Project description:Posttranslational modifications of histones such as methylation regulate chromatin structure and gene expression. Methylation of histone lysine residues is generally performed by SET domain methyltransferases. Here, we identify the heterodimeric C21orf127/TRMT112 complex as a specific histone methyltransferase. Assembly of the seven-b-strand protein C21orf127 (also named Hemk2, N6amt1 or PrmC) with TRMT112 is essential to form an active enzyme, hereafter named KMT9 that writes the histone mark H4K12me1 in vitro and in vivo. The H4K12me1 mark is enriched at promoters of KMT9 target genes and co-localises with the active histone mark H4K12ac. By controlling expression of genes involved in energy metabolism, KMT9 regulates oxidative phosphorylation in androgen receptor-dependent and -independent prostate tumour cells. Importantly, KMT9 depletion severely affects proliferation of castration and enzalutamide-resistant prostate cancer cells and xenograft tumours. Together, our data link the writing of the H4K12me1 histone mark by KMT9 with KMT9-dependent gene expression, which in consequence regulates energy metabolism and proliferation. KMT9 executes these functions independently of androgen receptor and androgen signalling thus, providing a promising paradigm for the treatment of castration resistant prostate cancer.
Project description:Androgen receptor (AR) is critical for the progression of prostate cancer to the castration resistant (CRPC) state. Despite initial response, AR antagonists are ineffective long term in stifling AR activity due to their inability to repress expression of the AR or its splice variant, AR-V7. Here, we report that ACK1 tyrosine kinase, frequently deregulated in CRPCs, phosphorylates histone H4 at tyrosine 88, upstream of the AR transcription start site. WDR5/MLL2 complex reads the H4Y88 marks and modifies H3 in trans to deposit the transcriptionally activating H3K4 trimethyl marks, promoting AR transcription. Reversal of the pY88-H4 epigenetic marks by ACK1 small molecule inhibitor, (R)-9bMS, sensitized naïve and enzalutamide-resistant cancer cells, repressed AR and AR-V7 levels to mitigate in vivo CRPC tumor growth. Thus, a feed-forward ACK1-H4-WDR5/MLL2-AR/AR-V7 epigenetic circuit drives CRPC and is necessary for maintenance of the malignant state.
Project description:Castration-resistant prostate cancer is a lethal disease. The cell type(s) that survive androgen-deprivation remain poorly described despite global efforts to understand the various mechanisms of therapy resistance. We recently identified in wild type mouse prostates a rare population of luminal progenitor cells that we called LSCmed according to their FACS profile (Lin?/Sca-1+/CD49fmed). Here we investigated the prevalence and castration resistance of LSCmed in various mouse models of prostate tumorigenesis. In intact mice, we show that LSCmed prevalence remains low (5-10% of epithelial cells) when prostatic androgen receptor signaling unaltered (malignant Hi-Myc mice) but significantly increases in models exhibiting reduced prostatic androgen receptor signaling, rising up to 30% in premalignant tumors (Pb-PRL mice) and to >80% in castration-resistant prostate tumors driven by Pten loss (Ptenpc-/- mice). LSCmed tolerance to androgen deprivation was demonstrated by their persistence (Ptenpc-/-) or further enrichment (Pb-PRL) 2-3 weeks after castration as evidenced by FACS analysis. Transcriptomic analysis revealed that LSCmed represent a unique cell entity as their gene-expression profile is different from luminal and basal/stem cells, but shares markers of each. Their intrinsic androgen signaling is markedly decreased, which explains why LSCmed tolerate androgen-deprivation. This also enlightens why Ptenpc-/- tumors are castration-resistant since LSCmed represent the most prevalent cell type in this model. We validated CK4 as a specific marker for LSCmed on sorted cells and prostate tissues by immunostaining, allowing for the detection of LSCmed in various mouse prostate specimens. In castrated Ptenpc-/- prostates, BrdU staining revealed massive proliferation of CK4+ cells, further demonstrating their key role in castration-resistant prostate cancer progression. In all, this study identifies LSCmed as a probable source of prostate cancer relapse after androgen deprivation and as a new therapeutic target for the prevention of castrate-resistant prostate cancer.
Project description:Cellular reprogramming remodels the gene expression program by re-setting the epigenome of somatic cells into an embryonic-like state. Post-translational modifications of histones play an important role in this process. We previously used ChIP-seq to profile the distribution of specific histone H3 marks during the entire reprogramming process and found widespread loss of H3K27me3 in the initial stages[1]. Here, using an unbiased middle-down proteomics approach we have identified 74 unique isoforms of histone H4 and quantified them across nine stages of reprogramming. Our data showed substantial differences between the precursor cells and late-phase reprogramming cells. Also, ESCs and iPSCs displayed higher levels of H4 acetylation and tri-methylation concomitantly with lower levels of mono- and di-methylation when compared to cells undergoing reprogramming. These results suggest that during reprogramming, the histone H4 “PTM code” experiences dynamic changes in multiple waves, with a final reset taking place during the transition to an ESC-like state, in perfect agreement with the in-parallel generated multi-omics data[1]. Together, these data represent an invaluable resource to study PTMs of H4 and their potential cross-talk and extend our knowledge on the epigenetic mechanisms involved in acquisition of induced pluripotency.
Project description:Castration resistant prostate cancer (CRPC) develops resistance to antiandrogens affecting Androgen Receptor (AR) signaling through a variety of mechanism. Because of this, the efficacy of androgen receptor targeted therapy remains limited for many patients with CRPC. We developed C42B-enzalutamide (ENZU) and resistance cells to study changes in transcriptomic profile compared to parental cells.
Project description:Castration resistant prostate cancer (CRPC) develops resistance to antiandrogens affecting Androgen Receptor (AR) signaling through a variety of mechanism. Because of this, the efficacy of androgen receptor targeted therapy remains limited for many patients with CRPC. We developed LNCaP-enzalutamide (ENZU) and resistance cells to study changes in transcriptomic profile compared to parental cells.
Project description:Castration resistant prostate cancer (CRPC) develops resistance to antiandrogens affecting Androgen Receptor (AR) signaling through a variety of mechanism. Because of this, the efficacy of androgen receptor targeted therapy remains limited for many patients with CRPC. We developed C42B-Abiraterone (Abi) and resistance cells to study changes in transcriptomic profile compared to parental cells.
Project description:More effective therapeutic approaches for castration-resistant prostate cancer (CRPC) are urgently needed, thus reinforcing the need to understand how prostate tumors progress to castration resistance. We have established a novel mouse xenograft model of prostate cancer, KUCaP-2, which expresses the wild-type androgen receptor (AR) and which produces the prostate-specific antigen (PSA). In this model, tumors regress soon after castration, but then reproducibly restore their ability to proliferate after 1 to 2 months without AR mutation, mimicking the clinical behavior of CRPC. In the present study, we used this model to identify novel therapeutic targets for CRPC. Evaluating tumor tissues at various stages by gene expression profiling, we discovered that the prostaglandin E receptor EP4 subtype (EP4) was significantly upregulated during progression to castration resistance. Immunohistochemical results of human prostate cancer tissues confirmed that EP4 expression was higher in CRPC compared with hormone-naïve prostate cancer. Ectopic overexpression of EP4 in LNCaP cells (LNCaP-EP4 cells) drove proliferation and PSA production in the absence of androgen supplementation in vitro and in vivo. Androgen-independent proliferation of LNCaP-EP4 cells was suppressed when AR expression was attenuated by RNA interference. Treatment of LNCaP-EP4 cells with a specific EP4 antagonist, ONO-AE3-208, decreased intracellular cyclic AMP levels, suppressed PSA production in vitro, and inhibited castration-resistant growth of LNCaP-EP4 or KUCaP-2 tumors in vivo. Our findings reveal that EP4 overexpression, via AR activation, supports an important mechanism for castration-resistant progression of prostate cancer. Furthermore, they prompt further evaluation of EP4 antagonists as a novel therapeutic modality to treat CRPC. 4 samples in each group: androgen-dependent growth (AD), castration-induced regression nadir (ND), and castration-resistant regrowth (CR) stages
Project description:Through comparative genomics using PDX models of androgen-dependent (AD) and castration-resistant (CR) tumors, we identify opioid receptor kappa 1 (OPRK1) as being associated with castration-resistance. Loss of OPRK1 function delays castration-resistance and inhibits castration-resistant growth of prostate cancer cells in culture and in vivo, suggesting OPRK1 as a therapeutic target. To gain insight with regard to biological function of OPRK1 under androgen-depleted condition, we set up two distinct comparisons using VCaP and AIVCaP cells. AIVCaP is an androgen-independent subline of VCaP which we established. VCaP or AIVCaP were treated with siRNA for AR plus siRNA for OPRK1 (combo-siRNA) or siRNA for AR alone (single siRNA) (n = 4 each), and then expression profile gained from microarray analysis of the respective cell line treated with combo-siRNA was compared with that of cells treated with single siRNA.
Project description:<p>Molecularly-targeted therapies for advanced prostate cancer include castration modalities that suppress ligand-dependent transcriptional activity of the androgen receptor (AR). However, persistent AR signaling undermines therapeutic efficacy and promotes progression to lethal castration-resistant prostate cancer (CRPC), even when patients are treated with potent second-generation AR-targeted therapies abiraterone and enzalutamide. Here we define diverse AR genomic structural rearrangements (AR-GSRs) as a class of molecular alterations occurring in one third of CRPC-stage tumors. AR-GSRs occur in the context of copy-neutral and amplified AR and display heterogeneity in breakpoint location, rearrangement class, and sub-clonal enrichment in tumors within and between patients. Despite this heterogeneity, one common outcome in tumors with high sub-clonal enrichment of AR-GSRs is outlier expression of diverse AR variant species lacking the ligand binding domain and possessing ligand-independent transcriptional activity. Collectively, these findings reveal AR-GSRs as important drivers of persistent AR signaling in CRPC.</p>