Steroid hormone receptors in breast cancer management

Proliferation rate, hormone receptor status and p53 expression in skeletal metastasis of breast carcinoma

Immunohistochemistry was used to analyze ER, PgR, MIB, and p53 of primary breast carcinomas and their skeletal metastases in 43 patients operated on for 47 pathological fractures. Femoral lesions predominated (24), followed by metastases to the spine (13). The median survival time from diagnosis of the primary breast carcinoma was 5.5 (0.5-20) years and from pathological fracture 5 (0-76) months. No clinical characteristics of the primary tumor were prognostic for survival after pathological fracture. Thirty of 47 tissue specimens from skeletal metastases were ER positive and 17 negative. Fourteen of 47 tissue specimens from skeletal metastasis were positive for PgR. Forty-five of the 47 metastases could be evaluated for p53 positivity and 43 tumors showed nuclear staining of varying intensity. In a majority of the cases there was a good correlation between ER, PgR and p53 in the primary tumors and their corresponding metastases. p53 negative primary tumors were associated with longer survival from diagnosis, but also found after pathological fracture. No correlation was observed between ER index or MIB-1 in the skeletal metastases and postoperative survival. PgR positivity in skeletal metastases was associated with longer survival after pathological fracture. This study shows that biological markers such as PgR and p53 provide prognostic information after pathological fracture. The findings should be regarded with caution as there are many confounding factors such as prior chemo- and radiotherapy. Nevertheless, the approach, to gather prognostic data at the time of pathological fracture, warrants further study as expected survival time is paramount in the choice of surgical treatment.

Prepubertal octylphenol exposure up-regulate BRCA1 expression, down-regulate ERalpha expression and reduce rat mammary tumorigenesis

BACKGROUND

Endogenous estrogens play an important role in the development of breast cancer. Octylphenol (OP) and genistein (GEN) are estrogen-like chemicals. Prepubertal estradiol and genistein exposure can up-regulate BRCA1 mRNA in mammary gland and reduce futuer breast cancer risk. In the present study, the effects of prepubertal exposure to high-dose OP and GEN on mammary carcinogenesis and the association with the expression of BRCA1 and ERalpha were investigated.

METHODS

Prepubertal female Sprague-Dawley rats were exposed to 20, 40, 80mg/kg OP daily from postnatal day (PND) 22-28, subsequently, the rats were given a single dose of 100mg/kg 7,12-dimethylbenz [a] anthracene (DMBA) on PND42 to induce mammary tumor.

RESULTS

The incidence of DMBA-induced mammary tumors significantly decreased when rats were treated with 40mg/kg OP. BRCA1 mRNA and protein expression were found up-regulated and ERalpha expression was down-regulated in the mammary tumor when rats were exposed to 40mg/kg octylphenol.

CONCLUSION

Exposure 40mg/kg octylphenol can reduce later breast cancer risk in prepubertal Sprague-Dawley rats, the protective effect of OP is associated with persistent up-regulation of BRCA1 and down-regulation of ERalpha in the mammary tumor.

Predictive value of eIF4E reduction after neoadjuvant therapy in breast cancer

INTRODUCTION

Initiation factor 4E (eIF4E) overexpression has prognostic significance in breast cancer. Up-regulation of downstream gene products associated with high eIF4E overexpression has been linked to chemoresistance. We hypothesize patients whose tumors had eIF4E reduction after neoadjuvant chemotherapy will have lower cancer recurrence compared with those who did not.

METHODS

Seventeen locally advanced breast cancer patients were accrued, and tumor specimens were obtained before and after neoadjuvant therapy. eIF4E was quantified by Western blots. Primary end-point was cancer recurrence.

RESULTS

Low eIF4E was defined as < or =7.5-fold elevation and high eIF4E was >7.5-fold elevation. Of 17 patients, six tumors remained low after neoadjuvant therapy, six dropped from high to low eIF4E, and five remained high. With a median follow-up of 29 mo, four of five patients with tumors that remained high have recurred while only three of 12 patients in the low eIF4E post-therapy group have recurred (P=0.05, chi(2)). Survival analysis using the Kaplan-Meier method showed a higher rate of cancer recurrence in patients with post-treatment high eIF4E overexpression (P=0.026, log rank test).

CONCLUSIONS

Breast cancer patients whose tumors had low eIF4E overexpression after neoadjuvant chemotherapy had lower cancer recurrence compared with those who did not.

HspBP1 levels are elevated in breast tumor tissue and inversely related to tumor aggressiveness

HspBP1 is a co-chaperone that binds to and regulates the chaperone Hsp70 (Hsp70 is used to refer to HSPA1A and HSPA1B). Hsp70 is known to be elevated in breast tumor tissue, therefore the purpose of these studies was to quantify the expression of HspBP1 in primary breast tumors and in serum of these patients with a follow-up analysis after 6 to 7 years. Levels of HspBP1, Hsp70, and anti-HspBP1 antibodies in sera of breast cancer patients and healthy individuals were measured by enzyme-linked immunosorbent assay. Expression of HspBP1 was quantified from biopsies of tumor and normal breast tissue by Western blot analysis. The data obtained were analyzed for association with tumor aggressiveness markers and with patient outcome. The levels of HspBP1 and Hsp70 were significantly higher in sera of patients compared to sera of healthy individuals. HspBP1 antibodies did not differ significantly between groups. HspBP1 levels were significantly higher in tumor (14.46 ng/microg protein, n = 51) compared to normal adjacent tissue (3.17 ng/microg protein, n = 41, p < 0.001). Expression of HspBP1 was significantly lower in patients with lymph node metastasis and positive for estrogen receptors. HspBP1 levels were also significantly lower in patients with a higher incidence of metastasis and death following a 6 to 7-year follow-up. The HspBP1/Hsp70 molar ratio was not associated with the prognostic markers analyzed. Our results indicate that low HspBP1 expression could be a candidate tumor aggressiveness marker.

Short-term prophylactic tamoxifen reduces the incidence of antiestrogen-resistant/estrogen receptor-positive/progesterone receptor-negative mammary tumors

Although many estrogen receptor-positive (ER+) breast cancers are effectively treated with selective estrogen receptor modulators and down-regulators (SERM/SERD), some are highly resistant. Resistance is more likely if primary cancers are devoid of progesterone receptors (PR-) or have high levels of growth factor activity. In this study, a transgenic mouse line that expresses transforming growth factor-alpha (NRL-TGFalpha mice) and that develops ER+/PR- mammary tumors was used to assess the possible effects of (a) therapeutic delivery of the SERM, tamoxifen, or SERD, ICI I82,780 (ICI), on the growth of established tumors and (b) short-term prophylactic tamoxifen administration on the initial development of new mammary tumors. To determine the therapeutic effects of tamoxifen and ICI on the growth of established tumors, mice were exposed to 3 weeks of drug treatment. Neither drug influenced tumor growth or glandular pathology. To determine if early prophylactic tamoxifen could alter tumorigenesis, a 60-day tamoxifen treatment was initiated in 8-week-old mice. Compared with placebo-treated mice, tamoxifen reduced tumor incidence by 50% and significantly decreased the degree of mammary hyperplasia. Prophylactic tamoxifen also significantly extended the life span of tumor-free mice. These data show that in this mouse model, established ER+/PR- mammary tumors are resistant to SERM/SERD treatment but the development of new mammary tumors can be prevented by an early course of tamoxifen. This study validates the utility of NRL-TGFalpha mice for (a) identifying candidate biomarkers of efficacious tamoxifen chemoprevention and (b) modeling the evolution of tamoxifen resistance.

Protein kinases C isozymes are differentially expressed in human breast carcinomas

AIMS

The protein kinase C (PKC) family of enzymes has been implicated in cellular proliferation, differentiation, and apoptosis. However, the distribution of specific PKC isoforms with varying functions in normal and malignant human tissues remains to be determined. The objective of this study was to investigate the expression of certain PKC isoforms (alpha, betaI, betaII, epsilon) in human breast cancer specimens relative to adjacent uninvolved tissue (n=24) and in the normal breast tissue obtained from patients undergoing reduction mammoplasty (n=12).

MAIN METHODS

Western blot analysis using PKC isoform specific antibodies was performed on tissue extracts from breast tumors, adjacent uninvolved tissues, and reduction mammoplasty tissues.

KEY FINDINGS

Mean levels of cytosolic and membrane PKC-alpha, PKC-betaI, and PKC-betaII were significantly higher in the cancer specimens than in the adjacent uninvolved breast tissues (Wilcoxon signed-ranks test; P<0.05 for each, after adjustment for multiple comparisons). There was a notably higher mean level of membrane PKC-betaII isozyme in Her-2 positive and in poorly differentiated tumors. No significant differences were observed when normal tissue adjacent to tumor was compared to breast tissue obtained from reduction mammoplasty specimens.

SIGNIFICANCE

Higher level of PKC-alpha, PKC-betaI, and PKC-betaII in cancer specimens and higher level of PKC-betaII in Her-2 positive tumors require further exploration of the intracellular pathways involving PKC-alpha and -beta isoforms in breast cancer because both could be specific targets for the development of new therapies and for the prevention and treatment of this disease.

The relevance of phosphorylated forms of estrogen receptor in human breast cancer in vivo

Estrogen receptor (ER)alpha activity is regulated by phosphorylation at several sites. Recently several antibodies specific for individual phosphorylated sites within ERalpha have became available. Validation and use of these antibodies suggests that several forms of phosphorylated ERalpha can be detected in multiple ER+ human breast tumor samples, thus providing relevance for investigating the regulation and function of phosphorylated ERalpha in human breast cancer. Generally, the phosphorylated ERalpha isoforms are associated with parameters that suggest that they are markers of an intact estrogen dependent signaling pathway and better clinical outcome with respect to tamoxifen therapy. Profiling of phosphorylated ERalpha may provide better biomarkers of endocrine therapy response over and above those currently available.

Phosphorylated ERα, HIF-1α, and MAPK Signaling As Predictors of Primary Endocrine Treatment Response and Resistance in Patients With Breast Cancer

Purpose

We aimed to identify signaling pathways involved in the response and resistance to aromatase inhibitor therapy in patients with breast cancer.

Patients and Methods

One hundred fourteen women with T2-4 N0-1, estrogen receptor (ER) α–positive tumors were randomly assigned to neoadjuvant letrozole or letrozole plus metronomic cyclophosphamide. Twenty-four tumor proteins involved in apoptosis, cell survival, hypoxia, angiogenesis, growth factor, and hormone signaling were assessed by immunohistochemistry in pretreatment samples (eg, caspase 3, phospho- mammalian target of rapamycin, hypoxia-inducible factor 1α [HIF-1α], vascular endothelial growth factor, mitogen-activated protein kinase [MAPK], phosphorylated epidermal growth factor receptor, phosphorylated ERα [pERα]). A multivariate generalized linear regression approach was applied using a penalized least-square minimization to perform variable selection and regularization. Ten-fold cross-validation and iterative leave-one-out were employed to validate and test the model, respectively. Tumor size, nodal status, age, tumor grade, histological type, and treatment were included in the analysis.

Results

Ninety-one patients (81%) attained a disease response, 48 achieved a complete clinical response (43%) whereas 22 did not respond (19%). Increased pERα and decreased p44/42 MAPK were significant factors for complete response to treatment in all leave-one-out iterations. Increased p44/42 MAPK and HIF-1α were significant factors for treatment resistance in all leave-one-out iterations. There was no significant interaction between these variables and treatment.

Conclusion

Activated ERα form was an independent factor for sensitivity to chemoendocrine treatment, whereas HIF-1α and p44/42 MAPK were independent factors for resistance. Although further confirmatory analyses are needed, these findings have clear potential implications for future strategies in the management of clinical trials with aromatase inhibitors in the breast cancer.

Using Frequent Co-expression Network to Identify Gene Clusters for Breast Cancer Prognosis

In this paper, we investigated the use of gene co-expression network analyses to identify potential biomarkers for breast carcinoma prognosis. The network mining algorithm CODENSE is used to identify highly connected genome-wide gene co-expression networks among a variety of cancer types, and the resulted gene clusters are applied to a series of breast cancer microarray sets to categorize the patients into different groups. As a result, we have identified a set of genes that are potential biomarkers for breast cancer prognosis which can categorize the patients into two groups with distinct prognosis. We also compared the gene clusters we discovered with gene subsets identified from similar studies using other clustering algorithms.

B-vitamin intake, one-carbon metabolism, and survival in a population-based study of women with breast cancer

Breast cancer is the second leading cause of cancer mortality among women. Given its important role in DNA methylation and synthesis, one-carbon metabolism may affect breast cancer mortality. We used a population-based cohort of 1,508 women with breast cancer to investigate possible associations of dietary intake of B vitamins before diagnosis as well as nine polymorphisms of one-carbon metabolizing genes and subsequent survival. Women newly diagnosed with a first primary breast cancer in 1996 to 1997 were followed for vital status for an average of 5.6 years. Kaplan-Meier survival and Cox proportional hazard regression analyses were used to evaluate the association between dietary intakes of B vitamins (1,479 cases), genotypes ( approximately 1,065 cases), and all-cause as well as breast cancer-specific mortality. We found that higher dietary intake of vitamin B(1) and B(3) was associated with improved survival during the follow-up period (P(trend) = 0.01 and 0.04, respectively). Compared with the major genotype, the MTHFR 677 T allele carriers have reduced all-cause mortality and breast cancer-specific mortality in a dominant model [hazard ratio (95% confidence interval): 0.69 (0.49-0.98) and 0.58 (0.38-0.89), respectively]. The BHMT 742 A allele was also associated with reduced all-cause mortality [hazard ratio, 0.70 (0.50-1.00)]. Estrogen receptor/progesterone receptor status modified the association between the MTHFR C677T polymorphism and survival (P = 0.05). The survival associations with one-carbon polymorphisms did not differ with the use of chemotherapy, although study power was limited for examining such effect modification. Our results indicate that one-carbon metabolism may be an important pathway that could be targeted to improve breast cancer survival.

Expression of 17beta-hydroxysteroid dehydrogenase type 2 and type 5 in breast cancer and adjacent non-malignant tissue: a correlation to clinicopathological parameters

Estrogens play an important role in the development and progression of breast cancer. 17beta-Hydroxysteroid dehydrogenase (17beta-HSD) type 2 and type 5 are involved in sex steroid metabolism. 17beta-HSD type 2 converts estradiol to estrone while 17beta-HSD type 5 converts androstenedione to testosterone. Using immunocytochemistry, we have studied the expression of 17beta-HSD type 2 and type 5 in 50 specimens of breast carcinoma and adjacent non-malignant tissues. The results were correlated with the estrogen receptor alpha (ERalpha) and beta (ERbeta), progesterone receptor A (PRA) and B (PRB), androgen receptor and CDC47 and with the tumor stage, tumor size, nodal status and menopausal status. 17beta-HSD type 2 was expressed in 20% and 17beta-HSD type 5 in 56% of breast cancer specimens. In adjacent normal tissues, both enzymes were highly expressed in almost all the patients. No significant association could be found between the expression of 17beta-HSD type 2 and 17beta-HSD type 5 and between the expression of each enzyme and the clinicopathological parameters studied. The decrease in 17beta-HSD type 2 and 17beta-HSD type 5 expressions in breast cancer may play a predominant role in the development and/or progression of the cancer by modifying the intratumoral levels of estrogens and androgens.

Breast cancer proteomics reveals correlation between estrogen receptor status and differential phosphorylation of PGRMC1

Introduction

Breast tumors lacking the estrogen receptor-α (ER-α) have increased incidence of resistance to therapy and poorer clinical prognosis.

Methods

Whole tissue sections from 16 cryopreserved breast cancer tumors that were either positive or negative for the ER (eight ER positive and eight ER negative) were differentially analyzed by multiplex imaging of two-dimensional PAGE gels using 54 cm isoelectric focusing. Differentially detected spots of Progesterone Receptor Membrane Component 1 (PGRMC1) were shown to differ in phosphorylation status by differential two dimensional polyacrylamide gel electrophoresis of phosphatase-treated tumor proteins. Site directed mutagenesis was used to create putative phosphorylation site point mutants in PGRMC1. Stable transfectants of these mutants in MCF7 cells were assayed for their survival after oxidative stress, and for AKT kinase phosphorylation. Immune fluorescence using anti-PGRMC1 monoclonal antibody 5G7 was performed on breast cancer tissue microarrays.

Results

Proteins significantly differentially abundant between estrogen receptor negative and estrogen receptor positive tumors at the 0.1% level were consistent with published profiles, suggesting an altered keratin pool, and increased inflammation and wound responses in estrogen receptor negative tumors. Two of three spots of PGRMC1 were more abundant in estrogen receptor negative tumors. Phosphatase treatment of breast tumor proteins indicated that the PGRMC1 isoforms differed in their phosphorylation status. Simultaneous mutation of PGRMC1 serine-56 and serine-181 fully abrogated the sensitivity of stably transfected MCF7 breast cancer cells to peroxide-induced cell death. Immune fluorescence revealed that PGRMC1 was primarily expressed in ER-negative basal epithelial cells of mammary ductules. Even in advanced tumors, high levels of ER or PGRMC1 were almost mutually exclusive in individual cells. In five out of five examined ductal in situ breast cancers of comedo type, PGRMC1 was expressed in glucose transporter 1 negative or positive poorly oxygenated cells surrounding the necrotic core, surrounded by a more distal halo of ER-positive cells.

Conclusions

PGRMC1 phosphorylation may be involved in the clinical differences that underpin breast tumors of differing ER status.

Alternative splicing and the progesterone receptor in breast cancer

Progesterone receptor status is a marker for hormone responsiveness and disease prognosis in breast cancer. Progesterone receptor negative tumours have generally been shown to have a poorer prognosis than progesterone receptor positive tumours. The observed loss of progesterone receptor could be through a range of mechanisms, including the generation of alternatively spliced progesterone receptor variants that are not detectable by current screening methods. Many progesterone receptor mRNA variants have been described with deletions of various whole, multiple or partial exons that encode differing protein functional domains. These variants may alter the progestin responsiveness of a tissue and contribute to the abnormal growth associated with breast cancer. Absence of specific functional domains from these spliced variants may also make them undetectable or indistinguishable from full length progesterone receptor by conventional antibodies. A comprehensive investigation into the expression profile and activity of progesterone receptor spliced variants in breast cancer is required to advance our understanding of tumour hormone receptor status. This, in turn, may aid the development of new biomarkers of disease prognosis and improve adjuvant treatment decisions.

Molecular profiles of progesterone receptor loss in human breast tumors

BACKGROUND

Patient prognosis and response to endocrine therapy in breast cancer correlate with protein expression of both estrogen receptor (ER) and progesterone receptor (PR), with poorer outcome in patients with ER+/PR- compared to ER+/PR+ tumors.

METHODS

To better understand the underlying biology of ER+/PR- tumors, we examined RNA expression (n > 1000 tumors) and DNA copy number profiles from five previously published studies of human breast cancers with clinically assigned hormone receptor status (ER+/PR+, ER+/PR-, and ER-/PR-).

RESULTS

We identified an expression "signature" of genes with either elevated or diminished RNA levels specifically in ER+/PR+ compared to ER-/PR- and ER+/PR- tumors. We similarly identified a gene signature specific to ER-/PR- tumors. ER+/PR- tumors, on the other hand, were a mixture of three different subtypes: tumors manifesting the ER+/PR+ signature, tumors manifesting the ER-/PR- signature, and tumors not associating with ER+/PR+ or ER-/PR- tumors (which we considered "true" ER+/PR-). In analyses of both tamoxifen-treated and untreated patients, ER+/PR- breast cancers defined by RNA profiling were associated with poor patient outcome, worse than those with pure ER+/PR+ patterns; these differences were not observed when using clinical assays to assign ER and PR status. ER+/PR- tumors also showed twice as many DNA copy number gains or losses compared to ER+/PR+ and ER-PR- tumors. Targets of transcriptional up-regulation by specific oncogenic pathways, including PI3 K/Akt/mTOR, were enriched in both ER+/PR- and ER-/PR- compared to ER+/PR+ tumors.

CONCLUSION

ER+/PR- tumors as defined by RNA profiling represent a distinct subset of breast cancer with aggressive features and poor outcome, despite being clinically ER+. Multigene assays derived from our gene signatures could conceivably provide an improved clinical assay for inferring PR status for prognostic and therapeutic purposes.

The Cdk inhibitor p27 in human cancer: prognostic potential and relevance to anticancer therapy

The cyclin-dependent kinase (Cdk) inhibitor p27 (also known as KIP1) regulates cell proliferation, cell motility and apoptosis. Interestingly, the protein can exert both positive and negative functions on these processes. Diverse post-translational modifications determine the physiological role of p27. Phosphorylation regulates p27 binding to and inhibition of cyclin-Cdk complexes, its localization and its ubiquitin-mediated proteolysis. In cancers, p27 is inactivated through impaired synthesis, accelerated degradation and by mislocalization. Moreover, studies in several tumour types indicate that p27 expression levels have both prognostic and therapeutic implications.

Comparison and identification of estrogen-receptor related gene expression profiles in breast cancer of different ethnic origins

The interactions between genetic variants in estrogen receptor (ER) have been identified to be associated with an increased risk of breast cancer. Available evidence indicates that genetic variance within a population plays a crucial role in the occurrence of breast cancer. Thus, the comparison and identification of ER-related gene expression profiles in breast cancer of different ethnic origins could be useful for the development of genetic variant cancer therapy. In this study, we performed microarray experiment to measure the gene expression profiles of 59 Taiwanese breast cancer patients; and through comparative bioinformatics analysis against published U.K. datasets, we revealed estrogen-receptor (ER) related gene expression between Taiwanese and British patients. In addition, SNP databases and statistical analysis were used to elucidate the SNPs associated with ER status. Our microarray results indicate that the expression pattern of the 65 genes in ER+ patients was dissimilar from that of the ER- patients. Seventeen mutually exclusive genes in ER-related breast cancer of the two populations with more than one statistically significant SNP in genotype and allele frequency were identified. These 17 genes and their related SNPs may be important in population-specific ER regulation of breast cancer. This study provides a global and feasible approach to study population-unique SNPs in breast cancer of different ethnic origins.

Expression of small breast epithelial mucin (SBEM) protein in tissue microarrays (TMAs) of primary invasive breast cancers

AIMS

Small breast epithelial mucin (SBEM) is a recently described gene product that shows promise as a new breast biomarker. The aim was to investigate for the first time SBEM protein expression in a large cohort (n = 300) of invasive breast cancers, its relationship to established clinical variables and its association with clinical outcome.

METHODS AND RESULTS

Immunohistochemical analysis was performed on tissue microarrays consisting of 149 oestrogen receptor (ER) alpha- and 151 ERalpha+ breast cancers. Overall, 18% of tumours were SBEM+ (n = 53/300). However, SBEM protein was more frequently observed in ER- (22%) than in ER+ cancers (13%; P = 0.049). A significant association with psoriasin/S100A7 expression (P < or = 0.0001) was observed in the entire cohort. SBEM was also positively associated with HER-2 (P = 0.046) in ER- cancers, and increased levels of SBEM were strongly associated with higher tumour grade (P = 0.0015). Furthermore, SBEM expression showed a trend towards an association with reduced overall survival and relapse-free survival in the ER+ cohort (P = 0.063 and P = 0.072, respectively).

CONCLUSIONS

Our results suggest that SBEM may identify a unique subset of breast cancers with poor prognosis and may have future implications for therapeutic management of this disease.

Estrogen receptor alpha negative breast cancer patients: estrogen receptor beta as a therapeutic target

Clinical management of breast cancer is increasingly guided by assessment of tumor phenotypic parameters. One of these is estrogen receptor (ER) status, currently defined by ERalpha expression. However with the discovery of a second ER, ERbeta and its variant isoforms, the definition of ER status is potentially more complex. In breast tumors there are two ERbeta expression cohorts. One where ERbeta is co-expressed with ERalpha and the other expressing ERbeta alone. In the latter subgroup of currently defined ER negative patients ERbeta has the potential to be a therapeutic target. Characterization of the nature and role of ERbeta in ERalpha negative tumors is essentially unexplored but available data suggest that the role of ERbeta may be different when co-expressed with ERalpha and when expressed alone. This review summarizes available data and explores the possibility that ERbeta signaling may be a therapeutic target in these tumors. Evidence so far supports the idea that the role of ERbeta in breast cancer is different in ERalpha negative compared to ERalpha positive tumors. However, cohort size and numbers of independent studies are small to date, and more studies are needed with better standardization of antibodies and protocols. Also, the ability to determine the role of ERbeta in ERalpha negative breast cancer and therefore assess ERbeta signaling pathways as therapeutic targets would be greatly facilitated by identification of specific downstream markers of ERbeta activity in breast cancer.

Forkhead box transcription factor FOXO3a suppresses estrogen-dependent breast cancer cell proliferation and tumorigenesis

INTRODUCTION

Estrogen receptors (ERs) play key roles in breast cancer development and influence treatment outcome in breast cancer patients. Identification of molecules that regulate ER function may facilitate development of breast cancer treatment strategies. The forkhead box class O (FOXO) transcription factor FOXO3a has been suggested to function as a tumor suppressor in breast cancer. Using protein-protein interaction screening, we found that FOXO3a interacted with ER-alpha and ER-beta proteins in the human breast carcinoma cell line MCF-7, suggesting that there exists a crosstalk between the FOXO3a and ER signaling pathways in estrogen-dependent breast cancer cells.

METHODS

The interaction between FOXO3a and ER was investigated by using co-immunoprecipitation and immunoblotting assays. Inhibition of ER-alpha and ER-beta transactivation activity by FOXO was determined by luciferase reporter assays. Cell proliferation in culture was evaluated by counting cell numbers. Tumorigenesis was assessed in athymic mice that were injected with MCF-7 cell lines over-expressing FOXO3a. Protein expression levels of cyclin-dependent kinase inhibitors, cyclins, ERs, FOXM1, and the proteins encoded by ER-regulated genes in MCF-7 cell lines and breast tumors were examined by immunoblotting analysis and immunohistochemical staining.

RESULTS

We found that FOXO3a interacted with ER-alpha and ER-beta proteins and inhibited 17beta-estradiol (E2)-dependent, ER-regulated transcriptional activities. Consistent with these observations, expression of FOXO3a in the ER-positive MCF-7 cells decreased the expression of several ER-regulated genes, some of which play important roles in cell proliferation. Moreover, we found that FOXO3a upregulated the expression of the cyclin-dependent kinase inhibitors p21Cip1, p27Kip1, and p57Kip2. These findings suggest that FOXO3a induces cell growth arrest to effect tumor suppression. FOXO3a repressed the growth and survival of MCF-7 cells in cell culture. In an orthotopic breast cancer xenograft model in athymic mice, over-expression of FOXO3a in MCF-7 cells suppressed their E2-induced tumorigenesis, whereas knockdown of FOXO3a in MCF-7 resulted in the E2-independent growth.

CONCLUSION

Functional interaction between FOXO3a and ER plays a critical role in suppressing estrogen-dependent breast cancer cell growth and tumorigenesis in vivo. This suggests that agents that activate FOXO3a may be novel therapeutic agents that can inhibit and prevent tumor proliferation and development in breast cancer.

Predictive markers in breast cancer--the present

Breast cancer is a heterogeneous disease and there is a continual drive to identify markers that will aid in predicting prognosis and response to therapy. To date, relatively few markers have established prognostic power. Oestrogen receptor (ER) is probably the most powerful predictive marker in breast cancer management, both in determining prognosis and in predicting response to hormone therapies. Progesterone receptor (PR) is also a widely used marker, although its value is less well established. HER-2 status has also become a routine prognostic and predictive factor in breast cancer. Given the importance of these biological markers in patient management, it is essential that assays are robust and quality controlled, and that interpretation is standardized. Furthermore, it is important to be aware of the limitations in their predictive power, and how this may be refined through addition of further biological markers. The aim of this review is to provide an overview of the established role of ER, PR and HER-2 in patient management, the current standards for assessing these markers, as well as highlighting the controversies that still surround their use and methods of assessment.

The role of estrogen receptor in melanoma

The estrogen receptor (ER) belongs to the group of sex hormone receptors and binds the biologically active form of estrogen, 17beta-estradiol. Expression of ER in tumor tissue is a well-established prognostic marker in breast cancer. The role of ER has been extensively studied in several other types of human cancers. This report investigates the potential role of ER as a surrogate marker for predicting melanoma progression, response to therapy, and patient survival. In addition, the authors review what is known, so far, about ER signaling pathways and their potential role in carcinogenesis and progression of cutaneous melanoma. Possibilities and limitations of using ER as a therapeutic target in the treatment of melanoma is also discussed.

Progesterone receptor expression is a marker for early stage breast cancer: implications for progesterone receptor as a therapeutic tool and target

We determined the association of estrogen receptor (ER) and progesterone receptor (PR) expression in invasive breast cancer with stage at diagnosis. Univariate analyses indicated that although ER and PR expression were inversely associated with grade (P<0.0001), only PR expression (P<0.01) was inversely associated with stage. Multivariate analyses, adjusted for covariates, including HER-2/neu expression, indicated that PR (odds ratio (OR), 0.88; confidence interval (CI), 0.77-0.99; P=0.03) and not ER expression (OR, 1.04; CI, 0.94-1.16; P=0.45) was inversely associated with stage. PR and not ER expression is a marker for early stage breast cancer.

Effects of exon-deleted estrogen receptor β transcript variants on growth, apoptosis and gene expression of human breast cancer cell lines

Estrogen receptor beta gene codes for a variety of transcript isoforms resulting from alternative splicing, which are expressed both in mammary gland and in breast cancer cells. We studied the function of two exon-deleted ERbeta isoforms recently identified by our group in comparison to ERbeta1 in regulation of growth, apoptosis and gene expression of two breast cancer cell lines with different ERalpha status. Overexpression of ERbeta1, but not of the exon-deleted variants exerted strong antitumoral effects both on ERalpha-positive MCF-7 and ERalpha-negative SK-BR-3 cells. ERbeta1 overexpression slowed growth of MCF-7 and SK-BR-3 cells in the absence of E2 and also inhibited E2-triggered growth stimulation of MCF-7 cells, but overexpression of the exon-skipped variants did not affect cell growth. Whereas overexpression of ERbeta1 triggered an increased basal and tamoxifen-induced apoptosis of MCF-7 and SK-BR-3 cells, the isoforms ERbetadelta125 or ERbetadelta1256 did not affect cellular tamoxifen response. The observed lack of function of the exon-deleted variants in terms of regulation of proliferation was accompanied both by their inability to affect expression of cyclins D1 and A2, p21 (WAF1) and PR and their disability to modulate estrogen response element (ERE) activation. In contrast, our results demonstrating antitumoral effects of ERbeta1 on breast cancer cells with different ERalpha-status support the hypothesis that ERbeta is able to exert antitumoral actions both on ERalpha-positive and -negative breast cancer cells.

The androgen receptor in prostate cancer: therapy target in search of an integrated diagnostic test

Despite the near ubiquitous use of therapies targeting the androgen receptor (AR) axis in prostate cancer, there remains, at this date, no integrated diagnostic test designed to select and individualize patients for hormonal-based treatments. From the article by Chmelar and coauthors, we may have a glimpse as to a way forward to the development of a test that can successfully guide the use of androgen ablation therapy. By turning our attention away from the AR gene and protein itself and focusing on coregulators of the AR pathway we may have a new opportunity to develop a single or group of slide-based tests designed to assess AR pathway status on the needle biopsy of a newly diagnosed prostate cancer patient and predict the clinical benefit of total androgen blockade treatment strategies.

PLD1 is overexpressed in an ER-negative MCF-7 cell line variant and a subset of phospho-Akt-negative breast carcinomas

We have used a novel variant of the human oestrogen receptor (ER)-positive MCF-7 cell line, TMX2-28, as a model to study breast cancer. TMX2-28 cells show no detectable levels of mRNA or protein expression for the ER and express basal cytokeratins (CKs) 5, 14, and 17. cDNA microarray comparison between TMX2-28 and its parent cell line, MCF-7, identified 1402 differentially expressed transcripts, one of which was, phospholipase D1 (PLD1). Using real-time RT–PCR, we confirmed that PLD1 mRNA levels are 10-fold higher in TMX2-28 cells than in MCF-7 cells. We next examined PLD1 expression in human breast carcinomas. Phospholipase D1 mRNA levels were higher in breast tumours that expressed high-mRNA levels of basal CKs 5 and/or 17, but PLD1 mRNA levels were not significantly higher in ER-negative tumours. Phospholipase D1 protein was overexpressed in 10 of 42 (24%) breast tumours examined by IHC. Phospholipase D1 was overexpressed in 6 of 31 ER-positive tumours and 4 of 11 ER-negative tumours. Phospholipase D1 was overexpressed in three of the four tumours that showed high CK5/17 expression. Five PLD1-positive tumours were negative for phospho-Akt expression, but positive for phospho-mammalian target of rapamycin (mTOR) expression. The other five PLD1-positive breast tumours showed positive expression for phospho-Akt; however, only two of these cases were positive for phospho-mTOR. In this study, we report that PLD1 and phospho-mTOR are coexpressed in a subset of phospho-Akt-negative breast carcinomas.

Delineation of molecular mechanisms of sensitivity to lapatinib in breast cancer cell lines using global gene expression profiles

Lapatinib (GW572016) is a small-molecule dual inhibitor of epidermal growth factor receptor (ErbB1) and ErbB2 receptor kinase activities currently in phase III clinical trials. We used phosphoprotein and microarray analyses to carry out targeted pathway studies of phosphorylation and gene expression changes in human breast cancer cell lines in the presence or absence of lapatinib. Studies were done in four breast cancer cell lines, two of which were responsive and two of which were nonresponsive to lapatinib. Responsive cell lines, BT474 and SKBr3, constitutively overexpress ErbB2 and show an IC(50) of 25 or 32 nmol/L for lapatinib, respectively. In contrast, nonresponsive MDA-MB-468 and T47D cells expressed a low basal level of ErbB2 and showed IC(50) values in the micromolar range. Cells responsive to lapatinib exhibited strong differential effects on multiple genes in the AKT pathway. After 12 h of exposure to 1.0 micromol/L of lapatinib, AKT1, MAPK9, HSPCA, IRAK1, and CCND1 transcripts were down-regulated 7- to 25-fold in responsive BT474 and SKBr3 cells. In contrast, lapatinib weakly down-regulated the AKT pathway in nonresponsive breast cancer cell lines (<5-fold down-regulation of most genes in the pathway). Furthermore, the proapoptotic gene FOXO3A, which is negatively regulated by AKT, was up-regulated 7- and 25-fold in lapatinib-responsive SKBr3 and BT474 cells, respectively. Phosphorylated Akt and Akt-mediated phosphorylation of FOXO3A also decreased in responsive breast cancer cell lines exposed to lapatinib. Gene expression profiling also revealed that lapatinib stimulated the expression of estrogen and progesterone receptors and modulated the expression of genes involved in cell cycle control, glycolysis, and fatty acid metabolism. In BT474 and T47D cells, which expressed moderate basal levels of the estrogen and progesterone receptors, 1.0 micromol/L of lapatinib induced expression by 7- to 11-fold. These data provide insight into the mechanism of action of lapatinib in breast cancer cells.

Age interacts with the expression of steroid and HER-2 receptors in operable invasive breast cancer

BACKGROUND

The negative association between the oestrogen receptor (ER) and the human epidermal growth factor receptor 2 (HER-2) in breast cancer travels in both directions. ER+ tumours are less likely HER-2+ and HER-2+ tumours are less likely ER+.

METHODS

We studied the age-related immunohistochemical (IHC) expression of ER, progesterone receptor (PR) and HER-2 in 2,227 tumours using age as a continuous variable. Steroid receptors were considered positive for any nuclear staining of invasive cancer cells and for HER-2, either for strong expression by IHC (score 3+) or gene amplification by fluorescence in situ hybridisation (FISH). Based on nonparametric regression, the age-related association between steroid receptors and HER-2 was presented as likelihood curves.

RESULTS

The association between ER or PR and HER-2 is age-related. The age-related expression of ER and PR is HER-2 dependent. In HER-2(-) cases, the odds ratio (OR) for being ER+ was 2.594 (95% CI = 1.874-3.591) up to age 50 and age-independent thereafter; for PR-expression the OR was 2.687 (95% CI = 1.780-4.057) up to age 45 and 0.847 (95% CI = 0.761-0.942) thereafter. In HER-2+ cases, the OR was 0.806 (95% CI = 0.656-0.991) to be ER+ and 0.722 (95% CI = 0.589-0.886) to be PR+. The age-related OR for breast cancers to be HER-2+ is steroid receptor dependent. Taking together, ER+PR+HER-2+ breast cancers appear on average 5.4 years earlier than breast cancers of any other ER/PR/HER-2 phenotype (95% CI = 3.3-7.5; P < 0.0001).

CONCLUSION

There is a qualitative interaction between age and expression of steroid and HER-2 receptors. Our findings suggest a strong age-related selective growth advantage for breast tumour cells belonging to the ER+PR+HER-2+ subgroup.

COUP-TFI modulates estrogen signaling and influences proliferation, survival and migration of breast cancer cells

We previously showed that COUP-TFI interacts with the Estrogen Receptor alpha (ER alpha) to recruit Extracellular signal Regulated Kinases (ERKs) in an Estradiol (E2)-independent manner, resulting in an enhancement of ER alpha transcriptional activity. However, the involvement of COUP-TFI in physiologically relevant functions of ER alpha, such as the mitogenic activity that E2 has on breast cancer cells, remains poorly understood. Here, we first showed that the amounts of COUP-TFI protein are higher in dedifferentiated mammary cell lines (MDA-MB-231) and tumor breast cells as compared to the differentiated MCF-7 cell line and normal breast cells. To evaluate the functional relevance of the COUP-TFI/ER alpha interplay in mammary cells, we generated MCF-7 cells that stably over-express COUP-TFI. We found that the over-expression of COUP-TFI enhances motility and invasiveness of MCF-7 cells. COUP-TFI also promotes the proliferation of MCF-7 cells through ER alpha-dependent mechanisms that target cell cycle progression and cell survival. To further investigate the mechanisms underlying these effects of COUP-TFI, we evaluated the expression of known E2-target genes in breast cancer, and found that COUP-TFI differentially regulated genes involved in cell proliferation, apoptosis, and migration/invasion. Notably, Cathepsin D (CTSD) transcript and protein levels were significantly higher in presence and absence of E2 in MCF-7 over-expressing COUP-TFI. Chromatin Immunoprecipitation assays showed that ER alpha, phospho-RNA Polymerase II, as well as p68 RNA Helicase, a phospho-Serine 118 dependent co-activator of ER alpha, were preferentially recruited onto the CTSD gene proximal promoter in COUP-TFI over-expressing cells. These results suggest that COUP-TFI selectively regulates the expression of endogenous E2-target genes and consequently modifies ER alpha positive mammary cells response to E2.

Vasoactive intestinal peptide (VIP) increases vascular endothelial growth factor (VEGF) expression and secretion in human breast cancer cells

Previous studies have shown that vasoactive intestinal peptide (VIP) and its receptors (VPAC(1) and VPAC(2) receptors) are involved in promotion and growth of many human tumours including breast cancer. Here we investigated whether VIP regulates the expression of the main angiogenic factor, vascular endothelial cell growth factor (VEGF) in human oestrogen-dependent (T47D) and oestrogen-independent (MDA-MB-4687) breast cancer cells. Semiquantitative and quantitative real-time RT-PCRs were used at mRNA level whereas enzyme immunoanalysis was performed at protein level. Both cancer cell lines expressed VIP and VPAC(1) (but not VPAC(2)) receptors that were functional as shown by VIP stimulation of adenylate cyclase activity. VIP induced VEGF expression at both mRNA and protein levels following a time-dependent pattern. The responses were faster in T47D than in MDA-MB-468 cells. The observed VIP regulation of VEGF expression appears to be modulated at least by the cAMP/protein kinase A (PKA) and the phosphoinositide 3-kinase (PI3-K) signalling systems as shown by studies of adenylate cyclase stimulation and using specific kinase inhibitors such as H89 and wortmannin. These actions suggest a proangiogenic potential of VIP in breast cancer.

Estrogen-regulated gene networks in human breast cancer cells: involvement of E2F1 in the regulation of cell proliferation

Estrogens generally stimulate the proliferation of estrogen receptor (ER)-containing breast cancer cells, but they also suppress proliferation of some ER-positive breast tumors. Using a genome-wide analysis of gene expression in two ER-positive human breast cancer cell lines that differ in their proliferative response to estrogen, we sought to identify genes involved in estrogen-regulated cell proliferation. To this end, we compared the transcriptional profiles of MCF-7 and MDA-MB-231ER+ cells, which have directionally opposite 17beta-estradiol (E2)-dependent proliferation patterns, MCF-7 cells being stimulated and 231ER+ cells suppressed by E2. We identified a set of approximately 70 genes regulated by E2 in both cells, with most being regulated by hormone in an opposite fashion. Using a variety of bioinformatics approaches, we found the E2F binding site to be overrepresented in the potential regulatory regions of many cell cycle-related genes stimulated by estrogen in MCF-7 but inhibited by estrogen in 231ER+ cells. Biochemical analyses confirmed that E2F1 and E2F downstream target genes were increased in MCF-7 and decreased in 231ER+ cells upon estrogen treatment. Furthermore, RNA interference-mediated knockdown of E2F1 blocked estrogen regulation of E2F1 target genes and resulted in loss of estrogen regulation of proliferation. These results demonstrate that regulation by estrogen of E2F1, and subsequently its downstream target genes, is critical for hormone regulation of the proliferative program of these breast cancer cells, and that gene expression profiling combined with bioinformatic analyses of transcription factor binding site enrichment in regulated genes can identify key components associated with nuclear receptor hormonal regulation of important cellular functions.

Improved biochemical strategies for targeted delivery of taxoids

Paclitaxel (Taxol) and docetaxel (Taxotere) are very important anti-tumor drugs in clinical use for cancer. However, their clinical utility is limited due to systemic toxicity, low solubility and inactivity against drug resistant tumors. To improve chemotherapeutic levels of these drugs, it would be highly desirable to design strategies which bypass the above limitations. In this respect various prodrug and drug targeting strategies have been envisioned either to improve oral bioavailability or tumor specific delivery of taxoids. Abnormal properties of cancer cells with respect to normal cells have guided in designing of these protocols. This review article records the designed biochemical strategies and their biological efficacies as potential taxoid chemotherapeutics.

Standardizing Slide-Based Assays in Breast Cancer: Hormone Receptors, HER2, and Sentinel Lymph Nodes

Despite the rapid expansion of novel diagnostics designed to personalize breast cancer care, there remain several significant unmet needs for improving the accuracy and reliability of tests that are already in common daily clinical practice. For example, although immunohistochemistry has been the predominant method for measuring estrogen receptor and progesterone receptor status for over 15 years, this assay remains unstandardized and there is a widespread concern that inaccuracy in immunohistochemistry technique and interpretation is leading to an unacceptably high error rate in determining the true hormone receptor status. Similarly, there is considerable concern that both false-negative and false-positive result rates for testing for HER2 status are unacceptably high in current clinical practice. This commentary considers a variety of factors, including preanalytic conditions and slide-scoring procedures, and other variables that may be contributing to current testing error rates and why there is a great need for the standardization of these biomarker assay procedures to further enable the highest possible quality of care for newly diagnosed breast cancer patients.

Hormone receptor status, tumor characteristics, and prognosis: a prospective cohort of breast cancer patients

Background

Breast cancer patients with tumors that are estrogen receptor (ER)-positive and/or progesterone receptor (PR)-positive have lower risks of mortality after their diagnosis compared to women with ER- and/or PR-negative disease. However, few studies have evaluated variations in the risks of breast cancer-specific mortality across ER/PR status by either demographic or clinical characteristics.

Methods

Using data from 11 population-based cancer registries that participate in the SEER (Surveillance, Epidemiology, and End Results) program, 155,175 women at least 30 years old with a primary diagnosis of invasive breast carcinoma from 1990 to 2001 were included in the study. Associations between joint hormone receptor status and breast cancer mortality risk within categories of diagnosis age, diagnosis year, race/ethnicity, histologic tumor type, stage, grade, size, and axillary lymph node status were evaluated using the Cox proportional hazards model.

Results

Compared to ER+/PR+ cases, elevations in risk of mortality were observed across all subcategories of age at diagnosis, ranging from 1.2- to 1.5-fold differences for ER+/PR- cases, 1.5- to 2.1-fold differences for ER-/PR+ cases, and 2.1- to 2.6-fold differences for ER-/PR- cases. Greater differences were observed in analyses stratified by grade; among women with low-grade lesions, ER-/PR- patients had a 2.6-fold (95% confidence interval [CI] 1.7 to 3.9) to 3.1-fold (95% CI 2.8 to 3.4) increased risk of mortality compared to ER+/PR+ patients, but among women with high-grade lesions, they had a 2.1-fold (95% CI 1.9 to 2.2) to 2.3-fold (95% CI 1.8 to 2.8) increased risk.

Conclusion

Compared to women with ER+/PR+ tumors, women with ER+/PR-, ER-/PR+, or ER-/PR- tumors experienced higher risks of mortality, which were largely independent of the various demographic and clinical tumor characteristics assessed in this study. The higher relative mortality risks identified among ER-/PR- patients with small or low-grade tumors raise the question of whether there may be a beneficial role for adjuvant chemotherapy in this population.

Prognostic implications of HER-2 status in steroid receptor-positive, lymph node-negative breast carcinoma

Patients with lymph node-negative breast carcinoma (LNNBC) and positive hormone receptor (HR) status during estrogen-based endocrine therapy have different prognoses. The contribution of HER-2 (human epidermal growth factor receptor-2) has not been extensively evaluated. We stained 230 LNNBCs for estrogen and progesterone receptors (ER and PR) and HER-2. HER-2 gene status was studied in 150 randomly selected tumors by chromogenic in situ hybridization and cases with discordant or nondefinitive results by fluorescence in situ hybridization. Patients with ER+ and/or PR+ tumors were treated with tamoxifen. We found positive expression of ER, PR, and HER-2 in 73.7%, 67%, and 27.8%, respectively, and HER-2 amplification in 18.0%. Poorer outcome was seen for patients with ER+ and/or PR+/HER-2 overexpressing tumors and as a trend for patients with HER-2 amplification. ER/PR and HER-2 expression showed an independent prognostic value. In LNNBCs with positive HR status, HER-2 overexpression and/or amplification confer an aggressive tumor phenotype, and this might be related to tamoxifen unresponsiveness.

Risk factors for hormone receptor-defined breast cancer in postmenopausal women

The effect of classic breast cancer risk factors on hormone receptor-defined breast cancer is not fully clarified. We explored these associations in a Swedish population-based study. Postmenopausal women ages 50 to 74 years, diagnosed with invasive breast cancer during 1993 to 1995, were compared with 3,065 age frequency-matched controls. We identified 332 estrogen receptor (ER-) and progesterone receptor (PR-) negative, 286 ER+PR-, 71 ER-PR+, 1,165 ER+PR+, and 789 tumors with unknown receptor status. Unconditional logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (95% CI). Women ages >or=30 years, compared with those ages 20 to 24 years at first birth, were at an increased risk of ER+PR+ tumors (OR, 1.5; 95% CI, 1.2-1.8) but not ER-PR- tumors (OR, 1.1; 95% CI, 0.8-1.6). Women who gained >or=30 kg in weight during adulthood had an approximately 3-fold increased relative risk of ER+PR+ tumors (OR, 2.7; 95% CI, 1.9-3.8), but no risk increase of ER-PR- tumors (OR, 1.0; 95% CI, 0.5-2.1), compared with women who gained <10 kg. Compared with never users, women who used menopausal estrogen-progestin therapy for at least 5 years were at increased risk of ER+PR+ tumors (OR, 3.0; 95% CI, 2.1-4.1) but not ER-PR- tumors (OR, 1.3; 95% CI, 0.7-2.5). In conclusion, other risk factors were similarly related to breast cancer regardless of receptor status, but high age at first birth, substantial weight gain in adult age, and use of menopausal estrogen-progestin therapy were more strongly related to receptor-positive breast cancer than receptor-negative breast cancer.

A single nucleotide polymorphism in the p53 pathway interacts with gender, environmental stresses and tumor genetics to influence cancer in humans

Cancer biology finds itself in a post-genomic era and the hopes of using inherited genetic variants to improve prevention and treatment strategies are widespread. One of the largest types of inherited genetic variation is the single nucleotide polymorphism (SNP), of which there are at least 4.5 million. The challenge now becomes how to discover which polymorphisms alter cancer in humans and how to begin to understand their mechanism of action. In this report, a series of recent publications will be reviewed that have studied a polymorphism in the p53 tumor suppressor pathway, MDM2 SNP309. These reports have lent insights into how germline genetic variants of the p53 pathway could interact with gender, environmental stresses and tumor genetics to affect cancer in humans. Importantly, these observations have also exposed potential nodes of intervention, which could prove valuable in both the prevention and treatment of this disease in humans.

New perspectives into the biological and clinical relevance of oestrogen receptors in the human breast

Oestrogen receptor (ER) is arguably the single most important biological predictive factor that exists today. In the last 10 years or so, however, our understanding of ER biology has undergone a paradigm shift following the identification of a second ER, ERbeta, with the original ER being renamed ERalpha. A number of isoforms have additionally been described, especially for ERbeta. Our knowledge of ER signalling has also increased with the recognition of accessory co-regulatory proteins, which help direct the transcriptional cascade. Here we outline these changes and discuss what biological and clinical implications these could have in the mammary gland.

Estrogen receptor-beta regulates psoriasin (S100A7) in human breast cancer

We have previously observed a paradoxical relationship of the psoriasin/S100A7 gene with estrogen response in-vitro in ERalpha positive cells but its association with ERalpha negative status in-vivo raising the possibility that S100A7 might be regulated by ERbeta in breast cancer. Using doxycycline-inducible ERbeta and ERalpha expressing MCF-7 cells the hypothesis that psoriasin/S100A7 is ERbeta regulated was investigated To explore the relationship between psoriasin/S100A7 and ERbeta expression in-vivo, we also assessed a cohort of 233 ERalpha negative breast tumors using tissue microarrays and immunohistochemistry. Psoriasin/S100A7 was increased by 17beta-estradiol (E2) following ERbeta induction, in several clones of ERbeta over-expressing but not in the original MCF-7 cells, nor clones over-expressing ERalpha. The effect of E2 on psoriasin/S100A7 was inhibited by 4-hydroxytamoxifen and ICI 182780 but not with a selective ERalpha antagonist. An ERbeta selective-agonist but not an ERalpha selective-agonist, induced psoriasin/S100A7. This induction still occurred after stable down-regulation of ERalpha using siRNA in ERbeta inducible cells. E2 increased psoriasin/S100A7 mRNA but cycloheximide treatment inhibited this effect. A relationship between ERbeta and psoriasin/S100A7 was observed in the p53 immunohistochemically negative subset of invasive breast tumors in-vivo (r = 0.225, p = 0.046, n = 79). In conclusion we demonstrate that E2 induction of psoriasin/S100A7 can be specifically regulated through ERbeta in-vitro and associated with ERbeta in-vivo. These data support the hypothesis that psoriasin/S100A7 is specifically regulated by ERbeta activity and could be useful to guide future therapies targeting ERbeta in certain phenotypic subsets of breast cancers in-vivo.

Geographic patterns of advanced breast cancer in Los Angeles: associations with biological and sociodemographic factors (United States)

OBJECTIVE

Examination of patterns of advanced breast cancer may provide evidence needed to direct health care resources to those communities or population groups in greatest need. We assessed to what degree biologic, ethnic, and sociodemographic factors could explain such patterns within Los Angeles County.

METHODS

The proportion of cases of advanced disease among all breast cancer cases identified during 1992-1996 were analyzed using generalized linear mixed models with random census tract effects. Models included characteristics of the individual and her tumor, census tract of residence, and aggregated health districts.

RESULTS

Approximately 6% of cases, ranging from 4% for Asian to 10% for Black women, were diagnosed as advanced, exhibiting striking geographic patterns. Tumor histology and hormone receptor status were most predictive of advanced disease. Sociodemographic variables such as marital status, median income, and distance to nearest mammography unit showed additional association with risk.

CONCLUSIONS

These models explain most of the geographical patterns and eliminate differences between White and Hispanic but not Asian or Black women, identify subpopulations at high risk of advanced disease, and suggest cancer control opportunities.

Breast cancer proteomics by laser capture microdissection, sample pooling, 54-cm IPG IEF, and differential iodine radioisotope detection

The presence of progesterone receptor (PR) in estrogen receptor (ER)-positive breast cancer is associated with a good prognosis, and indicates that tumors are likely to respond to tamoxifen. However, ER+/PR- tumors respond less well. To reveal the potential molecular mechanism of this phenomenon, we sought to identify differential protein abundances between invasive ductal carcinoma cells from cryopreserved ER+/PR+ and ER+/PR- mammary tumor specimens. Because current proteomics methods are hampered in the examination of most primary human tumor samples by the extreme tissue heterogeneity, we used laser capture microdissection (LCM) to isolate tumor cells and developed a sample pooling strategy to analyze small sample protein lysates. Proteins from LCM-harvested tumors were pooled into four sub-pools from each condition of three tumors/sub-pool, and proteins from respective paired sub-pools were co-electrophoresed by 2-DE using 54-cm IEF over pH 4-9. Abundance ratios were accurately quantified by a differential multiplex radioactive ProteoTope method at low attomole levels ( approximately 3.6 microg protein per labeling reaction, <180 ng per multiplex protein sample per 54-cm gel). Applying this approach, differentially displayed proteins were identified by MS using comigrating non-radioactively labeled tumor proteins. They include decreased cytochrome b5 and transgelin, and more abundant CRABP-II, cyclophilin A, Neudesin, and hemoglobin in ER+/PR+ tumors versus ER+/PR- providing a possible explanation for differential susceptibility against tamoxifen as a result of deregulated cytochrome b5-dependent metabolism. This study demonstrates the potential of ProteoTope and LCM to enable extremely sensitive and precise differential analyses from well-defined primary clinical specimen.