Onecut2 Research Articles

ONECUT2 acts as a lineage plasticity driver in adenocarcinoma as well as neuroendocrine variants of prostate cancer.

Androgen receptor- (AR-) indifference is a mechanism of resistance to hormonal therapy in prostate cancer (PC). Here we demonstrate that ONECUT2 (OC2) activates resistance through multiple drivers associated with adenocarcinoma, stem-like and neuroendocrine (NE) variants. Direct OC2 gene targets include the glucocorticoid receptor (GR; NR3C1) and the NE splicing factor SRRM4, which are key drivers of lineage plasticity. Thus, OC2, despite its previously described NEPC driver function, can indirectly activate a portion of the AR cistrome through epigenetic activation of GR. Mechanisms by which OC2 regulates gene expression include promoter binding, enhancement of genome-wide chromatin accessibility, and super-enhancer reprogramming. Pharmacologic inhibition of OC2 suppresses lineage plasticity reprogramming induced by the AR signaling inhibitor enzalutamide. These results demonstrate that OC2 activation promotes a range of drug resistance mechanisms associated with treatment-emergent lineage variation in PC and support enhanced efforts to therapeutically target OC2 as a means of suppressing treatment-resistant disease.

ONECUT2 is a druggable driver of luminal to basal breast cancer plasticity.

Tumor heterogeneity complicates patient treatment and can be due to transitioning of cancer cells across phenotypic cell states. This process is associated with the acquisition of independence from an oncogenic driver, such as the estrogen receptor (ER) in breast cancer (BC), resulting in tumor progression, therapeutic failure and metastatic spread. The transcription factor ONECUT2 (OC2) has been shown to be a master regulator protein of metastatic castration-resistant prostate cancer (mCRPC) tumors that promotes lineage plasticity to a drug-resistant neuroendocrine (NEPC) phenotype. Here, we investigate the role of OC2 in the dynamic conversion between different molecular subtypes in BC. We analyze OC2 expression and clinical significance in BC using public databases and immunohistochemical staining. In vitro, we perform RNA-Seq, RT-qPCR and western-blot after OC2 enforced expression. We also assess cellular effects of OC2 silencing and inhibition with a drug-like small molecule in vitro and in vivo. OC2 is highly expressed in a substantial subset of hormone receptor negative human BC tumors and tamoxifen-resistant models, and is associated with poor clinical outcome, lymph node metastasis and heightened clinical stage. OC2 inhibits ER expression and activity, suppresses a gene expression program associated with luminal differentiation and activates a basal-like state at the gene expression level. We also show that OC2 is required for cell growth and survival in metastatic BC models and that it can be targeted with a small molecule inhibitor providing a novel therapeutic strategy for patients with OC2 active tumors. The transcription factor OC2 is a driver of BC heterogeneity and a potential drug target in distinct cell states within the breast tumors.

Abstract 4302: ONECUT2 activates diverse resistance drivers of androgen receptor-independent heterogeneity in prostate cancer

Abstract Androgen receptor- (AR-) indifference is a mechanism of resistance to hormonal therapy in prostate cancer (PC). Here we demonstrate that ONECUT2 (OC2) activates resistance through multiple drivers associated with adenocarcinoma, stem-like and neuroendocrine (NE) variants. Direct OC2 targets include the glucocorticoid receptor (GR) and the NE splicing factor SRRM4, which are key drivers of lineage plasticity. Thus, OC2, despite its previously described NEPC driver function, can indirectly activate a portion of the AR cistrome through epigenetic activation of GR. Mechanisms by which OC2 regulates gene expression include promoter binding, enhancement of genome-wide chromatin accessibility, and super-enhancer reprogramming. Pharmacologic inhibition of OC2 suppresses lineage plasticity reprogramming induced by the AR signaling inhibitor enzalutamide. These results demonstrate that OC2 activation promotes a range of drug resistance mechanisms associated with treatment-emergent lineage variation in PC and support enhanced efforts to therapeutically target OC2 as a means of suppressing treatment-resistant disease. Citation Format: Chen Qian, Qian Yang, Mirja Rotinen, Rongrong Huang, Hyoyoung Kim, Brad Gallent, Yiwu Yan, Radu M. Cadaneanu, Baohui Zhang, Salma Kaochar, Stephen J. Freedland, Edwin M. Posadas, Leigh Ellis, Dolores Di Vizio, Colm Morrissey, Peter S. Nelson, Lauren Brady, Ramachandran Murali, Moray J. Campbell, Wei Yang, Beatrice S. Knudsen, Elahe A. Mostaghel, Huihui Ye, Isla P. Garraway, Sungyong You, Michael R. Freeman. ONECUT2 activates diverse resistance drivers of androgen receptor-independent heterogeneity in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4302.

Regulation of Onecut2 by miR-9-5p in Japanese encephalitis virus infected neural stem/progenitor cells.

MicroRNAs have emerged as key disease pathogenic markers and potential therapeutic targets. In this study, we solidify this concept by studying a key miRNA, miR-9-5p, in Japanese encephalitis virus infection of neural stem/progenitor cells. miRNA target Onecut2 has a possible role in stem cell pool biology. Here, we show a possible mechanistic axis worth investing in neurotropic viral biology.

ONECUT2 regulates proliferation and apoptosis in glioblastoma cell lines

Glioblastoma multiforme (GBM) is a highly aggressive brain tumor associated with a high mortality rate, with an average survival time of less than two years. GBM treatment faces significant challenges due to its infiltrative nature, genetic diversity, protection by the blood–brain barrier (BBB), drug resistance, and post-treatment side effects. Transcription factors (TFs) play a crucial role in regulating gene expression during cancer initiation and progression. This study aimed to investigate the impact of altering the function of ONECUT-2 (OC-2) in GBM cells, focusing on metabolic activity, proliferation, cell cycle, and apoptosis. To confirm the successful reduction of OC-2 expression in U251 and U87 cells compared to the control cells (wild types; WT), quantitative real-time polymerase chain reaction (qPCR) was performed. The downregulation of OC-2 resulted in a significant decrease in metabolic activity (MTT) of U251 cells by 47 % (P = 0.0056) and U87 cells by 36.4 % (P = 0.0003) compared to WT cells. In U251 cells, OC-2 downregulation caused cell cycle arrest in both the G0/G1 phase (13.6 %) and the S/G2 phase (52.52 %) compared to WT cells. Similarly, in U87 cells, downregulation of OC-2 led to cell cycle arrest in the G0/G1 phase (90.5 %) and the G2 phase (76.61 %) compared to WT cells. Furthermore, OC-2 downregulation significantly affected early-stage apoptosis in U251 cells (95.46 %, P = 0.0005) and U87 cells (19.64 %, P = 0.0004). Conversely, upregulation of OC-2 significantly increased the metabolic activity (MTT) of U251 cells by 94 % (P = 0.0067) and U87 cells by 58 % (P = 0.0028) compared to WT cells. These findings highlight the essential role of OC-2 in regulating the progression of GBM cells. Consequently, OC-2 represents a potential therapeutic target for inhibiting GBM. Overall, this study demonstrates that OC-2 plays a significant role in cell progression, suggesting its potential as a therapeutic target for GBM treatment.

Autonomous action and cooperativity between the ONECUT2 transcription factor and its 3' untranslated region.

The transcription factor ONECUT2 (OC2) is a master transcriptional regulator operating in metastatic castration-resistant prostate cancer that suppresses androgen receptor activity and promotes neural differentiation and tumor cell survival. OC2 mRNA possesses an unusually long (14,575nt), evolutionarily conserved 3' untranslated region (3' UTR) with many microRNA binding sites, including up to 26 miR-9 sites. This is notable because miR-9 targets many of the same genes regulated by the OC2 protein. Paradoxically, OC2 expression is high in tissues with high miR-9 expression. The length and complex secondary structure of OC2 mRNA suggests that it is a potent master competing endogenous RNA (ceRNA) capable of sequestering miRNAs. Here, we describe a novel role for OC2 3' UTR in lethal prostate cancer consistent with a function as a ceRNA. A plausible ceRNA network in OC2-driven tumors was constructed computationally and then confirmed in prostate cancer cell lines. Genes regulated by OC2 3' UTR exhibited high overlap (up to 45%) with genes driven by the overexpression of the OC2 protein in the absence of 3' UTR, indicating a cooperative functional relationship between the OC2 protein and its 3' UTR. These overlapping networks suggest an evolutionarily conserved mechanism to reinforce OC2 transcription by protection of OC2-regulated mRNAs from miRNA suppression. Both the protein and 3' UTR showed increased polycomb-repressive complex activity. The expression of OC2 3' UTR mRNA alone (without protein) dramatically increased the metastatic potential by in vitro assays. Additionally, OC2 3' UTR increased the expression of Aldo-Keto reductase and UDP-glucuronyl transferase family genes responsible for altering the androgen synthesis pathway. ONECUT2 represents the first-described dual-modality transcript that operates as both a key transcription factor driving castration-resistant prostate cancer and a master ceRNA that promotes and protects the same transcriptional network.

Abstract B014: ONECUT2 activates diverse drug-resistant phenotypes in prostate cancer

Abstract BACKGROUND. Prostate cancer (PC) cells can escape from lineage confinement and be reprogrammed to a drug-resistant, high-plasticity state, however the mechanism underlying this process is not understood. Our group identified the HOX/CUT transcription factor ONECUT2 (OC2) as a mediator of metastatic castration-resistant PC (mCRPC) that can be inhibited with a novel family of small molecules. OC2 was shown to be a lineage plasticity driver that promotes neuroendocrine prostate cancer (NEPC). In this study, we sought to uncover the mechanism whereby OC2 exerts effects on lineage plasticity. METHODS. RNAseq, CUT&RUNseq, scRNAseq, forced expression, shRNA, CRISPR-Cas9, co-precipitation/western blot, PCR, mutagenesis, human PC, PC models, computational modeling. RESULTS. We found that OC2 is capable of activating multiple androgen receptor- (AR)-indifferent, drug-resistant lineages, including programs not associated with NEPC, such as upregulation of the glucocorticoid receptor (GR). Consistent with the GR findings, OC2 regulated genes on the AR cistrome previously shown to be regulated by GR in CRPC, including KLK3/PSA. OC2 activated bivalent promoters of master regulator genes via epigenetic modification, and reprogramed multiple super-enhancers, including those associated with TMPRSS2 and SRRM4. OC2-expressing cells in human CRPC included populations that express AR, NE+/stem-like+, NE-/stem-like+, and “double negative” (NE-/AR-) phenotypes. OC2 also transcriptionally upregulated UDP-glucuronosyltransferase enzymes UGT2B15 and UGT2B17, which inactivate DHT, suggesting that the emergence of phenotypic plasticity also arises from AR suppression by ligand depletion. Consistent with this, low levels of androgen correlated with OC2 activation in human CRPC tumors. Enforced OC2 promoted both enzalutamide and docetaxel resistance in PC models. CONCLUSIONS. These findings identify OC2 as an upstream mediator of many lineage-defining factors that govern drug resistance, including those associated with adenocarcinoma. Because OC2 can be inhibited pharmacologically, these results suggest that suppressing this target may inhibit the emergence of a wide range of drug resistance mechanisms arising from loss of lineage confinement. Citation Format: Chen Qian, Qian Yang, HyoYoung Kim, Yiwu Yan, Elahe Mostaghel, Leigh Ellis, Beatrice Knudsen, Salma Kaochar, Huihui Ye, Isla Garraway, Sungyong You, Michael Freeman. ONECUT2 activates diverse drug-resistant phenotypes in prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr B014.

Abstract B064: ONECUT2 inhibition, a potential treatment for lethal prostate cancer

Abstract Prostate cancer (PCa) is the most common cancer and the second most lethal cancer in men, claiming over 30,000 lives each year in the US alone. These PCa patient deaths are typically due to castration-resistant PCa (CRPC) which is resistant to androgen deprivation therapy, androgen receptor signaling inhibitors, and chemotherapies. Our group and others have shown that the transcription factor ONECUT2 (OC2) is a critical driver of CRPC. We have discovered a low molecular weight inhibitor of OC2 (OC2i), known as CSRM617, which inhibits metastatic PCa in cell culture (IC50 of 5-15 uM depending on cell line used) and effectively treats xenograft CRPC tumors in mouse models. We have developed a large series of these OC2i based on the CSRM617 scaffold. A thorough understanding of how these OC2i bind to and inhibit OC2 function are imperative to developing them into a clinically viable treatment option. Our recent work shows CSRM617 binds Fe and that this Fe:CSRM617 complex is necessary in order to inhibit OC2 binding of DNA. We have solved the crystal structure of OC2 bound to its conjugate DNA response element, demonstrating their atomic-level interactions. We are working towards solving a crystal structure of these OC2i bound to OC2 in order understand their specific interactions and make rational modifications to the chemical scaffold for improvements in binding affinity and pharmacokinetic properties. Citation Format: Brad Gallent, Chen Qian, Avradip Chatterjee, Madhusudhanarao Katiki, Ramachandran Murali, Michael R Freeman. ONECUT2 inhibition, a potential treatment for lethal prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr B064.

Preparation of DSPE-PEG-cRGD Modified Cationic Liposomes for Delivery of OC-2 shRNA and The Antitumor Effects on Breast Cancer.

Cationic liposome delivery of interfering RNA (shRNA) plays an important role in tumor therapy. The cyclic Arg-Gly-Asp (cRGD) modified cationic liposomes (cRGD-CL) were designed for targeted delivery of ONECUT2 (OC-2) shRNA (pshOC-2) to breast cancer cells. The characterization analysis of cationic liposome showed that the prepared cRGD-CL/pshOC-2 lipoplexes had uniform particle size (150 ± 1.02 nm), moderate zeta potential (19.8 ± 0.249 mV) and high encapsulation efficiency (up to 96%). The results of flow cytometer showed that the introduction of cRGD could significantly promote the liposomes targeting tumor cells. In MCF-7 cells, the pshOC-2 could down-regulate expression of OC-2 and result in cell apoptosis, inhibition of the wound healing, migration and cell colony formation, in which the signal pathways of Bcl-xL, Bcl-2 were inhibited and the signal pathways of Bax and Cleaved Caspase-3 were promoted. In MCF-7 xenograft mice, intravenous administration of cRGD-CL/pshOC-2 lipoplexes could effectively reduce the expression of OC-2 in tumors and result in apparently antitumor effects, which suggested that the lipoplexes might be deeply penetrated into tumor through receptor-mediated transcytosis. The results revealed that the cationic liposome (cRGD-CL) was an effective delivery system for OC-2 shRNA, which might be an effective therapeutic candidate for breast cancer.

ONECUT2 upregulation is associated with CpG hypomethylation at promoter-proximal DNA in gastric cancer and triggers ACSL5.

Many studies have focused on global hypomethylation or hypermethylation of tumor suppressor genes, but less is known about the impact of promoter hypomethylation of oncogenes. We previously showed that promoter methylation may gradually increase or decrease during the transition from gastric mucosa (GM) to intestinal metaplasia (IM) to gastric cancer (GC). In our study, we focused on regional CpG hypomethylation of the promoter‐proximal DNA of the transcription factor ONECUT2 (OC2) in IM and GC cells. We validated the hypomethylation of promoter‐proximal DNA of OC2 in 160 primary GCs, in which methylation level correlated negatively with OC2 mRNA level. IM and GC cells stained positively for OC2, whereas GM cells did not. Stable transfection of OC2 in GC cells promoted colony formation, cell migration, invasion and proliferation. Moreover, OC2 knockdown with a short hairpin RNA suppressed tumorigenesis in nude mice. In addition, chromatin immunoprecipitation coupled with DNA sequencing and RNA‐seq analyses revealed that OC2 triggered ACSL5, which is strongly expressed in IM of the stomach but not in GM, indicating that OC2 and ACSL5 are early‐stage biomarkers for GC. We also observed a high correlation between the levels of OC2 and ACSL5 mRNAs in the GENT database These results suggest that epigenetic alteration of OC2 upregulates its expression, which then activates ACSL5; thus, OC2 is induced in IM by epigenetic alteration and triggers ACSL5 expression, and thus OC2 and ACSL5 may cooperatively promote intestinal differentiation and GC progression.

ONECUT2 is a targetable master regulator of lethal prostate cancer that suppresses the androgen axis.

Treatment of prostate cancer (PC) by androgen suppression promotes the emergence of aggressive variants that are androgen receptor (AR) independent. Here we identify the transcription factor ONECUT2 (OC2) as a master regulator of AR networks in metastatic castration-resistant prostate cancer (mCRPC). OC2 acts as a survival factor in mCRPC models, suppresses the AR transcriptional program by direct regulation of AR target genes and the AR licensing factor FOXA1, and activates genes associated with neural differentiation and progression to lethal disease. OC2 appears active in a substantial subset of human prostate adenocarcinoma and neuroendocrine tumors. Inhibition of OC2 by a newly identified small molecule suppresses metastasis in mice. These findings suggest that OC2 displaces AR-dependent growth and survival mechanisms in many cases where AR remains expressed, but where its activity is bypassed. OC2 is also a potential drug target in the metastatic phase of aggressive PC.

ONECUT2 Is a Targetable Master Regulator of Lethal Prostate Cancer That Suppresses the Androgen Axis

Treatment of prostate cancer (PC) by androgen suppression is associated with the emergence of aggressive variants that exhibit variable dependence on the androgen receptor (AR). Here we identify the developmental transcription factor ONECUT2 (OC2) as a master regulator of AR networks in metastatic castration-resistant prostate cancer (mCRPC). OC2 suppresses the AR transcriptional program and activates genes associated with neural differentiation and lethal progression. Inhibition of OC2 by a newly identified small molecule suppresses PC metastasis in mice. These findings suggest that OC2 displaces ARdependent growth and survival mechanisms in a substantial subset of mCRPC where AR remains expressed, but where its activity is bypassed. OC2 is also a potential drug target in the metastatic phase of aggressive PC.

Onecut transcription factor OC2 is a direct target of T-bet in type-1 T-helper cells

T-box transcription factor, T-bet, has a central role in the differentiation of T-helper (Th) progenitor cells to Th1 or Th2 effector cells, partly by regulating the expression of genes such as interferon-gamma (IFN-gamma). However, the direct target genes, especially those mediating the transcriptional network initiated by T-bet, are not yet fully understood. By combining chromatin immunoprecipitation from Th1 cells with human cytosine-phosphate-guanine-island array analysis, Onecut 2 (OC2), which encodes a member of the ONECUT class of transcriptional activators, was identified as a direct target gene of T-bet. OC2 is expressed in Th1 but not Th2 cells and reporter assays showed that T-bet transactivates OC2 transcription through putative T-bet half-sites locating -451 to -347 of OC2 promoter region. Moreover, we found that OC2 binds and transactivates human T-bet promoter. These results suggest that not only cell-extrinsic regulation via the IFN-gamma/STAT1 pathway, but also cell-intrinsic transcriptional positive feedback loop between T-bet and OC2 could be involved in Th1 development.

Retrograde BMP Signaling Regulates Trigeminal Sensory Neuron Identities and the Formation of Precise Face Maps

Somatosensory information from the face is transmitted to the brain by trigeminal sensory neurons. It was previously unknown whether neurons innervating distinct areas of the face possess molecular differences. We have identified a set of genes differentially expressed along the dorsoventral axis of the embryonic mouse trigeminal ganglion and thus can be considered trigeminal positional identity markers. Interestingly, establishing some of the spatial patterns requires signals from the developing face. We identified bone morphogenetic protein 4 (BMP4) as one of these target-derived factors and showed that spatially defined retrograde BMP signaling controls the differential gene expressions in trigeminal neurons through both Smad4-independent and Smad4-dependent pathways. Mice lacking one of the BMP4-regulated transcription factors, Onecut2 (OC2), have defects in the trigeminal central projections representing the whiskers. Our results provide molecular evidence for both spatial patterning and retrograde regulation of gene expression in sensory neurons during the development of the somatosensory map.

The Transcription Factor Hepatocyte Nuclear Factor-6/Onecut-1 Controls the Expression of Its Paralog Onecut-3 in Developing Mouse Endoderm

During development, the endoderm gives rise to several organs, including the pancreas and liver. This differentiation process requires spatial and temporal regulation of gene expression in the endoderm by a network of tissue-specific transcription factors whose elucidation is far from complete. These factors include the Onecut protein hepatocyte nuclear factor-6 (HNF-6), which controls pancreas and liver development as shown in our previous work on Hnf6 knock-out embryos. In mammals, HNF-6 has two paralogs, Onecut-2 (OC-2) and OC-3, whose patterns of expression in the adult overlap with that of HNF-6. In the present work, we examine the expression profile of the three Onecut factors in the developing mouse endoderm. We show that HNF-6, OC-2, and OC-3 are expressed sequentially, which defines new steps in endoderm differentiation. By analyzing Hnf6 knock-out embryos we find that HNF-6 is required for expression of the Oc3 gene in the endoderm. We show that OC-3 colocalizes with HNF-6 in the endoderm and in embryonic pancreas and liver. Based on transfection, chromatin immunoprecipitation, and whole embryo electroporation experiments, we demonstrate that HNF-6 can bind to and stimulate the expression of the Oc3 gene. This study identifies a regulatory cascade between two paralogous transcription factors, sheds new light on the interpretation of the Hnf6 knock-out phenotype, and broadens the transcription factors network operating during development of the endoderm, liver, and pancreas.

OC-3, a Novel Mammalian Member of the ONECUT Class of Transcription Factors

Transcription factors of the ONECUT class possess a single cut domain and a divergent homeodomain. They regulate gene networks by controlling the expression of other transcription factors and they play an important role in cell differentiation and metabolism. We identified earlier in mammals HNF-6 (ONECUT-1), the founding member of the class, and ONECUT-2 (OC-2). We have now characterized in the mouse a third ONECUT member, which we call OC-3. Its gene is located on chromosome 10. The sequence of OC-3 (490 residues) displays 51% amino acid identity with HNF-6 and 50% with OC-2. OC-3 has a DNA-binding specificity similar to that of HNF-6 and it is a stimulator of gene transcription. OC-3 mRNA is found in brain, stomach, and upper intestine in the adult and embryonic mouse. Our earlier work on HNF-6 and the expression patterns of the three mammalian ONECUT genes suggest that they all participate to the control of organ development from the foregut and midgut endoderm.

The Transcription Factor Onecut-2 Controls the Microphthalmia-Associated Transcription Factor Gene

Microphthalmia-associated transcription factor (MITF) is essential for melanocyte differentiation. MITF mutations are associated with some cases of Waardenburg syndrome (WS) type 2. WS is a dominantly inherited disease characterized by auditory-pigmentary defects that result from the absence of melanocytes. The lack of mutation in MITF coding sequences in some WS2 patients suggests that unidentified factors controlling MITF expression might be involved. We show here that the cut-homeodomain transcription factor Onecut-2 (OC-2) is expressed in melanocytes and binds to the MITF gene promoter. Overexpression of OC-2 in transfected cells stimulates MITF promoter activity. Mutations that prevent OC-2 binding decrease MITF promoter activity by 75%. Based on these results, we searched in 56 WS2 patients for mutations in the OC2 gene or in OC-2 binding sites in the MITF promoter, but none was found. These results show that OC-2 stimulates MITF expression and that OC2 is a candidate gene, but not a common cause, of WS.