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A Ligandable PNT-Domain Establishes ERG as a Directly Targetable Oncogenic Driver in Prostate Cancer

ABSTRACT: The TMPRSS2:ERG gene fusion, present in approximately 50% of prostate cancers in patients of European ancestry, drives oncogenesis through aberrant overexpression of the ERG transcription factor. Despite its role as a truncal oncogenic driver, ERG has long been considered undruggable due to the absence of enzymatic activity and an apparent lack of ligandable pockets. Here, we demonstrate continued dependency on ERG in metastatic prostate cancer and identify a druggable pocket within its structured N-terminal Pointed (PNT) domain. Using an inducible shRNA system in TMPRSS2:ERG-positive VCaP cells, we show that ERG depletion causes profound growth inhibition in vitro and in vivo. To therapeutically exploit this vulnerability, we conducted a domain-focused differential scanning fluorimetry screen targeting the ERG PNT domain, followed by structure–activity relationship optimization. This approach yielded PBITE-1 (PNT-Binding Inhibitor of the Transcription factor ERG), a lead small molecule that selectively binds the ERG PNT domain in biochemical assays. NMR chemical-shift perturbation mapping and molecular docking revealed that PBITE-1 engages a discrete, solvent-exposed surface comprising two α-helices and an adjacent flexible loop, thereby defining a coherent ligand-binding pocket within the PNT domain. In cellular models, PBITE-1 directly engaged ERG, selectively inhibited proliferation and invasion, and induced apoptosis in ERG-driven prostate and hematologic malignancies. PBITE-1 also potently suppressed growth of ERG-positive prostate organoids derived from genetically engineered mouse models, as well as patient-derived human prostate cancer organoids. Furthermore, PBITE-1 treatment significantly induced tumor cell apoptosis in vivo in VCaP xenograft models. These findings establish the ERG PNT domain as ligandable and provide the first preclinical evidence that ERG is directly targetable by small molecules, enabling future development of ERG-directed inhibitors and targeted protein degraders.

ORGANISM(S): Homo sapiens

PROVIDER: GSE331048 | GEO | 2026/05/15

REPOSITORIES: GEO

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Project description:Antineoplastic effects of siRNA against TMPRSS2-ERG junction oncogene in prostate cancer: from molecular and cellular studies to preclinical investigations. Background of the study.:TMPRSS2-ERG junction oncogene is present in more than 50% of patients with prostate cancer, and its expression is frequently associated with poor prognosis. We knockdown by siRNA the two TMPRSS2-ERG fusion variants (III and IV) most frequently identified in patients’ biopsies and found an inhibition of TMPRSS2-ERG of above 70% in human prostate cancer VCaP cell line expressing TMPRSS2-ERG junction oncogene. To point out genes regulated after TMPRSS2-ERG oncogene silencing, microarray analysis was performed.. Materiel and Methods. Human prostate cancer VCaP cell line expressing TMPRSS2-ERG oncogene (ATCC® CRL-2876™ Manassas, USA) was grown in Dulbecco's Modified Eagle Medium (DMEM) (Invitrogen, Cergy-Pontoise, France) supplemented with 10% fetal bovine serum (FBS), 100 units/ml penicillin and 100 μg/ml streptomycin (Invitrogen). Cells were incubated at 37°C in a humidified atmosphere containing 5% CO2. Transfection was carried out using Lipofectamine RNAiMAX transfecting agent (Invitrogen) according to manufacturer's instructions. Briefly, 8×105 VCaP cells were seeded in six-well plates in DMEM supplemented with 10% FCS, penicillin (100U/ml) and streptomycin (10µg/ml) and transfected with 50 nM siRNA TMPRSS2-ERG III, siRNA TMPRSS2-ERG IV and siRNA Control and 6 μL Lipofectamine® RNAiMAX. Cells were incubated with siRNA for 48h. At the end of the treatments, total RNAs of untreated cells (NT) and transfected cells were extracted using RNeasy mini-kit (Quiagen, Courtaboeuf, France). Three independent experiments were performed. Results. Microarray analysis confirmed ERG inhibition by both siRNA TMPRSS2-ERG III and IV and revealed a common down-regulated gene, ADRA2A, involved in cell proliferation and migration. Experiments are performed with Agilent Whole Genome 8x60K (028004) microarray. In triplicate with a non treated control cells, a control with ascramble siRNA, a siRNA TMPRSS2-ERG III, a siRNA TMPRSS2 IV.

Project description:Androgen receptor (AR) is a transcription factor that plays a central role in the growth and development of the normal prostate and its malignant transformation. More recently, a majority of prostate cancers have been shown to harbor recurrent gene fusions of the androgen-regulated gene, TMPRSS2, to the oncogenic ETS transcription factor ERG. Here we employed chromatin immunoprecipitation coupled to massively parallel sequencing (ChIP-Seq) to explore the genome-wide localization of these transcription factors in human prostate cancer cell lines as well as tissues. Unexpectedly, transcriptional networks emanating from AR and ERG were found to be highly overlapping. Furthermore, AR was found to regulate known 5’ fusion partners in prostate cancer including TMPRSS2, as well as negatively regulating its own expression. While induced by androgen through fusion to TMPRSS2, ERG itself was shown to inhibit AR expression and positively regulate the genomic locus of wild-type ERG, thus revealing multiple levels of molecular cross-talk between AR and ERG. Importantly, androgen-sensitive prostate cancer cells in which ERG is overexpressed are able to proliferate and invade in the absence of androgen. Thus, we dissected the intertwined genomic landscape of two master transcriptional regulators of prostate cancer and suggest a role for ERG in maintaining transcriptional networks necessary for androgen-independent prostate cancer growth. These studies may suggest that future therapies against prostate cancer should target both AR and ERG, rather than AR alone, in order to achieve maximum effectiveness. ChIP_Seq examination of histone modifications and key transcription factors in LNCaP and VCaP prostate cancer cell lines in un-treated, vehicle treated or 10nM R1881 treated conditions. LNCaP ChIP-Seq experiments include samples GSM353609-GSM353618, GSM353625-GSM353628, GSM353633-GSM353635, GSM353641-GSM353644, and GSM353648. VCaP ChIP-Seq experiments include samples GSM353601-GSM353608, GSM353619-GSM353624, GSM353629-GSM353632, and GSM353645-GSM353647. In addition, we performed re-ChIP of AR and ERG in VCaP cells (GSM356767), and examined the effect of ERG knockdown on AR and ERG binding (samples GSM353636-GSM353639). To study ectopic ERG binding we performed ERG ChIP-Seq in stable RWPE+ERG or control cells (samples GSM353649-GSM353650). AR ChIP-Seq was also done in the AR-positive but ETS fusion-negative 22RV1 cells (GSM353640). To further study transcription factor binding and chromatin state we performed ChIP-Seq of AR, ERG, H3K4me3, H3K9me3, H3K27me3 and RNA Pol II in a metastatic prostate tumor tissue (samples GSM353651-GSM353656). To couple the ChIP-Seq experiments with gene expression, we have also done Illumian SAGE-tag profiling in LNCaP cells following androgen treatment for 0, 24 and 48hrs. These DGE experiments correspond to samples GSM353657-GSM353659.

Project description:Common epithelial cancers are believed to become more aggressive through the accumulation of multiple independent molecular events that lead to the deregulation of cell signaling. However, the discovery that the majority of prostate cancers harbor gene fusions of the 5'-untranslated region of androgen regulated TMPRSS2 promoter with ETS transcription factor family members has brought this paradigm into question1,2. TMPRSS2-ERG gene fusion is the most common molecular sub-type of prostate cancer. Recent work suggests that the TMPRSS2-ERG fusion is associated with a more aggressive clinical phenotype3. In the most advanced castration resistant prostate cancers where the androgen receptor has been inactivated, the TMPRSS2-ERG fusion remains functionally active. Here we show compelling clinical and gene expression data supporting the existence of a TMPRSS2-ERG fusion prostate cancer subclass. Using expression array profiling on 455 primary prostate tumors, we identified an 87 gene expression signature, distinguishing TMPRSS2-ERG fusion prostate cancer as a discrete molecular entity. Computational analysis suggested that this fusion signature was associated with estrogen receptor signaling. Functional studies demonstrated regulation of the TMPRSS2-ERG fusion transcript by estrogenic compounds. These data identify a previously unrecognized mechanism for regulation of the TMPRSS2-ERG, even in the absence of a functional androgen receptor, and thus may have broader implications in the treatment of prostate cancer. Keywords: Prostate cancer, Expression array, Illumina, gene fusion, TMPRSS2, ERG, Signatures, Estrogen Test Cohort: 388 cases from the population based Swedish-Watchful Waiting cohort. The cohort consists of men with localized prostate cancer (clinical stage T1-T2, Mx, N0); Validation cohort: The PhysiciansM-bM-^@M-^Y Health Study (PHS) cohort included 116 US men diagnosed with incidental prostate cancer between 1983 and 2003; 455 cases were annotated for TMPRSS2-ERG fusion. Test Set: GSM208029 ... GSM208392 Validation Set: GSM208404 ... GSM208512

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A Ligandable PNT-Domain Establishes ERG as a Directly Targetable Oncogenic Driver in Prostate Cancer

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