Julia Oliwia Misiorek

Glioblastoma (GBM) is the most common and malignant type of brain tumor in adults and no effective therapies exist to combat this disease. Surgical resection, radio- and temozolomide-based-chemotherapy are insufficient mainly due to inter- and intra-tumoral heterogeneity of GBM tumors, therefore personalized approaches are required. Additionally, diverse tumor microenvironment with a leading role of glioblastoma stem cells (GSCs) in hypoxic core underlie the aggressiveness and recurrence of GBM. However, the molecules and pathways which directly promote tumor aggressiveness together with the driving process of epithelial-to-mesenchymal transition (EMT) and the components of extracellular matrix (ECM), remain only partially covered with prior studies focused mainly on coding oncogenes and tumor suppressor genes. Over the past years, a special attention has been paid to non-coding, circular RNAs (circRNAs) differentially expressed in various cancers, including GBM. Despite high abundance and stability, the exact biological roles of most individual circRNAs have not been fully revealed, so far. Besides anti-cancer targets, circRNAs have been considered as essential biomarkers and stratifying criterion of malignancy. Thus, studies on functions of differentially expressed circRNAs in GBM are an emerging field to be explored. In herein study, the biological role of circRNA CLIP2 (circCLIP2) was found highly overexpressed in primary tumor tissues. Upon the knock-down of circCLIP2 in 2D and 3D in vitro models, functional tests performed clearly indicate a significant contribution of circCLIP2 to aggressive potential of GBM as showed by decreased rates of proliferation, migration and invasion. Additional studies indicated predominant expression of circCLIP2 in GSC fractions additionally elevated by hypoxic conditions. The increased rates of proliferation and migration as well as molecular analyses were also confirmed in in vivo settings where xenograft model was applied. The expression of EMT marker Snail2 and ECM-degrading enzyme metalloproteinase 9 ( MMP9 ) were significantly downregulated in the tumors formed from circCLIP2 silenced cells. Taken together, these results indicate a strong contribution of circCLIP2 in the aggressive phenotype of GBM which is due to a modulation of GSC proliferative potential as well as migration and invasion via EMT together with the modulator of ECM composition.

Huntington's disease (HD) is a neurodegenerative polyglutamine (polyQ) disease resulting from the expansion of CAG repeats located in the ORF of the huntingtin gene ( HTT ). The extent to which mutant mRNA‐driven disruptions contribute to HD pathogenesis, particularly in comparison to the dominant mechanisms related to the gain‐of‐function effects of the mutant polyQ protein, is still debatable. To evaluate this contribution in vivo, we generated two mouse models through a knock‐in strategy at the Rosa26 locus. These models expressed distinct variants of human mutant HTT cDNA fragment: a translated variant (HD/100Q model, serving as a reference) and a nontranslated variant (HD/100CAG model). The cohorts of animals were subjected to a broad spectrum of molecular, behavioral, and cognitive analysis for 21 months. Behavioral testing revealed alterations in both models, with the HD/100Q model exhibiting late disease phenotype. The rotarod, static rod, and open‐field tests showed some motor deficits in HD/100CAG and HD/100Q model mice during the light phase, while ActiMot indicated hyperkinesis during the dark phase. Both models also exhibited certain gene deregulations in the striatum that are related to disrupted pathways and phenotype alterations observed in HD. In conclusion, we provide in vivo evidence for a minor contributory role of mutant RNA in HD pathogenesis. The separated effects resulting from the presence of mutant RNA in the HD/100CAG model led to less severe but, to some extent, similar types of impairments as in the HD/100Q model. Increased anxiety was one of the most substantial effects caused by mutant HTT RNA.

Choroba Charcot-Marie-Tooth (CMT) to genetycznie uwarunkowana, nieuleczalna choroba neurodegenracyjna, w której etiologie zaangażowane są mutacje w prawie stu różnych genach. Choroba dotyka nerwy obwodowe kontrolujące pracę mięśni oraz ich osłonki mielinowe, co prowadzi w efekcie do postępującego zaniku mięśni. Jednymi z ciekawszych genów, których mutacje są powiązane z fenotypem CMT, są geny kodujące syntetazy aminoacylo-tRNA (aaRS). Białka te są enzymami, których powszechną rolą jest katalizowanie reakcji przenoszenia poszczególnych aminokwasów na cząsteczki tRNA, a tym samym udział w tłumaczeniu kodu genetycznego na język białek. aaRS w wyniku powstających w toku ewolucji mutacji zaczęły nabywać nowe funkcje, które do dziś pozostają niezidentyfikowane, pomimo poznawania molekuł wiążących się z aaRS. Jednakże badania molekularne przypadków mutacji u pacjentów z CMT oraz organizmów modelowych, przybliżają naukowców do poznania nowych procesów, w które zaangażowane są aaRS i potencjalnie tłumaczyłyby ich kluczową rolę w patogenezie CMT.

Head and Neck Squamous Cell Carcinoma (HNSCC) is often aggressive, with poor response to current therapies in approximately 40–50% of the patients. Current therapies are restricted to operation and irradiation, often combined with a small number of standard-of-care chemotherapeutic drugs, preferentially for advanced tumour patients. Only very recently, newer targeted therapies have entered the clinics, including Cetuximab, which targets the EGF receptor (EGFR), and several immune checkpoint inhibitors targeting the immune receptor PD-1 and its ligand PD-L1. HNSCC tumour tissues are characterized by a high degree of intra-tumour heterogeneity (ITH), and non-genetic alterations that may affect both non-transformed cells, such as cancer-associated fibroblasts (CAFs), and transformed carcinoma cells. This very high degree of heterogeneity likely contributes to acquired drug resistance, tumour dormancy, relapse, and distant or lymph node metastasis. ITH, in turn, is likely promoted by pronounced tumour cell plasticity, which manifests in highly dynamic and reversible phenomena such as of partial or hybrid forms of epithelial-to-mesenchymal transition (EMT), and enhanced tumour stemness. Stemness and tumour cell plasticity are strongly promoted by Notch signalling, which remains poorly understood especially in HNSCC. Here, we aim to elucidate how Notch signal may act both as a tumour suppressor and proto-oncogenic, probably during different stages of tumour cell initiation and progression. Notch signalling also interacts with numerous other signalling pathways, that may also have a decisive impact on tumour cell plasticity, acquired radio/chemoresistance, and metastatic progression of HNSCC. We outline the current stage of research related to Notch signalling, and how this pathway may be intricately interconnected with other, druggable targets and signalling mechanisms in HNSCC.

Background: Glioblastoma (GBM) is the deadliest and the most common primary brain tumor in adults. The invasiveness and proliferation of GBM cells can be decreased through the inhibition of Wnt/β-catenin pathway. In this regard, celecoxib is a promising agent, but other COXIBs and 2,5-dimethylcelecoxib (2,5-DMC) await elucidation. Thus, the aim of this study was to analyze the impact of celecoxib, 2,5-DMC, etori-, rofe-, and valdecoxib on GBM cell viability and the activity of Wnt/β-catenin pathway. In addition, the combination of the compounds with temozolomide (TMZ) was also evaluated. Cell cycle distribution and apoptosis, MGMT methylation level, COX-2 and PGE2 EP4 protein levels were also determined in order to better understand the molecular mechanisms exerted by these compounds and to find out which of them can serve best in GBM therapy. Methods: Celecoxib, 2,5-DMC, etori-, rofe- and valdecoxib were evaluated using three commercially available and two patient-derived GBM cell lines. Cell viability was analyzed using MTT assay, whereas alterations in MGMT methylation level were determined using MS-HRM method. The impact of COXIBs, in the presence and absence of TMZ, on Wnt pathway was measured on the basis of the expression of β-catenin target genes. Cell cycle distribution and apoptosis analysis were performed using flow cytometry. COX-2 and PGE2 EP4 receptor expression were evaluated using Western blot analysis. Results: Wnt/β-catenin pathway was attenuated by COXIBs and 2,5-DMC irrespective of the COX-2 expression profile of the treated cells, their MGMT methylation status, or radio/chemoresistance. Celecoxib and 2,5-DMC were the most cytotoxic. Cell cycle distribution was altered, and apoptosis was induced after the treatment with celecoxib, 2,5-DMC, etori- and valdecoxib in T98G cell line. COXIBs and 2,5-DMC did not influence MGMT methylation status, but inhibited COX-2/PGE2/EP4 pathway. Conclusions: Not only celecoxib, but also 2,5-DMC, etori-, rofe- and valdecoxib should be further investigated as potential good anti-GBM therapeutics.

The Notch signaling pathway is a critical player in embryogenesis but also plays various roles in tumorigenesis, with both tumor suppressor and oncogenic activities. Mutations, deletions, amplifications, or over-expression of Notch receptors, ligands, and a growing list of downstream Notch-activated genes have by now been described for most human cancer types. Yet, it often remains unclear what may be the functional impact of these changes for tumor biology, initiation, and progression, for cancer therapy, and for personalized medicine. Emerging data indicate that Notch signaling can also contribute to increased aggressive properties such as invasion, tumor heterogeneity, angiogenesis, or tumor cell dormancy within solid cancer tissues; especially in epithelial cancers, which are in the center of this review. Notch further supports the “stemness” of cancer cells and helps define the stem cell niche for their long-term survival, by integrating the interaction between cancer cells and the cells of the tumor microenvironment (TME). The complexity of Notch crosstalk with other signaling pathways and its roles in cell fate and trans-differentiation processes such as epithelial-to-mesenchymal transition (EMT) point to this pathway as a decisive player that may tip the balance between tumor suppression and promotion, differentiation and invasion. Here we not only review the literature, but also explore genomic databases with a specific focus on Notch signatures, and how they relate to different stages in tumor development. Altered Notch signaling hereby plays a key role for tumor cell survival and coping with a broad spectrum of vital issues, contributing to failed therapies, poor patient outcome, and loss of lives.

Friedreich’s ataxia (FRDA) is a genetic neurodegenerative disease that is caused by guanine-adenine-adenine (GAA) nucleotide repeat expansions in the first intron of the frataxin (FXN) gene. Although present in the intron, this mutation leads to a substantial decrease in protein expression. Currently, no effective treatment is available for FRDA, and, in addition toFXN, other targets with therapeutic potential are continuously sought. As miRNAs can regulate the expression of a broad spectrum of genes, are used as biomarkers, and can serve as therapeutic tools, we decided to identify and characterize differentially expressed miRNAs and their targets in FRDA cells compared to unaffected control (CTRL) cells. In this study, we performed an integrated miRNAseq and RNAseq analysis using the same cohort of primary FRDA and CTRL cells. The results of the transcriptome studies were supported by bioinformatic analyses and validated by qRT-PCR. miRNA interactions with target genes were assessed by luciferase assays, qRT-PCR, and immunoblotting. In silico analysis identified theFXNtranscript as a target of five miRNAs upregulated in FRDA cells. Further studies confirmed that miRNA-224-5p indeed targetsFXN,resulting in decreases in mRNA and protein levels. We also validated the ability of miRNA-10a-5p to bind and regulate the levels of brain-derived neurotrophic factor (BDNF), an important modulator of neuronal growth. We observed a significant decrease in the levels of miRNA-10a-5p and increase in the levels ofBDNFupon correction of FRDA cells via zinc-finger nuclease (ZFN)-mediated excision of expanded GAA repeats. Our comprehensive transcriptome analyses identified miRNA-224-5p and miRNA-10a-5p as negative regulators of theFXNandBDNFexpression, respectively. These results emphasize not only the importance of miRNAs in the pathogenesis of FRDA but also their potential as therapeutic targets for this disease.

Introduction: Friedreich’s ataxia (FRDA) is an autosomal recessive multisystem disease mainly affecting the peripheral and central nervous systems, and heart. FRDA is caused by a GAA repeat expansion in the first intron of the frataxin (FXN) gene, that leads to reduced expression of FXN mRNA and frataxin protein. Neuronal and cardiac cells are primary targets of frataxin deficiency and generating models via differentiation of induced pluripotent stem cells (iPSCs) into these cell types is essential for progress towards developing therapies for FRDA. Areas covered: This review is focused on modeling FRDA using human iPSCs and various iPSC-differentiated cell types. We emphasized the importance of patient and corrected isogenic cell line pairs to minimize effects caused by biological variability between individuals. Expert opinion: The versatility of iPSC-derived cellular models of FRDA is advantageous for developing new therapeutic strategies, and rigorous testing in such models will be critical for approval of the first treatment for FRDA. Creating a well-characterized and diverse set of iPSC lines, including appropriate isogenic controls, will facilitate achieving this goal. Also, improvement of differentiation protocols, especially towards proprioceptive sensory neurons and organoid generation, is necessary to utilize the full potential of iPSC technology in the drug discovery process.

Keratins (K) are intermediate filament proteins important in stress protection and mechanical support of epithelial tissues. K8, K18 and K19 are the main colonic keratins, and K8-knockout (K8^−/−) mice display a keratin dose-dependent hyperproliferation of colonic crypts and a colitis-phenotype. However, the impact of the loss of K8 on intestinal cell differentiation has so far been unknown. Here we show that K8 regulates Notch1 signalling activity and differentiation in the epithelium of the large intestine. Proximity ligation and immunoprecipitation assays demonstrate that K8 and Notch1 co-localize and interact in cell cultures, and in vivo in the colonic epithelial cells. K8 with its heteropolymeric partner K18 enhance Notch1 protein levels and activity in a dose dependent manner. The levels of the full-length Notch1 receptor (FLN), the Notch1 intracellular domain (NICD) and expression of Notch1 downstream target genes are reduced in the absence of K8, and the K8-dependent loss of Notch1 activity can be rescued with re-expression of K8/K18 in K8-knockout CRISPR/Cas9 Caco-2 cells protein levels. In vivo, K8 deletion with subsequent Notch1 downregulation leads to a shift in differentiation towards a goblet cell and enteroendocrine phenotype from an enterocyte cell fate. Furthermore, the K8^−/− colonic hyperproliferation results from an increased number of transit amplifying progenitor cells in these mice. K8/K18 thus interact with Notch1 and regulate Notch1 signalling activity during differentiation of the colonic epithelium.

Keratins (K) are intermediate filament proteins important in protection from cellular stress. K8, K18 and K19 are the main components of keratin filaments in colonic epithelia but their role in intestinal diseases remains ambiguous. A function for keratins in intestinal health is supported by the K8-knock-out (K8^-/-) mouse which manifests an early chronic ulcerative colitis-like inflammatory bowel disease and epithelial hyperproliferation. We tested whether K8^-/- mice are more susceptible to colorectal cancer (CRC) compared to K8 wild type (K8^+/+), and K8 heterozygote (K8^+/-) mice showing increased proliferation but no inflammation. K8^-/- mice did not develop CRC spontaneously, but had dramatically increased numbers of tumors in the distal colon in the azoxymethane (AOM) and Apc^Min/+ CRC models where neither K8^+/+ nor K8^+/- mice were susceptible. Upregulation of IL-22 in combination with a complete loss of its negative regulator IL-22BP, and increased downstream STAT3-signaling in K8^-/- and K8^-/-Apc^Min/+ colonic epithelia confirmed that the IL-22 pathway, important in inflammation, proliferation and tissue regeneration, was activated. The nearly total loss of IL-22BP correlated with an activated inflammasome leading to increased cleaved caspase-1, and the putative IL-22BP inhibitor, IL-18, as well as a decrease in ALDH1/2. Ablation of K8 in a colorectal cancer cell line similarly resulted in increased IL-18 and decreased ALDH1/2. K8/K18 co-immunoprecipitated with pro-caspase-1, a component of the inflammasome in the colon, which suggests that keratins modulate inflammasome activity and protect the colon from inflammation and tumorigenesis. The K8-null mouse models also provide novel epithelial derived robust colon-specific CRC-models.