Showing papers by "James N. Ingle published in 2014"

AXL induces epithelial-to-mesenchymal transition and regulates the function of breast cancer stem cells.

Abstract: Despite significant progress in the treatment of breast cancer, particularly through the use of targeted therapy, relapse and chemoresistance remain a major hindrance to the fight to minimize the burden of the disease. It is becoming increasingly clear that a rare subpopulation of cells known as cancer stem cells (CSC), able to be generated through epithelial-to-mesenchymal transition (EMT) and capable of tumor initiation and self-renewal, contributes to treatment resistance and metastases. This means that a more effective therapy should target both the chemoresistant CSCs and the proliferating epithelial cells that give rise to them to reverse EMT and to attenuate their conversion to CSCs. Here, we demonstrate a novel function of AXL in acting upstream to induce EMT in normal and immortalized human mammary epithelial cells in an apparent positive feedback loop mechanism and regulate breast CSC (BCSC) self-renewal and chemoresistance. Downregulation of AXL using MP470 (Amuvatinib) reversed EMT in mesenchymal normal human mammary epithelial cells and murine BCSCs attenuating self-renewal and restored chemosensitivity of the BCSCs. AXL expression was also found to be associated with the expression of stem cell genes, regulation of metastases genes, increased tumorigenicity and was important for BCSC invasion and migration. Inactivation of AXL also led to the downregulation of nuclear factor-κB pathway and reduced tumor formation in vivo. Taken together, our data suggest that targeted therapy against AXL, in combination with systemic therapies, has the potential to improve response to anticancer therapies and to reduce breast cancer recurrence and metastases.

Genome-wide association study identifies 25 known breast cancer susceptibility loci as risk factors for triple-negative breast cancer

Abstract: Triple-negative (TN) breast cancer is an aggressive subtype of breast cancer associated with a unique set of epidemiologic and genetic risk factors. We conducted a two-stage genome-wide association study of TN breast cancer (stage 1: 1529 TN cases, 3399 controls; stage 2: 2148 cases, 1309 controls) to identify loci that influence TN breast cancer risk. Variants in the 19p13.1 and PTHLH loci showed genome-wide significant associations (P < 5 × 10(-) (8)) in stage 1 and 2 combined. Results also suggested a substantial enrichment of significantly associated variants among the single nucleotide polymorphisms (SNPs) analyzed in stage 2. Variants from 25 of 74 known breast cancer susceptibility loci were also associated with risk of TN breast cancer (P < 0.05). Associations with TN breast cancer were confirmed for 10 loci (LGR6, MDM4, CASP8, 2q35, 2p24.1, TERT-rs10069690, ESR1, TOX3, 19p13.1, RALY), and we identified associations with TN breast cancer for 15 additional breast cancer loci (P < 0.05: PEX14, 2q24.1, 2q31.1, ADAM29, EBF1, TCF7L2, 11q13.1, 11q24.3, 12p13.1, PTHLH, NTN4, 12q24, BRCA2, RAD51L1-rs2588809, MKL1). Further, two SNPs independent of previously reported signals in ESR1 [rs12525163 odds ratio (OR) = 1.15, P = 4.9 × 10(-) (4)] and 19p13.1 (rs1864112 OR = 0.84, P = 1.8 × 10(-) (9)) were associated with TN breast cancer. A polygenic risk score (PRS) for TN breast cancer based on known breast cancer risk variants showed a 4-fold difference in risk between the highest and lowest PRS quintiles (OR = 4.03, 95% confidence interval 3.46-4.70, P = 4.8 × 10(-) (69)). This translates to an absolute risk for TN breast cancer ranging from 0.8% to 3.4%, suggesting that genetic variation may be used for TN breast cancer risk prediction.

Novel Methylated Biomarkers and a Robust Assay to Detect Circulating Tumor DNA in Metastatic Breast Cancer

Abstract: The ability to consistently detect cell-free tumor-specific DNA in peripheral blood of patients with metastatic breast cancer provides the opportunity to detect changes in tumor burden and to monitor response to treatment. We developed cMethDNA, a quantitative multiplexed methylation-specific PCR assay for a panel of ten genes, consisting of novel and known breast cancer hypermethylated markers identified by mining our previously reported study of DNA methylation patterns in breast tissue (103 cancer, 21 normal on the Illumina HumanMethylation27 Beadchip) and then validating the 10-gene panel in The Cancer Genome Atlas project breast cancer methylome database. For cMethDNA, a fixed physiologic level (50 copies) of artificially constructed, standard nonhuman reference DNA specific for each gene is introduced in a constant volume of serum (300 μL) before purification of the DNA, facilitating a sensitive, specific, robust, and quantitative assay of tumor DNA, with broad dynamic range. Cancer-specific methylated DNA was detected in training (28 normal, 24 cancer) and test (27 normal, 33 cancer) sets of recurrent stage IV patient sera with a sensitivity of 91% and a specificity of 96% in the test set. In a pilot study, cMethDNA assay faithfully reflected patient response to chemotherapy (N = 29). A core methylation signature present in the primary breast cancer was retained in serum and metastatic tissues collected at autopsy two to 11 years after diagnosis of the disease. Together, our data suggest that the cMethDNA assay can detect advanced breast cancer, and monitor tumor burden and treatment response in women with metastatic breast cancer.

Phase III Comparison of Tamoxifen Versus Tamoxifen Plus Ovarian Function Suppression in Premenopausal Women With Node-Negative, Hormone Receptor–Positive Breast Cancer (E-3193, INT-0142): A Trial of the Eastern Cooperative Oncology Group

Abstract: Purpose The effects of ovarian function suppression (OFS) on survival and patient-reported outcomes were evaluated in a phase III trial in which premenopausal women were randomly assigned to tamoxifen with or without OFS. Patients and Methods Premenopausal women with axillary node-negative, hormone receptor‐positive breast cancer tumors measuring 3 cm were randomly assigned to tamoxifen alone versus tamoxifen plus OFS; adjuvant chemotherapy was not permitted. Primary end points were disease-free survival (DFS) and overall survival (OS). Secondary end points included toxicity and patient-reported outcomes. Patient-reported outcome data included health-related quality of life, menopausal symptoms, and sexual function. These were evaluated at baseline, 6 months, 12 months, and then annually for up to 5 years after registration. Results In all, 345 premenopausal women were enrolled: 171 on tamoxifen alone and 174 on tamoxifen plus OFS. With a median follow-up of 9.9 years, there was no significant difference between arms for DFS (5-year rate: 87.9% v 89.7%; log-rank P .62) or OS (5-year rate: 95.2% v 97.6%; log-rank P .67). Grade 3 or higher toxicity was more common in the tamoxifen plus OFS arm (22.4% v 12.3%; P .004). Patients treated with tamoxifen plus OFS had more menopausal symptoms, lower sexual activity, and inferior health-related quality of life at 3-year follow-up (P .01 for all). Differences diminished with further follow-up. Conclusion When added to tamoxifen, OFS results in more menopausal symptoms and sexual dysfunction, which contributes to inferior self-reported health-related quality of life. Because of early closure, this study is underpowered for drawing conclusions about the impact on survival when adding OFS to tamoxifen. J Clin Oncol 32:3948-3958. © 2014 by American Society of Clinical Oncology

ERβ1: characterization, prognosis, and evaluation of treatment strategies in ERα-positive and -negative breast cancer.

Abstract: The role and clinical value of ERβ1 expression is controversial and recent data demonstrates that many ERβ antibodies are insensitive and/or non-specific. Therefore, we sought to comprehensively characterize ERβ1 expression across all sub-types of breast cancer using a validated antibody and determine the roles of this receptor in mediating response to multiple forms of endocrine therapy both in the presence and absence of ERα expression. Nuclear and cytoplasmic expression patterns of ERβ1 were analyzed in three patient cohorts, including a retrospective analysis of a prospective adjuvant tamoxifen study and a triple negative breast cancer cohort. To investigate the utility of therapeutically targeting ERβ1, we generated multiple ERβ1 expressing cell model systems and determined their proliferative responses following anti-estrogenic or ERβ-specific agonist exposure. Nuclear ERβ1 was shown to be expressed across all major sub-types of breast cancer, including 25% of triple negative breast cancers and 33% of ER-positive tumors, and was associated with significantly improved outcomes in ERα-positive tamoxifen-treated patients. In agreement with these observations, ERβ1 expression sensitized ERα-positive breast cancer cells to the anti-cancer effects of selective estrogen receptor modulators (SERMs). However, in the absence of ERα expression, ERβ-specific agonists potently inhibited cell proliferation rates while anti-estrogenic therapies were ineffective. Using a validated antibody, we have confirmed that nuclear ERβ1 expression is commonly present in breast cancer and is prognostic in tamoxifen-treated patients. Using multiple breast cancer cell lines, ERβ appears to be a novel therapeutic target. However, the efficacy of SERMs and ERβ-specific agonists differ as a function of ERα expression.

Quality of life in MAP.3 (Mammary Prevention 3): A randomized, placebo-controlled trial evaluating exemestane for prevention of breast cancer

Abstract: Purpose Exemestane, a steroidal aromatase inhibitor, reduced invasive breast cancer incidence by 65% among 4,560 postmenopausal women randomly assigned to exemestane (25 mg per day) compared with placebo in the National Cancer Institute of Canada (NCIC) Clinical Trials Group MAP.3 (Mammary Prevention 3) trial, but effects on quality of life (QOL) were not fully described. Patients and Methods Menopause-specific and health-related QOL were assessed by using the four Menopause-Specific Quality of Life Questionnaire (MENQOL) domains and the eight Medical Outcomes Study Short Form Health Survey (SF-36) scales at baseline, 6 months, and yearly thereafter. MENQOL questionnaire completion was high (88% to 98%) in both groups at each follow-up visit. Change scores for each MENQOL and SF-36 scale, calculated at each assessment time relative to baseline, were compared by using the Wilcoxon rank-sum test. Clinically important worsened QOL was defined as a MENQOL change score increase of more than 0.5 (of 8) points a...

Inhibition of Cdk2 kinase activity selectively targets the CD44+/CD24−/Low stem-like subpopulation and restores chemosensitivity of SUM149PT triple-negative breast cancer cells

Abstract: Inflammatory breast cancer (IBC) is an angioinvasive and most aggressive type of advanced breast cancer characterized by rapid proliferation, chemoresistance, early metastatic development and poor prognosis. IBC tumors display a triple-negative breast cancer (TNBC) phenotype characterized by centrosome amplification, high grade of chromosomal instability (CIN) and low levels of expression of estrogen receptor α (ERα), progesterone receptor (PR) and HER-2 tyrosine kinase receptor. Since the TNBC cells lack these receptors necessary to promote tumor growth, common treatments such as endocrine therapy and molecular targeting of HER-2 receptor are ineffective for this subtype of breast cancer. To date, not a single targeted therapy has been approved for non-inflammatory and inflammatory TNBC tumors and combination of conventional cytotoxic chemotherapeutic agents remains the standard therapy. IBC tumors generally display activation of epithelial to mesenchymal transition (EMT) that is functionally linked to a CD44+/CD24−/Low stem-like phenotype. Development of EMT and consequent activation of stemness programming is responsible for invasion, tumor self-renewal and drug resistance leading to breast cancer progression, distant metastases and poor prognosis. In this study, we employed the luminal ER+ MCF-7 and the IBC SUM149PT breast cancer cell lines to establish the extent to which high grade of CIN and chemoresistance were mechanistically linked to the enrichment of CD44+/CD24low/− CSCs. Here, we demonstrate that SUM149PT cells displayed higher CIN than MCF-7 cells characterized by higher percentage of structural and numerical chromosomal aberrations. Moreover, centrosome amplification, cyclin E overexpression and phosphorylation of retinoblastoma (Rb) were restricted to the stem-like CD44+/CD24−/Low subpopulation isolated from SUM149PT cells. Significantly, CD44+/CD24−/Low CSCs displayed resistance to conventional chemotherapy but higher sensitivity to SU9516, a specific cyclin-dependent kinase 2 (Cdk2) inhibitor, demonstrating that aberrant activation of cyclin E/Cdk2 oncogenic signaling is essential for the maintenance and expansion of CD44+/CD24−/Low CSC subpopulation in IBC. In conclusion, our findings propose a novel therapeutic approach to restore chemosensitivity and delay recurrence of IBC tumors based on the combination of conventional chemotherapy with small molecule inhibitors of the Cdk2 cell cycle kinase.

Effects of adjuvant exemestane versus anastrozole on bone mineral density for women with early breast cancer (MA.27B): a companion analysis of a randomised controlled trial

Abstract: Summary Background Treatment of breast cancer with aromatase inhibitors is associated with damage to bones. NCIC CTG MA.27 was an open-label, phase 3, randomised controlled trial in which women with breast cancer were assigned to one of two adjuvant oral aromatase inhibitors—exemestane or anastrozole. We postulated that exemestane—a mildly androgenic steroid—might have a less detrimental effect on bone than non-steroidal anastrozole. In this companion study to MA.27, we compared changes in bone mineral density (BMD) in the lumbar spine and total hip between patients treated with exemestane and patients treated with anastrozole. Methods In MA.27, postmenopausal women with early stage hormone (oestrogen) receptor-positive invasive breast cancer were randomly assigned to exemestane 25 mg versus anastrozole 1 mg, daily. MA.27B recruited two groups of women from MA.27: those with BMD T-scores of −2·0 or more (up to 2 SDs below sex-matched, young adult mean) and those with at least one T-score (hip or spine) less than −2·0. Both groups received vitamin D and calcium; those with baseline T-scores of less than −2·0 also received bisphosphonates. The primary endpoints were percent change of BMD at 2 years in lumbar spine and total hip for both groups. We analysed patients according to which aromatase inhibitor and T-score groups they were allocated to but BMD assessments ceased if patients deviated from protocol. This study is registered with ClinicalTrials.gov, NCT00354302. Findings Between April 24, 2006, and May 30, 2008, 300 patients with baseline T-scores of −2·0 or more were accrued (147 allocated exemestane, 153 anastrozole); and 197 patients with baseline T-scores of less than −2·0 (101 exemestane, 96 anastrozole). For patients with T-scores greater than −2·0 at baseline, mean change of bone mineral density in the spine at 2 years did not differ significantly between patients taking exemestane and patients taking anastrozole (−0·92%, 95% CI −2·35 to 0·50 vs −2·39%, 95% CI −3·77 to −1·01; p=0·08). Respective mean loss in the hip was −1·93% (95% CI −2·93 to −0·93) versus −2·71% (95% CI −4·32 to −1·11; p=0·10). Likewise for those who started with T-scores of less than −2·0, mean change of spine bone mineral density at 2 years did not differ significantly between the exemestane and anastrozole treatment groups (2·11%, 95% CI −0·84 to 5·06 vs 3·72%, 95% CI 1·54 to 5·89; p=0·26), nor did hip bone mineral density (2·09%, 95% CI −1·45 to 5·63 vs 0·0%, 95% CI −3·67 to 3·66; p=0·28). Patients with baseline T-score of −2·0 or more taking exemestane had two fragility fractures and two other fractures, those taking anastrozole had three fragility fractures and five other fractures. For patients who had baseline T-scores of less than −2·0 taking exemestane, one had a fragility fracture and four had other fractures, whereas those taking anastrozole had five fragility fractures and one other fracture. Interpretation Our results demonstrate that adjuvant treatment with aromatase inhibitors can be considered for breast cancer patients who have T-scores less than −2·0. Funding Canadian Cancer Society Research Institute, Pfizer, Canadian Institutes of Health Research.

Aromatase inhibitor-associated bone fractures: a case-cohort GWAS and functional genomics.

Abstract: Bone fractures are a major consequence of osteoporosis. There is a direct relationship between serum estrogen concentrations and osteoporosis risk. Aromatase inhibitors (AIs) greatly decrease serum estrogen levels in postmenopausal women, and increased incidence of fractures is a side effect of AI therapy. We performed a discovery case-cohort genome-wide association study (GWAS) using samples from 1071 patients, 231 cases and 840 controls, enrolled in the MA.27 breast cancer AI trial to identify genetic factors involved in AI-related fractures, followed by functional genomic validation. Association analyses identified 20 GWAS single nucleotide polymorphism (SNP) signals with P < 5E-06. After removal of signals in gene deserts and those composed entirely of imputed SNPs, we applied a functional validation "decision cascade" that resulted in validation of the CTSZ-SLMO2-ATP5E, TRAM2-TMEM14A, and MAP4K4 genes. These genes all displayed estradiol (E2)-dependent induction in human fetal osteoblasts transfected with estrogen receptor-α, and their knockdown altered the expression of known osteoporosis-related genes. These same genes also displayed SNP-dependent variation in E2 induction that paralleled the SNP-dependent induction of known osteoporosis genes, such as osteoprotegerin. In summary, our case-cohort GWAS identified SNPs in or near CTSZ-SLMO2-ATP5E, TRAM2-TMEM14A, and MAP4K4 that were associated with risk for bone fracture in estrogen receptor-positive breast cancer patients treated with AIs. These genes displayed E2-dependent induction, their knockdown altered the expression of genes related to osteoporosis, and they displayed SNP genotype-dependent variation in E2 induction. These observations may lead to the identification of novel mechanisms associated with fracture risk in postmenopausal women treated with AIs.

Re: Concordance Between CYP2D6 Genotypes Obtained From Tumor-Derived and Germline DNA

Abstract: The accuracy of CYP2D6 genotyping and its value for the prediction of tamoxifen outcome are a matter of intense debate (1–11). Technical issues related to genotyping of DNA derived from tumor cores and the resultant unprecedented violation of Hardy-Weinberg equilibrium (HWE) (2) has been at the heart of this debate. Rae et al. (12) published new information comparing CYP2D6 genotypes obtained from various tissue sources. They conclude that “based on less than 10% misclassification rate … this could not alter the conclusions of the CYP2D6 BIG1-98 investigation” (12). We applaud Rae and colleagues for obtaining CYP2D6 genotypes within HWE; however, their results and conclusions are irrelevant to our concerns regarding the validity of the BIG 1-98 data (2). That is, Rae et al. did not duplicate the methods of BIG 1-98, where formalin-fixed, paraffin-embedded (FFPE) tumor cores obtained for somatic biomarker studies were used for DNA extraction and CYP2D6 genotypes (obtained after upward of 60 polymerase chain reaction [PCR] cycles (5)) demonstrated massive deviation from HWE (P = 2.5×10-92). Instead, Rae et al. utilized FFPE cores containing some normal tissue and standard PCR methodology. In his editorial, Berry compared the North Central Cancer Treatment Group (NCCTG) 89-30-52 (13) and BIG 1-98 data (2) (both used tumor cores), and argues that “since both studies had the same HWE status, the Regan study was resoundingly clear in failing to corroborate the Goetz observation” (14). Berry seems to accept the argument that deletion of the CYP2D6 gene in breast tumor tissue is driving the observed departures from HWE, but inappropriately argues that the genomic constitution of the tumor is the relevant aspect of genome biology to consider, even though it is inherited variation in the germline that alters plasma endoxifen concentrations. To address NCCTG 89-30-52 HWE issues (13), CYP2D6 genotyping was repeated at Mayo using DNA from FFPE tissue blocks containing nonmalignant tissue as previously published (1) and submitted to the International Tamoxifen Pharmacogenomics Consortium (ITPC) (15). The CYP2D6*4 genotype met HWE (P = .28) and the CYP2D6 genotype was statistically significantly associated with the risk of recurrence, both within NCCTG 89-30-52 and in postmenopausal ITPC patients receiving tamoxifen monotherapy for five years at 20mg/day (15). To address Berry’s concerns that the ITPC results were “ad hoc,” a secondary analysis in the prospective ABCSG 8 clinical trial (using similar eligibility criteria as ITPC) demonstrated that CYP2D6 genotype was statistically significantly associated with the risk of recurrence or death (8). Medical practice and the evidence supporting it must pass accepted scientific standards. Data that cannot pass minimal standards for quality cannot be used to test hypotheses critically related to patient care. It is unquestionably true that the oncology community generally focuses on the tumor genome to direct treatment decisions. But because tamoxifen is metabolized in the liver, it is the germline genome that is relevant for considering its metabolism. Using tumor genome data to classify individuals with respect to their ability to metabolize tamoxifen is scientifically, medically, and practically inappropriate when an unacceptably high proportion of individuals will be misclassified with respect to their ability to metabolize tamoxifen. Does HWE matter? Assuredly, yes, from any rational point of view.

Aurora-A mitotic kinase induces endocrine resistance through down-regulation of ERα expression in initially ERα+ breast cancer cells.

Abstract: Development of endocrine resistance during tumor progression represents a major challenge in the management of estrogen receptor alpha (ERα) positive breast tumors and is an area under intense investigation. Although the underlying mechanisms are still poorly understood, many studies point towards the ‘cross-talk’ between ERα and MAPK signaling pathways as a key oncogenic axis responsible for the development of estrogen-independent growth of breast cancer cells that are initially ERα+ and hormone sensitive. In this study we employed a metastatic breast cancer xenograft model harboring constitutive activation of Raf-1 oncogenic signaling to investigate the mechanistic linkage between aberrant MAPK activity and development of endocrine resistance through abrogation of the ERα signaling axis. We demonstrate for the first time the causal role of the Aurora-A mitotic kinase in the development of endocrine resistance through activation of SMAD5 nuclear signaling and down-regulation of ERα expression in initially ERα+ breast cancer cells. This contribution is highly significant for the treatment of endocrine refractory breast carcinomas, because it may lead to the development of novel molecular therapies targeting the Aurora-A/SMAD5 oncogenic axis. We postulate such therapy to result in the selective eradication of endocrine resistant ERαlow/− cancer cells from the bulk tumor with consequent benefits for breast cancer patients.

TGFβ inducible early gene-1 plays an important role in mediating estrogen signaling in the skeleton.

Abstract: TGFβ Inducible Early Gene-1 (TIEG1) knockout (KO) mice display a sex-specific osteopenic phenotype characterized by low bone mineral density, bone mineral content, and overall loss of bone strength in female mice. We, therefore, speculated that loss of TIEG1 expression would impair the actions of estrogen on bone in female mice. To test this hypothesis, we employed an ovariectomy (OVX) and estrogen replacement model system to comprehensively analyze the role of TIEG1 in mediating estrogen signaling in bone at the tissue, cell, and biochemical level. Dual-energy X-ray absorptiometry (DXA), peripheral quantitative computed tomography (pQCT), and micro-CT analyses revealed that loss of TIEG1 expression diminished the effects of estrogen throughout the skeleton and within multiple bone compartments. Estrogen exposure also led to reductions in bone formation rates and mineralizing perimeter in wild-type mice with little to no effects on these parameters in TIEG1 KO mice. Osteoclast perimeter per bone perimeter and resorptive activity as determined by serum levels of CTX-1 were differentially regulated after estrogen treatment in TIEG1 KO mice compared with wild-type littermates. No significant differences were detected in serum levels of P1NP between wild-type and TIEG1 KO mice. Taken together, these data implicate an important role for TIEG1 in mediating estrogen signaling throughout the mouse skeleton and suggest that defects in this pathway are likely to contribute to the sex-specific osteopenic phenotype observed in female TIEG1 KO mice.

SWOG S0307 phase III trial of bisphosphonates as adjuvant therapy in primary breast cancer: Comparison of toxicities and patient-stated preference for oral versus intravenous delivery.

Abstract: 558 Background: Bone metastases are a common site of distant recurrence in breast cancer. Evidence from randomized trials, including a recent meta-analysis, suggests that adjuvant bisphosphonates c...

The Effects of a Novel Hormonal Breast Cancer Therapy, Endoxifen, on the Mouse Skeleton

Abstract: Endoxifen has recently been identified as the predominant active metabolite of tamoxifen and is currently being developed as a novel hormonal therapy for the treatment of endocrine sensitive breast cancer. Based on past studies in breast cancer cells and model systems, endoxifen classically functions as an anti-estrogenic compound. Since estrogen and estrogen receptors play critical roles in mediating bone homeostasis, and endoxifen is currently being implemented as a novel breast cancer therapy, we sought to comprehensively characterize the in vivo effects of endoxifen on the mouse skeleton. Two month old ovariectomized C57BL/6 mice were treated with vehicle or 50 mg/kg/day endoxifen hydrochloride via oral gavage for 45 days. Animals were analyzed by dual-energy x-ray absorptiometry, peripheral quantitative computed tomography, micro-computed tomography and histomorphometry. Serum from control and endoxifen treated mice was evaluated for bone resorption and bone formation markers. Gene expression changes were monitored in osteoblasts, osteoclasts and the cortical shells of long bones from endoxifen treated mice and in a human fetal osteoblast cell line. Endoxifen treatment led to significantly higher bone mineral density and bone mineral content throughout the skeleton relative to control animals. Endoxifen treatment also resulted in increased numbers of osteoblasts and osteoclasts per tissue area, which was corroborated by increased serum levels of bone formation and resorption markers. Finally, endoxifen induced the expression of osteoblast, osteoclast and osteocyte marker genes. These studies are the first to examine the in vivo and in vitro impacts of endoxifen on bone and our results demonstrate that endoxifen increases cancellous as well as cortical bone mass in ovariectomized mice, effects that may have implications for postmenopausal breast cancer patients.

Genes associated with serum estrone, estrone conjugates, and androstenedione concentrations in postmenopausal women with estrogen receptor-positive breast cancer.

Abstract: 593 Background: Estrone (E1), the predominant estrogen in postmenopausal women, is synthesized from androstenedione (A) in the ovaries and adipocytes and can be converted to conjugates (E1Cs). Both...