1. Cyanobacterial cyclic peptides can disrupt cytoskeleton organization in human astrocytes : a contribution to the understanding of the systemic toxicity of cyanotoxinsAnja Bubik, Robert Frangež, Monika C. Žužek, Ion Gutiérrez-Aguirre, Tamara Lah Turnšek, Bojan Sedmak, 2024, original scientific article Abstract: The systemic toxicity of cyclic peptides produced by cyanobacteria (CCPs) is not yet completely understood. Apart from the most known damages to the liver and kidneys, symptoms of their neurotoxicity have also been reported. Hepatotoxic CCPs, like microcystins, as well as non-hepatotoxic anabaenopeptins and planktopeptins, all exhibit cytotoxic and cytostatic effects on mammalian cells. However, responses of different cell types to CCPs depend on their specific modes of interaction with cell membranes. This study demonstrates that non-hepatotoxic planktopeptin BL1125 and anabaenopeptins B and F, at concentrations up to 10 µM, affect normal and tumor human astrocytes (NHA and U87-GM) in vitro by their almost immediate insertion into the lipid monolayer. Like microcystin-LR (up to 1 µM), they inhibit Ser/Thr phosphatases and reorganize cytoskeletal elements, with modest effects on their gene expression. Based on the observed effects on intermediate filaments and intermediate filament linkage elements, their direct or indirect influence on tubulin cytoskeletons via post-translational modifications, we conclude that the basic mechanism of CCP toxicities is the induction of inter- and intracellular communication failure. The assessed inhibitory activity on Ser/Thr phosphatases is also crucial since the signal transduction cascades are modulated by phosphorylation/dephosphorylation processes. Keywords: astrocytes, cyclic cyanobacterial peptides, cytoskeletal organization, Ser/Thr phosphatases, systemic toxicity, cyanobacteria Published in DiRROS: 28.08.2024; Views: 88; Downloads: 230
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2. Proteases and cytokines as mediators of interactions between cancer and stromal cells in tumoursBarbara Breznik, Helena Motaln, Tamara Lah Turnšek, 2017, review article Abstract: Proteolytic enzymes are highly relevant in different processes of cancer progression. Their interplay with other signalling molecules such as cytokines represents important regulation of multicellular cross-talk. In this review, we discuss protease regulation mechanisms of cytokine signalling in various types of cancer. Additionally, we highlight the reverse whereby cytokines have an impact on protease expression in an autocrine and paracrine manner, representing complex feedback mechanisms among multiple members of these two protein families. The relevance of the protease-cytokine axis is illustrated in glioblastoma, where interactions between normal mesenchymal stem cells and cancer cells play an important role in this very malignant form of brain cancer. Keywords: cellular cross-talk, glioblastoma, invasion, mesenchymal stem cells, protease-cytokine signalling Published in DiRROS: 06.08.2024; Views: 146; Downloads: 94
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3. Cytokine CCL5 and receptor CCR5 axis in glioblastoma multiformeMiha Koprivnikar Krajnc, Metka Novak, Richard G. Pestell, Tamara Lah Turnšek, 2019, review article Abstract: Background
Glioblastoma is the most frequent and aggressive brain tumour in humans with median survival from 12 to 15 months after the diagnosis. This is mostly due to therapy resistant glioblastoma stem cells in addition to intertumour heterogeneity that is due to infiltration of a plethora of host cells. Besides endothelial cells, mesenchymal stem cells and their differentiated progenies, immune cells of various differentiation states, including monocytes, comprise resident, brain tumour microenvironment. There are compelling evidence for CCL5/CCR5 in the invasive and metastatic behaviour of many cancer types. CCR5, a G-protein coupled receptor, known to function as an essential co-receptor for HIV entry, is now known to participate in driving tumour heterogeneity, the formation of cancer stem cells and the promotion of cancer invasion and metastasis. Clinical trials have recently opened targeting CCR5 using a humanized monoclonal antibody (leronlimab) for metastatic triple negative breast cancer (TNBC) or a small molecule inhibitor (maraviroc) for metastatic colon cancer. There are important CCL5 and CCR5 structure and signalling mechanisms in glioblastoma. In addition, the CCL5/CCR5 axis directs infiltration and interactions with monocytes/macrophages and mesenchymal stem cells, comprising glioblastoma stem cell niches.
Conclusions
CCR5 is highly expressed in glioblastoma and is associated with poor prognosis of patients. CCL5/CCR5 is suggested to be an excellent new target for glioblastoma therapy. The molecular mechanisms, by which chemoattractant and receptor respond within the complex tissue microenvironment to promote cancer stem cells and tumour heterogeneity, should be considered in forthcoming studies. Keywords: cytokines, CCL5-RANTES, glioblastoma, tumour microenvironment, mesenchymal stem cells, signalling Published in DiRROS: 06.08.2024; Views: 141; Downloads: 82
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4. Epithelial-to-mesenchymal transition as the driver of changing carcinoma and glioblastoma microenvironmentBernarda Majc, Tilen Sever, Miki Zarić, Barbara Breznik, Boris Turk, Tamara Lah Turnšek, 2020, review article Abstract: Epithelial-to-mesenchymal transition (EMT) is an essential molecular and cellular process that is part of normal embryogenesis and wound healing, and also has a ubiquitous role in various types of carcinoma and glioblastoma. EMT is activated and regulated by specific microenvironmental endogenous triggers and a complex network of signalling pathways. These mostly include epigenetic events that affect protein translation-controlling factors and proteases, altogether orchestrated by the switching on and off of oncogenes and tumour-suppressor genes in cancer cells. The hallmark of cancer-linked EMT is that the process is incomplete, as it is opposed by the reverse process of mesenchymal-to-epithelial transition, which results in a hybrid epithelial/mesenchymal phenotype that shows notable cell plasticity. This is a characteristic of cancer stem cells (CSCs), and it is of the utmost importance in their niche microenvironment, where it governs CSC migratory and invasive properties, thereby creating metastatic CSCs. These cells have high resistance to therapeutic treatments, in particular in glioblastoma. Keywords: carcinomas, cancer stem cellsInvasion, proteases, tumour microenvironment Published in DiRROS: 06.08.2024; Views: 213; Downloads: 213
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5. Brain malignancies : glioblastoma and brain metastasesTamara Lah Turnšek, Metka Novak, Barbara Breznik, 2020, review article Abstract: Brain, the major organ of the central nervous system controls and processes most of body activities. Therefore, the most aggressive brain tumor – glioblastoma and metastases from other organs to the brain are lethal leaving the patients with very short time of survival. The brain tissue landscape is very different from any other tissues and the specific microenvironment, comprising stem cells niches and blood-brain barrier, significantly influences the low rate of glioblastoma metastasis out of the brain, but better accommodates brain-invading cancer. In contrast to low frequency (0.5%) of all glioblastoma metastases, 10%–45% of other primary cancers do metastasize to the brain. This review addresses general cellular and molecular pathways that are to some extent similar in both types of metastases, involving circulating tumor cells (CTCs) with cancer stem cells (CSCs) characteristics, and metastatic niches. The invasion is a dynamic process involving reversible epithelial-to-mesenchymal (EMT) cell process, creating a transient gradient state that is inter-connected with epigenetic plasticity of the metastasizing (m)CSCs. These cells can switch between stationary, low proliferating/dormant state to a migratory, mesenchymal-like state. Settling in their respective niches as dormant CSCs in the secondary organ is a common feature in all types of metastases. In glioblastoma metastasis, the malignant mGSC cells express markers of mesenchymal GSC subtype (MES-GSC), such as CD44 and YK-40 and their major obstacle seems to be propagating in the in various organs’ microenvironments, different from the niches that home GSCs in the primary glioblastoma. Focusing on one stromal component in the glioblastoma niches, the mesenchymal stem cells (MSCs), we report herein on their differential effects on glioblastoma cells, highly depending on their genetic subtype. On the other hand, in brain metastases, the major hindrance to metastatic progression of mCSCs seem to be crossing the blood-brain-barrier. Novel therapeutic approaches for brain metastases from various cancer types are advancing slowly, and the general trends involve targeting metastatic sub-clones and selective determinants of their niches. The update on the four most common brain metastases from lung, breast, melanoma and colorectal carcinoma is presented. Keywords: glioblastoma, cancer stem cells, invasion, metastasis, tumor microenvironment Published in DiRROS: 06.08.2024; Views: 223; Downloads: 162
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6. Bioactive peptides from venoms against glioma progressionBernarda Majc, Metka Novak, Tamara Lah Turnšek, Igor Križaj, 2022, review article Abstract: Venoms are complex mixtures of different molecules and ions. Among them, bioactive peptides have been found to affect cancer hallmarks, such as cell proliferation, cell invasion, cell migration, and can also modulate the immune response of normal and cancer-bearing organisms. In this article, we review the mechanisms of action on these cancer cell features, focusing on bioactive peptides being developed as potential therapeutics for one of the most aggressive and deadly brain tumors, glioblastoma (GB). Novel therapeutic approaches applying bioactive peptides may contribute to multiple targeting of GB and particularly of GB stem cells. Bioactive peptides selectively target cancer cells without harming normal cells. Various molecular targets related to the effects of bioactive peptides on GB have been proposed, including ion channels, integrins, membrane phospholipids and even immunomodulatory treatment of GB. In addition to therapy, some bioactive peptides, such as disintegrins, can also be used for diagnostics or are used as labels for cytotoxic drugs to specifically target cancer cells. Given the limitations described in the last section, successful application in cancer therapy is rather low, as only 3.4% of such peptides have been included in clinical trials and have passed successfully phases I to III. Combined approaches of added bioactive peptides to standard cancer therapies need to be explored using advanced GB in vitro models such as organoids. On the other hand, new methods are also being developed to improve translation from research to practice and provide new hope for GB patients and their families. Published in DiRROS: 05.08.2024; Views: 157; Downloads: 122
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7. CD133/prominin1 is prognostic for GBM patient's survival, but inversely correlated with cysteine cathepsine' expression in gliobastoma derived spheroidsSeyed Yousef Ardebili, Irena Zajc, Boris Gole, Benito Campos, Christel Herold-Mende, Sara Drmota Prebil, Tamara Lah Turnšek, 2011, original scientific article Abstract: Introduction. CD133 is a marker for a population of glioblastoma (GBM) and normal neural stem cells (NNSC). We aimed to reveal whether the migratory potential and differentiation of these stem cells is associated with CD133 expression and with cathepsin proteases (Cats).
Materials and methods. The invasiveness of normal NNSC, GBM/CD133+ cell lines and GBM spheroids was evaluated in 3D collagen, as well as of U87-MG and normal astrocytes (NHA) grown in monolayers in 2D Matrigel. Expression of Cats B, L and S was measured at mRNA and activity levels and their relation to invasiveness, to CD133 mRNA in 26 gliomas, and to the survival of these patients.
Results. The average yield of CD133+ cells from GBM samples was 9.6%. Survival of patients with higher CD133 mRNA expression was significantly shorter (p< 0.005). Invasion, associated with proteolytic degradation of matrix, was higher in normal stem cells and GBM spheroids and cells than in isolated GBM CD133+ cells. In glioma samples, there was no correlation between CD133 mRNA expression and Cat mRNAs, but there was an inverse correlation with Cat activities.
Conclusions. The study confirms CD133 as a prognostic marker for the survival of GBM patients. We demonstrated that NNSC have higher invasion potential and invade the collagen matrix in a mode different from that of GBM, initiating stem cell spheres. This result could have implications for the design of new therapeutics, including protease inhibitors that specifically target invasive tumour stem cells. Increased activity of cathepsins in CD133- cells suggests their role in the invasive behaviour of GBM. Published in DiRROS: 05.08.2024; Views: 155; Downloads: 94
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8. Vloga matičnih celic pri napredovanju in zdravljenju gliomaUrška Verbovšek, Tamara Lah Turnšek, Helena Motaln, Mateja Robič, 2013, original scientific article Abstract: Izvor tumorjev in stohastično naravo procesa karcinogeneze najbolje opisuje hierarhični model, ki predvideva obstoj tumorskih matičnih celic (TMC). Slednje predstavljajo populacijo celic z neomejenim samoobnovitvenim potencialom, ki so se sposobne diferencirati v vrste celic vseh treh zarodnih linij in so manj občutljive na večino protirakavih učinkovin. Zato predstavljajo glavni vir za razvoj in rast tumorja, zaradi svoje odpornosti na kemoterapijo pa so vzrok za ponovitev bolezni. Za uspešno zdravljenje možganskega tumorja glioma in njegove najbolj maligne oblike, glioblastoma multiformae (GBM), bi zato bilo potrebno odstraniti prav vse TMC. Žal slednjega zaradi prehitre infiltrativne vrasti subpopulacije GBM celic z visoko izraženimi geni za gibljivost (migratom) v okolno zdravo možgansko tkivo, ni možno doseči s trenutno uporabljanimi načini zdravljenja (npr. kirurškim izrezom)
Poleg TMC, ki so ključne za razvoj in razrast tumorja, tkivo tumorja vsebuje še hematopoetske matične celice, endotelne predniške celice in mezenhimske matične celice (MMC). Delovanje teh drugih vrst matičnih celic, kjer je bila celicam MMC že dokazana protitumorska aktivnost v GBM, pa je odvisno od tumorskega mikrookolja. Žal mehanizmi in delovanje MMC med modulacijo rasti tumorja preko parakrinih in neposrednih interakcij z GBM (matičnimi) celicami še niso znani. Kljub temu pa matične celice, s poudarkom na MMC, predstavljajo nove nosilce npr. za ciljni vnos terapevtske učinkovine v tumor, ki bi lahko izboljšali učinkovitost trenutnih protitumorskih terapij. Razvoj celičnih zdravil veliko obeta, saj so MMC, poleg svojih imunomodulacijskih lastnosti, sposobne tudi usmerjenega gibanja v GBM in tam učinkovati, o čemer razpravlja ta prispevek. Keywords: tumorske matične celice, mezenhimske matične celice, mikrookolje tumorja, celična terapija Published in DiRROS: 02.08.2024; Views: 184; Downloads: 109
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9. Identification of plasma biomarker candidates in glioblastoma using an antibody-array-based proteomic approachKlemen Zupančič, Marjan Koršič, Urška Verbovšek, Primož Rožman, Tamara Lah Turnšek, Andrej Blejec, Kristina Gruden, Helena Motaln, Miomir Knežević, Matija Veber, Ana Herman, 2014, original scientific article Abstract: Background. Glioblastoma multiforme (GBM) is a brain tumour with a very high patient mortality rate, with a median survival of 47 weeks. This might be improved by the identification of novel diagnostic, prognostic and predictive
therapy-response biomarkers, preferentially through the monitoring of the patient blood. The aim of this study was to define the impact of GBM in terms of alterations of the plasma protein levels in these patients.
Materials and methods. We used a commercially available antibody array that includes 656 antibodies to analyse
blood plasma samples from 17 healthy volunteers in comparison with 17 blood plasma samples from patients with
GBM.
Results. We identified 11 plasma proteins that are statistically most strongly associated with the presence of GBM.
These proteins belong to three functional signalling pathways: T-cell signalling and immune responses; cell adhesion and migration; and cell-cycle control and apoptosis. Thus, we can consider this identified set of proteins as potential diagnostic biomarker candidates for GBM. In addition, a set of 16 plasma proteins were significantly associated with the overall survival of these patients with GBM. Guanine nucleotide binding protein alpha (GNAO1) was associated with both GBM presence and survival of patients with GBM.
Conclusions. Antibody array analysis represents a useful tool for the screening of plasma samples for potential cancer biomarker candidates in small-scale exploratory experiments; however, clinical validation of these candidates requires their further evaluation in a larger study on an independent cohort of patients. Keywords: glioblastoma, proteomics, biomarker Published in DiRROS: 02.08.2024; Views: 177; Downloads: 148
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10. TRIM28 and [beta]-actin identified via nanobody-based reverse proteomics approach as possible human glioblastoma biomarkersIvana Jovchevska, Neja Šamec, Nina Kočevar Britovšek, Daniela Cesselli, Neža Podergajs, Clara Limbaeck Stanic, Michael P. Myers, Serge Muyldermans, Gholamreza Hassanzadeh Ghassabeh, Helena Motaln, Maria Elisabetta Ruaro, Evgenia Bourkoula, Tamara Lah Turnšek, Radovan Komel, 2014, original scientific article Abstract: Malignant gliomas are among the rarest brain tumours, and they have the worst prognosis. Grade IV astrocytoma, known as glioblastoma multiforme (GBM), is a highly lethal disease where the standard therapies of surgery, followed by radiation and chemotherapy, cannot significantly prolong the life expectancy of the patients. Tumour recurrence shows more aggressive form compared to the primary tumour, and results in patient survival from 12 to 15 months only. Although still controversial, the cancer stem cell hypothesis postulates that cancer stem cells are responsible for early relapse of the disease after surgical intervention due to their high resistance to therapy. Alternative strategies for GBM therapy are thus urgently needed. Nanobodies are single-domain antigen-binding fragments of heavy-chain antibodies, and together with classical antibodies, they are part of the camelid immune system. Nanobodies are small and stable, and they share a high degree of sequence identity to the human heavy chain variable domain, and these characteristics offer them advantages over classical antibodies or antibody fragments. We first immunised an alpaca with a human GBM stem-like cell line prepared from primary GBM cultures. Next, a nanobody library was constructed in a phage-display vector. Using nanobody phage-display technology, we selected specific GBM stem-like cell binders through a number of affinity selections, using whole cell protein extracts and membrane protein-enriched extracts from eight different GBM patients, and membrane protein-enriched extracts from two established GBM stem-like cell lines (NCH644 and NCH421K cells). After the enrichment, periplasmic extract ELISA was used to screen for specific clones. These nanobody clones were recloned into the pHEN6 vector, expressed in Escherichia coli WK6, and purified using immobilised metal affinity chromatography and size-exclusion chromatography. Specific nanobody:antigen pairs were obtained and mass spectrometry analysis revealed two proteins, TRIM28 and β-actin, that were up-regulated in the GBM stem-like cells compared to the controls. Keywords: malignant gliomas, cancer stem cells, nanobodies Published in DiRROS: 02.08.2024; Views: 171; Downloads: 154
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