Effects of Estrogen and Tamoxifen on Ishikawa cells after 24h and 48h

Treatment with the breast cancer drug tamoxifen confers a risk of developing uterine tumors or other endometrial pathologies. Tamoxifen is a selective estrogen receptor modulator, which demonstrates tissue-specific activity although the mechanisms remain poorly understood. Both estradiol and tamoxifen act as estrogen agonists on the human uterus, and therefore have the potential to promote carcinogenicity. Estradiol and tamoxifen elicit cellular responses via the estrogen receptors (ER), which are involved in multiple signalling pathways. The effects at the molecular level are further influenced by the differential recruitment of co-factors and the presence of specific promoter motifs in target genes. In this study, ER positive (+) Ishikawa cells are used as a model to investigate the overall effect of treatment with either 17b-estradiol or 4-hydroxytamoxifen on the gene expression profiles. Keywords: Comparison of estradiol and tamoxifen on Ishikawa human uterine cells after 24h or 48h Ishikawa cells were serum-starved for 72 hours prior to treatment with 10-8M 17b-estradiol (E2) or 10-6M 4-hydroxytamoxifen (tam) for 24 or 48 hours. Cells were collected for total RNA extraction, and the quality and quantity of the RNA was determined spectrophotometrically. cDNA was prepared from treated (tam or E2) and control (vehicle only) Ishikawa cells, and was both forward and reverse labelled using Cy-3 dUTP/ Cy-5 dUTP and hybridised to oligo microarray slides representing >19,000 human genes (MRC HGMP-RFC). The data were analysed using GenePix Pro 3.0 software (Axon instruments) and statistical analyses applied to select significant gene changes (p<0.05).