HDAC9 promotes glioblastoma growth via TAZ-mediated EGFR pathway activation

HDAC9 as a Privileged Target: Reviewing its Role in Different Diseases and Structure-activity Relationships (SARs) of its Inhibitors

HDAC9 is a histone deacetylase enzyme belonging to the class IIa of HDACs which catalyses histone deacetylation. HDAC9 inhibit cell proliferation by repairing DNA, arresting the cell cycle, inducing apoptosis, and altering genetic expression. HDAC9 plays a significant part in human physiological system and are involved in various type of diseases like cancer, diabetes, atherosclerosis and CVD, autoimmune response, inflammatory disease, osteoporosis and liver fibrosis. This review discusses the role of HDAC9 in different diseases and structure-activity relationships (SARs) of various hydroxamate and non-hydroxamate-based inhibitors. SAR of compounds containing several scaffolds have been discussed in detail. Moreover, structural requirements regarding the various components of HDAC9 inhibitor (cap group, linker and zinc-binding group) has been highlighted in this review. Though, HDAC9 is a promising target for the treatment of a number of diseases including cancer, a very few research are available. Thus, this review may provide useful information for designing novel HDAC9 inhibitors to fight against different diseases in the future.

The Spectrum of Molecular Pathways in Gliomas-An Up-to-Date Review

During the last 20 years, molecular alterations have gained increasing significance in the diagnosis and biological assessment of tumors. Gliomas represent the largest group of tumors of the central nervous system, and the main aim of this review is to present the current knowledge on molecular pathways and their alterations in gliomas. A wide range of new insights has been gained, including evidence for the involvement of the WNT pathway or the hippo pathway in the pathobiology of gliomas, indicating a broad involvement of different pathways formerly not considered to play a central role in gliomas. Even new aspects of angiogenic, apoptotic, and metabolic pathways are presented, as well as the rapidly growing field of epigenetic processes, including non-coding RNAs. The two major conclusions drawn from the present review are the distinct interconnectivity of the whole spectrum of molecular pathways and the prominent role of non-coding RNAs, especially circular RNAs, in the regulation of specific targets. All these new insights are discussed, even considering the topic of the resistance to therapy of gliomas, along with aspects that are still incompletely understood, like the role of hydroxymethylation, or even ferroptosis, in the pathobiology of gliomas.

The function of histone methylation and acetylation regulators in GBM pathophysiology

Glioblastoma (GBM) is the most common and lethal primary brain malignancy and is characterized by a high degree of intra and intertumor cellular heterogeneity, a starkly immunosuppressive tumor microenvironment, and nearly universal recurrence. The application of various genomic approaches has allowed us to understand the core molecular signatures, transcriptional states, and DNA methylation patterns that define GBM. Histone posttranslational modifications (PTMs) have been shown to influence oncogenesis in a variety of malignancies, including other forms of glioma, yet comparatively less effort has been placed on understanding the transcriptional impact and regulation of histone PTMs in the context of GBM. In this review we discuss work that investigates the role of histone acetylating and methylating enzymes in GBM pathogenesis, as well as the effects of targeted inhibition of these enzymes. We then synthesize broader genomic and epigenomic approaches to understand the influence of histone PTMs on chromatin architecture and transcription within GBM and finally, explore the limitations of current research in this field before proposing future directions for this area of research.

Role of circular RNAs in retinoblastoma

Retinoblastoma (RB), the most common malignant retinal tumor among children under 3 years old, is lethal if left untreated. Early diagnosis, together with timely and effective treatment, is important to improve retinoblastoma-related outcomes. Circular RNAs (circRNAs), a new class of non-coding RNAs with the capacity to regulate cellular activities, have great potential in retinoblastoma diagnosis and treatment. Recent studies have identified circular RNAs that regulate multiple cellular processes involved in retinoblastoma, including cell viability, proliferation, apoptosis, autophagy, migration, and invasion. Six circular RNAs (circ-FAM158A, circ-DHDDS, circ-E2F3, circ-TRHDE, circ-E2F5, and circ-RNF20) promote disease progression and metastasis in retinoblastoma and function as oncogenic factors. Other circular RNAs, such as circ-TET1, circ-SHPRH, circ-MKLN1, and circ-CUL2, play tumor suppressive roles in retinoblastoma. At present, the studies on the regulatory mechanism of circular RNAs in retinoblastoma are not very clear. The purpose of this review is to summarize recent studies on the functional roles and molecular mechanisms of circular RNAs in retinoblastoma and highlight novel strategies for retinoblastoma diagnosis, prognosis, and treatment.

Epigenetic alterations in glioblastomas: Diagnostic, prognostic and therapeutic relevance

Glioblastoma, the most common and heterogeneous tumor affecting brain parenchyma, is dismally characterized by a very poor prognosis. Thus, the search of new, more effective treatments is a vital need. Here, we will review the druggable epigenetic features of glioblastomas that are, indeed, currently explored in preclinical studies and in clinical trials for the development of more effective, personalized treatments. In detail, we will review the studies that have led to the identification of epigenetic signatures, IDH mutations, MGMT gene methylation, histone modification alterations, H3K27 mutations and epitranscriptome landscapes of glioblastomas, in each case discussing the corresponding targeted therapies and their potential efficacy. Finally, we will emphasize how recent technological improvements permit to routinely investigate many glioblastoma epigenetic biomarkers in clinical practice, further enforcing the hope that personalized drugs, targeting specific epigenetic features, could be in future a therapeutic option for selected patients.

Potential role of melatonin in prevention and treatment of lung cancer

Lung cancer is the second most common cancer and the most lethal cancer worldwide. Melatonin, an indoleamine produced in the pineal gland, shows anticancer effects on a variety of cancers, especially lung cancer. Herein, we clarify the pathophysiology of lung cancer, the association of circadian rhythm with lung, and the relationship between shift work and the incidence of lung cancer. Special focus is placed on the role of melatonin receptors in lung cancer, the relationship between inflammation and lung cancer, control of cell proliferation, apoptosis, autophagy, and immunomodulation in lung cancer by melatonin. A review of the drug synergy of melatonin with other anticancer drugs suggests its usefulness in combination therapy. In summary, the information compiled may serve as a comprehensive reference for the various mechanisms of action of melatonin against lung cancer, as a guide for the design of future experimental research and for advancing melatonin as a therapeutic agent for lung cancer.

Latest updates on cellular and molecular biomarkers of gliomas

Gliomas are the most common central nervous system malignancies, compromising almost 80% of all brain tumors and is associated with significant mortality. The classification of gliomas has shifted from basic histological perspective to one that is based on molecular biomarkers. Treatment of this type of tumors consists currently of surgery, chemotherapy and radiation therapy. During the past years, there was a limited development of effective glioma diagnostics and therapeutics due to multiple factors including the presence of blood-brain barrier and the heterogeneity of this type of tumors. Currently, it is necessary to highlight the advantage of molecular diagnosis of gliomas to develop patient targeted therapies based on multiple oncogenic pathway. In this review, we will evaluate the development of cellular and molecular biomarkers for the diagnosis of gliomas and the impact of these diagnostic tools for better tailored and targeted therapies.

A Selective Histone Deacetylase Inhibitor Induces Autophagy and Cell Death via SCNN1A Downregulation in Glioblastoma Cells

Glioblastoma multiforme (GBM) is a grade IV, highly malignant brain tumor. Because of the heterogeneity of GBM, a multitarget drug is a rational strategy for GBM treatment. Histone deacetylase inhibitors (HDACis) regulate the expression of numerous genes involved in cell death, apoptosis, and tumorigenesis. We found that the HDAC4/HDAC5 inhibitor LMK235 at 0.5 µM significantly reduced the cell viability and colony formation of patient-derived, temozolomide-resistant GBM P#5 TMZ-R, U-87 MG, and T98G cells. Moreover, LMK235 also significantly increased TUBA acetylation, which is an indicator of HDAC inhibition. Interestingly, LMK235 induced MAP1LC3 robust readout and puncta accumulation but did not enhance PARP1 cleavage or the proportion of annexin V-positive cells, suggesting that LMK235-induced cell death occurred via autophagy activation. Further RNA-seq analysis after LMK235 treatment showed that 597 different expression genes compared to control. After bioinformatic analysis by KEGG and STRING, we focused on 34 genes and validated their mRNA expression by qPCR. Further validation showed that 2 µM LMK235 significantly reduced the mRNA and protein expression of SCNN1A. Cell viability of SCNN1A-silenced cells were reduced, but cells were rescued while treated with an autophagy inhibitor bafilomycin A1. Conclusively, SCNN1A plays a role in LMK235-induced autophagy and cell death in GBM cells.

Deoxyelephantopin Induces Apoptosis and Enhances Chemosensitivity of Colon Cancer via miR-205/Bcl2 Axis

Colon cancer (CC) is one of the major causes of cancer death in humans. Despite recent advances in the management of CC, the prognosis is still poor and a new strategy for effective therapy is imperative. Deoxyelephantopin (DET), extracted from an important medicinal plant, Elephantopus scaber L., has been reported to exhibit excellent anti-inflammatory and -cancer activities, while the detailed anti-cancer mechanism remains unclear. Herein, we found that DET showed a significant CC inhibiting effect in vitro and in vivo without obvious organ toxicity. Mechanistically, DET inhibited CC cells and tumor growth by inducing G2/M phase arrest and subsequent apoptosis. DET-mediated cell cycle arrest was caused by severe DNA damage, and DET decreased the Bcl2 expression level in a dose-dependent manner to promote CC cell apoptosis, whereas restoring Bcl2 expression reduced apoptosis to a certain extent. Moreover, we identified a microRNA complementary to the 3'-UTR of Bcl2, miR-205, that responded to the DET treatment. An inhibitor of miR-205 could recover Bcl2 expression and promoted the survival of CC cells upon DET treatment. To further examine the potential value of the drug, we evaluated the combinative effects of DET and 5-Fluorouracil (5FU) through Jin's formula and revealed that DET acted synergistically with 5FU, resulting in enhancing the chemotherapeutic sensitivity of CC to 5FU. Our results consolidate DET as a potent drug for the treatment of CC when it is used alone or combined with 5FU, and elucidate the importance of the miR-205-Bcl2 axis in DET treatment.

New locus underlying auriculocondylar syndrome (ARCND): 430 kb duplication involving TWIST1 regulatory elements

Background

Auriculocondylar syndrome (ARCND) is a rare genetic disease that affects structures derived from the first and second pharyngeal arches, mainly resulting in micrognathia and auricular malformations. To date, pathogenic variants have been identified in three genes involved in the EDN1-DLX5/6 pathway (PLCB4, GNAI3 and EDN1) and some cases remain unsolved. Here we studied a large unsolved four-generation family.

Methods

We performed linkage analysis, resequencing and Capture-C to investigate the causative variant of this family. To test the pathogenicity of the CNV found, we modelled the disease in patient craniofacial progenitor cells, including induced pluripotent cell (iPSC)-derived neural crest and mesenchymal cells.

Results

This study highlights a fourth locus causative of ARCND, represented by a tandem duplication of 430 kb in a candidate region on chromosome 7 defined by linkage analysis. This duplication segregates with the disease in the family (LOD score=2.88) and includes HDAC9, which is located over 200 kb telomeric to the top candidate gene TWIST1. Notably, Capture-C analysis revealed multiple cis interactions between the TWIST1 promoter and possible regulatory elements within the duplicated region. Modelling of the disease revealed an increased expression of HDAC9 and its neighbouring gene, TWIST1, in neural crest cells. We also identified decreased migration of iPSC-derived neural crest cells together with dysregulation of osteogenic differentiation in iPSC-affected mesenchymal stem cells.

Conclusion

Our findings support the hypothesis that the 430 kb duplication is causative of the ARCND phenotype in this family and that deregulation of TWIST1 expression during craniofacial development can contribute to the phenotype.

Histone deacetylase (HDAC) 9: versatile biological functions and emerging roles in human cancer

BACKGROUND

HDAC9 (histone deacetylase 9) belongs to the class IIa family of histone deacetylases. This enzyme can shuttle freely between the nucleus and cytoplasm and promotes tissue-specific transcriptional regulation by interacting with histone and non-histone substrates. HDAC9 plays an essential role in diverse physiological processes including cardiac muscle development, bone formation, adipocyte differentiation and innate immunity. HDAC9 inhibition or activation is therefore a promising avenue for therapeutic intervention in several diseases. HDAC9 overexpression is also common in cancer cells, where HDAC9 alters the expression and activity of numerous relevant proteins involved in carcinogenesis.

CONCLUSIONS

This review summarizes the most recent discoveries regarding HDAC9 as a crucial regulator of specific physiological systems and, more importantly, highlights the diverse spectrum of HDAC9-mediated posttranslational modifications and their contributions to cancer pathogenesis. HDAC9 is a potential novel therapeutic target, and the restoration of aberrant expression patterns observed among HDAC9 target genes and their related signaling pathways may provide opportunities to the design of novel anticancer therapeutic strategies.

Emerging roles for the YAP/TAZ transcriptional regulators in brain tumour pathology and targeting options

The transcriptional co-activators Yes-associated protein 1/transcriptional co-activator with PDZ-binding motif (YAP/TAZ) have emerged as significant regulators of a wide variety of cellular and organ functions with impact in early embryonic development, especially during the expansion of the neural progenitor cell pool. YAP/TAZ signalling regulates organ size development, tissue homeostasis, wound healing and angiogenesis by participating in a complex network of various pathways. However, recent evidence suggests an association of these physiologic regulatory effects of YAP/TAZ with pro-oncogenic activities. Herein, we discuss the physiological functions of YAP/TAZ as well as the extensive network of signalling pathways that control their expression and activity, leading to brain tumour development and progression. Furthermore, we describe current targeting approaches and drug options including direct YAP/TAZ and YAP-TEA domain transcription factor (TEAD) interaction inhibitors, G-protein coupled receptors (GPCR) signalling modulators and kinase inhibitors, which may be used to successfully attack YAP/TAZ-dependent tumours.

EGFR Activates a TAZ-Driven Oncogenic Program in Glioblastoma

Hyperactivated EGFR signaling is a driver of various human cancers, including glioblastoma (GBM). Effective EGFR-targeted therapies rely on knowledge of key signaling hubs that transfer and amplify EGFR signaling. Here we focus on the transcription factor TAZ, a potential signaling hub in the EGFR signaling network. TAZ expression was positively associated with EGFR expression in clinical GBM specimens. In patient-derived GBM neurospheres, EGF induced TAZ through EGFR-ERK and EGFR-STAT3 signaling, and the constitutively active EGFRvIII mutation caused EGF-independent hyperactivation of TAZ. Genome-wide analysis showed that the EGFR-TAZ axis activates multiple oncogenic signaling mechanisms, including an EGFR-TAZ-RTK positive feedback loop, as well as upregulating HIF1α and other oncogenic genes. TAZ hyperactivation in GBM stem-like cells induced exogenous mitogen-independent growth and promoted GBM invasion, radioresistance, and tumorigenicity. Screening a panel of brain-penetrating EGFR inhibitors identified osimertinib as the most potent inhibitor of the EGFR-TAZ signaling axis. Systemic osimertinib treatment inhibited the EGFR-TAZ axis and in vivo growth of GBM stem-like cell xenografts. Overall these results show that the therapeutic efficacy of osimertinib relies on effective TAZ inhibition, thus identifying TAZ as a potential biomarker of osimertinib sensitivity. SIGNIFICANCE: This study establishes a genome-wide map of EGFR-TAZ signaling in glioblastoma and finds osimertinib effectively inhibits this signaling, justifying its future clinical evaluation to treat glioblastoma and other cancers with EGFR/TAZ hyperactivation. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/13/3580/F1.large.jpg.

Genotoxic therapy and resistance mechanism in gliomas

Glioma is one of the most common and lethal brain tumors. Surgical resection followed by radiotherapy plus chemotherapy is the current standard of care for patients with glioma. The existence of resistance to genotoxic therapy, as well as the nature of tumor heterogeneity greatly limits the efficacy of glioma therapy. DNA damage repair pathways play essential roles in many aspects of glioma biology such as cancer progression, therapy resistance, and tumor relapse. O6-methylguanine-DNA methyltransferase (MGMT) repairs the cytotoxic DNA lesion generated by temozolomide (TMZ), considered as the main mechanism of drug resistance. In addition, mismatch repair, base excision repair, and homologous recombination DNA repair also play pivotal roles in treatment resistance as well. Furthermore, cellular mechanisms, such as cancer stem cells, evasion from apoptosis, and metabolic reprogramming, also contribute to TMZ resistance in gliomas. Investigations over the past two decades have revealed comprehensive mechanisms of glioma therapy resistance, which has led to the development of novel therapeutic strategies and targeting molecules.

Potential new targets and drugs related to histone modifications in glioma treatment

Glioma accounts for 40-50% of craniocerebral tumors, whose outcome rarely improves after standard treatment. The development of new therapeutic targets for glioma treatment has important clinical significance. With the deepening of research on gliomas, recent researchers have found that the occurrence and development of gliomas is closely associated with histone modifications, including methylation, acetylation, phosphorylation, and ubiquitination. Additionally, evidence has confirmed the close relationship between histone modifications and temozolomide (TMZ) resistance. Therefore, histone modification-related proteins have been widely recognized as new therapeutic targets for glioma treatment. In this review, we summarize the potential histone modification-associated targets and related drugs for glioma treatment. We have further clarified how histone modifications regulate the pathogenesis of gliomas and the mechanism of drug action, providing novel insights for the current clinical glioma treatment. Herein, we have also highlighted the limitations of current clinical therapies and have suggested future research directions and expected advances in potential areas of disease prognosis. Due to the complicated glioma pathogenesis, in the present review, we have acknowledged the limitations of histone modification applications in the related clinical treatment.

MiR-365a-3p-Mediated Regulation of HELLS/GLUT1 Axis Suppresses Aerobic Glycolysis and Gastric Cancer Growth

Gastric cancer (GC) is a common and invasive malignancy, which lacks effective treatment and is the third main reason of cancer death. Metabolic reprogramming is one of the main reasons that GC is difficult to treat in various environments. Particularly, abnormal glycolytic activity is the most common way of metabolism reprogramming in cancer cells. Numerous studies have shown that microRNAs play important roles in reprogramming glucose metabolism. Here, we found a microRNA-miR-365a-3p, was significantly downregulated in GC according to bioinformatics analysis. Low expression of miR-365a-3p correlated with poor prognosis of GC patients. Overexpression of miR-365a-3p in GC cells significantly inhibited cell proliferation by inducing cell cycle arrest at G1 phase. Notably, miR-365a-3p induced downregulation of HELLS through binding to its 3' untranslated region (UTR). Additionally, we found that miR-365a-3p suppressed aerobic glycolysis by inhibiting HELLS/GLUT1 axis. Lastly, we shown that overexpression of miR-365a-3p significantly inhibited tumor growth in nude mice. Conversely, Reconstituted the expression of HELLS rescued the suppressive effects of miR-365a-3p. Our data collectively indicated that miR-365a-3p functioned as a tumor suppressor in GC through downregulating HELLS. Therefore, targeting of the novel miR-365a-3p/HELLS axis could be a potentially effective therapeutic approach for GC.

Quis Custodiet Ipsos Custodes (Who Controls the Controllers)? Two Decades of Studies on HDAC9

Understanding how an epigenetic regulator drives different cellular responses can be a tricky task. Very often, their activities are modulated by large multiprotein complexes, the composition of which is context- and time-dependent. As a consequence, experiments aimed to unveil the functions of an epigenetic regulator can provide different outcomes and conclusions, depending on the circumstances. HDAC9 (histone deacetylase), an epigenetic regulator that influences different differentiating and adaptive responses, makes no exception. Since its discovery, different phenotypes and/or dysfunctions have been observed after the artificial manipulation of its expression. The cells and the microenvironment use multiple strategies to control and monitor HDAC9 activities. To date, some of the genes under HDAC9 control have been identified. However, the exact mechanisms through which HDAC9 can achieve all the different tasks so far described, remain mysterious. Whether it can assemble into different multiprotein complexes and how the cells modulate these complexes is not clearly defined. In summary, despite several cellular responses are known to be affected by HDAC9, many aspects of its network of interactions still remain to be defined.

Mechanism and Molecular Network of RBM8A-Mediated Regulation of Oxaliplatin Resistance in Hepatocellular Carcinoma

RNA-binding motif protein 8A (RBM8A) is abnormally overexpressed in hepatocellular carcinoma (HCC) and involved in the epithelial-mesenchymal transition (EMT). The EMT plays an important role in the development of drug resistance, suggesting that RBM8A may be involved in the regulation of oxaliplatin (OXA) resistance in HCC. Here we examined the potential involvement of RBM8A and its downstream pathways in OXA resistance using in vitro and in vivo models. RBM8A overexpression induced the EMT in OXA-resistant HCC cells, altering cell proliferation, apoptosis, migration, and invasion. Moreover, whole-genome microarrays combined with bioinformatics analysis revealed that RBM8A has a wide range of transcriptional regulatory capabilities in OXA-resistant HCC, including the ability to regulate several important tumor-related signaling pathways. In particular, histone deacetylase 9 (HDAC9) emerged as an important mediator of RBM8A activity related to OXA resistance. These data suggest that RBM8A and its related regulatory pathways represent potential markers of OXA resistance and therapeutic targets in HCC.

Hippo Signaling Pathway in Gliomas

The Hippo signaling pathway is a highly conserved pathway involved in tissue development and regeneration that controls organ size through the regulation of cell proliferation and apoptosis. The core Hippo pathway is composed of a block of kinases, MST1/2 (Mammalian STE20-like protein kinase 1/2) and LATS1/2 (Large tumor suppressor 1/2), which inhibits nuclear translocation of YAP/TAZ (Yes-Associated Protein 1/Transcriptional co-activator with PDZ-binding motif) and its downstream association with the TEAD (TEA domain) family of transcription factors. This pathway was recently shown to be involved in tumorigenesis and metastasis in several cancers such as lung, breast, or colorectal cancers but is still poorly investigated in brain tumors. Gliomas are the most common and the most lethal primary brain tumors representing about 80% of malignant central nervous system neoplasms. Despite intensive clinical protocol, the prognosis for patients remains very poor due to systematic relapse and treatment failure. Growing evidence demonstrating the role of Hippo signaling in cancer biology and the lack of efficient treatments for malignant gliomas support the idea that this pathway could represent a potential target paving the way for alternative therapeutics. Based on recent advances in the Hippo pathway deciphering, the main goal of this review is to highlight the role of this pathway in gliomas by a state-of-the-art synthesis.

Targeting post-translational histone modifying enzymes in glioblastoma

Glioblastoma (GBM) is the most common primary brain tumor in adults, and the most lethal form of glioma, characterized by variable histopathology, aggressiveness and poor clinical outcome and prognosis. GBMs constitute a challenge for oncologists because of their molecular heterogeneity, extensive invasion, and tendency to relapse. Glioma cells demonstrate a variety of deregulated genomic pathways and extensive interplay with epigenetic alterations. Epigenetic modifications have emerged as essential players in GBM research, with biomarker potential for tumor classification and prognosis and for drug targeting. Histone posttranslational modifications (PTMs) are crucial regulators of chromatin architecture and gene expression, playing a pivotal role in malignant transformation, tumor development and progression. Alteration in the expression of genes coding for lysine and arginine methyltransferases (G9a, SUV39H1 and SETDB1) and acetyltransferases and deacetylases (KAT6A, SIRT2, SIRT7, HDAC4, 6, 9) contribute to GBM pathogenesis. In addition, proteins of the sumoylation pathway are upregulated in GBM cell lines, including E1 (SAE1), E2 (Ubc9) components, and a SUMO-specific protease (SENP1). Preclinical and clinical studies are currently in progress targeting epigenetic enzymes in gliomas, including a new generation of histone deacetylase (HDAC), protein arginine methyltransferase (PRMT) and bromodomain (BRD) inhibitors. Herein, we provide an update on recent advances in glioma epigenetic research, focusing on the role of histone modifications and the use of epigenetic therapy as a valid treatment option for glioblastoma.

E2F7-EZH2 axis regulates PTEN/AKT/mTOR signalling and glioblastoma progression

BACKGROUND

E2F transcription factors are considered to be important drivers of tumour growth. E2F7 is an atypical E2F factor, and its role in glioblastoma remains undefined.

METHODS

E2F7 expression was examined in patients by IHC and qRT-PCR. The overall survival probability was determined by statistical analyses. MTT assay, colony formation, cell-cycle assay, cell metastasis and the in vivo model were employed to determine the functional role of E2F7 in glioblastoma. Chromatin immunoprecipitation, luciferase assay and western blot were used to explore the underlying mechanisms.

RESULTS

E2F7 was found to be up-regulated in glioblastoma patients, and high E2F7 expression was associated with poor overall survival in glioblastoma patients. Functional studies showed that E2F7 promoted cell proliferation, cell-cycle progression, cell metastasis and tumorigenicity abilities in vitro and in vivo. E2F7 promoted the transcription of EZH2 by binding to its promoter and increased H3K27me3 level. EZH2 recruited H3K27me3 to the promoter of PTEN and inhibited PTEN expression, and then activated the AKT/mTOR signalling pathway. In addition, restored expression of EZH2 recovered the abilities of cell proliferation and metastasis in E2F7-silencing cells.

CONCLUSION

Collectively, our findings indicate that E2F7 promotes cell proliferation, cell metastasis and tumorigenesis via EZH2-mediated PTEN/AKT/mTOR pathway in glioblastoma.

The application of histone deacetylases inhibitors in glioblastoma

The epigenetic abnormality is generally accepted as the key to cancer initiation. Epigenetics that ensure the somatic inheritance of differentiated state is defined as a crucial factor influencing malignant phenotype without altering genotype. Histone modification is one such alteration playing an essential role in tumor formation, progression, and resistance to treatment. Notably, changes in histone acetylation have been strongly linked to gene expression, cell cycle, and carcinogenesis. The balance of two types of enzyme, histone acetyltransferases (HATs) and histone deacetylases (HDACs), determines the stage of histone acetylation and then the architecture of chromatin. Changes in chromatin structure result in transcriptional dysregulation of genes that are involved in cell-cycle progression, differentiation, apoptosis, and so on. Recently, HDAC inhibitors (HDACis) are identified as novel agents to keep this balance, leading to numerous researches on it for more effective strategies against cancers, including glioblastoma (GBM). This review elaborated influences on gene expression and tumorigenesis by acetylation and the antitumor mechanism of HDACis. Besdes, we outlined the preclinical and clinical advancement of HDACis in GBM as monotherapies and combination therapies.

Advances in histone deacetylase inhibitors in targeting glioblastoma stem cells

Glioblastoma multiforme (GBM) is a lethal grade IV glioma (WHO classification) and widely prevalent primary brain tumor in adults. GBM tumors harbor cellular heterogeneity with the presence of a small subpopulation of tumor cells, described as GBM cancer stem cells (CSCs) that pose resistance to standard anticancer regimens and eventually mediate aggressive relapse or intractable progressive GBM. Existing conventional anticancer therapies for GBM do not target GBM stem cells and are mostly palliative; therefore, exploration of new strategies to target stem cells of GBM has to be prioritized for the development of effective GBM therapy. Recent developments in the understanding of GBM pathophysiology demonstrated dysregulation of epigenetic mechanisms along with the genetic changes in GBM CSCs. Altered expression/activity of key epigenetic regulators, especially histone deacetylases (HDACs) in GBM stem cells has been associated with poor prognosis; inhibiting the activity of HDACs using histone deacetylase inhibitors (HDACi) has been promising as mono-therapeutic in targeting GBM and in sensitizing GBM stem cells to an existing anticancer regimen. Here, we review the development of pan/selective HDACi as potential anticancer agents in targeting the stem cells of glioblastoma as a mono or combination therapy.

PHF14 Promotes Cell Proliferation and Migration through the AKT and ERK1/2 Pathways in Gastric Cancer Cells

PHF14 is a new member belonging to PHD finger proteins. PHF14 is involved in multiple biologic processes including Dandy-Walker syndrome, mesenchyme growth, lung fibrosis, renal fibrosis, persistent pulmonary hypertension, and tumor development. This study aims to explore whether PHF14 plays an important role in gastric cancer. Here, PHF14 is indicated as a tumor promoter. The expression of PHF14 enhances no matter in clinical samples or in gastric cancer cells. High expression of PHF14 impairs survival of patients. Attenuation of PHF14 inhibits cell proliferation in gastric cancer cells. PHF14 downregulation inhibits the expression of cell cycle-related proteins, CDK6 and cyclin D1. Furthermore, silencing of PHF14 reduces the level of phosphorylated AKT as well as phosphorylated ERK1/2. Finally, downregulation of PHF14 in gastric cancer cells inhibits colony formation in vitro and tumorigenesis in vivo. These results indicate that PHF14 promotes tumor development in gastric cancer, so PHF14 thereby acts as a potential target for gastric cancer therapy.

High HDAC9 is associated with poor prognosis and promotes malignant progression in pancreatic ductal adenocarcinoma

Histone deacetylase 9 (HDAC9) is involved in a variety of malignant tumors, and leads to malignant tumor development and poor prognosis. However, the association between HDAC9 expression, and the prognosis and clinicopathological features of patients with pancreatic ductal adenocarcinoma (PDAC) remains unclear. The present study used reverse transcription‑quantitative PCR, western blotting and immunohistochemistry to detect the expression level of HDAC9 in PDAC tumors and cell lines. The Kaplan‑Meier method and Pearson's χ2 test were applied to evaluate the prognostic impact of HDAC9. The present study investigated the effect of HDAC9 on the biological function of PDAC cells. The present results indicated that HDAC9 was highly expressed in PDAC tissue and PDAC cell lines (P<0.05). HDAC9 expression level in tumor tissues was negatively associated with tumor size (P=0.026), T stage (P=0.014) and N stage (P=0.004). Kaplan‑Meier analysis suggested that patients with high HDAC9 had shorter recurrence‑free survival (RFS; P=0.017) and disease‑specific survival (DSS; P=0.022). Moreover, the present results suggested that T stage, N stage and HDAC9 expression level were independent predictive factors for RFS and DSS in patients with PDAC. In addition, silencing HDAC9 significantly inhibited the proliferation and migration of PDAC cells. The present results indicated that high expression levels of HDAC9 were associated with tumor progression and poor prognosis; thus, HDAC9 may serve as a prognostic predictor of PDAC.

MicroRNA‑936 inhibits the malignant phenotype of retinoblastoma by directly targeting HDAC9 and deactivating the PI3K/AKT pathway

MicroRNA-936 (miR-936) has been reported to play important roles in the progression of non-small cell lung cancer and glioma. However, the expression and functions of miR-936 in retinoblastoma (RB) remain elusive and need to be further elucidated. Herein, the aims were to measure miR-936 expression in RB, identify the functional importance of miR-936 in the oncogenicity of RB, and investigate the underlying molecular mechanisms. Reverse-transcription quantitative PCR was carried out to determine miR-936 expression in RB tissues and cell lines. Cell proliferation, colony formation, apoptosis, migration, and invasion in vitro and tumor growth in vivo were examined respectively by Cell Counting Kit-8, colony formation, flow cytometric, and Transwell migration and invasion assays and a subcutaneous heterotopic xenograft experiment. The potential target of miR-936 was predicted by bioinformatic analysis and was subsequently validated by luciferase reporter assay, reverse-transcription quantitative PCR, and western blotting. miR-936 expression was weak in both RB tissues and cell lines and was correlated with differentiation, lymph node metastasis and TNM staging in RB. RB cell proliferation, colony formation, migration, and invasion in vitro and tumor growth in vivo were attenuated by exogenous miR-936, whereas apoptosis was enhanced by miR-936 overexpression. Further molecular investigation identified histone deacetylase 9 (HDAC9) as a direct target gene of miR-936 in RB cells. HDAC9 depletion had effects similar to those of miR-936 overexpression in RB cells. Recovery of HDAC9 expression counteracted the tumor-suppressive action of miR-936 on the oncogenicity of RB cells. Ectopic miR-936 expression deactivated the PI3K/AKT pathway in RB cells in vitro and in vivo by decreasing HDAC9 expression. Downregulated miR-936 is related to poor prognosis in RB, and its upregulation inhibits RB aggressiveness via direct targeting of HDAC9 mRNA and thereby inactivation of the PI3K/AKT pathway.

MicroRNA-30c-regulated HDAC9 mediates chemoresistance of breast cancer

PURPOSE

Although histone deacetylase (HDAC) inhibitors have been shown to effectively induce the inhibition of proliferation and migration in breast cancer, the mechanism of HDAC9's contribution to chemoresistance remains poorly understood. The aim of this study was to investigate the role of miR-30c-regulated HDAC9 in chemoresistance of breast cancer and to determine the potential of selective inhibition of HDAC9 in sensitizing resistant breast cancer cells to chemotherapy.

METHODS

Expression levels of HDAC9 and miR-30c were measured in breast cancer cells and tissues using quantitative PCR analysis. The effect of selective inhibition of HDAC9 on sensitizing MDR cells to chemotherapy was assessed. MiR-30c/HDAC9 pathways' potential to mediate chemoresistance was analyzed.

RESULTS

Our studies show that HDAC9 was significantly up-regulated in chemoresistant breast cancer cell lines compared to a chemosensitive cell line and was inversely correlated with the levels of miR-30c. MiR-30c mimics and HDAC9 inhibitors reversed the chemoresistance of multidrug-resistant breast cancer cells.

CONCLUSIONS

These results indicate that the mechanism of chemoresistance reversal with selective HDAC inhibition was partially realized by regulating miR-30c via directly targeting HDAC9. Our findings suggest that the miR-30c/HDAC9 signaling axis could be a novel and potential therapeutic target in chemoresistant breast cancer.

Cancer-testis specific gene OIP5: a downstream gene of E2F1 that promotes tumorigenesis and metastasis in glioblastoma by stabilizing E2F1 signaling

Background

The cancer-testis specific gene Opa interacting protein 5 (OIP5) is reactivated in many human cancers, but its functions in glioblastoma remain unclear. Here, we assessed the significance of OIP5 in the tumorigenesis and metastasis of glioblastoma for the first time.

Methods

An immunohistochemistry assay was performed to detect OIP5 expression changes in glioblastoma patients. Overall survival analysis was performed to evaluate the prognostic significance of OIP5. Growth curve, colony formation, and transwell assays were used to analyze cell proliferation and metastasis. Tumorigenicity potential was investigated in orthotopic tumor models, and immunoprecipitation, chromatin immunoprecipitation, and luciferase assays were employed to explore the mechanisms underlying the activation of OIP5 expression by E2F transcription factor 1 (E2F1) to stabilize and maintain E2F1 signaling.

Results

OIP5 was found to be upregulated in glioblastoma patients and to impair patient survival, and the increased expression of OIP5 was positively correlated with tumor stage. Compared with short hairpin green fluorescent protein cells, cells in which OIP5 was knocked down exhibited significantly reduced proliferation, metastasis, colony formation, and tumorigenicity abilities, whereas OIP5 recovery enhanced these abilities. OIP5 was highly correlated with cell cycle progression but had no obvious effects on apoptosis. Notably, we demonstrated a feedback loop in which E2F1 activates the expression of OIP5 to stabilize and maintain E2F1 signaling and promote the E2F1-regulated gene expression that is required for aggressive tumor biology.

Conclusions

Collectively, our findings demonstrate that OIP5 promotes glioblastoma progression and metastasis, suggesting that OIP5 is a potential target for anticancer therapy.

The Atherosclerosis Risk Variant rs2107595 Mediates Allele-Specific Transcriptional Regulation of HDAC9 via E2F3 and Rb1

Background and Purpose- Genome-wide association studies have identified the HDAC9 (histone deacetylase 9) gene region as a major risk locus for atherosclerotic stroke and coronary artery disease in humans. Previous results suggest a role of altered HDAC9 expression levels as the underlying disease mechanism. rs2107595, the lead single nucleotide polymorphism for stroke and coronary artery disease resides in noncoding DNA and colocalizes with histone modification marks suggestive of enhancer elements. Methods- To determine the mechanisms by which genetic variation at rs2107595 regulates HDAC9 expression and thus vascular risk we employed targeted resequencing, proteome-wide search for allele-specific nuclear binding partners, chromatin immunoprecipitation, genome-editing, reporter assays, circularized chromosome conformation capture, and gain- and loss-of-function experiments in cultured human cell lines and primary immune cells. Results- Targeted resequencing of the HDAC9 locus in patients with atherosclerotic stroke and controls supported candidacy of rs2107595 as the causative single nucleotide polymorphism. A proteomic search for nuclear binding partners revealed preferential binding of the E2F3/TFDP1/Rb1 complex (E2F transcription factor 3/transcription factor Dp-1/Retinoblastoma 1) to the rs2107595 common allele, consistent with the disruption of an E2F3 consensus site by the risk allele. Gain- and loss-of-function studies showed a regulatory effect of E2F/Rb proteins on HDAC9 expression. Compared with the common allele, the rs2107595 risk allele exhibited higher transcriptional capacity in luciferase assays and was associated with higher HDAC9 mRNA levels in primary macrophages and genome-edited Jurkat cells. Circularized chromosome conformation capture revealed a genomic interaction of the rs2107595 region with the HDAC9 promoter, which was stronger for the common allele as was the in vivo interaction with E2F3 and Rb1 determined by chromatin immunoprecipitation. Gain-of-function experiments in isogenic Jurkat cells demonstrated a key role of E2F3 in mediating rs2107595-dependent transcriptional regulation of HDAC9. Conclusions- Collectively, our findings imply allele-specific transcriptional regulation of HDAC9 via E2F3 and Rb1 as a major mechanism mediating vascular risk at rs2107595.

Histone deacetylase 9 downregulation decreases tumor growth and promotes apoptosis in non-small cell lung cancer after melatonin treatment

Histone deacetylase 9 functions as an oncogene in a variety of cancers, but its role on non-small cell lung cancer (NSCLC) has not been reported. Melatonin was proven to possess anticancer actions, whereas its effect on NSCLC and underlying mechanisms remains poorly understood. In this study, 337 patients with complete clinicopathologic characteristics who underwent NSCLC surgery were recruited for the study. We found that NSCLC patients with high HDAC9 expression were correlated with worse overall survival and poor prognosis. HDAC9 knockdown significantly reduced NSCLC cell growth and induced apoptosis both in vivo and in vitro. Melatonin application also markedly inhibited cell proliferation, metastasis, and invasion and promoted apoptosis in NSCLC cells. Moreover, RNA-seq, real-time quantitative polymerase chain reaction, and western blot analyses showed that melatonin treatment decreased the HDAC9 level in NSCLC cells. A mechanistic study revealed that HDAC9 knockdown further enhanced the anticancer activities of melatonin treatment, whereas HDAC9 overexpression partially reversed the melatonin's anticancer effects. Additionally, the in vivo study found melatonin exerted anti-proliferative and pro-apoptotic effects on xenograft tumors which were also strengthened by HDAC9 knockdown. These results indicated that HDAC9 downregulation mediated the anti-NSCLC actions of melatonin, and targeting HDAC9 may be the novel therapeutic strategy for NSCLC.

MicroRNA-383-5p inhibits the progression of gastric carcinoma via targeting HDAC9 expression

MicroRNAs (miRNAs), as post-transcriptional regulators, have been reported to be involved in the initiation and progression of various types of cancer, including gastric cancer (GC). The present study aimed to investigate the role of miR-383-5p in gastric carcinogenesis. Cell viability was analyzed using CCK-8 kit. Annexin V-fluorescein isothiocyanate/propidium iodide double staining was used to evaluate cell apoptosis. The expression levels of miR-383-5p and histone deacetylase 9 (HDAC9) mRNA in GC tissues and cell lines were analyzed using RT-qPCR. The protein expression of HDAC9 was detected by western blotting. We found that HDAC9 was up-regulated and miR-383-5p was down-regulated in GC tissues and cell lines. High HDAC9 expression or low miR-383-5p expression was closely related to poor prognosis and metastasis in GC patients. HDAC9 knockout or miR-383-5p mimics led to growth inhibition and increased apoptosis in AGS and SGC-7901 cells. More importantly, we validated that miR-383-5p as a post-transcriptional regulator inhibited HDAC9 expression and was inversely correlated with HDAC9 expression in GC tissues. miR-383-5p had the opposite effects to HDAC9 in gastric carcinogenesis. miR-383-5p played an important role in gastric carcinogenesis, and it is one of the important mechanisms to regulate oncogenic HDAC9 in GC, which might be helpful in the development of novel therapeutic strategies for the treatment of GC.

Advances in Targeting the Epidermal Growth Factor Receptor Pathway by Synthetic Products and Its Regulation by Epigenetic Modulators As a Therapy for Glioblastoma

Glioma is the most common primary tumor of the nervous system, and approximately 50% of patients exhibit the most aggressive form of the cancer, glioblastoma. The biological function of epidermal growth factor receptor (EGFR) in tumorigenesis and progression has been established in various types of cancers, since it is overexpressed, mutated, or dysregulated. Its overexpression has been shown to be associated with enhanced metastatic potential in glioblastoma, with EGFR at the top of a downstream signaling cascade that controls basic functional properties of glioblastoma cells such as survival, cell proliferation, and migration. Thus, EGFR is considered as an important therapeutic target in glioblastoma. Many anti-EGFR therapies have been investigated both in vivo and in vitro, making their way to clinical studies. However, in clinical trials, the potential efficacy of anti-EGFR therapies is low, primarily because of chemoresistance. Currently, a range of epigenetic drugs including histone deacetylase (HDAC) inhibitors, DNA methylation and histone inhibitors, microRNA, and different types of EGFR inhibitor molecules are being actively investigated in glioblastoma patients as therapeutic strategies. Here, we describe recent knowledge on the signaling pathways mediated by EGFR/EGFR variant III (EGFRvIII) with regard to current therapeutic strategies to target EGFR/EGFRvIII amplified glioblastoma.

Combined Inhibition of HDAC and EGFR Reduces Viability and Proliferation and Enhances STAT3 mRNA Expression in Glioblastoma Cells

Changes in expression of histone deacetylases (HDACs), which epigenetically regulate chromatin structure, and mutations and amplifications of the EGFR gene, which codes for the epidermal growth factor receptor (EGFR), have been reported in glioblastoma (GBM), the most common and malignant type of brain tumor. There are likely interplays between HDACs and EGFR in promoting GBM progression, and HDAC inhibition can cooperate with EGFR blockade in reducing the growth of lung cancer cells. Here, we found that either HDAC or EGFR inhibitors dose-dependently reduced the viability of U87 and A-172 human GBM cells. In U87 cells, the combined inhibition of HDACs and EGFR was more effective than inhibiting either target alone in reducing viability and long-term proliferation. In addition, HDAC or EGFR inhibition, alone or combined, led to G0/G1 cell cycle arrest. The EGFR inhibitor alone or combined with HDAC inhibition increased mRNA expression of the signal transducer and activator of transcription 3 (STAT3), which can act either as an oncogene or a tumor suppressor in GBM. These data provide early evidence that combining HDAC and EGFR inhibition may be an effective strategy to reduce GBM growth, through a mechanism possibly involving STAT3.

Molecular imaging HDACs class IIa expression-activity and pharmacologic inhibition in intracerebral glioma models in rats using PET/CT/(MRI) with [18F]TFAHA

HDAC class IIa enzymes (HDAC4, 5, 7, 9) are important for glioma progression, invasion, responses to TMZ and radiotherapy, and prognosis. In this study, we demonstrated the efficacy of PET/CT/(MRI) with [¹⁸F]TFAHA for non-invasive and quantitative imaging of HDAC class IIa expression-activity in intracerebral 9L and U87-MG gliomas in rats. Increased accumulation of [¹⁸F]TFAHA in 9L and U87-MG tumors was observed at 20 min post radiotracer administration with SUV of 1.45 ± 0.05 and 1.08 ± 0.05, respectively, and tumor-to-cortex SUV ratios of 1.74 ± 0.07 and 1.44 ± 0.03, respectively. [¹⁸F]TFAHA accumulation was also observed in normal brain structures known to overexpress HDACs class IIa: hippocampus, n.accumbens, PAG, and cerebellum. These results were confirmed by immunohistochemical staining of brain tissue sections revealing the upregulation of HDACs 4, 5, and 9, and HIF-1α, hypoacetylation of H2AK5ac, H2BK5ac, H3K9ac, H4K8ac, and downregulation of KLF4. Significant reduction in [¹⁸F]TFAHA accumulation in 9L tumors was observed after administration of HDACs class IIa specific inhibitor MC1568, but not the SIRT1 specific inhibitor EX-527. Thus, PET/CT/(MRI) with [¹⁸F]TFAHA can facilitate studies to elucidate the roles of HDAC class IIa enzymes in gliomagenesis and progression and to optimize therapeutic doses of novel HDACs class IIa inhibitors in gliomas.

Large Chromosomal Rearrangements Yield Biomarkers to Distinguish Low-Risk From Intermediate- and High-Risk Prostate Cancer

OBJECTIVE

To test the hypothesis that chromosomal rearrangements (CRs) can distinguish low risk of progression (LRP) from intermediate and high risk of progression (IHRP) to prostate cancer (PCa) and if these CRs have the potential to identify men with LRP on needle biopsy that harbor IHRP PCa in the prostate gland.

PATIENTS AND METHODS

Mate pair sequencing of amplified DNA from pure populations of Gleason patterns in 154 frozen specimens from 126 patients obtained between August 14, 2001, and July 15, 2011, was used to detect CRs including abnormal junctions and copy number variations. Potential CR biomarkers with higher incidence in IHRP than in LRP to cancer and having significance in PCa biology were identified. Independent validation was performed by fluorescence in situ hybridization in 152 specimens from 124 patients obtained between February 12, 2002, and July 12, 2008.

RESULTS

The number of abnormal junctions did not distinguish LRP from IHRP. Loci corresponding to genes implicated in PCa were more frequently altered in IHRP. Integrated analysis of copy number variations and microarray data yielded 6 potential markers that were more frequently detected in Gleason pattern 3 of a Gleason score 7 of PCa than in Gleason pattern 3 of a Gleason score 6 PCa. Five of those were cross-validated in an independent sample set with statistically significant areas under the receiver operating characteristic curves (AUCs) (P≤.01). Probes detecting deletions in PTEN and CHD1 had AUCs of 0.87 (95% CI, 0.77-0.97) and 0.73 (95% CI, 0.60-0.86), respectively, and probes detecting gains in ASAP1, MYC, and HDAC9 had AUCs of 0.71 (95% CI, 0.59-0.84), 0.82 (95% CI, 0.71-0.93), and 0.77 (95% CI, 0.66-0.89), respectively (for expansion of gene symbols, use search tool at www.genenames.org).

CONCLUSION

Copy number variations in regions encompassing important PCa genes were predictive of cancer significance and have the potential to identify men with LRP PCa by needle biopsy who have IHRP PCa in their prostate gland.

Histone deacetylase enzymes and selective histone deacetylase inhibitors for antitumor effects and enhancement of antitumor immunity in glioblastoma

Glioblastoma multiforme (GBM), which is the most common primary central nervous system malignancy in adults, has long presented a formidable challenge to researchers and clinicians alike. Dismal 5-year survival rates of the patients with these tumors and the ability of the recurrent tumors to evade primary treatment strategies have prompted a need for alternative therapies in the treatment of GBM. Histone deacetylase (HDAC) inhibitors are currently a potential epigenetic therapy modality under investigation for use in GBM with mixed results. While these agents show promise through a variety of proposed mechanisms in the pre-clinical realm, only several of these agents have shown this same promise when translated into the clinical arena, either as monotherapy or for use in combination regimens. This review will examine the current state of use of HDAC inhibitors in GBM, the mechanistic rationale for use of HDAC inhibitors in GBM, and then examine an exciting new mechanistic revelation of certain HDAC inhibitors that promote antitumor immunity in GBM. The details of this antitumor immunity will be discussed with an emphasis on application of this antitumor immunity towards developing alternative therapies for treatment of GBM. The final section of this article will provide an overview of the current state of immunotherapy targeted specifically to GBM.

Myt1 and Myt1l transcription factors limit proliferation in GBM cells by repressing YAP1 expression

Myelin transcription factor 1 (Myt1) and Myt1l (Myt1-like) are zinc finger transcription factors that regulate neuronal differentiation. Reduced Myt1l expression has been implicated in glioblastoma (GBM), and the related St18 was originally identified as a potential tumor suppressor for breast cancer. We previously analyzed changes in gene expression in a human GBM cell line with re-expression of either Myt1 or Myt1l. This revealed largely overlapping gene expression changes, suggesting similar function in these cells. Here we show that re-expression of Myt1 or Myt1l reduces proliferation in two different GBM cell lines, activates gene expression programs associated with neuronal differentiation, and limits expression of proliferative and epithelial to mesenchymal transition gene-sets. Consistent with this, expression of both MYT1 and MYT1L is lower in more aggressive glioma sub-types. Examination of the gene expression changes in cells expressing Myt1 or Myt1l suggests that both repress expression of the YAP1 transcriptional coactivator, which functions primarily in the Hippo signaling pathway. Expression of YAP1 and its target genes is reduced in Myt-expressing cells, and there is an inverse correlation between YAP1 and MYT1/MYT1L expression in human brain cancer datasets. Proliferation of GBM cell lines is reduced by lowering YAP1 expression and increased with YAP1 over-expression, which overcomes the anti-proliferative effect of Myt1/Myt1l expression. Finally we show that reducing YAP1 expression in a GBM cell line slows the growth of orthotopic tumor xenografts. Together, our data suggest that Myt1 and Myt1l directly repress expression of YAP1, a protein which promotes proliferation and GBM growth.

HDAC9 overexpression confers invasive and angiogenic potential to triple negative breast cancer cells via modulating microRNA-206

Triple negative breast cancer (TNBC) is among the most aggressive breast cancer subtypes with poor prognosis. The purpose of this study is to better understand the molecular basis of TNBC as well as develop new therapeutic strategies. Our results demonstrate that HDAC9 is overexpressed in TNBC compared to non-TNBC cell lines and tissues and is inversely proportional with miR-206 expression levels. We show that HDAC9 selective inhibition blocked the invasion of TNBC cells in vitro and repressed the angiogenesis shown via in vivo Matrigel plug assays. Subsequent HDAC9 siRNA knockdown was then shown to restore miR-206 while also decreasing VEGF and MAPK3 levels. Furthermore, the inhibition of miR-206 neutralized the action of HDAC9 siRNA on decreasing VEGF and MAPK3 levels. This study highlights HDAC9 as a mediator of cell invasion and angiogenesis in TNBC cells through VEGF and MAPK3 by modulating miR-206 expression and suggests that selective inhibition of HDAC9 may be an efficient route for TNBC therapy.

Llgl1 prevents metaplastic survival driven by epidermal growth factor dependent migration

We have previously demonstrated that Llgl1 loss results in a gain of mesenchymal phenotypes and a loss of apicobasal and planar polarity. We now demonstrate that these changes represent a fundamental shift in cellular phenotype. Llgl1 regulates the expression of multiple cell identity markers, including CD44, CD49f, and CD24, and the nuclear translocation of TAZ and Slug. Cells lacking Llgl1 form mammospheres, where survival and transplantability is dependent upon the Epidermal Growth Factor Receptor (EGFR). Additionally, Llgl1 loss allows cells to grow in soft-agar and maintain prolonged survival as orthotopic transplants in NOD-SCIDmice. Lineage tracing and wound healing experiments demonstrate that mammosphere survival is due to enhanced EGF-dependent migration. The loss of Llgl1 drives EGFR mislocalization and an EGFR mislocalization point mutation (P667A) drives these same phenotypes, including activation of AKT and TAZ nuclear translocation. Together, these data indicate that the loss of Llgl1 results in EGFR mislocalization, promoting pre-neoplastic changes.

Overexpression of FZD7 promotes glioma cell proliferation by upregulating TAZ

Gliomas are the most prevalent type of primary brain tumors in adults, accounting for more than 40% of neoplasm in the central nervous system. Frizzled-7 (FZD7) is a seven-pass trans-membrane Wnt receptor that plays a critical role in the development of various tumors. In this study, we detected high-level FZD7 expression in glioma and its overexpression was associated with advanced tumor stage. In vitro functional assays showed that forced overexpression of FZD7 promoted proliferation of gliomas cells, whereas knockdown of endogenous FZD7 significantly suppressed proliferation ability of these cells. In a xenograft assay, FZD7 was also found to promote the growth of glioma cells. We further found that FZD7 could activate transcriptional coactivator with PDZ-binding motif (TAZ), and TAZ was required for FZD7 to promote cell proliferation in glioma. Furthermore, the univariate analysis of survival shows that glioma patients with high FZD7 expression have a shorter survival. In conclusion, our findings demonstrate that FZD7 may promote glioma cell proliferation via upregulation of TAZ.

The Hippo transducer TAZ promotes cell proliferation and tumor formation of glioblastoma cells through EGFR pathway

TAZ, a WW-domain-containing transcriptional co-activator, is important for development of various tissues in mammals. Recently, TAZ has been found to be overexpressed in some types of human cancers. However, the role of TAZ in glioblastoma remains unclear. In this study, we found that TAZ was overexpressed in prognostically poor glioblastoma patients. Through knocking down or overexpressing TAZ in U87 and LN229 cells, the expression level of TAZ was found to be positively related to cell proliferation in vitro and tumor formation in vivo. Further investigation indicated that TAZ could significantly promote the acceleration of cell cycle. Moreover, the western blot for p-EGFR, p-AKT, p-ERK1/2, p21, cyclin E and CDK2 proteins, target genes of the EGFR pathway, indicated that TAZ significantly activated EGFR/AKT/ERK signaling. Additionally, the blockage of EGFR pathway resulted in a significantly inhibition of cell proliferation induced by TAZ. Taken together, these results demonstrate that TAZ can promote proliferation and tumor formation in glioblastoma cells by potentiating the EGFR/AKT/ERK pathway, and provide the evidence for promising target for the treatment of glioblastoma.

Advances in epigenetic glioblastoma therapy

Glioblastoma multiforme (GBM) is the most lethal primary brain tumor in adults despite contemporary gold-standard first-line treatment strategies. This type of tumor recurs in virtually all patients and no commonly accepted standard treatment exists for the recurrent disease. Therefore, advances in all scientific and clinical aspects of GBM are urgently needed. Epigenetic mechanisms are one of the major factors contributing to the pathogenesis of cancers, including glioblastoma. Epigenetic modulators that regulate gene expression by altering the epigenome and non-histone proteins are being exploited as therapeutic drug targets. Over the last decade, numerous preclinical and clinical studies on histone deacetylase (HDAC) inhibitors have shown promising results in various cancers. This article provides an overview of the anticancer mechanisms of HDAC inhibitors and the role of HDAC isoforms in GBM. We also summarize current knowledge on HDAC inhibitors on the basis of preclinical studies and emerging clinical data.

Panobinostat sensitizes KRAS-mutant non-small-cell lung cancer to gefitinib by targeting TAZ

Mutation of KRAS in non-small-cell lung cancer (NSCLC) shows a poor response to epidermal growth factor receptor (EGFR) inhibitors and chemotherapy. Currently, there are no direct anti-KRAS therapies available. Thus, new strategies have emerged for targeting KRAS downstream signaling. Panobinostat is a clinically available histone deacetylase inhibitor for treating myelomas and also shows potentiality in NSCLC. However, the therapeutic efficacy of panobinostat against gefitinib-resistant NSCLC is unclear. In this study, we demonstrated that panobinostat overcame resistance to gefitinib in KRAS-mutant/EGFR-wild-type NSCLC. Combined panobinostat and gefitinib synergistically reduced tumor growth in vitro and in vivo. Mechanistically, we identified that panobinostat-but not gefitinib-inhibited TAZ transcription, and the combination of panobinostat and gefitinib synergistically downregulated TAZ and TAZ downstream targets, including EGFR and EGFR ligand. Inhibition of TAZ by panobinostat or short hairpin RNA sensitized KRAS-mutant/EGFR-wild-type NSCLC to gefitinib through abrogating AKT/mammalian target of rapamycin (mTOR) signaling. Clinically, TAZ was positively correlated with EGFR signaling, and coexpression of TAZ/EGFR conferred a poorer prognosis in lung cancer patients. Our findings identify that targeting TAZ-mediated compensatory mechanism is a novel therapeutic approach to overcome gefitinib resistance in KRAS-mutant/EGFR-wild-type NSCLC.

Epigenetic Regulation of Telomere Maintenance for Therapeutic Interventions in Gliomas

High-grade astrocytoma of WHO grade 4 termed glioblastoma multiforme (GBM) is a common human brain tumor with poor patient outcome. Astrocytoma demonstrates two known telomere maintenance mechanisms (TMMs) based on telomerase activity (TA) and on alternative lengthening of telomeres (ALT). ALT is associated with lower tumor grades and better outcome. In contrast to ALT, regulation of TA in tumors by direct mutation and epigenetic activation of the hTERT promoter is well established. Here, we summarize the genetic background of TMMs in non-malignant cells and in cancer, in addition to clinical and pathological features of gliomas. Furthermore, we present new evidence for epigenetic mechanisms (EMs) involved in regulation of ALT and TA with special emphasis on human diffuse gliomas as potential therapeutic drug targets. We discuss the role of TMM associated telomeric chromatin factors such as DNA and histone modifying enzymes and non-coding RNAs including microRNAs and long telomeric TERRA transcripts.

MiR-613 suppresses retinoblastoma cell proliferation, invasion, and tumor formation by targeting E2F5

Retinoblastoma is a common intraocular malignancy that occurs during childhood. MicroRNAs play critical roles in the regulation of retinoblastoma initiation and progression, and aberrant expression of miR-613 had been reported in various types of cancer. However, the role and mechanism of its function in retinoblastoma are still unclear. In this study, we found that miR-613 was downregulated in retinoblastoma tissues and cell lines. Overexpression of miR-613 suppressed retinoblastoma cell proliferation, migration, and invasion and induced cell cycle arrest in vitro. Additionally, overexpressed miR-613 also inhibited tumor formation of retinoblastoma cells in vivo. We further identified E2F5 as a direct target of miR-613. Reintroduction of E2F5 without 3'-untranslated region reversed the inhibitory effects of miR-613 on cell proliferation and invasion. Our data collectively indicate that miR-613 functions as a tumor suppressor in retinoblastoma through downregulating E2F5, supporting the targeting of the novel miR-613/E2F5 axis as a potentially effective therapeutic approach for retinoblastoma.

Downregulation of miR-377 Promotes Oral Squamous Cell Carcinoma Growth and Migration by Targeting HDAC9

microRNAs are the post-transcriptional regulators implicated in the initiation and progression of various cancer types, including oral squamous cell carcinoma (OSCC). Here, we investigated the role of miR-377 in OSCC tumorigenesis. miR-377 expression was reduced in OSCC samples and cell line (UPCI-SCC-116), and was associated with patient survival. In vitro restoration of miR-377 repressed cell growth, induced apoptosis, and reduced cell migration. We identified HDAC9 as a target of miR-377 and found miR-377 to regulate HDAC9 and its pro-apoptotic target, NR4A1/Nur77. Our findings show that miR-377 targets HDAC9 pathway in OSCC, suggesting that miR-377-HDAC9 axis may provide a novel therapeutic target for OSCC therapy.

CD73 promotes proliferation and migration of human cervical cancer cells independent of its enzyme activity

Background

CD73 has both enzymatic and non-enzymatic functions in cells. As a nucleotidase, CD73 plays its enzymatic function by catalyzing the hydrolysis of AMP into adenosine and phosphate. In addition to this, accumulating data have shown that CD73 is a key regulatory molecule involved in cancer growth and metastasis, but this non-enzymatic function of CD73 in cervical cancer cells has not been well studied.

Methods

CD73 was overexpressed by pcDNA-NT5E expression vector transfection in Hela and SiHa cells. Cell’s proliferation and migration were evaluated by MTT and scratch healing assay. The CD73 specific antagonist -APCP was used to inhibit CD73 enzymatic activity. And the effect of APCP on CD73 activity was determined by high performance liquid chromatography (HPLC). Expression level was assessed by qRT-PCR and western blotting.

Results

In the present study, we used Hela and SiHa cell lines to evaluate the effects of CD73 on cervical cancer cells proliferation and migration, and further explore the potential regulating mechanisms. Our data showed that CD73 overexpression significantly promoted cervical cancer cells proliferation and migration, and this promotive effect was not reverted by blocking CD73 enzymatic activity, both in Hela and SiHa cells. On the other hand, our data also showed that high concentration of adenosine inhibited Hela and SiHa cells proliferation and migration. These results demonstrated that the promotive effect of CD73 on cervical cancer cells proliferation and migration in vitro was independent from its enzymatic activity (i.e. production of adenosine). Furthermore, the expressions of EGFR, VEGF and Akt were significantly increased in CD73 overexpression Hela and SiHa cells.

Conclusions

Our data suggested that CD73 might promote proliferation and migration via potentiating EGFR/Akt and VEGF/Akt pathway, which was independent of CD73 enzyme activity. These data provide a novel insight into the regulating function of CD73 in cancer cells and suggest that CD73 may be promising therapeutic target in cervical cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3128-5) contains supplementary material, which is available to authorized users.