{"owner": "ArrayExpress Uploader", "pop_total": 0, "species": "human", "factors": [{"GSM149278": {"TREATMENT": "3 hours with 0.1% Ethanol"}}, {"GSM1492782": {"TREATMENT": "3 hours with 10-6M estradiol"}}, {"GSM1492783": {"TREATMENT": "3 hours with 10-6M tamoxifen"}}], "id": 4813, "ownerprofile_id": "arrayexpress_sid", "platform": 4, "summary_wrapped": "Tamoxifen is the treatment of choice in estrogen receptor alpha breast cancer patients. However, ~50% of ER\u03b1-positive tumors exhibit...", "geo_gse_id": "E-GEOD-60879", "owner_profile": "/profile/8773/arrayexpressuploader", "factor_count": 1, "sample_count": 3, "tags": ["breast", "breast cancer", "cancer", "cell", "estrogen", "line"], "lastmodified": "Dec.12, 2014", "is_default": false, "geo_gds_id": "", "slug": "effect-of-tamoxifen-on-early-gene-expression-in-md", "geo_id_plat": "E-GEOD-60879_A-AFFY-44", "name": "Effect of tamoxifen on early gene expression in MDA-MB-231 cells", "created": "Sep.21, 2014", "summary": "Tamoxifen is the treatment of choice in estrogen receptor alpha breast cancer patients. However, ~50% of ER\u03b1-positive tumors exhibit intrinsic or rapidly acquire resistance to endocrine treatment, requiring chemotherapy. \u0399t has been difficult to predict de novo resistance to endocrine therapy and/or assess the likelihood of early relapse, while no concrete mechanism regulating the acquisition and the maintenance of endocrine resistance has been identified. We have performed a whole transcriptome analysis of an ER-positive (T47D) and a triple-negative (MDA-MBA-231) breast cancer cell line exposed to tamoxifen for a short time frame (hours) in order to study resistance mechanisms that are initiated early after initiation of tamoxifen treatment. Cells after a 4h incubation with medium containing 10% charcoal stripped FBS were incubated with vehicle,E2 (10-6M) or tamoxifen (10-6M) in RPMI 1640 supplemented with 10% charcoal stripped FBS, for 3 hours. Total RNA was isolated using Nucleospin II columns (Macheray-Nagel, Dttren, Germany), according to the manufacturer\u2019s instructions. RNA was labeled and hybridized according to the Affymetrix protocol (Affymetrix Gene-Chip Expression Analysis Technical Manual), using the HGU133A plus 2 chip, analyzing a total of 54675 transcripts. Signals were detected by an Affymetrix microarray chip reader.", "source": "http://www.ebi.ac.uk/arrayexpress/experiments/E-GEOD-60879", "sample_source": "http://www.ebi.ac.uk/arrayexpress/experiments/E-GEOD-60879/samples/"}