Project description:dataset of 60 patients with ER-positive primary breast cancer and treated with tamoxifen monotherapy for 5 years. Data were generated from whole tissue sections of breast cancers. Sample_keyword: breast cancer, tamoxifen, recurrence Keywords: other
Project description:dataset of 60 patients with ER-positive primary breast cancer and treated with tamoxifen monotherapy for 5 years. Data were generated from LCMed cancer cells. Sample_keyword: breast cancer, tamoxifen, recurrence Keywords: other
Project description:Five years of tamoxifen reduces breast cancer risk by nearly 50% but is associated with significant side-effects and toxicities. A better understanding of the direct and indirect effects of tamoxifen in benign breast tissue could elucidate new mechanisms of breast carcinogenesis, suggest novel chemoprevention targets, and provide relevant early response biomarkers for Phase II prevention trials. Seventy-three women at increased risk for breast cancer were randomized to tamoxifen (20 mg daily) or placebo for three months. Blood and breast tissue samples were collected at baseline and post-treatment. Sixty-nine women completed all study activities (37 tamoxifen and 32 placebo). The selected biomarkers focused on estradiol and IGFs in the blood, DNA methylation and cytology in random periareolar fine needle aspirates, and tissue morphometry, proliferation, apoptosis, and gene expression (microarray and RT-PCR) in the tissue core samples. Tamoxifen downregulated ets-oncogene family members ETV4 and ETV5 and reduced breast epithelial cell proliferation independent of CYP2D6 genotypes or effects on estradiol, ESR1 or IGFs. Reduction in proliferation was correlated with downregulation of ETV4 and DNAJC12. Tamoxifen also modulated expression of RAB GTPases, and several genes involved in epithelial-stromal interaction, and reduced tumor suppressor gene methylation. Three months of tamoxifen did not affect breast tissue composition, cytological atypia, preneoplasia or apoptosis. Tamoxifen may durably reduce breast cancer risk through downregulation of ETV4 and ETV5 which could deplete mammary progenitor populations. This pathway has the potential to provide novel targets and early response biomarkers for phase II prevention trials. Randomized prospective double blinded placebo-controlled trial of tamoxifen (20 mg daily) versus placeo in women at increased risk for breast cancer. Gene expression was assessed in whole breast tissue cores obtained at baseline and after three months of treatment for 35 women. Core biopsies were obtained in the late luteal phase (day 28 +/- 2) for premenopausal women (N = 19). Breast lobules from the baseline and post-treatment cores were microdissected for 5 tamoxifen subjects.
Project description:Endocrine resistance in breast cancer is a major clinical problem with poorly understood mechanisms. Mass spectrometry-based proteomics of a clinically-relevant tamoxifen-resistant cell line model identified increased levels of minichromosome maintenance proteins (MCM), including MCM3, as central in cell cycle and DNA replication protein-protein interaction networks associated with tamoxifen resistance. Lowering MCM3 protein expression in tamoxifen-resistant cells restored tamoxifen sensitivity and altered phosphorylation of several cell cycle regulators, such as p53(Ser315, 33), CHK1(Ser317) and cdc25b(Ser323), suggesting that MCM3 activation of important cell cycle-associated proteins overcomes tamoxifen’s anti-proliferative effects. High MCM3 expression in primary tumor tissue from two independent cohorts of ER+ breast cancer patients receiving adjuvant tamoxifen mono-therapy was an independent prognostic marker significantly associated with a shorter recurrence-free survival.
Project description:A total of 38 flash-frozen breast cancer tissues were collected from three medical centers in the Netherlands (i.e. National Cancer institute: n=19; Radboud University Medical Center: n=4; Erasmus University Medical Center: n=15). All tissues were analyzed as laser capture microdissected (LCM) and whole samples (whole tissue lysate: WTL). All gathered samples were primary estrogen receptor (ER) tumors, which were subdivided in two patient groups according to outcome to first line (i.e. recurrent disease setting) tamoxifen therapy based on time-to-progression (TTP): patients which manifested progression of disease before (i.e. TTP <=) 6 months were defined as "poor outcome", while patients which manifested progression after (i.e. TTP>) 6 months were defined as "good outcome". All patients did not receive adjuvant hormonal therapy (i.e. tamoxifen or aromatase inhibitors post-surgical resection of primary tumor). The LCM subset derives from PXD000484 (Erasmus Medical Center samples) and PXD000485 (National Cancer Institute and Radboud University Medical Center).