Project description:Inhibitors for cyclin-dependent kinase (CDK) 4 and CDK6 have been established as effective therapeutic options for hormone receptor (HR)-positive, HER2-negative advanced breast cancer. Although the CDK4/6 inhibitors mainly target the cyclin D-CDK4/6-retinoblastoma tumor suppressor protein (RB) axis, little is known about clinical impact of inhibiting phosphorylation of other CDK4/6 target proteins. Here, we have focused on other CDK4/6 targets, SMAD proteins. We showed that a CDK4/6 inhibitor Palbociclib and Activin-SMAD2 signaling cooperatively inhibited cell cycle progression of a luminal-type breast cancer cell line T47D. Mechanistically, Palbociclib enhanced SMAD2 binding to the genome through inhibiting linker phosphorylation of the SMAD2 protein by CDK4/6. Comparison of the SMAD2 ChIP-seq data of T47D with those of a triple-negative breast cancer cell line Hs578T indicated that Palbociclib augments different SMAD2-mediated program defined based on types of cells, and enhances SMAD2 binding to the target regions on the genome without affecting its binding pattern. Collectively, the CDK4/6 inhibitor facilitates the cytostatic effects of Activin-SMAD2, while it also enhances its tumor promoting effects depending on types of breast cancer.
Project description:We performed genome-wide PADI2 ChIP seq experiments in T47D cell lines and also RNP2 ChIP seq in T47D cells only expressing HA Tagged amanitin resistant wild type in comparison to R1810A mutant form of RNAP2.
Project description:Gene expression profiling of the downstream transcriptional changes induced by ESR1 fusion genes observed in human breast tumors resistant to hormone therapy Experimental T47D cells stably expressing ESR1 fusion genes (or T47D cells treated with estradiol) vs. T47D cells expressing YFP
Project description:In breast cancer cells, some topologically associating domains (TADs) behave as hormonal gene regulation units, within which genes transcription is coordinately regulated in response to steroid hormones. Here we further described that responsive TADs contain 20-100 kb-long clusters of intermingled estrogen receptor (ER) and progesterone receptor (PR) binding sites, hereafter called Hormone-Control Regions (HCRs). In T47D cells, we identified more than 200 HCRs, which are frequently bound by unliganded ER and PR. These HCRs establish steady long-distance inter-TAD interactions between them and organize characteristic looping structures with promoters even in the absence of hormones in ER+-PR+ cells. This organization is dependent on the expression of the receptors and is further dynamically modulated in response to steroid hormones. HCRs function as platforms integrating different signals resulting in some cases in opposite transcriptional responses to estrogens or progestins. Altogether, these results suggest that steroid hormone receptors act not only as hormone-regulated sequence-specific transcription factors, but also as local and global genome organizers.
