Project description:Transcriptional profilling of 60 day old prostate tissue from Rb1F/F:Trp53F/F:PB-Cre4 or Rb1R654W/F:Trp53F/F:PB-cre4 mice versus wild type prostate tissue. Profiles used to compare deregulation of known E2F target genes in prostate tissue expressing a mutant Rb1 gene to tissue lacking Rb1 expression. Tissue from two Rb1F/F:Trp53F/F:PB-Cre4 (null) mice or two Rb1654/F:Trp53F/F:PB-cre4 (mutant) mice compared to a pool of tissue from 3 wild type mice using two color arrays.
Project description:Transcriptional profilling of 60 day old prostate tissue from Rb1F/F:Trp53F/F:PB-Cre4 or Rb1R654W/F:Trp53F/F:PB-cre4 mice versus wild type prostate tissue. Profiles used to compare deregulation of known E2F target genes in prostate tissue expressing a mutant Rb1 gene to tissue lacking Rb1 expression.
Project description:Genomic loss of RB1 is a common alteration in castration-resistant prostate cancer (CRPC) and is associated with poor patient outcomes. RB1-loss is also a driver event that promotes the neuroendocrine transdifferentiation of prostate cancer (PCa). The loss of Rb protein disrupts the Rb-E2F repressor complex and thus hyperactivates E2F transcription activators. While the impact of RB1-loss on PCa progression and linage plasticity has been previously studied, the underline mechanisms remain unclear. Using an integrated cistromic and transcriptomic analysis, we have characterized Rb activities in multiple CRPC models by identifying Rb directly regulated genes and revealed that Rb has distinct binding sites and targets in TP53-mutated CRPC. Significantly, we show that RB1-loss promotes the noncanonical activator function of LSD1/KDM1A, which stabilizes chromatin binding of E2F1, and hence sensitizes CRPC tumor to the LSD1 inhibitor treatment. These results provide new molecular insights of Rb activity in PCa progression and suggest LSD1 as a potential therapeutic target in CRPC with RB1-loss.
Project description:Genomic loss of RB1 is a common alteration in castration-resistant prostate cancer (CRPC) and is associated with poor patient outcomes. RB1-loss is also a driver event that promotes the neuroendocrine transdifferentiation of prostate cancer (PCa). The loss of Rb protein disrupts the Rb-E2F repressor complex and thus hyperactivates E2F transcription activators. While the impact of RB1-loss on PCa progression and linage plasticity has been previously studied, the underline mechanisms remain unclear. Using an integrated cistromic and transcriptomic analysis, we have characterized Rb activities in multiple CRPC models by identifying Rb directly regulated genes and revealed that Rb has distinct binding sites and targets in TP53-mutated CRPC. Significantly, we show that RB1-loss promotes the noncanonical activator function of LSD1/KDM1A, which stabilizes chromatin binding of E2F1, and hence sensitizes CRPC tumor to the LSD1 inhibitor treatment. These results provide new molecular insights of Rb activity in PCa progression and suggest LSD1 as a potential therapeutic target in CRPC with RB1-loss.
Project description:The retinoblastoma protein (pRB) is best known for regulating cell proliferation through E2F transcription factors. In this report we investigate the properties of a targeted mutation that disrupts pRB interactions with the transactivation domain of E2Fs. Mice that carry this mutation endogenously (Rb1∆G) are defective in regulating E2F target genes. Surprisingly, cell cycle regulation in Rb1∆G/∆G MEFs strongly resembles that of wild type. In a serum deprivation induced cell cycle exit, Rb1∆G/∆G MEFs display a similar magnitude of E2F target gene derepression as Rb1-/-, even though Rb1∆G/∆G cells exit the cell cycle normally. Interestingly, cell cycle arrest in Rb1∆G/∆G MEFs is responsive to p16 expression, indicating that the ΔG-pRB protein can be activated in G1 to arrest proliferation through non-E2F mechanisms. Some Rb1∆G/∆G mice die neonatally with a muscle degeneration phenotype, while the others live a normal lifespan with no evidence of spontaneous tumor formation. Histological analysis reveals discrete examples of hyperplasia in the mammary epithelium, but most tissues appear normal while being accompanied by derepression of pRB regulated E2F targets. This suggests that non-E2F, pRB dependent pathways may have a more relevant role in proliferative control than previously identified.
Project description:E2F/RB activity is altered in most human tumors. The retinoblastoma family of proteins plays a key role in regulating the progression of the cell cycle from the G1 to S phases. This is achieved through negative regulation of E2F transcription factors, important positive regulators of cell cycle entry. E2F family members are divided in two groups: activators (E2F1-E2F3a) and repressors (E2F3b-E2F8). E2F4 accounts for a large part of the E2F activity and is a main E2F repressor member in vivo. Perturbations in the balance from quiescence towards proliferation contribute to increased mitotic gene expression levels frequently observed in cancer. We have previously reported that combined Rb1-Rbl1 and Rb1-E2F1 ablation in epidermis produces important alterations in epidermal proliferation and differentiation, leading to tumor development. However, the possible roles of E2F4 in this context are still to be determined. Here we show the absence of any discernible phenotype in the skin of mice lacking of E2F4. In contrast, the inducible loss of Rb1 in the epidermis of E2F4-null mice produced multiple skin abnormalities including altered differentiation and proliferation, spontaneous wounds, carcinoma in situ development and stem cell perturbations. All these phenotypic alterations are associated with extensive gene expression changes, the induction of c-myc and the Akt activation. Moreover, the whole transcriptome analyses in comparison with previous models generated also revealed extensive changes in multiple repressive complexes and in transcription factor activity. These results point to E2F4 as a master regulator in multiple steps of epidermal homeostasis in Rb1 absence.
Project description:Increasing evidence suggests that prostate cancer is overdiagnosed and overtreated, and prognostic biomarkers would aid in treatment selection. To define prognostic biomarkers for aggressive prostate cancer, we carried out gene-expression profiling of 98 prostate tumors and 52 benign adjacent prostate tissue samples with detailed clinical annotation. We identified 28 transcripts significantly associated with recurrence after radical prostatectomy including NuSAP, a protein that binds DNA to the mitotic spindle. Elevated NuSAP transcript levels were associated with poor outcome in two independent prostate cancer gene-expression datasets. To characterize the role and regulation of NuSAP in prostate cancer, we studied the expression of NuSAP in the LNCaP and PC3 human prostate cancer cell lines. Posttranscriptional silencing of the NuSAP gene severely hampered the ability of PC3 to invade and proliferate in vitro. The promoter region of the NuSAP gene contains two CCAAT boxes and binding sites for E2F. Transient transfection of an E2F1 cDNA and 431bp of the NuSAP promoter demonstrated E2F1 as an important regulator of expression. Deletion of the E2F-binding site at nucleotide 246 negated the effects of E2F1 on NuSAP expression. Electrophoretic mobility shift assays demonstrated that nuclear extracts of cells overexpressing E2F1 bound directly to the E2F-binding site in the NuSAP promoter region. Finally, immunohistochemistry showed a strong correlation between E2F1 and NuSAP expression in human prostate cancer samples. NuSAP is a novel biomarker for prostate cancer recurrence after surgery and its overexpression appears to be driven in part by E2F1 activation. disease_state_design
Project description:The specific ablation of Rb1 gene in epidermis (RbF/F;K14cre) promotes proliferation and altered differentiation but does not produce spontaneous tumour development. These phenotypic changes are associated with increased expression of E2F members and E2F-dependent transcriptional activity. Here, we have focused on the possible dependence on E2F1 gene function. We have generated mice that lack Rb1 in epidermis in an inducible manner (RbF/F;K14creERTM). These mice are indistinguishable from those lacking pRb in this tissue in a constitutive manner (RbF/F;K14cre). In an E2F1-null background (RbF/F;K14creERTM; E2F1-/- mice), the phenotype due to acute Rb1 loss is not ameliorated by E2F1 loss, but rather exacerbated, indicating that pRb functions in epidermis do not rely solely on E2F1. On the other hand, RbF/F;K14creERTM;E2F1-/- mice develope spontaneous epidermal tumours of hair follicle origin with high incidence. These tumours, which retain a functional p19arf/p53 axis, also show aberrant activation of βcatenin/Wnt pathway. Gene expression studies revealed that these tumours display relevant similarities with specific human tumours. These data demonstrate that the Rb/E2F1 axis exerts essential functions not only in maintaining epidermal homeostasis, but also in suppressing tumour development in epidermis, and that the disruption of this pathway may induce tumour progression through specific alteration of developmental programs. Gene expression was compared between normal mouse skin, skin from transgenic RbF/F;K14creERTM; E2F1-/- , E2F1-/-, and RbF/F;K14creERTM; E2F1-/- mouse, and carcinomas arising in the skin of RbF/F;K14creERTM; E2F1-/- mouse. All mice were treated with tamoxifen.
Project description:To define the epigenomic response to AR activation, we employed the 3D organoid model of murine prostate tissue. Control and SPOP-mutant prostate organoids were stimulated with 10 nM dihydrotestosterone (DHT) or vehicle. Next, we performed the transcriptomic analysis (mRNA-seq) together with profiling of the accessibility landscape (ATAC-seq), transcription factor (AR, and FOXA1) binding and H3K4me2 modified nucleosomes.