Project description:Prostate cancer is dependent on androgen receptor (AR) signaling at all stages of the disease and cyclin D1 has been shown to negatively modulate the expression of the AR-dependent gene prostate specific antigen (KLK3/PSA). Unbiased gene expression profiling was performed to determine the androgen-regulated geneset that is sensitive to cyclin D1. Androgen-sensitive LNCaP cells were straved of androgen, then transduced with control green fluorescent protein (GFP) or cyclin D1 (CCND1) adenovirus, then subsequently stimulated with control (Ethanol) or dihydrotestosterone (DHT).
Project description:Prostate cancer is dependent on androgen receptor (AR) signaling at all stages of the disease and cyclin D1 has been shown to negatively modulate the expression of the AR-dependent gene prostate specific antigen (KLK3/PSA). Unbiased gene expression profiling was performed to determine the androgen-regulated geneset that is sensitive to cyclin D1.
Project description:AMBRA1 is a tumour suppressor protein that functions as a substrate receptor in the ubiquitin conjugation system and regulates the stability of D-type cyclins and cell proliferation. Here, we present the cryo-EM structure of cyclin D1 bound AMBRA1-DDB1 complex at 3.55 Å resolution. The structure reveals a substrate interaction surface on the AMBRA1 WD40 domain that specifically binds to the C-terminal region of D-type cyclins. This interaction is dependent on the phosphorylation of Thr286 residue in the C-terminal phosphodegron site of D-type cyclins. The phosphodegron motif folds into a turn-like conformation followed by a 310 helix that promotes its assembly with AMBRA1. Additionally, we show that AMBRA1 mutants, which are defective in cyclin D1 binding, lead to cyclin D1 accumulation and DNA damage. Understanding the AMBRA1-D-type cyclins structure enhances the knowledge of the molecular mechanisms that govern the cell cycle control and may lead to new therapeutic approaches for cancers linked to abnormal cyclin D activity.
Project description:Abstract Background. The cellular effects of androgen are transduced through the androgen receptor, which controls the expression of genes that regulate biosynthetic processes, cell growth, and metabolism. Androgen signaling also impacts DNA damage signaling through mechanisms involving gene expression and transcription-associated DNA damaging events. Defining the contributions of androgen signaling to DNA repair is important for understanding androgen receptor function, and it also has important translational implications. Methods. We generated RNA-seq data from multiple prostate cancer lines and used bioinformatic analyses to characterize androgen-regulated gene expression. We compared the results from cell lines with gene expression data from prostate cancer xenografts, and patient samples, to query how androgen signaling and prostate cancer progression influences the expression of DNA repair genes. We performed whole genome sequencing to help characterize the status of the DNA repair machinery in widely used prostate cancer lines. Finally, we tested a DNA repair enzyme inhibitor for effects on androgen-dependent transcription. Results. Our data indicates that androgen signaling regulates a subset of DNA repair genes that are largely specific to the respective model system and disease state. We identified deleterious mutations in the DNA repair genes RAD50 and CHEK2. We found that inhibition of the DNA repair enzyme MRE11 with the small molecule mirin inhibits androgen-dependent transcription and growth of prostate cancer cells. Conclusions. Our data supports the view that crosstalk between androgen signaling and DNA repair occurs at multiple levels, and that DNA repair enzymes in addition to PARPs, could be actionable targets in prostate cancer.
Project description:The CCND1 gene, which is frequently overexpressed in cancers, encodes the regulatory subunit of a holoenzyme that phosphorylates the retinoblastoma protein (pRb). It is known that cyclin D1 regulates ERα transactivation using heterologous reporter systems, the significance of this observation to E2 dependent gene activation is unknow. E2 stimulated MCF7 cells treated with cyclin D1 siRNA in order to analyze the genes regulated by estradiol in a cyclin D1 dependent manner. Hormone deprived MCF7 cells were treated with cyclin D1 siRNA or control siRNA and stimulated with E2 or vehicle
Project description:Recent observations show that the single-cell response of p53 to ionizing radiation (IR) is “digital” in that it is the number of oscillations rather than the amplitude of p53 that shows dependence on the radiation dose. We present a model of this phenomenon. In our model, double-strand break (DSB) sites induced by IR interact with a limiting pool of DNA repair proteins, forming DSB–protein complexes at DNA damage foci. The persisting complexes are sensed by ataxia telangiectasia mutated (ATM), a protein kinase that activates p53 once it is phosphorylated by DNA damage. The ATM-sensing module switches on or off the downstream p53 oscillator, consisting of a feedback loop formed by p53 and its negative regulator, Mdm2. In agreement with experiments, our simulations show that by assuming stochasticity in the initial number of DSBs and the DNA repair process, p53 and Mdm2 exhibit a coordinated oscillatory dynamics upon IR stimulation in single cells, with a stochastic number of oscillations whose mean increases with IR dose. The damped oscillations previously observed in cell populations can be explained as the aggregate behavior of single cell