HOTAIR-EZH2 inhibitor AC1Q3QWB upregulates CWF19L1 and enhances cell cycle inhibition of CDK4/6 inhibitor palbociclib in glioma

Inhibition of the TCF12/VSIG4 axis by palbociclib diminishes the proliferation and migration of glioma cells and decreases the M2 polarization of glioma-associated microglia

The CDK4/CDK6 inhibitor palbociclib has shown the encouraging promise in the treatment of glioma. Here, we elucidated how palbociclib exerts suppressive functions in the M2 polarization of glioma-related microglia and the progression of glioma. Xenograft experiments were used to evaluate the function in vivo. The mRNA levels of transcription factor 12 (TCF12) and VSIG4 were detected by RT-qPCR, and their protein levels were assessed by immunoblotting. Cell migration was tested by wound-healing assay. Cell cycle distribution and M1/M2 microglia phenotype analysis were performed by flow cytometry. The levels of IFN-γ, TNF-α, IL-6，and TGF-β were measured by ELISA. The TCF12/VSIG4 association was verified by luciferase reporter and chromatin immunoprecipitation (ChIP) assays. In U251 and LN229 glioma cells, TCF12 and VSIG4 were overexpressed, and palbociclib reduced their expression levels. TCF12 upregulation enhanced the proliferation and migration of glioma cells and the M2 polarization of glioma-associated microglia in vitro as well as the tumorigenicity of U251 glioma cells in vivo, which could be reversed by palbociclib. Mechanistically, TCF12 could enhance VSIG4 transcription and expression by binding to the VSIG4 promoter. TCF12 deficiency led to repression in glioma cell proliferation and migration as well as microglia M2 polarization, which could be abolished by increased VSIG4 expression. Our study reveals the novel TCF12/VSIG4 axis responsible for the efficacy of palbociclib in combating glioma, offering a rationale for the application of palbociclib in glioma treatment.

The multifaceted functions of long non-coding RNA HOTAIR in neuropathologies and its potential as a prognostic marker and therapeutic biotarget

Long non-coding RNAs (lncRNAs) are progressively being perceived as prominent molecular agents controlling multiple aspects of neuronal (patho)physiology. Amongst these is the HOX transcript antisense intergenic RNA, often abbreviated as HOTAIR. HOTAIR epigenetically regulates its target genes via its interaction with two different chromatin-modifying agents; histone methyltransferase polycomb-repressive complex 2 and histone demethylase lysine-specific demethylase 1. Parenthetically, HOTAIR elicits trans-acting sponging function against multiple micro-RNA species. Oncological research studies have confirmed the pathogenic functions of HOTAIR in multiple cancer types, such as gliomas and proposed it as a pro-oncological lncRNA. In fact, its expression has been suggested to be a predictor of the severity/grade of gliomas, and as a prognostic biomarker. Moreover, a propound influence of HOTAIR in other aspects of brain heath and disease states is just beginning to be unravelled. The objective of this review is to recapitulate all the relevant data pertaining to the regulatory roles of HOTAIR in neuronal (patho)physiology. To this end, we discuss the pathogenic mechanisms of HOTAIR in multiple neuronal diseases, such as neurodegeneration, traumatic brain injury and neuropsychiatric disorders. Finally, we also summarize the results from the studies incriminating HOTAIR in the pathogeneses of gliomas and other brain cancers. Implications of HOTAIR serving as a suitable therapeutic target in neuropathologies are also discussed.

Roles of HOTAIR Long Non-coding RNA in Gliomas and Other CNS Disorders

HOX transcript antisense intergenic RNA (HOTAIR) is a long non-coding RNA (lncRNA) which is increasingly being perceived as a tremendous molecular mediator of brain pathophysiology at multiple levels. Epigenetic regulation of target gene expression carried out by HOTAIR is thorough modulation of chromatin modifiers; histone methyltransferase polycomb repressive complex 2 (PRC2) and histone demethylase lysine-specific demethylase 1 (LSD1). Incidentally, HOTAIR was the first lncRNA shown to elicit sponging of specific microRNA (miRNA or miR) species in a trans-acting manner. It has been extensively studied in various cancers, including gliomas and is regarded as a prominent pro-tumorigenic and pro-oncogenic lncRNA. Indeed, the expression of HOTAIR may serve as glioma grade predictor and prognostic biomarker. The objective of this timely review is not only to outline the multifaceted pathogenic roles of HOTAIR in the development and pathophysiology of gliomas and brain cancers, but also to delineate the research findings implicating it as a critical regulator of overall brain pathophysiology. While the major focus is on neuro-oncology, wherein HOTAIR represents a particularly potent underlying pathogenic player and a suitable therapeutic target, mechanisms underlying the regulatory actions of HOTAIR in neurodegeneration, traumatic, hypoxic and ischemic brain injuries, and neuropsychiatric disorders are also presented.

Compound AC1Q3QWB upregulates CDKN1A and SOX17 by interrupting the HOTAIR-EZH2 interaction and enhances the efficacy of tazemetostat in endometrial cancer

Endometrial cancer (EC) is a common malignancy of the female reproductive system, with an escalating incidence. Recurrent/metastatic EC presents a poor prognosis. The interaction between the long non-coding RNA (lncRNA) HOTAIR and the polycomb repressive complex 2 (PRC2) induces abnormal silencing of tumor suppressor genes, exerting a pivotal role in tumorigenesis. We have previously discovered AC1Q3QWB (AQB), a small-molecule compound targeting HOTAIR-EZH2 interaction. In the present study, we unveil that AQB selectively hampers the interaction between HOTAIR and EZH2 within EC cells, thus reversing the epigenetic suppression of tumor suppressor genes. Furthermore, our findings demonstrate AQB's synergistic effect with tazemetostat (TAZ), an EZH2 inhibitor, significantly boosting the expression of CDKN1A and SOX17. This, in turn, induces cell cycle arrest and impedes EC cell proliferation, migration, and invasion. In vivo experiments further validate AQB's potential by enhancing TAZ's anti-tumor efficacy at lower doses. Our results advocate AQB, a recently discovered small-molecule inhibitor, as a promising agent against EC cells. When combined with TAZ, it offers a novel therapeutic strategy for EC treatment.

Novel CWF19L1 mutations in patients with spinocerebellar ataxia, autosomal recessive 17

Spinocerebellar ataxia, autosomal recessive-17 (SCAR17) is a rare hereditary ataxia characterized by ataxic gait, cerebellar signs and occasionally accompanied by intellectual disability and seizures. Pathogenic mutations in the CWF19L1 gene that code for CWF19 like cell cycle control factor 1 cause SCAR17. We report here two unrelated families with the clinical characteristics of global developmental delay, cerebellar ataxia, pyramidal signs, and seizures. Cerebellar atrophy, and T2/FLAIR hypointense transverse pontine stripes were observed in brain imaging. Exome sequencing identified novel homozygous mutations including a splice acceptor site variant c.1375-2 A > G on intron 12 in a male patient and a single nucleotide variant c.452 T > G on exon 5 resulting in a missense variant p.Ile151Ser in the female patient from two unrelated families, respectively. Sanger sequencing confirmed the segregation of these variants in the family members with autosomal recessive inheritance. Transcript analysis of the splice site variant revealed activation of a novel cryptic splice acceptor site on exon 13 resulting in an alternative transcription with a loss of nine nucleotides on exon 13. Translation of this transcript predicted an in-frame deletion of three amino acids p.(459_461del). We also observed a novel exon 13 skipping which results in premature termination of the protein product. Our study expands the phenotype, radiological features, and genotypes known in SCAR17.

Multimodal perturbation analyses of cyclin-dependent kinases reveal a network of synthetic lethalities associated with cell-cycle regulation and transcriptional regulation

Cell-cycle control is accomplished by cyclin-dependent kinases (CDKs), motivating extensive research into CDK targeting small-molecule drugs as cancer therapeutics. Here we use combinatorial CRISPR/Cas9 perturbations to uncover an extensive network of functional interdependencies among CDKs and related factors, identifying 43 synthetic-lethal and 12 synergistic interactions. We dissect CDK perturbations using single-cell RNAseq, for which we develop a novel computational framework to precisely quantify cell-cycle effects and diverse cell states orchestrated by specific CDKs. While pairwise disruption of CDK4/6 is synthetic-lethal, only CDK6 is required for normal cell-cycle progression and transcriptional activation. Multiple CDKs (CDK1/7/9/12) are synthetic-lethal in combination with PRMT5, independent of cell-cycle control. In-depth analysis of mRNA expression and splicing patterns provides multiple lines of evidence that the CDK-PRMT5 dependency is due to aberrant transcriptional regulation resulting in premature termination. These inter-dependencies translate to drug-drug synergies, with therapeutic implications in cancer and other diseases.

Loss of p53 Concurrent with RAS and TERT Activation Induces Glioma Formation

There is an ongoing debate regarding whether gliomas originate due to functional or genetic changes in neural stem cells (NSCs). Genetic engineering has made it possible to use NSCs to establish glioma models with the pathological features of human tumors. Here, we found that RAS, TERT, and p53 mutations or abnormal expression were associated with the occurrence of glioma in the mouse tumor transplantation model. Moreover, EZH2 palmitoylation mediated by ZDHHC5 played a significant role in this malignant transformation. EZH2 palmitoylation activates H3K27me3, which in turn decreases miR-1275, increases glial fibrillary acidic protein (GFAP) expression, and weakens the binding of DNA methyltransferase 3A (DNMT3A) to the OCT4 promoter region. Thus, these findings are significant because RAS, TERT, and p53 oncogenes in human neural stem cells are conducive to a fully malignant and rapid transformation, suggesting that gene changes and specific combinations of susceptible cell types are important factors in determining the occurrence of gliomas.

Functions and underlying mechanisms of lncRNA HOTAIR in cancer chemotherapy resistance

Chemotherapy has been one of the most important treatments for advanced cancer in recent decades. Although the sensitivity rate of initial chemotherapy is high, patients with chemotherapy resistant tumors, experience tumor recurrence. In recent years, many studies have shown that homeobox transcript antisense intergenic RNA (HOTAIR) is involved in many pathological processes including carcinogenesis. The abnormal regulation of a variety of cell functions by HOTAIR, such as apoptosis, the cell cycle, epithelial-mesenchymal transition, autophagy, self-renewal, and metabolism, is associated with chemotherapy resistance. Therefore, there is an urgent need to understand the biology and mechanism underlying the role of HOTAIR in tumor behavior and its potential as a biomarker for predicting the effect of chemotherapy. In this manuscript, we review the mechanisms underlying HOTAIR-related drug resistance and discuss the limitations of current knowledge and propose potential future directions.

Radiosynthesis of a novel antisense imaging probe targeting LncRNA HOTAIR in malignant glioma

Background

Long non-coding RNA (LncRNA) HOTAIR was amplified and overexpressed in many human carcinomas, which could serve as a useful target for cancer early detection and treatment. The 99mTc radiolabeled antisense oligonucleotides (ASON) could visualize the expression of HOTAIR and provide a diagnostic value for malignant tumors. The aim of this study was to evaluate whether liposome-coated antisense oligonucleotide probe 99mTc-HYNIC-ASON targeting HOTAIR can be used in in vivo imaging of HOTAIR in malignant glioma xenografts.

Methods

The ASON targeting LncRNA HOTAIR as well as mismatched ASON (ASONM) were designed and modified. The radiolabeling of 99mTc with two probes were via the conjugation of bifunctional chelator HYNIC. Then probes were purified by Sephadex G25 and tested for their radiolabeling efficiency and purity, as well as stability by ITLC (Instant thin-layer chromatography) and gel electrophoresis. Then the radiolabeled probes were transfected with lipofectamine 2000 for cellular uptake test and the next experimental use. Furthermore, biodistribution study and SPECT imaging were performed at different times after liposome-coated 99mTc-HYNIC-ASON/ASONM were intravenously injected in glioma tumor-bearing mice models. All data were analyzed by statistical software.

Results

The labeling efficiencies of 99mTc-HYNIC-ASON and 99mTc-HYNIC-ASONM measured by ITLC were (91 ± 1.5) % and (90 ± 0.6) %, respectively, and both radiochemical purities were more than 89%. Two probes showed good stability within 12 h. Gel electrophoresis confirmed that the oligomers were successfully radiolabeled no significant degradation were found. Biodistribution study demonstrated that liposome-coated antisense probes were excreted mainly through the kidney and bladder and has higher uptake in the tumor. Meanwhile, the tumor was clearly shown after injection of liposome coated 99mTc-HYNIC-ASON, and its T/M ratio was higher than that in the non-transfection group and mismatched group. No tumor was seen in mismatched and blocking group.

Conclusion

The liposome encapsulated 99mTc-HYNIC-ASON probe can be used in the in vivo, real-time imaging of LncRNA HOTAIR expression in malignant glioma.

EZH2 as a new therapeutic target in brain tumors: Molecular landscape, therapeutic targeting and future prospects

Brain tumors are responsible for high mortality and morbidity worldwide. The brain tumor treatment depends on identification of molecular pathways involved in progression and malignancy. Enhancer of zeste homolog 2 (EZH2) has obtained much attention in recent years in field of cancer therapy due to its aberrant expression and capacity in modulating expression of genes by binding to their promoter and affecting methylation status. The present review focuses on EZH2 signaling in brain tumors including glioma, glioblastoma, astrocytoma, ependymomas, medulloblastoma and brain rhabdoid tumors. EZH2 signaling mainly participates in increasing proliferation and invasion of cancer cells. However, in medulloblastoma, EZH2 demonstrates tumor-suppressor activity. Furthermore, EZH2 can regulate response of brain tumors to chemotherapy and radiotherapy. Various molecular pathways can function as upstream mediators of EZH2 in brain tumors including lncRNAs and miRNAs. Owing to its enzymatic activity, EZH2 can bind to promoter of target genes to induce methylation and affects their expression. EZH2 can be considered as an independent prognostic factor in brain tumors that its upregulation provides undesirable prognosis. Both anti-tumor agents and gene therapies such as siRNA have been developed for targeting EZH2 in cancer therapy.

HOTAIR Up-Regulation Activates NF-κB to Induce Immunoescape in Gliomas

Background

Checkpoint blockade therapies targeting programmed death ligand 1 (PD-L1) and its receptor programmed cell death 1 promote T cell-mediated immune surveillance against tumors and have been associated with significant clinical benefit in cancer patients. The long-stranded non-coding RNA HOTAIR is highly expressed and associated with metastasis in a variety of cancer types and promotes tumor metastasis at least in part through association with the PRC2 complex that induces redirection to hundreds of genes involved in tumor metastasis. Here, we report that HOTAIR is an activator lncRNA of the NF-κB pathway and demonstrate that its apparent upregulation promotes inflammatory signaling and immune escape in glioma cells.

Methods

Bioinformatics analysis was used to elucidate the relationship between HOTAIR and NF-κB pathway in HOTAIR knockdown glioma cells. At the cytological level, protein hybridization and immunofluorescence were used to detect the response of proteins in the NF-κB signaling pathway to HOTAIR regulation. ChIP and ChIRP experiments identified HOTAIR target genes. Animal experiments verified alterations in inflammation and immune escape following HOTAIR knockdown and activity inhibition.

Results

HOTAIR activated the expression of proteins involved in NF-κB, TNFα, MAPK and other inflammatory signaling pathways. In addition, HOTAIR induced various proteins containing protein kinase structural domains and promoted the enrichment of proteins and complexes of important inflammatory signaling pathways, such as the TNFα/NF-κB signaling protein complex, the IκB kinase complex, and the IKKA-IKKB complex. In addition, HOTAIR aberrantly activated biological processes involved in glioma immune responses, T-cell co-stimulation and transcription initiation by RNA polymerase II. HOTAIR facilitated the induction of IκBα phosphorylation by suppressing the expression of the NF-κB upstream protein UBXN1, promoting NF-κB phosphorylation and nuclear translocation. In vivo, reduction of HOTAIR decreased PD-L1 protein expression, indicating that cells are more likely to be targeted by immune T cells.

Conclusion

In conclusion, our results provide convincing evidence that lncRNA HOTAIR drives aberrant gene transcription and immune escape from tumor cells through the NF-κB pathway.

LncRNA HOTAIR: A Potential Prognostic Factor and Therapeutic Target in Human Cancers

Long non-coding RNAs (lncRNAs) are emerging as crucial regulators of gene expression and physiological processes. LncRNAs are a class of ncRNAs of 200 nucleotides in length. HOX transcript antisense RNA (HOTAIR), a trans-acting lncRNA with regulatory function on transcription, can repress gene expression by recruiting chromatin modifiers. HOTAIR is an oncogenic lncRNA, and numerous studies have determined that HOTAIR is highly upregulated in a wide variety of human cancers. In this review, we briefly summarize the impact of lncRNA HOTAIR expression and functions on different human solid tumors, and emphasize the potential of HOTAIR on tumor prognosis and therapy. Here, we review the recent studies that highlight the prognostic potential of HOTAIR in drug resistance and survival, and the progress of therapies developed to target HOTAIR to date. Furthermore, targeting HOTAIR results in the suppression of HOTAIR expression or function. Thus, HOTAIR knockdown exhibits great therapeutic potential in various cancers, indicating that targeting lncRNA HOTAIR may serve as a promising strategy for cancer therapy. We also propose that preclinical studies involving HOTAIR are required to provide a better understanding of the exact molecular mechanisms underlying the dysregulation of its expression and function in different human cancers and to explore effective methods of targeting HOTAIR and engineering efficient and targeted drug delivery methods in vivo.

The Role of Non-coding RNAs in the Pathogenesis of Glial Tumors

Among the many malignant neoplasms, glioblastoma (GBM) leads to one of the worst prognosis for patients and has an almost 100% recurrence rate. The only chemotherapeutic drug that is widely used for treating glioblastoma is temozolomide, a DNA alkylating agent. Its impact, however, is only minor; it increases patients' survival just by 12 to 14 months. Multiple highly selective compounds that affect specific proteins and have performed well in other types of cancer have proved ineffective against glioblastoma. Hence, there is an urgent need for novel methods that could help achieve the long-awaited progress in glioblastoma treatment. One of the potentially promising approaches is the targeting of non-coding RNAs (ncRNAs). These molecules are characterized by extremely high multifunctionality and often act as integrators by coordinating multiple key signaling pathways within the cell. Thus, the impact on ncRNAs has the potential to lead to a broader and stronger impact on cells, as opposed to the more focused action of inhibitors targeting specific proteins. In this review, we summarize the functions of long noncoding RNAs, circular RNAs, as well as microRNAs, PIWI-interacting RNAs, small nuclear and small nucleolar RNAs. We provide a classification of these transcripts and describe their role in various signaling pathways and physiological processes. We also provide examples of oncogenic and tumor suppressor ncRNAs belonging to each of these classes in the context of their involvement in the pathogenesis of gliomas and glioblastomas. In conclusion, we considered the potential use of ncRNAs as diagnostic markers and therapeutic targets for the treatment of glioblastoma.

HDAC6 regulates primordial follicle activation through mTOR signaling pathway

Primordial follicle pool established perinatally is a non-renewable resource which determines the female fecundity in mammals. While the majority of primordial follicles in the primordial follicle pool maintain dormant state, only a few of them are activated into growing follicles in adults in each cycle. Excessive activation of the primordial follicles accelerates follicle pool consumption and leads to premature ovarian failure. Although previous studies including ours have emphasized the importance of keeping the balance between primordial follicle activation and dormancy via molecules within the primordial follicles, such as TGF-β, E-Cadherin, mTOR, and AKT through different mechanisms, the homeostasis regulatory mechanisms of primordial follicle activation remain unclear. Here, we reported that HDAC6 acts as a key negative regulator of mTOR in dormant primordial follicles. In the cytoplasm of both oocytes and granulosa cells of primordial follicles, HDAC6 expressed strong, however in those activated primordial follicles, its expression level is relatively weaker. Inhibition or knockdown of HDAC6 significantly promoted the activation of limited primordial follicles while the size of follicle pool was not affected profoundly in vitro. Importantly, the expression level of mTOR in the follicle and the activity of PI3K in the oocyte of the follicle were simultaneously up-regulated after inhibiting of HDAC6. The up-regulated mTOR leads to not only the growth and differentiation of primordial follicles granulosa cells (pfGCs) into granulosa cells (GCs), but the increased secretion of KITL in these somatic cells. As a result, inhibition of HDAC6 awaked the dormant primordial follicles of mice in vitro. In conclusion, HDAC6 may play an indispensable role in balancing the maintenance and activation of primordial follicles through mTOR signaling in mice. These findings shed new lights on uncovering the epigenetic factors involved physiology of sustaining female reproduction.

AGAP2-AS1 May Promote the Occurrence and Development of Glioblastoma by Sponging miR-9-5p: Evidence From a ceRNA Network

Glioblastoma (GBM), the primary malignant brain tumor, is typically associated with a poor prognosis and poor quality of life, mainly due to the lack of early diagnostic biomarkers and therapeutic targets. However, gene sequencing technologies and bioinformatics analysis are currently being actively utilized to explore potential targets for the diagnosis and management of malignancy. Herein, based on a variety of bioinformatics tools for the reverse prediction of target genes associated with the prognosis of GBM, a ceRNA network of AGAP2-AS1-miR-9-5p-MMP2/MMP9 was constructed, and a potential therapeutic target for GBM was identified. Enrichment analysis predicted that the ceRNA regulatory network participates in the processes of cell proliferation, differentiation, and migration.

Cyclin-dependent kinase inhibitors in head and neck cancer and glioblastoma-backbone or add-on in immune-oncology?

Cyclin-dependent kinases (CDK) control the cell cycle and play a crucial role in oncogenesis. Pharmacologic inhibition of CDK has contributed to the recent clinical approval of dual CDK4/6 inhibitors for the treatment of breast and small cell lung cancer. While the anticancer cell effects of CDK inhibitors are well-established, preclinical and early clinical studies describe additional mechanisms of action such as chemo- and radiosensitization or immune stimulation. The latter offers great potential to incorporate CDK inhibitors in immune-based treatments. However, dosing schedules and accurate timing of each combination partner need to be respected to prevent immune escape and resistance. In this review, we provide a detailed summary of CDK inhibitors in the two solid cancer types head and neck cancer and glioblastoma multiforme; it describes the molecular mechanisms of response vs. resistance and covers strategies to avoid resistance by the combination of immunotherapy or targeted therapy.

Critical role of HOX transcript antisense intergenic RNA (HOTAIR) in gliomas

Despite extensive research, gliomas are associated with high morbidity and mortality, mainly attributed to the rapid growth rate, excessive invasiveness, and molecular heterogeneity, as well as regenerative potential of cancer stem cells. Therefore, elucidation of the underlying molecular mechanisms and the identification of potential molecular diagnostic and prognostic biomarkers are of paramount importance. HOX transcript antisense intergenic RNA (HOTAIR) is a well-studied long noncoding RNA, playing an emerging role in tumorigenesis of several human cancers. A growing amount of preclinical and clinical evidence highlights the pro-oncogenic role of HOTAIR in gliomas, mainly attributed to the enhancement of proliferation and migration, as well as inhibition of apoptosis. In vitro and in vivo studies demonstrate that HOTAIR modulates the activity of specific transcription factors, such as MXI1, E2F1, ATF5, and ASCL1, and regulates the expression of cell cycle-associated genes along with related signaling pathways, like the Wnt/β-catenin axis. Moreover, it can interact with specific miRNAs, including miR-326, miR-141, miR-148b-3p, miR-15b, and miR-126-5p. Of importance, HOTAIR has been demonstrated to enhance angiogenesis and affect the permeability of the blood-tumor barrier, thus modulating the efficacy of chemotherapeutic agents. Herein, we provide evidence on the functional role of HOTAIR in gliomas and discuss the benefits of its targeting as a novel approach toward glioma treatment.