A series of transcription factors critical for maintenance of the neural stem cell state have been identified, but the role of functionally important corepressors in maintenance of the neural stem cell state and early neurogenesis remains unclear. Previous studies have characterized the expression of both SMRT (also known as NCoR2, nuclear receptor co-repressor 2) and NCoR in a variety of developmental systems; however, the specific role of the SMRT corepressor in neurogenesis is still to be determined. Here we report a critical role for SMRT in forebrain development and in maintenance of the neural stem cell state. Analysis of a series of markers in SMRT-gene-deleted mice revealed the functional requirement of SMRT in the actions of both retinoic-acid-dependent and Notch-dependent forebrain development. In isolated cortical progenitor cells, SMRT was critical for preventing retinoic-acid-receptor-dependent induction of differentiation along a neuronal pathway in the absence of any ligand. Our data reveal that SMRT represses expression of the jumonji-domain containing gene JMJD3, a direct retinoic-acid-receptor target that functions as a histone H3 trimethyl K27 demethylase and which is capable of activating specific components of the neurogenic program.

Next-generation sequencing technologies have greatly expanded our understanding of cancer genetics. Antisense technology is an attractive platform with the potential to translate these advances into improved cancer therapeutics, because antisense oligonucleotide (ASO) inhibitors can be designed on the basis of gene sequence information alone. Recent human clinical data have demonstrated the potent activity of systemically administered ASOs targeted to genes expressed in the liver. Here, we describe the preclinical activity and initial clinical evaluation of a class of ASOs containing constrained ethyl modifications for targeting the gene encoding the transcription factor STAT3, a notoriously difficult protein to inhibit therapeutically. Systemic delivery of the unformulated ASO, AZD9150, decreased STAT3 expression in a broad range of preclinical cancer models and showed antitumor activity in lymphoma and lung cancer models. AZD9150 preclinical activity translated into single-agent antitumor activity in patients with highly treatment-refractory lymphoma and non-small cell lung cancer in a phase I dose escalation study.

BackgroundThe Janus kinase (JAK) and signal transduction and activation of transcription (STAT) signaling pathway is an attractive target in multiple cancers. Activation of the JAK-STAT pathway is important in both tumorigenesis and activation of immune responses. In diffuse large B-cell lymphoma (DLBCL), the transcription factor STAT3 has been associated with aggressive disease phenotype and worse overall survival. While multiple therapies inhibit upstream signaling, there has been limited success in selectively targeting STAT3 in patients. Antisense oligonucleotides (ASOs) represent a compelling therapeutic approach to target difficult to drug proteins such as STAT3 through of mRNA targeting. We report the evaluation of a next generation STAT3 ASO (AZD9150) in a non-Hodgkin’s lymphoma population, primarily consisting of patients with DLBCL.MethodsPatients with relapsed or treatment refractory lymphoma were enrolled in this expansion cohort. AZD9150 was administered at 2 mg/kg and the 3 mg/kg (MTD determined by escalation cohort) dose levels with initial loading doses in the first week on days 1, 3, and 5 followed by weekly dosing. Patients were eligible to remain on therapy until unacceptable toxicity or progression. Blood was collected pre- and post-treatment for analysis of peripheral immune cells.ResultsThirty patients were enrolled, 10 at 2 mg/kg and 20 at 3 mg/kg dose levels. Twenty-seven patients had DLBCL. AZD9150 was safe and well tolerated at both doses. Common drug-related adverse events included transaminitis, fatigue, and thrombocytopenia. The 3 mg/kg dose level is the recommended phase 2 dose. All responses were seen among DLBCL patients, including 2 complete responses with median duration of response 10.7 months and 2 partial responses. Peripheral blood cell analysis of three patients without a clinical response to therapy revealed a relative increase in proportion of macrophages, CD4+, and CD8+ T cells; this trend did not reach statistical significance.ConclusionsAZD9150 was well tolerated and demonstrated efficacy in a subset of heavily pretreated patients with DLBCL. Studies in combination with checkpoint immunotherapies are ongoing.Trial registrationRegistered at ClinicalTrials.gov: NCT01563302. First submitted 2/13/2012.Electronic supplementary materialThe online version of this article (10.1186/s40425-018-0436-5) contains supplementary material, which is available to authorized users.

Purpose: Enzalutamide (ENZ) is a potent androgen receptor (AR) antagonist with activity in castration-resistant prostate cancer (CRPC); however, progression to ENZ-resistant (ENZ-R) CRPC frequently occurs with rising serum PSA levels, implicating AR full-length (AR FL ) or variants (AR-Vs) in disease progression.Experimental Design: To define functional roles of AR FL and AR-Vs in ENZ-R CRPC, we designed 3 antisense oligonucleotides (ASO) targeting exon-1, intron-1, and exon-8 in AR pre-mRNA to knockdown AR FL alone or with AR-Vs, and examined their effects in three CRPC cell lines and patient-derived xenografts.Results: ENZ-R-LNCaP cells express high levels of both AR FL and AR-V7 compared with CRPC-LNCaP; in particular, AR FL levels were approximately 12-fold higher than AR-V7. Both AR FL and AR-V7 are highly expressed in the nuclear fractions of ENZ-RLNCaP cells even in the absence of exogenous androgens. In ENZ-R-LNCaP cells, knockdown of AR FL alone, or AR FL plus AR-Vs, similarly induced apoptosis, suppressed cell growth and ARregulated gene expression, and delayed tumor growth in vivo. In 22Rv1 cells that are inherently ENZ-resistant, knockdown of both AR FL and AR-Vs more potently suppressed cell growth, AR transcriptional activity, and AR-regulated gene expression than knockdown of AR FL alone. Exon-1 AR-ASO also inhibited tumor growth of LTL-313BR patient-derived CRPC xenografts.Conclusions: These data identify the AR as an important driver of ENZ resistance, and while the contributions of AR FL and AR-Vs can vary across cell systems, AR FL is the key driver in the ENZ-R LNCaP model. AR targeting strategies against both AR FL and AR-Vs is a rational approach for AR-dependent CRPC.

Transcription in human papillomaviruses (HPVs) is mainly regulated by cellular transcription factors and virus-encoded E2 proteins that act as sequence-specific DNA-binding proteins. Although the functions of E2 as a transcriptional activator and a repressor have been well documented, the role of cellular factors involved in E2-mediated regulation of the HPV promoters and the mechanism by which E2 modulates viral gene expression remain unclear. Using reconstituted cell-free transcription systems, we found that cellular enhancerbinding factors and general cofactors, such as TAF II s, TFIIA, Mediator, and PC4, are not required for E2-mediated repression. Unlike other transcriptional repressors that function through recruitment of histone deacetylase or corepressor complexes, HPV E2 is able to directly target components of the general transcription machinery to exert its repressor activity on the natural HPV E6 promoter. Interestingly, preincubation of TATA binding protein (TBP) or TFIID with HPV template is not sufficient to overcome E2-mediated repression, which can be alleviated only via formation of a minimal TBP (or TFIID)-TFIIB-RNA polymerase II-TFIIF preinitiation complex. Our data therefore indicate that E2 does not simply work by displacing TBP or TFIID from binding to the adjacent TATA box. Instead, E2 appears to function as an active repressor that directly inhibits HPV transcription at steps after TATA recognition by TBP or TFIID.Transcription in eukaryotes is often regulated by extracellular molecules that act through distinct signal transduction pathways to modulate specific gene expression via controlling the activity of gene-specific transcription factors. These genespecific transcription factors then work in conjunction with general transcription factors (GTFs) and cofactors to enhance or inhibit the level of transcription. Although many studies have been conducted to elucidate the mechanisms of transcriptional activation in eukaryotes, relatively little is known about the mechanisms of repression. In general, transcriptional repressors can work either passively to antagonize the activator function or actively to inhibit the activity of the general transcription machinery (30). Counteraction of the activator function by passive repressors can be achieved by direct competition of the same DNA-binding sites (36,37,41,54,55), interference of overlapping or neighboring activator-binding sites (21,24,38,58), modification of the DNA-binding property of the activators (60), titrating away limiting protein factors required for activator function (15, 31), or masking and/or altering the function of the activation domain or blocking the DNA-binding activity of the activators through protein-protein interactions (3,24,46,61). In contrast, active repressors are able to directly inhibit the activity or the assembly of the general transcription machinery, with or without the help of corepressors (2,23,27,29,40,43,45,51). The recruitment of histone deacetylase complexes by some repressors or corepressors represen...