Download or read book Dissecting the Role of Estrogen Receptor Palmitoylation in Breast Cancer Cells written by and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Estrogen signaling is primarily mediated by two estrogen receptors (ERs), ER[alpha] and ER[beta]. ER[alpha] is expressed in ~70% of breast cancers and is an important diagnostic and therapeutic target. Developing better treatment options and overcoming limitations of endocrine therapy depend on a detailed understanding of ER[alpha]-signaling pathways. ER[alpha], a member of the class I nuclear receptor superfamily of transcription factors, localizes mainly to the nucleus and interacts with DNA regulatory sequences either directly or through interaction with other transcription factors to regulate gene transcription. ER[alpha] is also rapidly activates signaling cascades. S-palmitoylation, a reversible lipid modification is catalyzed by palmitoyl acyl-transferases (PAT), which increase affinity of proteins to the membrane. Based on the results of previous studies, it is hypothesized that palmitoylation of ER[alpha] regulates extranuclear and nuclear signaling of ER[alpha]. We utilized palmitoylation-defective mutant ER[alpha]C447A-expressing MDA-MB-468 breast cancer cells to dissect the role of palmitoylation in a breast cancer cell line model. The substitution of ER[alpha] palmitoylation site abrogated ER[alpha] palmitoylation, membrane localization and estrogen-dependent phosphorylation of ERK1/2 in MDA-MB-468 cell line. Besides loss of E2-dependent extranuclear signaling, the substitution of palmitoylation sites led to the loss of other ER[alpha]-dependent events in ER[alpha]C447A-expressing MDA-MB-468 cells, such as decreased E2-dependent S118 phosphorylation, impaired regulation of certain target genes, and loss of estrogen-dependent cell cycle inhibition. This study thus highlights the importance of ER[alpha] palmitoylation in both nuclear and extranuclear ER signaling pathways in breast cancer cells. A better understanding of the mechanisms of estrogen action will help us to design more effective drugs affecting signal pathways depending on both membrane and nuclear receptors.