaluation as anti-cancer drug developments, especially therapies that by-pass the agonist effects of tamoxifen.

ER re-expression and re-sensitization to endocrine therapies in ER-negative breast cancers

Breast cancer is the leading cause of cancer amongst women in the westernized world. The presence or absence of ERalpha in breast cancers is an important prognostic indicator. About 30-40% of breast cancers lack detectable ERalpha protein. ERalpha- breast cancers are resistant to endocrine therapies and have a worse prognosis than ERalpha+ breast cancers. Since expression of ERalpha is necessary for response to endocrine therapies, investigational studies are ongoing in order to understand the generation of the ERalpha- phenotype and develop interventions to restore ERalpha expression in ERalpha- breast cancers. DNA methylation and chromatin remodeling are two epigenetic mechanisms that have been linked with the lack of ERalpha expression and in these cases; demethylation of the ERalpha promoter or treatment with HDAC inhibitors shows promise in restoring ERalpha expression in ERalpha- breast cancers. Two additional potential mechanisms underlying generation of the ERalpha- phenotype involve E6-AP and Src, both of which have been shown to be elevated in ERalpha- breast cancer and can drive the proteasomal degradation of ERalpha. Recently, studies have demonstrated that upregulated growth factor signaling due to hyperactive MAPK activity significantly contributes to generation of the ERalpha- phenotype and that inhibition of MAPK activity can cause re-expression of the ERalpha and restore sensitivity to endocrine therapies. Given the challenges in treating ERalpha- breast cancer, understanding and manipulating the cellular mechanisms that effect expression of ERalpha are imperative in order to restore sensitivity to endocrine therapies and to design novel therapeutics for the treatment of ERalpha- breast cancers.

Progesterone and estrogen receptors in pregnant and premenopausal non-pregnant normal human breast

We report here our studies of nuclear staining for the progesterone and estrogen receptors (PRA, PRB, ERalpha) and cell proliferation (MIB1) in the breast terminal duct lobular unit epithelium of 26 naturally cycling premenopausal women and 30 pregnant women (median 8.1 weeks gestation). Square root transformations of the PRA, PRB and ERalpha values, and a logarithmic transformation of the MIB1 values, were made to achieve more normal distributions of the values. PRA expression decreased from a mean of 17.8% of epithelial cells in cycling subjects to 6.2% in pregnant subjects (P = 0.013). MIB1 expression increased from 1.7% in cycling subjects to 16.0% in pregnant subjects (P < 0.001). PRB and ERalpha expression was slightly lower in pregnant subjects but the differences were not statistically significant. Sixteen of the non-pregnant subjects were nulliparous and ten were parous so that we had limited power to detect changes associated with parity. PRA was statistically significantly lower in parous women than in nulliparous women (32.2% in nulliparous women vs. 10.2%; P = 0.014). PRB (23.5 vs. 12.9%), ERalpha (14.4 vs. 8.6%) and MIB1 (2.2 vs. 1.2%) were also lower in parous women, but the differences were not statistically significant. The marked decreases in PRA in pregnancy and in parous women has also been found in the rat. A reduction in PRA expression may be a useful marker of the reduction in risk with pregnancy and may be of use in evaluating the effect of any chemoprevention regimen aimed at mimicking pregnancy. Short-term changes in PRA expression while the chemoprevention is being administered may be a more useful marker.

Quantification of angiogenesis in estrogen receptor-positive and negative breast carcinoma

BACKGROUND

The objective of this study was to evaluate angiogenesis according to CD34 antigen expression in estrogen receptor (ER)-positive and negative breast carcinomas.

METHODS

This study comprised 64 cases of infiltrating ductal carcinoma in postmenopausal women divided into two groups: Group A: ER-positive, n = 35; and Group B: ER-negative, n = 29. The anti-CD34 monoclonal antibody was used as a marker for endothelial cells. Microvessel count was carried out in 10 fields per slide using a 40x objective lens (magnification 400x). Statistical analysis of the data was performed using Student's t-test (p < 0.05).

RESULTS

The mean number of vessels stained with the anti-CD34 antibody in the estrogen receptor-positive and negative tumors was 23.51 +/- 1.15 and 40.24 +/- 0.42, respectively. The number of microvessels was significantly greater in the estrogen receptor-negative tumors (p < 0.001).

CONCLUSION

ER-negative tumors have significantly greater CD34 antigen expression compared to ER-positive tumors.

Nonproliferative epithelial alteration and expression of estrogen receptor and Ki67 in the contralateral breast of women treated with tamoxifen for breast cancer

The aim of study was to evaluate the frequency of nonproliferative epithelial alteration and expression of Ki67 and estrogen receptors (ER) in patients using tamoxifen. Forty-four women were selected who had been taking 20mg of tamoxifen daily for at least 12 months for adjuvant treatment of breast cancer. The women underwent core biopsy in the contralateral breast into an area of highest fibroglandular mammographic density. Fragments were analyzed by immunohistochemistry for monoclonal antibody Ki67 and ER, and histopathologic analysis. It was verified that 82% of the patients presented nonproliferative epithelial alteration, 70% were ER-negative, and all had low Ki67 expression. There was no association between duration of tamoxifen therapy, patient age, mammographic density, and presence of nonproliferative alteration (P>0.05). In conclusion, tamoxifen for more than a year showed a high frequency of nonproliferative epithelial alteration and low expression of Ki67 and ER in the normal breast tissue, consistent with low cell proliferation.

Increased expression of fatty acid synthase and progesterone receptor in early steps of human mammary carcinogenesis

Progestins increase the risk of breast cancer in the hormone therapy of menopause, and progesterone receptor-induced fatty acid synthase (FAS) is a potential therapeutical target of breast cancer. In a first attempt to specify in which lesions at risk of breast cancer progestins might be acting, we have compared the progesterone receptor (PR) and FAS expression in preinvasive breast lesions and in adjacent "normal" mammary glands. We used archive paraffin-embedded tissues from 116 patients, with 164 lesions of increasing histological risk from nonproliferative "benign" breast disease (BBD) to in situ breast carcinomas. Immunostaining using our FAS antibody and a PR antibody from Dako was quantified as continuous variables by computer-assisted image analysis. FAS level increased (p < 10(-3) by the Kruskall-Wallis test) in all lesions, starting from nonproliferative BBD, and was maximal in in situ carcinoma. The % of PR-positive cells increased from nonproliferative BBD and was higher in proliferative atypia (p < 10(-3)). It was very low in high-grade DCIS corresponding to a likely different carcinogenesis pathway. There was a trend for a positive correlation between FAS and PR in normal glands. However, the 2 markers increased independently in BBD and were negatively correlated in in situ carcinomas. FAS and PR were positively correlated with Ki67 in BBD. The increased PR level in premalignant steps of mammary carcinogenesis suggests an early increased responsiveness to progestins. The increased FAS expression, in lesions parallel to their increased breast cancer risk, suggests further studies to develop new markers of high-risk lesions and to prevent breast cancer.

Selective reduction of estrogen receptor (ER) positive breast cancer occurrence by estrogen receptor modulators supports etiological distinction between ER positive and ER negative breast cancers

Reports that selective estrogen receptor modulators (SERMs) reduce occurrence of only estrogen receptor (ER) positive tumors strongly support the etiological distinction between ER positive and ER negative breast cancers. Based on these evidences three concepts are described: Concept I. The occurrence of ER negative tumor cells might be a consequence of the clonal selection among tumor cells. This would lead to mosaicism in the ER expression. If ER negative cells become the most prevalent clone, the patient will be diagnosed to have an ER negative breast cancer. Since all cancers start as ER positive, SERMs should equally prevent occurrence of ER positive and ER negative breast cancers, but this prediction is evidently wrong. Concept II. Mammary ducts normally contain ER positive and ER negative cells, both prone to malignancy. Cancer occurrence in ductal cells that normally lack ER would be unrelated to estrogen exposure or SERMs protection. Estrogen and SERMs can influence cancer occurrence only in ER positive ductal cells. The main drawback is that this concept does not predict occurrence of mosaicism in ER expression among tumor cells. Unified Concept I and II. To overcome limitations of described concept a unified concept is presented. Cancers from ER positive ductal cells start as pure ER positive tumors and those from ER negative ductal cells as pure ER negative tumors. During the preclinical phase, in some ER positive tumors, clonal selection introduces ER negative clones. These tumors become mosaic in the cellular ER expression, some of them predominantly ER positive other ER negative. Estrogen deprivation, or SERMs can help mostly to patients with pure ER positive, or mosaic ER positive tumors. Since the dominant metastatic clone can have different ER status from the primary breast tumor, both surprising successes and failures of endocrine therapy can be expected in tumors with mosaic ER expression.

Assessment of the proliferative, apoptotic and cellular renovation indices of the human mammary epithelium during the follicular and luteal phases of the menstrual cycle

Introduction

During the menstrual cycle, the mammary gland goes through sequential waves of proliferation and apoptosis. In mammary epithelial cells, hormonal and non-hormonal factors regulate apoptosis. To determine the cyclical effects of gonadal steroids on breast homeostasis, we evaluated the apoptotic index (AI) determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining in human mammary epithelial cells during the spontaneous menstrual cycle and correlated it with cellular proliferation as determined by the expression of Ki-67 during the same period.

Methods

Normal breast tissue samples were obtained from 42 randomly selected patients in the proliferative (n = 21) and luteal (n = 21) phases. Menstrual cycle phase characterization was based on the date of the last and subsequent menses, and on progesterone serum levels obtained at the time of biopsy.

Results

The proliferation index (PI), defined as the number of Ki-67-positive nuclei per 1,000 epithelial cells, was significantly larger in the luteal phase (30.46) than in the follicular phase (13.45; P = 0.0033). The AI was defined as the number of TUNEL-positive cells per 1,000 epithelial cells. The average AI values in both phases of the menstrual cycle were not statistically significant (P = 0.21). However, the cell renewal index (CRI = PI/AI) was significantly higher in the luteal phase (P = 0.033). A significant cyclical variation of PI, AI and CRI was observed. PI and AI peaks occurred on about the 24th day of the menstrual cycle, whereas the CRI reached higher values on the 28th day.

Conclusions

We conclude that proliferative activity is dependent mainly on hormonal fluctuations, whereas apoptotic activity is probably regulated by hormonal and non-hormonal factors.

Estrogen receptor alpha expression in normal human breast epithelium is consistent over time

If increased expression of estrogen receptor alpha (ER) in benign breast epithelium increases susceptibility to breast cancer, such overexpression should be stable over time. There are no published data regarding this important aspect of ER expression in breast epithelium. We examined the temporal consistency of ER expression in the normal breast tissue of 28 women who had 2 separate breast surgical procedures, at least 6 months apart (mean interval, 2.8 years). Paraffin embedded breast tissue blocks containing an adequate sample of normal breast epithelium and no cancer, were sectioned and processed using the 6F11 antibody and standard immunohistochemical techniques. The ER labelling index (ER LI) was calculated by counting a mean of 2,000 epithelial cells. The median ER LI at first sampling was 13.6 and at second sample 15.5, with R(2) = 0.34 and p = 0.001. The ER LI was categorized into high and low values, using a threshold of 10. Twenty-four women (85.7%) showed concordance of high and low expression between the 2 samples (p = 0.002). There were 11 women who were premenopausal at both time points. Among them, much of the variation in ER LI was explained by differences in the menstrual cycle day at the time of sampling and adding the day of cycle to the regression model substantially improved the correlation between first and second labeling indices. These data suggest that ER expression of normal breast tissue is fairly consistent over time and support the notion that overexpression of ER in normal epithelium is a constant feature of the high risk breast.

A novel method for growing human breast epithelium in vivo using mouse and human mammary fibroblasts

A novel system is described for studying the growth of normal human mammary epithelium in vivo as grafts in athymic nude mice. The key feature of this model is reconstitution of the epithelial-stromal interactions required for normal growth and differentiation of the human mammary epithelium, which produces ducts that are comparable to those in the normal human mammary gland. Human breast epithelial organoids were combined with mammary fibroblasts from mouse or human origin in collagen gels, which were subsequently transplanted under the renal capsule of female nude mice hosts. The resulting grafts showed an increase in the ductal density compared with that observed previously. These ducts expressed appropriate markers for luminal and myoepithelial cells and steroid receptors. Treatment of the host with diethylstilbestrol or estradiol and progesterone significantly increased the number of ducts observed and increased cell proliferation. The grafts also displayed production of beta-casein and milk fat globule membrane protein when the hosts were allowed to become pregnant. This model allows for a variety of epithelial and stromal cells to be used in combination, which would aid in understanding key factors that regulate normal human mammary gland development.

Distinct expression patterns of ER alpha and ER beta in normal human mammary gland

AIM

Two oestrogen receptors (ERs) have been identified to date-the "classic" ER alpha and the more recently described ER beta. Although much is known about ER alpha at the mRNA and protein levels, our knowledge of the expression and distribution of ER beta protein is much more limited. The aim of this study was to compare the cellular distribution of ER alpha and ER beta in normal human mammary gland.

METHODS

Formalin fixed, paraffin wax embedded material was obtained from reduction mammoplasty specimens, normal tissue adjacent to breast tumour, or fibroadenoma. Sections were immunohistochemically stained for ER alpha, ER beta, and the progesterone receptor. The staining pattern for each antibody was evaluated and compared.

RESULTS

ER alpha was restricted to the cell nuclei of epithelial cells lining ducts and lobules. Although ER beta was also seen in these cells, additional strong staining was detected specifically in the cell nuclei of myoepithelial cells. Occasional staining was seen in surrounding stromal and endothelial cell nuclei and in lymphocytes.

CONCLUSIONS

ER subtypes have distinct distribution patterns in the normal mammary gland. The widespread distribution of ER beta suggests that it may be the dominant ER in the mammary gland where it may be acting as a natural suppressor.

Loss of co-ordinate expression of progesterone receptors A and B is an early event in breast carcinogenesis

Progesterone receptor (PR) mediates the effects of progesterone in mammary tissues and plays a crucial role in normal breast development and in breast cancer. PR proteins are expressed as two isoforms, PRA and PRB, that have different capacities to activate target genes, yet it is unknown whether progesterone action in normal and malignant breast is mediated by PRA and/or PRB. This study determines the relative expression of PRA and PRB in normal breast and in benign, premalignant and malignant archival breast lesions by dual immunofluorescent histochemistry. In normal breast and in proliferative disease without atypia (PDWA) PRA and PRB were co-expressed within the same cells in comparable amounts, implicating both isoforms in progesterone action. In atypical lesions, however, there was a significant increase in predominant expression of PRA or PRB, with lesion progression from the normal state to malignancy. PR isoform predominance, especially PRA predominance, was evident in a high proportion of ductal carcinomas in situ (DCIS) and invasive breast lesions. In the normal breast and in PDWA, the relative expression of PRA and PRB in adjacent cells was homogenous. There was a significant increase in cell-to-cell heterogeneity of PR isoform expression in ADH and DCIS lesions and in the majority of breast cancers. Heterogeneous cell-to-cell expression of PR isoforms occurred prior to overall predominant expression of one isoform in premalignant breast lesions, demonstrating that loss of control of relative PRA:PRB expression is an early event in the development of breast cancer. PRA:PRB ratios within a breast lesion are likely to be important as both markers and effectors of tumor growth and development, and progressively aberrant PR isoform expression may play a role in the etiology of breast cancer.

Breast cancer incidence and estrogen receptor alpha in normal mammary tissue--an epidemiologic study among Japanese women in Japan and Hawaii

We have undertaken a study to examine whether the difference in breast cancer incidence between 2 populations of similar genetic background is reflected in a similar pattern of estrogen receptor alpha expression in normal mammary gland. Study participants were 92 Japanese women from Sapporo, Japan (mean age 48.2 years) and 49 Japanese women from Honolulu, Hawaii (mean age 45.4 years), who underwent biopsy indicating normal breast tissue or benign, nonproliferative breast disease in hospitals in Sapporo, Japan and Honolulu, Hawaii. The breast tissue samples were formalin-fixed and paraffin-embedded. The estrogen receptor immunohistochemistry assays were conducted using Dako kits. Japanese women in Hawaii, who have a higher incidence of breast cancer compared with Japanese women in Sapporo, also had, as predicted, higher mean percentage of estrogen receptor alpha-positive normal mammary cells (2-tailed test, p approximately 0.09). The results of our study are compatible with the hypothesis that estrogen receptor alpha expression in normal mammary tissue increases breast cancer risk and they also indicate that the expression of these receptors is dependent, at least in part, on nongenetic factors.

Identification of wild-type and exon 5 deletion variants of estrogen receptor beta in normal human mammary gland

We have examined messenger RNA (mRNA) expression of estrogen receptor (ER) alpha, wild-type ERbeta (mRNA and protein), and ERbeta exon 5 deletion variants (ERbeta delta5) in samples of normal human mammary gland obtained from 37 premenopausal subjects undergoing reduction mammoplasty. Comparing individual expression, ERbetaP mRNA predominated, expressed in 34 of 37 samples (91%), whereas ERalpha was found in 21 of 37 cases (57%). Receptor combinations were then analyzed and compared. Most samples either coexpressed ERalpha with ERbeta (54%) or expressed just ERbeta (38%). Immunohistochemical analysis revealed that ERbeta mRNA expression mirrored that of protein. Immunoreactivity was observed in the nucleus with additional evidence of cytoplasmic staining in those epithelial cells lining the breast ducts. Sporadic immunoreactivity was also detected in stromal cells. Expression of wild type and ERbeta delta5 was analyzed, and their association with ERalpha was compared. Most samples coexpressed wild-type ERbeta and the splice variant (62%; P = 0.05), with 30% exclusively expressing wild-type ERbeta. Although samples coexpressing wild type and variant ERbeta showed no statistical association with ERalpha, those samples expressing only wild-type ERP, showed a trend toward associations with ERalpha (P = 0.07). In conclusion, our data would support a role for ERbeta in the normal human mammary gland, where we propose it may be the dominant receptor.

Pattern of distribution of cells positive for estrogen receptor alpha and progesterone receptor in relation to proliferating cells in the mammary gland

Since cell proliferation is indispensable for the growth and development of the breast, and estrogens are considered to play a major role in promoting cell proliferation, while progesterone influences its differentiation, the present work was designed with the purpose of verifying the relationship between cells containing steroid hormone receptors and proliferating cells in the normal human breast. Twelve breast samples were analyzed for their content of lobules type 1 (Lob1), Lob2, Lob3, and Lob4, and the number of cells containing estrogen receptor alpha (ER-alpha), progesterone receptor (PgR), or expressing Ki67 antibody was determined by double immunocytochemical technique with specific antibodies. The highest percentage of ER-alpha, PgR, and Ki67 positive cells was found in Lob1, with a progressive reduction in the more differentiated Lob2 and Lob3. ER-alpha and PgR positive cells were found exclusively in the breast epithelium and were negative for Ki67, while cells positive for Ki67 did not express receptors. These findings were compared with the distribution of ER-alpha and PgR in the autoradiographs of mammary gland of young virgin rats inoculated with 3H-thymidine for determination of the DNA labeling index (DNA-LI). Both the DNA-LI and the percentage of ER-alpha and PgR positive cells were maximal in the epithelium of terminal end buds, and these values were reduced in alveolar buds and lobules. ER-alpha and PgR positive cells did not proliferate, and those cells that had incorporated 3H-thymidine were negative for both receptors. Our results led us to conclude that the content of ER-alpha and PgR in the normal mammary tissue varies with the degree of lobular development, in parallel with cell proliferation. However, the expression of receptors occurs in cells other than the proliferating cells, indicating that they represent at least two separate cell populations. These findings open new avenues towards the understanding of the mechanisms through which estrogens and progesterone affect the proliferative activity of breast epithelial cells, and their role in the initiation of the cascade of events that leads a normal cell to cancer.

Epithelial proliferation and hormone receptor status in the normal post-menopausal breast and the effects of hormone replacement therapy

The proliferation rate (as assessed by Ki67 expression) and expression of oestrogen-regulated progesterone receptor (PR) was studied in normal post-menopausal breast epithelium. Normal breast epithelium from patients receiving hormone replacement therapy (HRT) at the time of surgery containing either oestrogen alone (E2) or oestrogen and progesterone combined activities (E2 + P) was also studied, as HRT has been linked to an increased breast cancer risk. Samples of breast tissue, containing normal epithelium, from 185 patients undergoing surgery for benign or malignant disease were immunocytochemically stained for PR and Ki67. The percentage of labelled cells was expressed as the labelling index (LI). The median Ki67 LI in normal post-menopausal breast epithelium was 0.19 and median PR LI was 4.75, and both were unaffected by patient age, duration of menopause or if the tissue sample originated from a breast with benign or malignant disease. Proliferation did not alter significantly in patients taking HRT (P = 0.61); however, PR expression was up-regulated in both E2 and E2 + P users (P = 0.01). The dose and duration of HRT had no effect on either parameter. A possible attenuation of sensitivity to oestradiol-induced proliferation but not to PR expression occurs in the post-menopausal breast.

Expression of estrogen receptors during growth of human pancreatic adenocarcinoma cells (Capan-1)-relationship with differentiation

In steroid target tissues, the presence of the corresponding hormone receptors is indicative of hormone dependence. In an attempt to assess the possible role of steroid hormones in the mechanism of growth and/or differentiation of cancerous pancreatic duct cells, the expression of estrogen receptor (ERalpha) was evaluated in human cancerous pancreatic duct cells (Capan-1) maintained in culture. These cells were selected as they acquire progressively a high degree of differentiation during growth in culture. In the present study, we showed that Capan-1 cells during growth in steroid-free medium associate spontaneously, become polarized, and form duct-like structures, features that are indicative of a high degree of differentiation. Capan-1 cells were also found to express ERalpha and progesterone receptor (PR). Immunoenzymatic assay showed maximal expression of ERalpha (236 +/ 55 fmol/mg protein) on the first day of the exponential growth phase, followed by a marked fall in expression (76.3%). At the onset of the stationary phase (Day 5), ERalpha levels were below 10 fmol/mg protein, becoming undetectable by Day 7. A similar time course was observed for PR: 18 +/- 0.9 fmol/mg protein at the onset of the exponential growth phase and no expression during the stationary phase. Addition of estradiol to 1-d-old cultures resulted in a twofold increase in PR expression, suggesting an induction of PR expression by estrogen. Immunocytochemical analysis with anti-ERalpha-1D5 antibodies showed nuclear and cytoplasmic localization of ERalpha in Capan-1 cells in the first 24 h of culture followed by a progressive disappearance thereafter. We also showed that cellular multiplication was increased by estradiol and progesterone during the exponential growth phase, pointing to the involvement of steroid hormones in the proliferation of nonpolarized Capan-1 cells. These results indicate that the expression of ERalpha is linked to the state of differentiation of the cells and make Capan-1 cells a model of choice to study ER regulation in nontarget tissues.

Use of the autopsy to study ontogeny and expression of the estrogen receptor gene in human breast

Historically, autopsies have been a valuable resource for morphologic studies of the human breast, and have been used in conjunction with radiologic evaluation and epidemiology to provide information about population prevalence of pre-malignant and malignant disease. More recently, well-preserved post-mortem breast tissue has also been used to evaluate the status of genes and their expression. Using molecular techniques and immunohistochemistry, quantitation of gene expression and localization of proteins of hormone receptors, growth factor receptors, growth factors, cell-proliferation related antigens and proto-oncogenes can be evaluated in autopsy-derived breast tissue. Expression of the estrogen receptor (ER)3 gene at the mRNA and protein product levels has been evaluated in breast tissue from infants, children, adolescent girls, and adult women in various phases of the menstrual cycle, pregnancy and post-menopausal. The results of these studies support a role for the ER gene in early as well as pubescent breast development, and also in normal cyclical and abnormal cell proliferation in the terminal-duct-lobular-units (TDLU) of adult women.

Auto-regulation of the estrogen receptor promoter

The presence or absence of estrogen receptor (ER) plays a key role in the diagnosis and treatment of breast tumors. It is known that patients with breast tumors classified as ER-positive have a better prognosis. Observations such as this have led us to explore the question of what makes some breast tumors overexpress ER whereas others express either very low levels or none at all. To begin a study of ER regulation, we first chose to examine a 200 bp region of the ER promoter located immediately upstream from the transcribed sequence of the human ER gene. We found that this region of the ER promoter contained basal activity when transiently transfected into ER-negative HeLa cells. ER promoter activity was further increased by co-transfection of a wild-type ER expression vector, and this increased activity was hormone-dependent. Several ER deletion mutant constructs were also able to increase the activity of the ER promoter fragment, but none could support equivalent activity as was seen with the full-length ER. Therefore, we conclude that the ER can contribute to its own expression, and we hypothesize that this auto-regulation may contribute to its overexpression in some breast tumors.

Breast cancer: further metabolic-endocrine risk markers?

There is evidence that increased oestrogen receptor (ER) expression in normal mammary epithelium may be a risk marker for the development of breast cancer. Insulin-like growth factor 1 (IGF1) is a potent inducer of mitosis and has been shown to synergize with oestrogen in stimulating the growth of human breast cancer in vitro. In these cells oestradiol has been shown to upregulate IGF type 1 receptor (IGFR), and recently a similar effect has been reported in normal human breast tissue xenografts in vivo. It has been postulated that the combined effect of oestradiol and IGF1 may stimulate proliferation in normal mammary epithelium and increase breast cancer risk. The bioavailability of IGF1 to the tissues is modulated by IGF-binding proteins (IGFBPs), and higher circulating levels of IGF1 and lower levels of IGFBP3 have been reported in breast cancer patients. Breast cancer specimens show a positive correlation between ER status and IGF receptor status, and also a negative correlation between ER status and IGFBP3 expression. Finally, ectopic growth hormone expression has been shown in a majority of specimens of normal and malignant breast tissue, and this may contribute to breast cancer risk, possibly by increasing the local level of bioavailable IGF1. Expansion of such findings may provide clinically useful markers of increased risk to breast cancer in women.

Expression of the estrogen receptor gene in developing and adult human breast

Although studies of the estrogen receptor gene abound in rodent models and breast cancer cell lines, little is known about expression of this gene in normal human breast. Information regarding the physiology of this gene's expression is important if we are to elucidate abnormalities of the gene that may be involved in breast carcinogenesis. We evaluated levels of mRNA expression of the estrogen receptor (ER) gene and its protein product in a set of 89 breasts from clinically normal female infants, children, adolescents, and adult premenopausal and post-menopausal women. mRNA expression of the gene varied with the hormonal status. Relatively higher levels of gene transcripts were found in breasts of peri-menarchal girls, women in the luteal phase of the menstrual cycle, and in those with fibrocystic change. Higher levels were also occasionally found in breasts of infants and in most pre-adolescent children. Lower levels were seen in breasts of women in the follicular phase of the menstrual cycle, during pregnancy, and after menopause. Nuclear protein staining was common in breasts of normal children and peri-menarchal adolescents, and in post-menopausal atrophic breasts. Nuclear ER protein was infrequently detected in reproductive aged women's breasts, but was more often seen in follicular than in luteal menstrual phase or pregnant breast. ER protein was more frequently seen in post-menopausal than in pre-menopausal breasts with fibrocystic change. The results fit a model in which circulating levels of estrogen are inversely related to levels of mRNA transcribed from the estrogen receptor gene in normal physiologic states. Abnormally high levels of gene transcription may occur in some cases of fibrocystic change.

Hormones and mammary carcinogenesis in mice, rats, and humans: a unifying hypothesis

An attempt has been made to put forward a unifying hypothesis explaining the role hormones play in the genesis of mammary cancers of different phenotypes and genotypes in mice, rats, and humans. Most mammary cancers in these species originate in luminal mammary epithelial cells lining the mammary ducts and alveoli. These cancers are histopathologically diverse and are classified on the basis of growth requirements as hormone-dependent or hormone-independent tumors. In most strains of mice, mammary cancers at the time of detection are largely of the hormone-independent type; in rats, almost all mammary cancers are hormone-dependent, while humans have both phenotypes. In spite of these differences, in vivo studies show that hormones (ovarian and pituitary) are essential for luminal mammary epithelial cell proliferation and also for the development of mammary cancers of both hormone-independent and hormone-dependent types. This article, based on our extensive in vivo and in vivo studies and on current literature, proposes a model to explain the central role of hormones in the genesis of all types of mammary cancers. The model attempts to address the following questions: (i) how hormones regulate luminal mammary epithelial cell proliferation, (ii) why hormones are required for the genesis of mammary cancers of all phenotypes and genotypes, including those which are always classified as hormone-independent tumors, and (iii) why the three species (mouse, rat, and human) have consistently different ratios of hormone-dependent to hormone-independent tumors.

The endocrine prevention of breast cancer

A clear explanation for the high incidence of breast cancer in modern women is now possible. The risk of breast cancer rises steeply from menarche until menopause. Associated with the reproductive process, the ovary, including the corpus luteum, produces substantial amounts of estrogen and progesterone, both of which induce growth of the breast epithelium. This sex-steroid-driven breast epithelial cell proliferation increases the risk of carcinogenesis by accelerating the occurrence of somatic genetic errors. Postmenopausally, as there is little cell proliferation, the breast epithelium is more "resistant" to mutagenic effects, and breast cancer risk rises at a low rate. Unfortunately, the genetic errors accumulated during the premenopausal period are not lost following menopause, and breast cancer risk remains high. Sex-steroid antagonists, such as tamoxifen, may reduce breast cancer incidence both by blocking breast epithelial cell proliferation and by direct antitumor effects on clinically occult breast cancers. The rationale for a contraceptive designed to reduce breast cell proliferation by decreasing premenopausal sex-steroid exposure is presented.

Hormonal carcinogenesis in breast cancer: cellular and molecular studies of malignant progression

We have established and characterized a series of variant cell lines in which to identify the critical factors associated with E2-induced malignant progression, and the acquisition to tamoxifen resistance in human breast cancer. Sublines of the hormone-dependent MCF-7 cell line (MCF7/MIII and MCF7/LCC1) form stable, invasive, estrogen independent tumors in the mammary fat pads of ovariectomized athymic nude mice. These cells retain expression of both estrogen (ER) and progesterone receptors (PGR), but retain sensitivity to each of the major structural classes of antiestrogens. The tamoxifen-resistant MCF7/LCC2 cells retain sensitivity to the inhibitory effects of the steroidal antiestrogen ICI 182780. By comparing the parental hormone-dependent and variant hormone-independent cells, we have demonstrated an altered expression of some estrogen regulated genes (PGR, pS2, cathepsin D) in the hormone-independent variants. Other genes remain normally estrogen regulated (ER, laminin receptor, EGF-receptor). These data strongly implicate the altered regulation of a specific subset or network of estrogen regulated genes in the malignant progression of human breast cancer. Some of the primary response genes in this network may exhibit dose-response and induction kinetics similar to pS2, which is constitutively upregulated in the MCF7/MIII, MCF7/LCC1 and MCF7/LCC2 cells.

Immunohistochemical studies of early breast cancer evolution

Despite modern therapy, one third to one half of patients who get breast cancer will eventually die from it. This disconcerting circumstance has focused attention on prevention, and preventing breast cancer will require a much better understanding of the biological abnormalities underlying its development and progression. Many studies into the mechanisms of invasive breast cancer evolution have evaluated presumed precursor lesions (e.g. proliferative disease without atypia, atypical ductal hyperplasia, and ductal carcinoma in-situ) for genetic alterations known to occur in fully developed invasive carcinomas. This approach has shed some light on events which may be important in early malignant transformation, including the observations that overexpression of the c-erbB-2 oncogene and mutations of the p53 tumor suppressor gene are present in significant subsets of DCIS, but not PDWA or ADH. Although this approach is limited by our incomplete knowledge of cancer genetics, there is still a great deal to learn about breast cancer evolution by evaluating cancer-associated genes in potential precursor lesions using established techniques such as immunohistochemistry and in situ hybridization.

William L. McGuire Memorial Symposium. Estrogen and progestin effects in human breast carcinogenesis

The influences of estrogen and progestin on human mammary neoplasia are reviewed with a view to identifying what is known about their effects. Estrogens promote growth of established cancer and pharmacological levels of progestins induce remission. In vivo, highest proliferation of histologically normal mammary epithelium occurs in the progestogenic phase of the menstrual cycle or under the progestogenic influence of oral contraceptives. Little additional hard data exist to indicate whether progestins promote or inhibit human mammary carcinogenesis. Effects on proliferation, steroid receptor content and development are discussed together with interpretation of epidemiological data on risk factors that have hormonal components. Progestins may not be the benign or beneficial agents previously supposed, and there are virtually no data to suggest that they are antiestrogenic. It is hypothesized that carcinogenesis may be accompanied by increased sensitivity to estrogen, which provides a growth advantage to the tumor by maximizing use of the low estrogen concentrations encountered in the postmenopausal state.

Biomarkers in early breast neoplasia

Early breast neoplasia may be defined in many ways. Any non-invasive or invasive but nonmetastatic breast cancer qualifies as early neoplasia in the sense that they are non-lethal. Before we can prevent lethal breast cancer, we must gain a better understanding of the biological abnormalities underlying its development and progression. Many studies into the mechanisms of breast cancer evolution have evaluated potential precursor lesions (e.g., proliferative disease without atypia [PDWA], atypical ductal hyperplasia [ADH], and ductal carcinoma in situ [DCIS]) for genetic alterations known to occur in fully developed invasive carcinomas. This approach has shed some light on events which may be important in early malignant transformation, including the observations that overexpression of the c-erbB-2 oncogene and mutations of the p53 tumor suppressor gene are present in significant subsets of DCIS, but not PDWA or ADH. This approach is limited by our incomplete knowledge of cancer genetics. However, there is more to learn by evaluating known cancer-associated genes in potential precursor lesions using established techniques such as immunohistochemistry and in situ hybridization. Until recently, technology could not detect unknown genetic abnormalities in microscopic lesions such as PDWA, ADH, or DCIS. Now, PCR-based techniques have the theoretical ability to detect novel tumor promoter and suppressor genes in clinical samples of these very small lesions. For example, suppressor-type genes may be detected using comprehensive mapping probes to identify loss of heterozygosity in PCR-amplified DNA extracted from a few hundred cells microdissected from either fresh or archival tissue.(ABSTRACT TRUNCATED AT 250 WORDS)