Structural basis for reactivating the mutant TERT promoter by cooperative binding of p52 and ETS1

Shaping DNA damage responses: Therapeutic potential of targeting telomeric proteins and DNA repair factors in cancer

Shelterin proteins regulate genomic stability by preventing inappropriate DNA damage responses (DDRs) at telomeres. Unprotected telomeres lead to persistent DDR causing cell cycle inhibition, growth arrest, and apoptosis. Cancer cells rely on DDR to protect themselves from DNA lesions and exogenous DNA-damaging agents such as chemotherapy and radiotherapy. Therefore, targeting DDR machinery is a promising strategy to increase the sensitivity of cancer cells to existing cancer therapies. However, the success of these DDR inhibitors depends on other mutations, and over time, patients develop resistance to these therapies. This suggests the need for alternative approaches. One promising strategy is co-inhibiting shelterin proteins with DDR molecules, which would offset cellular fitness in DNA repair in a mutation-independent manner. This review highlights the associations and dependencies of the shelterin complex with the DDR proteins and discusses potential co-inhibition strategies that might improve the therapeutic potential of current inhibitors.

Clinical, histological, and molecular differences in melanoma due to different TERT promoter mutations subtypes. A retrospective cross-sectional study in 684 melanoma patients

Differences in survival according to the pTERT mutation subtypes (-124C > T, -146C > T, and tandem -138_139CC > TT) have been observed. The present study aimed to describe the clinical as the histopathological and molecular cutaneous melanoma features according to the presence of the three most prevalent pTERT mutation subtypes (-124C > T, -146C > T, and tandem -138_139CC > TT). A retrospective cross-sectional study including 684 patients was designed, and a Partial Least-Squares Discriminant Analysis (PLS-DA) was performed. After the PSL-DA, it was observed that the tandem -138_139CC > TT subtype differs from the other subtypes. The model demonstrated that the -124C > T and the -138_139 CC > TT subtypes were associated with fast-growing melanomas (OR 0.5, CI 0.29-0.86, p = .012) and with Breslow >2 mm (OR 0.6, CI 0.37-0.97, p = .037), compared to the -146C > T mutation. Finally, the -124C > T appeared to be more associated with the presence of TILs (non-brisk) than the -146C > T (OR 0.6, CI 0.40-1.01, p = .05). These findings confirmed that the -124C > T and the tandem -138_139 CC > TT subtypes are both highly associated with the presence of features of aggressiveness; however, only the -124C > T was highly associated with TILs. This difference could explain the worse survival rate associated with the tandem -138_139CC > TT mutations.

Aberrant non-canonical NF-κB signalling reprograms the epigenome landscape to drive oncogenic transcriptomes in multiple myeloma

In multiple myeloma, abnormal plasma cells establish oncogenic niches within the bone marrow by engaging the NF-κB pathway to nurture their survival while they accumulate pro-proliferative mutations. Under these conditions, many cases eventually develop genetic abnormalities endowing them with constitutive NF-κB activation. Here, we find that sustained NF-κB/p52 levels resulting from such mutations favours the recruitment of enhancers beyond the normal B-cell repertoire. Furthermore, through targeted disruption of p52, we characterise how such enhancers are complicit in the formation of super-enhancers and the establishment of cis-regulatory interactions with myeloma dependencies during constitutive activation of p52. Finally, we functionally validate the pathological impact of these cis-regulatory modules on cell and tumour phenotypes using in vitro and in vivo models, confirming RGS1 as a p52-dependent myeloma driver. We conclude that the divergent epigenomic reprogramming enforced by aberrant non-canonical NF-κB signalling potentiates transcriptional programs beneficial for multiple myeloma progression.

Extracellular vesicles derived from mesenchymal stem cells: the wine in Hebe's hands to treat skin aging

Owing to its constant exposure to the external environment and various stimuli, skin ranks among the organs most vulnerable to manifestations of aging. Preventing and delaying skin aging has become one of the prominent research subjects in recent years. Mesenchymal stem cells (MSCs) are multipotent stem cells derived from mesoderm with high self-renewal ability and multilineage differentiation potential. MSC-derived extracellular vesicles (MSC-EVs) are nanoscale biological vesicles that facilitate intercellular communication and regulate biological behavior. Recent studies have shown that MSC-EVs have potential applications in anti-aging therapy due to their anti-inflammatory, anti-oxidative stress, and wound healing promoting abilities. This review presents the latest progress of MSC-EVs in delaying skin aging. It mainly includes the MSC-EVs promoting the proliferation and migration of keratinocytes and fibroblasts, reducing the expression of matrix metalloproteinases, resisting oxidative stress, and regulating inflammation. We then briefly discuss the recently discovered treatment methods of MSC-EVs in the field of skin anti-aging. Moreover, the advantages and limitations of EV-based treatments are also presented.

Telomerase and hallmarks of cancer: An intricate interplay governing cancer cell evolution

Transformed cells must acquire specific characteristics to be malignant. Weinberg and Hanahan characterize these characteristics as cancer hallmarks. Though these features are independently driven, substantial signaling crosstalk in transformed cells efficiently promotes these feature acquisitions. Telomerase is an enzyme complex that maintains telomere length. However, its main component, Telomere reverse transcriptase (TERT), has been found to interact with various signaling molecules like cMYC, NF-kB, BRG1 and cooperate in transcription and metabolic reprogramming, acting as a strong proponent of malignant features such as cell death resistance, sustained proliferation, angiogenesis activation, and metastasis, among others. It allows cells to avoid replicative senescence and achieve endless replicative potential. This review summarizes both the canonical and noncanonical functions of TERT and discusses how they promote cancer hallmarks. Understanding the role of Telomerase in promoting cancer hallmarks provides vital insight into the underlying mechanism of cancer genesis and progression and telomerase intervention as a possible therapeutic target for cancer treatment. More investigation into the precise molecular mechanisms of telomerase-mediated impacts on cancer hallmarks will contribute to developing more focused and customized cancer treatment methods.

Reactivation of telomerase reverse transcriptase expression in cancer: the role of TERT promoter mutations

Telomerase activity and telomere elongation are essential conditions for the unlimited proliferation of neoplastic cells. Point mutations in the core promoter region of the telomerase reverse transcriptase (TERT) gene have been found to occur at high frequencies in several tumour types and considered a primary cause of telomerase reactivation in cancer cells. These mutations promote TERT gene expression by multiple mechanisms, including the generation of novel binding sites for nuclear transcription factors, displacement of negative regulators from DNA G-quadruplexes, recruitment of epigenetic activators and disruption of long-range interactions between TERT locus and telomeres. Furthermore, TERT promoter mutations cooperate with TPP1 promoter nucleotide changes to lengthen telomeres and with mutated BRAF and FGFR3 oncoproteins to enhance oncogenic signalling in cancer cells. TERT promoter mutations have been recognized as an early marker of tumour development or a major indicator of poor outcome and reduced patients survival in several cancer types. In this review, we summarize recent findings on the role of TERT promoter mutations, telomerase expression and telomeres elongation in cancer development, their clinical significance and therapeutic opportunities.

POT1 mutations cause differential effects on telomere length leading to opposing disease phenotypes

The protection of telomere protein (POT1) is a telomere-binding protein and is an essential component of the six-membered shelterin complex, which is associated with the telomeres. POT1 directly binds to the 3' single-stranded telomeric overhang and prevents the activation of DNA damage response at telomeres thus preventing the telomere-telomere fusions and genomic instability. POT1 also plays a pivotal role in maintaining telomere length by regulating telomerase-mediated telomere elongation. Mutations in POT1 proteins result in three different telomere phenotypes, which include long, short, or aberrant telomere length. Long telomeres predispose individuals to cancer, while short or aberrant telomere phenotypes result in pro-aging diseases referred to as telomeropathies. Here, we review the function of POT1 proteins in telomere length hemostasis and how the spectrum of mutations reported in POT1 can be segregated toward developing very distinct disease phenotypes of cancer and telomeropathies.

NF-κB/p52 augments ETS1 binding genome-wide to promote glioma progression

Gliomas are highly invasive and chemoresistant cancers, making them challenging to treat. Chronic inflammation is a key driver of glioma progression as it promotes aberrant activation of inflammatory pathways such as NF-κB signalling, which drives cancer cell invasion and angiogenesis. NF-κB factors typically dimerise with its own family members, but emerging evidence of their promiscuous interactions with other oncogenic factors has been reported to promote transcription of new target genes and function. Here, we show that non-canonical NF-κB activation directly regulates p52 at the ETS1 promoter, activating its expression. This impacts the genomic and transcriptional landscape of ETS1 in a glioma-specific manner. We further show that enhanced non-canonical NF-κB signalling promotes the co-localisation of p52 and ETS1, resulting in transcriptional activation of non-κB and/or non-ETS glioma-promoting genes. We conclude that p52-induced ETS1 overexpression in glioma cells remodels the genome-wide regulatory network of p52 and ETS1 to transcriptionally drive cancer progression.

The Role of Natural Flavonoids as Telomerase Inhibitors in Suppressing Cancer Growth

Cancer is a complex and multifaceted group of diseases characterized by the uncontrolled growth and spread of abnormal cells. While cancer can be challenging and life-altering, advances in research and development have led to the identification of new promising anti-cancer targets. Telomerase is one such target that is overexpressed in almost all cancer cells and plays a critical role in maintaining telomere length, which is essential for cell proliferation and survival. Inhibiting telomerase activity can lead to telomere shortening and eventual cell death, thus presenting itself as a potential target for cancer therapy. Naturally occurring flavonoids are a class of compounds that have already been shown to possess different biological properties, including the anti-cancer property. They are present in various everyday food sources and richly present in fruits, nuts, soybeans, vegetables, tea, wine, and berries, to name a few. Thus, these flavonoids could inhibit or deactivate telomerase expression in cancer cells by different mechanisms, which include inhibiting the expression of hTERT, mRNA, protein, and nuclear translocation, inhibiting the binding of transcription factors to hTERT promoters, and even telomere shortening. Numerous cell line studies and in vivo experiments have supported this hypothesis, and this development could serve as a vital and innovative therapeutic option for cancer. In this light, we aim to elucidate the role of telomerase as a potential anti-cancer target. Subsequently, we have illustrated that how commonly found natural flavonoids demonstrate their anti-cancer activity via telomerase inactivation in different cancer types, thus proving the potential of these naturally occurring flavonoids as useful therapeutic agents.

TERT promoter mutations in head and neck squamous cell carcinoma: A systematic review and meta-analysis on prevalence and prognostic significance

OBJECTIVES

To estimate the prevalence of two most common and mutually exclusive -124 C > T and -146 C > T TERT promoter mutations in HNSCC and analyse their prognostic role.

MATERIALS AND METHODS

The databases Medline (via Ovid), Embase (via Ovid), Cochrane Library, Scopus, and Web of Science (Core Collection) were searched from inception to December 2022 to identify studies analysing TERT promoter mutations in HNSCC. Pooled prevalence of TERT promoter mutations and hazard ratio (sHR) of death/progression, with corresponding confidence intervals (CI), were estimated.

RESULTS

The initial search returned 6416 articles, of which 17 studies, including 1830 patients, met the criteria for prevalence meta-analysis. Among them, 8 studies fitted the inclusion criterion to analyse the prognostic impact of TERT promoter mutations. Overall, 21% (95% CI: 12%-31%) of HNSCCs harboured TERT promoter mutation. TERT promoter mutations were more commonly found in oral cavity cancer (prevalence = 47%, 95% CI: 33%-61%), followed by laryngeal/hypopharyngeal cancer (prevalence = 12%, 95% CI: 4%-25%), while they were quite rare in oropharyngeal cancer (prevalence = 1%, 95% CI: 0%-4%). TERT promoter mutation -124 C > T was associated with a higher risk of death (sHR = 2.01, 95% CI: 1.25-3.23) and progression (sHR = 2.79, 95% CI: 1.77-4.40), while -146 C > T TERT promoter mutation did not show any significant correlation neither to overall nor progression-free survival.

CONCLUSION

TERT promoter mutations were mainly topographically restricted to oral cavity cancer. -124 C > T was the most common TERT promoter mutation and was significantly associated to worse outcome in HNSCC.

Long noncoding RNAs induced control of ferroptosis: Implications in cancer progression and treatment

A novel kind of nonapoptotic, iron-dependent cell death brought on by lipid peroxidation is known as ferroptosis. Numerous pathological processes, including neurotoxicity, neurological disorders, ischemia-reperfusion damage, and particularly cancer, have been demonstrated to be influenced by changes in the ferroptosis-regulating network. Recent studies have established the critical roles that ferroptosis can play in cancer development and the evolution of resistance to standard chemoradiotherapy, thus suggesting that ferroptosis may be a feasible therapeutic strategy for cancer management. Gene expression may be regulated at the transcriptional and posttranscriptional levels by long noncoding RNAs (lncRNAs). They have been implicated in tumorigenesis. Some lncRNAs participate in the biological process of ferroptosis, which represents an exciting alternative to regulate ferroptosis as a means of cancer therapy. Even though there is evidence that lncRNAs have a mechanistic role in the ferroptosis of cancer cells, research on the mechanism and potential treatments for these lncRNAs is still lacking. We elucidate the potential mechanisms by which lncRNAs modulate ferroptosis in cancer and examine the promise and challenges of employing lncRNAs as novel therapeutic targets in cancer.

Transcriptional Regulation during Aberrant Activation of NF-κB Signalling in Cancer

The NF-κB signalling pathway is a major signalling cascade involved in the regulation of inflammation and innate immunity. It is also increasingly recognised as a crucial player in many steps of cancer initiation and progression. The five members of the NF-κB family of transcription factors are activated through two major signalling pathways, the canonical and non-canonical pathways. The canonical NF-κB pathway is prevalently activated in various human malignancies as well as inflammation-related disease conditions. Meanwhile, the significance of non-canonical NF-κB pathway in disease pathogenesis is also increasingly recognized in recent studies. In this review, we discuss the double-edged role of the NF-κB pathway in inflammation and cancer, which depends on the severity and extent of the inflammatory response. We also discuss the intrinsic factors, including selected driver mutations, and extrinsic factors, such as tumour microenvironment and epigenetic modifiers, driving aberrant activation of NF-κB in multiple cancer types. We further provide insights into the importance of the interaction of NF-κB pathway components with various macromolecules to its role in transcriptional regulation in cancer. Finally, we provide a perspective on the potential role of aberrant NF-κB activation in altering the chromatin landscape to support oncogenic development.

Transcriptional analysis links B cells and TERT expression to favorable prognosis in head and neck cancer

Telomerase reverse transcriptase (TERT) is a conserved self-tumor antigen overexpressed in ∼85% of tumor cells and is immunogenic in cancer patients. The effect of TERT expression on the regulation of intratumor adaptive immunity has not yet been investigated. We used RNA sequencing data from The Cancer Genome Atlas (TCGA) in 11 solid tumor types to investigate potential interactions between TERT expression, and B and T cell infiltrate in the tumor microenvironment. We found a positive correlation between TERT expression, B and T cells in four cancer types with the strongest association in head and neck squamous cell carcinoma (HSNCC). In HNSCC a Bhigh/TERThigh signature was associated with improved progression-free survival (PFS) (P = 0.0048). This effect was independent of HPV status and not shared in comparable analysis by other conserved tumor antigens (NYESO1, MUC1, MAGE, and CEA). Bhigh/TERThigh HNSCC tumors also harbored evidence of tertiary lymphoid structure (TLS) such as signatures for germinal center (GC) and switched memory B cells, central memory CD4 and effector memory CD8 T cells. Bhigh/TERThigh HNSCC tumors also showed an up-regulation of genes and pathways related to B and T cell activation, proliferation, migration, and cytotoxicity, while factors associated with immunosuppression and cancer cell invasiveness were down-regulated. In summary, our study uncovers a new association between high TERT expression and high B cell infiltrate in HNSCC, suggesting a potential benefit from therapeutic strategies that invigorate intratumor TERT-mediated T-B cooperation.

ETS transcription factors: Multifaceted players from cancer progression to tumor immunity

The E26 transformation specific (ETS) family comprises 28 transcription factors, the majority of which are involved in tumor initiation and development. Serving as a group of functionally heterogeneous gene regulators, ETS factors possess a structurally conserved DNA-binding domain. As one of the most prominent families of transcription factors that control diverse cellular functions, ETS activation is modulated by multiple intracellular signaling pathways and post-translational modifications. Disturbances in ETS activity often lead to abnormal changes in oncogenicity, including cancer cell survival, growth, proliferation, metastasis, genetic instability, cell metabolism, and tumor immunity. This review systematically addresses the basics and advances in studying ETS factors, from their tumor relevance to clinical translational utility, with a particular focus on elucidating the role of ETS family in tumor immunity, aiming to decipher the vital role and clinical potential of regulation of ETS factors in the cancer field.

AgeAnno: a knowledgebase of single-cell annotation of aging in human

Aging is a complex process that accompanied by molecular and cellular alterations. The identification of tissue-/cell type-specific biomarkers of aging and elucidation of the detailed biological mechanisms of aging-related genes at the single-cell level can help to understand the heterogeneous aging process and design targeted anti-aging therapeutics. Here, we built AgeAnno (https://relab.xidian.edu.cn/AgeAnno/#/), a knowledgebase of single cell annotation of aging in human, aiming to provide comprehensive characterizations for aging-related genes across diverse tissue-cell types in human by using single-cell RNA and ATAC sequencing data (scRNA and scATAC). The current version of AgeAnno houses 1 678 610 cells from 28 healthy tissue samples with ages ranging from 0 to 110 years. We collected 5580 aging-related genes from previous resources and performed dynamic functional annotations of the cellular context. For the scRNA data, we performed analyses include differential gene expression, gene variation coefficient, cell communication network, transcription factor (TF) regulatory network, and immune cell proportionc. AgeAnno also provides differential chromatin accessibility analysis, motif/TF enrichment and footprint analysis, and co-accessibility peak analysis for scATAC data. AgeAnno will be a unique resource to systematically characterize aging-related genes across diverse tissue-cell types in human, and it could facilitate antiaging and aging-related disease research.

Noncanonical NF-κB factor p100/p52 regulates homologous recombination and modulates sensitivity to DNA-damaging therapy

Homologous recombination (HR) serves multiple roles in DNA repair that are essential for maintaining genomic stability, including double-strand DNA break (DSB) repair. The central HR protein, RAD51, is frequently overexpressed in human malignancies, thereby elevating HR proficiency and promoting resistance to DNA-damaging therapies. Here, we find that the non-canonical NF-κB factors p100/52, but not RelB, control the expression of RAD51 in various human cancer subtypes. While p100/p52 depletion inhibits HR function in human tumor cells, it does not significantly influence the proficiency of non-homologous end joining, the other key mechanism of DSB repair. Clonogenic survival assays were performed using a pair DLD-1 cell lines that differ only in their expression of the key HR protein BRCA2. Targeted silencing of p100/p52 sensitizes the HR-competent cells to camptothecin, while sensitization is absent in HR-deficient control cells. These results suggest that p100/p52-dependent signaling specifically controls HR activity in cancer cells. Since non-canonical NF-κB signaling is known to be activated after various forms of genomic crisis, compensatory HR upregulation may represent a natural consequence of DNA damage. We propose that p100/p52-dependent signaling represents a promising oncologic target in combination with DNA-damaging treatments.

NF-κB as a regulator of cancer metastasis and therapy response: A focus on epithelial-mesenchymal transition

Metastasis of tumor cells is a complex challenge and significantly diminishes the overall survival and prognosis of cancer patients. The epithelial-to-mesenchymal transition (EMT) is a well-known mechanism responsible for the invasiveness of tumor cells. A number of molecular pathways can regulate the EMT mechanism in cancer cells and nuclear factor-kappaB (NF-κB) is one of them. The nuclear translocation of NF-κB p65 can induce the transcription of several genes involved in EMT induction. The present review describes NF-κB and EMT interaction in cancer cells and their association in cancer progression. Due to the oncogenic role NF-κB signaling, its activation enhances metastasis of tumor cells via EMT induction. This has been confirmed in various cancers including brain, breast, lung and gastric cancers, among others. The ZEB1/2, transforming growth factor-β, and Slug as inducers of EMT undergo upregulation by NF-κB to promote metastasis of tumor cells. After EMT induction driven by NF-κB, a significant decrease occurs in E-cadherin levels, while N-cadherin and vimentin levels undergo an increase. The noncoding RNAs can potentially also function as upstream mediators and modulate NF-κB/EMT axis in cancers. Moreover, NF-κB/EMT axis is involved in mediating drug resistance in tumor cells. Thus, suppressing NF-κB/EMT axis can also promote the sensitivity of cancer cells to chemotherapeutic agents.

Emerging mechanisms of telomerase reactivation in cancer

Mutations in the promoter of human telomerase reverse transcriptase (hTERT) result in hyperactivation of hTERT. Notably, all mutations are G>A transitions, frequently found in a wide range of cancer types, and causally associated with cancer progression. Initially, the mutations were understood to reactivate hTERT by generating novel E26 transformation-specific (ETS) binding sites. Recent work reveals the role of DNA secondary structure G-quadruplexes, telomere binding factor(s), and chromatin looping in hTERT regulation. Here, we discuss these emerging findings in relation to the clinically significant promoter mutations to provide a broader understanding of the context-dependent outcomes that result in hTERT activation in normal and pathogenic conditions.

Differential ETS1 binding to T:G mismatches within a CpG dinucleotide contributes to C-to-T somatic mutation rate of the IDH2 hotspot at codon Arg140

Cytosine to thymine (C>T) somatic mutation is highly enriched in certain types of cancer, and most commonly occurs via deamination of a 5-methylcytosine (5mC) to thymine, in the context of a CpG dinucleotide. In theory, deamination should occur at equal rates to both 5mC nucleotides on opposite strands. In most cases, the resulting T:G or G:T mismatch can be repaired by thymine DNA glycosylase activities. However, while some hotspot-associated CpG mutations have approximately equal numbers of mutations that resulted either from C>T or G>A in a CpG dinucleotide, many showed strand bias, being skewed toward C>T of the first base pair or G>A of the second base pair. Using the IDH2 Arg140 codon as a case study, we show that the two possible T:G mismatches at the codon-specific CpG site have differing effects on transcription factor ETS1 binding affinity, differentially affecting access of a repair enzyme (MBD4) to the deamination-caused T:G mismatch. Our study thus provides a plausible mechanism for exclusion of repair enzymes by the differential binding of transcription factors affecting the rate at which the antecedent opposite-strand mutations occur.

Detection of TERT Promoter Mutations as a Prognostic Biomarker in Gliomas: Methodology, Prospects, and Advances

This article reviews the existing approaches to determining the TERT promoter mutational status in patients with various tumoral diseases of the central nervous system. The operational characteristics of the most common methods and their transferability in medical practice for the selection or monitoring of personalized treatments based on the TERT status and other related molecular biomarkers in patients with the most common tumors, such as glioblastoma, oligodendroglioma, and astrocytoma, are compared. The inclusion of new molecular markers in the course of CNS clinical management requires their rapid and reliable assessment. Availability of molecular evaluation of gliomas facilitates timely decisions regarding patient follow-up with the selection of the most appropriate treatment protocols. Significant progress in the inclusion of molecular biomarkers for their subsequent clinical application has been made since 2016 when the WHO CNS classification first used molecular markers to classify gliomas. In this review, we consider the methodological approaches used to determine mutations in the promoter region of the TERT gene in tumors of the central nervous system. In addition to classical molecular genetical methods, other methods for determining TERT mutations based on mass spectrometry, magnetic resonance imaging, next-generation sequencing, and nanopore sequencing are reviewed with an assessment of advantages and disadvantages. Beyond that, noninvasive diagnostic methods based on the determination of the mutational status of the TERT promoter are discussed.

Genome-wide screens identify specific drivers of mutant hTERT promoters

Mutations in hTERT promoter are seen in over 19% of human cancers, irrespective of the cancer type. Understanding the molecular players that regulate Mut-hTERT promoters may help the design of effective targeting strategies to inhibit telomerase reactivation specifically in cancer cells. Our work uses genome-wide functional screens to identify 30 specific regulators of Mut-hTERT promoters. These candidates identified from the screening serve as an excellent resource to understand how telomerase is reactivated and as targets for making inhibitors to telomerase, a key driver of cancer.

Cancer-specific hTERT promoter mutations reported in 19% of cancers result in enhanced telomerase activity. Understanding the distinctions between transcriptional regulation of wild-type (WT) and mutant (Mut) hTERT promoters may open up avenues for development of inhibitors which specially block hTERT expression in cancer cells. To comprehensively identify physiological regulators of WT- or Mut-hTERT promoters, we generated several isogenic reporter cells driven by endogenous hTERT loci. Genome-wide CRISPR-Cas9 and small interfering RNA screens using these isogenic reporter lines identified specific regulators of Mut-hTERT promoters. We validate and characterize one of these hits, namely, MED12, a kinase subunit of mediator complex. We demonstrate that MED12 specifically drives expression of hTERT from the Mut-hTERT promoter by mediating long-range chromatin interaction between the proximal Mut-hTERT promoter and T-INT1 distal regulatory region 260 kb upstream. Several hits identified in our screens could serve as potential therapeutic targets, inhibition of which may specifically block Mut-hTERT promoter driven telomerase reactivation in cancers.

Non-coding RNA-based regulation of inflammation

Inflammation is a multifactorial process and various biological mechanisms and pathways participate in its development. The presence of inflammation is involved in pathogenesis of different diseases such as diabetes mellitus, cardiovascular diseases and even, cancer. Non-coding RNAs (ncRNAs) comprise large part of transcribed genome and their critical function in physiological and pathological conditions has been confirmed. The present review focuses on miRNAs, lncRNAs and circRNAs as ncRNAs and their potential functions in inflammation regulation and resolution. Pro-inflammatory and anti-inflammatory factors are regulated by miRNAs via binding to 3'-UTR or indirectly via affecting other pathways such as SIRT1 and NF-κB. LncRNAs display a similar function and they can also affect miRNAs via sponging in regulating levels of cytokines. CircRNAs mainly affect miRNAs and reduce their expression in regulating cytokine levels. Notably, exosomal ncRNAs have shown capacity in inflammation resolution. In addition to pre-clinical studies, clinical trials have examined role of ncRNAs in inflammation-mediated disease pathogenesis and cytokine regulation. The therapeutic targeting of ncRNAs using drugs and nucleic acids have been analyzed to reduce inflammation in disease therapy. Therefore, ncRNAs can serve as diagnostic, prognostic and therapeutic targets in inflammation-related diseases in pre-clinical and clinical backgrounds.

Origin of the Functional Distinctiveness of NF-κB/p52

The transcription regulators of the NF-κB family have emerged as a critical factor affecting the function of various adult tissues. The NF-κB family transcription factors are homo- and heterodimers made up of five monomers (p50, p52, RelA, cRel and RelB). The family is distinguished by sequence homology in their DNA binding and dimerization domains, which enables them to bind similar DNA response elements and participate in similar biological programs through transcriptional activation and repression of hundreds of genes. Even though the family members are closely related in terms of sequence and function, they all display distinct activities. In this review, we discuss the sequence characteristics, protein and DNA interactions, and pathogenic involvement of one member of family, NF-κB/p52, relative to that of other members. We pinpoint the small sequence variations within the conserved region that are mostly responsible for its distinct functional properties.

TERT Promoter Mutations and rs2853669 Polymorphism: Useful Markers for Clinical Outcome Stratification of Patients With Oral Cavity Squamous Cell Carcinoma

Objective

To date, no useful prognostic biomarker exists for patients with oral squamous cell carcinoma (OCSCC), a tumour with uncertain biological behaviour and subsequent unpredictable clinical course. We aim to investigate the prognostic significance of two recurrent somatic mutations (-124 C>T and -146 C>T) within the promoter of telomerase reverse transcriptase (TERT) gene and the impact of TERT single nucleotide polymorphism (SNP) rs2853669 in patients surgically treated for OCSCC.

Methods

The genetic frequencies of rs2853669, -124 C>T and -146 C>T as well as the telomere length were investigated in 144 tumours and 57 normal adjacent mucosal (AM) specimens from OCSCC patients.

Results

Forty-five tumours harboured TERT promoter mutations (31.3%), with -124 C>T and -146 C>T accounting for 64.4% and 35.6% of the alterations respectively. Patients with -124 C>T TERT promoter mutated tumours had the shortest telomeres in the AM (p=0.016) and showed higher risk of local recurrence (hazard ratio [HR]:2.75, p=0.0143), death (HR:2.71, p=0.0079) and disease progression (HR:2.71, p=0.0024) with the effect being potentiated by the co-occurrence of T/T genotype of rs2853669.

Conclusion

-124 C>T TERT promoter mutation as well as the T/T genotype of the rs2853669 SNP are attractive independent prognostic biomarkers in patients surgically treated for OCSCC, with the coexistence of these genetic variants showing a synergistic impact on the aggressiveness of the disease.

Mast cells: Therapeutic targets for COVID-19 and beyond

Mast cells (MCs) are innate immune cells that widely distribute throughout all tissues and express a variety of cell surface receptors. Upon activation, MCs can rapidly release a diverse array of preformed mediators residing within their secretory granules and newly synthesize a broad spectrum of inflammatory and immunomodulatory mediators. These unique features of MCs enable them to act as sentinels in response to rapid changes within their microenvironment. There is increasing evidence now that MCs play prominent roles in other pathophysiological processes besides allergic inflammation. In this review, we highlight the recent findings on the emerging roles of MCs in the pathogenesis of coronavirus disease-2019 (COVID-19) and discuss the potential of MCs as novel therapeutic targets for COVID-19 and other non-allergic inflammatory diseases.

Effect of APOBEC3A functional polymorphism on renal cell carcinoma is influenced by tumor necrosis factor-α and transcriptional repressor ETS1

Human apolipoprotein B mRNA editing enzyme, catalytic polypeptide (APOBEC) 3 cytidine deaminases are the prominent drivers of somatic mutations in cancers. However, the effect of APOBEC3s functional polymorphisms on the development of renal cell carcinoma (RCC) remains unknown. Five genetic polymorphisms affecting the expression of APOBEC3A (A3A), APOBEC3B, and APOBEC4 and uracil DNA glycosylase (UNG) were genotyped in 728 RCC patients and 1500 healthy controls. The effects of tumor necrosis factor-α (TNFα) and interleukin-6 on the activity of the A3A promoter with rs12157810-A or -C in four RCC cell lines (786-O, A498, Caki2, ACHN) and two colorectal cancer cell lines (HCT116, SW620) were evaluated using dual-luciferase assays. Transcriptional repressors to the A3A promoter were identified by chromatin immunoprecipitation-quantitative PCR. The proapoptotic effect of A3A on RCC cells was evaluated using cytometry. The prognostic values of A3A and ETS1 were evaluated by the Cox regression analysis. The expressions of A3A and ETS1 were evaluated in clear cell RCC (ccRCC) specimens with different polymorphic genotypes using quantitative RT-PCR and immunohistochemistry. Of those functional polymorphisms, CC genotype at rs12157810 in the A3A promoter was significantly associated with a decreased risk of ccRCC, compared to the AA genotype (odds ratio adjusted for age and gender, 0.41, 95% confidence interval [CI], 0.28-0.57). Other polymorphic genotypes were not associated with the risk of RCC. The activity of the A3A promoter with rs12157810-C was significantly higher than that with rs12157810-A in the four RCC cell lines and two colorectal cancer cell lines. The activity of the A3A promoter with rs12157810-C was greatly up-regulated by TNFα and predominantly inhibited by a transcriptional repressor ETS1. The binding of ETS1 to the A3A promoter with rs12157810-C was looser than that with rs12157810-A. Ectopic expression of A3A significantly promoted apoptosis in ccRCC cells, rather than in colorectal cancer cells. Higher ETS1 expression predicted a favorable prognosis in ccRCC, with a hazard ratio of 0.58 (95% CI, 0.43-0.78). Rs121567810-C up-regulates the A3A promoter activity, possibly due to higher response to TNFα and looser transcriptional repression by ETS1. Up-regulation of A3A increases apoptosis, thus decreasing ccRCC risk in those carrying rs121567810-C.

Occurrence, functionality and abundance of the TERT promoter mutations

Telomere shortening at chromosomal ends due to the constraints of the DNA replication process acts as a tumor suppressor by restricting the replicative potential in primary cells. Cancers evade that limitation primarily through the reactivation of telomerase via different mechanisms. Mutations within the promoter of the telomerase reverse transcriptase (TERT) gene represent a definite mechanism for the ribonucleic enzyme regeneration predominantly in cancers that arise from tissues with low rates of self-renewal. The promoter mutations cause a moderate increase in TERT transcription and consequent telomerase upregulation to the levels sufficient to delay replicative senescence but not prevent bulk telomere shortening and genomic instability. Since the discovery, a staggering number of studies have resolved the discrete aspects, effects and clinical relevance of the TERT promoter mutations. The promoter mutations link transcription of TERT with oncogenic pathways, associate with markers of poor outcome and define patients with reduced survivals in several cancers. In this review, we discuss the occurrence and impact of the promoter mutations and highlight the mechanism of TERT activation. We further deliberate on the foundational question of the abundance of the TERT promoter mutations and a general dearth of functional mutations within noncoding sequences, as evident from pan-cancer analysis of the whole-genomes. We posit that the favorable genomic constellation within the TERT promoter may be less than a common occurrence in other noncoding functional elements. Besides, the evolutionary constraints limit the functional fraction within the human genome, hence the lack of abundant mutations outside the coding sequences.

Regulation of Nuclear Factor-KappaB (NF-κB) signaling pathway by non-coding RNAs in cancer: Inhibiting or promoting carcinogenesis?

The nuclear factor-kappaB (NF-κB) signaling pathway is considered as a potential therapeutic target in cancer therapy. It has been well established that transcription factor NF-κB is involved in regulating physiological and pathological events including inflammation, immune response and differentiation. Increasing evidences suggest that deregulated NF-κB signaling can enhance cancer cell proliferation, metastasis and also mediate radio-as well as chemo-resistance. On the contrary, non-coding RNAs (ncRNAs) have been found to modulate NF-κB signaling pathway under different settings. MicroRNAs (miRNAs) can dually inhibit/induce NF-κB signaling thereby affecting the growth and migration of cancer cells. Furthermore, the response of cancer cells to radiotherapy and chemotherapy may also be regulated by miRNAs. Regulation of NF-κB by miRNAs may be mediated via binding to 3^/-UTR region. Interestingly, anti-tumor compounds can increase the expression of tumor-suppressor miRNAs in inhibiting NF-κB activation and the progression of cancers. Long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) can also effectively modulate NF-κB signaling thus affecting tumorigenesis. It is noteworthy that several studies have demonstrated that lncRNAs and circRNAs can affect miRNAs in targeting NF-κB activation. They can act as competing endogenous RNA (ceRNA) thereby reducing miRNA expression to induce NF-κB activation that can in turn promote cancer progression and malignancy.

Non-canonical roles of canonical telomere binding proteins in cancers

Reactivation of telomerase is a major hallmark observed in 90% of all cancers. Yet paradoxically, enhanced telomerase activity does not correlate with telomere length and cancers often possess short telomeres; suggestive of supplementary non-canonical roles that telomerase might play in the development of cancer. Moreover, studies have shown that aberrant expression of shelterin proteins coupled with their release from shortening telomeres can further promote cancer by mechanisms independent of their telomeric role. While targeting telomerase activity appears to be an attractive therapeutic option, this approach has failed in clinical trials due to undesirable cytotoxic effects on stem cells. To circumvent this concern, an alternative strategy could be to target the molecules involved in the non-canonical functions of telomeric proteins. In this review, we will focus on emerging evidence that has demonstrated the non-canonical roles of telomeric proteins and their impact on tumorigenesis. Furthermore, we aim to address current knowledge gaps in telomeric protein functions and propose future research approaches that can be undertaken to achieve this.

Pharmacological significance of the non-canonical NF-κB pathway in tumorigenesis

The understanding of the impact of the non-canonical NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) pathway in several human diseases including autoimmune, inflammatory and cancers has been on the rise. This pathway induces the expression of several important genes involved in diverse biological processes. Though progress has been made in understanding the activation, regulation and biological functions of the non-canonical NF-κB signaling mechanism, no specific drug has been approved to target NF-κB inducing kinase (NIK), the key signaling molecule in this pathway. The inhibition of NIK can serve as a potential therapeutic strategy for various ailments, especially for the treatment of different types of human cancers. There are other targetable downstream molecules in this pathway as well. This review highlights the possible role of the non-canonical NF-κB pathway in normal physiology as well as in different cancers and discusses about various pharmacological strategies to modulate the activation of this pathway.

Cyclin-Dependent Kinase 9 (CDK9) Inhibitor Atuveciclib Suppresses Intervertebral Disk Degeneration via the Inhibition of the NF-κB Signaling Pathway

Intervertebral disk degeneration (IVDD) is a spinal disk condition caused by an inflammatory response induced by various proinflammatory cytokines, such as interleukin (IL)-1β and tumor necrosis factor (TNF)-α. cyclin-dependent kinase 9 (CDK9) is a transcriptional regulator and potential therapeutic target for many diseases, especially in regulating the activation of primary inflammatory response genes. Our study investigated a highly selective CDK9 inhibitor, atuveciclib, which protects nucleus pulposus (NP) cells from proinflammatory stimuli-induced catabolism. The effects of CDK9 inhibition were determined in human and rat NP cells treated with IL-1β in the presence or absence of atuveciclib or small interfering RNA target CDK9. Inhibition of CDK9 led to the attenuation of inflammatory response. In addition, rat intervertebral disk (IVD) explants were used to determine the role of CDK9 inhibition in extracellular matrix degradation. The rat IVDD model also proved that CDK9 inhibition attenuated IVDD, as validated using magnetic resonance imaging and immunohistochemistry. Taken together, CDK9 is a potential therapeutic target to prevent IVDD.

Targeting NF-κB Signaling for Multiple Myeloma

Multiple myeloma (MM) is the second most common hematologic malignancy in the world. Even though survival rates have significantly risen over the past years, MM remains incurable, and is also far from reaching the point of being managed as a chronic disease. This paper reviews the evolution of MM therapies, focusing on anti-MM drugs that target the molecular mechanisms of nuclear factor kappa B (NF-κB) signaling. We also provide our perspectives on contemporary research findings and insights for future drug development.

Small Molecule NF-κB Pathway Inhibitors in Clinic

Nuclear factor kappa B (NF-κB) signaling is implicated in all major human chronic diseases, with its role in transcription of hundreds of gene well established in the literature. This has propelled research into targeting the NF-κB pathways for modulating expression of those genes and the diseases mediated by them. In-spite of the critical, but often promiscuous role played by this pathway and the inhibition causing adverse drug reaction, currently many biologics, macromolecules, and small molecules that modulate this pathway are in the market or in clinical trials. Furthermore, many marketed drugs that were later found to also have NF-κB targeting activity were repurposed for new therapeutic interventions. Despite the rising importance of biologics in drug discovery, small molecules got around 76% of US-FDA (Food and Drug Administration-US) approval in the last decade. This encouraged us to review information regarding clinically relevant small molecule inhibitors of the NF-κB pathway from cell surface receptor stimulation to nuclear signaling. We have also highlighted the underexplored targets in this pathway that have potential to succeed in clinic.

Clinical, environmental and histological distribution of BRAF, NRAS and TERT promoter mutations among patients with cutaneous melanoma: a retrospective study of 563 patients

BACKGROUND

The distinct somatic mutations that define clinical and histopathological heterogeneity in cutaneous melanoma could be dependent on host susceptibility to exogenous factors like ultraviolet radiation.

OBJECTIVES

Firstly, to characterize patients with cutaneous melanoma clinically and pathologically based on the mutational status of BRAF, NRAS and TERT promoter. Secondly, to elucidate the modified features due to the presence of TERT promoter mutations over the background of either BRAF or NRAS mutations.

METHODS

We performed a retrospective study on 563 patients with melanoma by investigating somatic mutations in BRAF, NRAS and TERT promoter.

RESULTS

We observed co-occurrence of TERT promoter mutations with BRAF and NRAS mutations in 26.3% and 6.9% of melanomas, respectively. Multivariate analysis showed an independent association between BRAF mutations and a decreased presence of cutaneous lentigines at the melanoma site, and an increased association with the presence of any MC1R polymorphism. We also observed an independent association between TERT promoter mutations and increased tumour mitotic rate. Co-occurrence of BRAF and TERT promoter mutations was independently associated with occurrence of primary tumours at usually sun-exposed sites, lack of histological chronic sun damage in surrounding unaffected skin at the melanoma site, and increased tumour mitotic rate. Co-occurrence of NRAS and TERT promoter mutations was independently associated with increased tumour mitotic rate. The presence of TERT promoter together with BRAF or NRAS mutations was associated with statistically significantly worse survival.

CONCLUSIONS

The presence of TERT promoter mutations discriminates BRAF- and NRAS-mutated tumours and indicates a higher involvement of ultraviolet-induced damage and tumours with worse melanoma-specific survival than those without any mutation. These observations refine classification of patients with melanoma based on mutational status.

Role of Telomeres and Telomeric Proteins in Human Malignancies and Their Therapeutic Potential

Telomeres are the ends of linear chromosomes comprised of repetitive nucleotide sequences in humans. Telomeres preserve chromosomal stability and genomic integrity. Telomere length shortens with every cell division in somatic cells, eventually resulting in replicative senescence once telomere length becomes critically short. Telomere shortening can be overcome by telomerase enzyme activity that is undetectable in somatic cells, while being active in germline cells, stem cells, and immune cells. Telomeres are bound by a shelterin complex that regulates telomere lengthening as well as protects them from being identified as DNA damage sites. Telomeres are transcribed by RNA polymerase II, and generate a long noncoding RNA called telomeric repeat-containing RNA (TERRA), which plays a key role in regulating subtelomeric gene expression. Replicative immortality and genome instability are hallmarks of cancer and to attain them cancer cells exploit telomere maintenance and telomere protection mechanisms. Thus, understanding the role of telomeres and their associated proteins in cancer initiation, progression and treatment is very important. The present review highlights the critical role of various telomeric components with recently established functions in cancer. Further, current strategies to target various telomeric components including human telomerase reverse transcriptase (hTERT) as a therapeutic approach in human malignancies are discussed.

Coding and noncoding somatic mutations in candidate genes in basal cell carcinoma

Basal cell carcinoma (BCC) represents the most commonly diagnosed human cancer among persons of European ancestry with etiology mainly attributed to sun-exposure. In this study we investigated mutations in coding and flanking regions of PTCH1 and TP53 and noncoding alterations in the TERT and DPH3 promoters in 191 BCC tumors. In addition, we measured CpG methylation within the TERT hypermethylated oncological region (THOR) and transcription levels of the reverse transcriptase subunit. We observed mutations in PTCH1 in 58.6% and TP53 in 31.4% of the tumors. Noncoding mutations in TERT and DPH3 promoters were detected in 59.2% and 38.2% of the tumors, respectively. We observed a statistically significant co-occurrence of mutations at the four investigated loci. While PTCH1 mutations tended to associate with decreased patient age at diagnosis; TP53 mutations were associated with light skin color and increased number of nevi; TERT and DPH3 promoter with history of cutaneous neoplasms in BCC patients. Increased reverse transcriptase subunit expression was observed in tumors with TERT promoter mutations and not with THOR methylation. Our study signifies, in addition to the protein altering mutations in the PTCH1 and TP53 genes, the importance of noncoding mutations in BCC, particularly functional alterations in the TERT promoter.

Mechanisms of allergen-specific immunotherapy for allergic rhinitis and food allergies

Allergen-specific immunotherapy (AIT) is currently the only potential treatment for allergies including allergic rhinitis (AR) and food allergies (FA) that can modify the underlying course of the diseases. Although AIT has been performed for over a century, the precise and detailed mechanism for AIT is still unclear. Previous clinical trials have reported that successful AIT induces the reinstatement of tolerance against the specific allergen. In this review, we aim to provide an updated summary of the knowledge on the underlying mechanisms of IgE-mediated AR and FA as well as the immunological changes observed after AIT and discuss on how better understanding of these can lead to possible identification of biomarkers and novel strategies for AIT.

TERT Promoter Mutations Differently Correlate with the Clinical Outcome of MAPK Inhibitor-Treated Melanoma Patients

Resistance is a major challenge in the management of mitogen-activated protein kinase inhibitor (MAPKi)-treated metastatic melanoma. Tumor genetic alterations can cause MAPK pathway reactivation, leading to lack of response and poor outcome. Characterization of the mutational profile in patients with melanoma might be crucial for patient-tailored treatment choices. Mutations in the promoter region of the telomerase reverse transcriptase gene (TERTprom) lead to increased TERT expression and telomerase activity and are frequent in BRAF^V600 mutant melanoma. Reportedly, TERTprom, and BRAF^V600 mutations cooperate in driving cancer progression and aggressiveness. We evaluated the effect of the TERTprom status on the clinical outcome in 97 MAPKi-treated melanoma patients. We observed that patients with the c.-146C > T mutation showed a significantly worse progression-free survival (PFS) compared to those carrying the c.-124C > T mutation and a two-fold increased risk of progression (median 5.4 vs. 9.5 months; hazard ratio (HR) 1.9; 95% confidence interval (CI) 1.2–3.2; p = 0.013). This trend was also observed for the overall survival (OS); melanoma patients with the c.-146C > T mutation showed a poorer prognosis compared to those with the c.-124C > T mutation (median 13.3 vs. 25.5 months; HR 1.9, 95% CI 1.1–3.3, p = 0.023). Our results disclose a different correlation of the two TERTprom mutations with MAPKi-treated melanoma patient outcome, highlighting a different impact of the pathway blockade.

Telomerase: Key regulator of inflammation and cancer

The telomerase holoenzyme, which has a highly conserved role in maintaining telomere length, has long been regarded as a high-profile target in cancer therapy due to the high dependency of the majority of cancer cells on constitutive and elevated telomerase activity for sustained proliferation and immortality. In this review, we present the salient findings in the telomerase field with special focus on the association of telomerase with inflammation and cancer. The elucidation of extra-telomeric roles of telomerase in inflammation, reactive oxygen species (ROS) generation, and cancer development further complicated the design of anti-telomerase therapy. Of note, the discovery of the unique mechanism that underlies reactivation of the dormant telomerase reverse transcriptase TERT promoter in somatic cells not only enhanced our understanding of the critical role of TERT in carcinogenesis but also opens up new intervention ideas that enable the differential targeting of cancer cells only. Despite significant effort invested in developing telomerase-targeted therapeutics, devising efficacious cancer-specific telomerase/TERT inhibitors remains an uphill task. The latest discoveries of the telomere-independent functionalities of telomerase in inflammation and cancer can help illuminate the path of developing specific anti-telomerase/TERT therapeutics against cancer cells.

A comparative anatomy of protein crystals: lessons from the automatic processing of 56 000 samples

The fully automatic processing of crystals of macromolecules has presented a unique opportunity to gather information on the samples that is not usually recorded. This has proved invaluable in improving sample-location, characterization and data-collection algorithms. After operating for four years, MASSIF-1 has now processed over 56 000 samples, gathering information at each stage, from the volume of the crystal to the unit-cell dimensions, the space group, the quality of the data collected and the reasoning behind the decisions made in data collection. This provides an unprecedented opportunity to analyse these data together, providing a detailed landscape of macromolecular crystals, intimate details of their contents and, importantly, how the two are related. The data show that mosaic spread is unrelated to the size or shape of crystals and demonstrate experimentally that diffraction intensities scale in proportion to crystal volume and molecular weight. It is also shown that crystal volume scales inversely with molecular weight. The results set the scene for the development of X-ray crystallography in a changing environment for structural biology.

MiR-16-5p inhibits breast cancer by reducing AKT3 to restrain NF-κB pathway

Background: Breast cancer endangers the life of women and has become the major cause of deaths among them. MiRNAs are found to exert a regulatory effect on the migration, proliferation and apoptosis of breast cancer cells. This research aims at investigating the miR-16-5p expression and its effect on the pathogenesis of breast cancer. Methods: Their clinical data were analyzed with qRT-PCR. CCK8, EdU and Transwell was performed to explore the function of miR-16-5p in cell migration and proliferation of breast cancer cells. Dual-luciferase reporter assay, immunohistochemistry and Western blotting were carried out to explore the relation between miR-16-5p and AKT3. Results: It was discovered that miR-16-5p was lowly expressed in breast cancer patients. Meanwhile, breast cancer patients with under-expressed miR-16-5p had a lower survival rate than those with highly expressed miR-16-5p. Furthermore, decreased miR-16-5p in cell and animal models enhanced migration and proliferation of breast cancer cells, stimulated cell cycle and reduced cell apoptosis. Finally, we found miR-16-5p restrained the NF-κB pathway and decreased AKT3 gene, thereby suppressing the breast cancer development. Conclusion: It can be seen that miR-16-5p exhibits a low expression in breast cancer tissues, which can inhibit breast cancer by restraining the NF-κB pathway and elevating reducing AKT3.

TERT expression is susceptible to BRAF and ETS-factor inhibition in BRAFV600E/TERT promoter double-mutated glioma

The BRAF gene and the TERT promoter are among the most frequently altered genomic loci in low-grade (LGG) and high-grade-glioma (HGG), respectively. The coexistence of BRAF and TERT promoter aberrations characterizes a subset of aggressive glioma. Therefore, we investigated interactions between those alterations in malignant glioma. We analyzed co-occurrence of BRAFV600E and TERT promoter mutations in our clinical data (n = 8) in addition to published datasets (n = 103) and established a BRAFV600E-positive glioma cell panel (n = 9) for in vitro analyses. We investigated altered gene expression, signaling events and TERT promoter activity upon BRAF- and E-twenty-six (ETS)-factor inhibition by qRT-PCR, chromatin immunoprecipitation (ChIP), Western blots and luciferase reporter assays. TERT promoter mutations were significantly enriched in BRAFV600E-mutated HGG as compared to BRAFV600E-mutated LGG. In vitro, BRAFV600E/TERT promoter double-mutant glioma cells showed exceptional sensitivity towards BRAF-targeting agents. Remarkably, BRAF-inhibition attenuated TERT expression and TERT promoter activity exclusively in double-mutant models, while TERT expression was undetectable in BRAFV600E-only cells. Various ETS-factors were broadly expressed, however, only ETS1 expression and phosphorylation were consistently downregulated following BRAF-inhibition. Knock-down experiments and ChIP corroborated the notion of a functional role for ETS1 and, accordingly, all double-mutant tumor cells were highly sensitive towards the ETS-factor inhibitor YK-4-279. In conclusion, our data suggest that concomitant BRAFV600E and TERT promoter mutations synergistically support cancer cell proliferation and immortalization. ETS1 links these two driver alterations functionally and may represent a promising therapeutic target in this aggressive glioma subgroup.

Oncogenic ETS Factors in Prostate Cancer

Prostate cancer is unique among carcinomas in that a fusion gene created by a chromosomal rearrangement is a common driver of the disease. The TMPRSS2/ERG rearrangement drives aberrant expression of the ETS family transcription factor ERG in 50% of prostate tumors. Similar rearrangements promote aberrant expression of the ETS family transcription factors ETV1 and ETV4 in another 10% of cases. Together, these three ETS factors are thought to promote tumorigenesis in the majority of prostate cancers. A goal of precision medicine is to be able to apply targeted therapeutics that are specific to disease subtypes. ETS gene rearrangement positive tumors represent the largest molecular subtype of prostate cancer, but to date there is no treatment specific to this marker. In this chapter we will review the latest findings regarding the molecular mechanisms of ETS factor function in the prostate. These molecular details may provide a path towards new therapeutic targets for this subtype of prostate cancer. Further, we will describe efforts to target the oncogenic functions of ETS family transcription factors directly as well as indirectly.