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"Zaravinos, Apostolos"
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The Regulatory Role of MicroRNAs in EMT and Cancer
2015
The epithelial to mesenchymal transition (EMT) is a powerful process in tumor invasion, metastasis, and tumorigenesis and describes the molecular reprogramming and phenotypic changes that are characterized by a transition from polarized immotile epithelial cells to motile mesenchymal cells. It is now well known that miRNAs are important regulators of malignant transformation and metastasis. The aberrant expression of the miR-200 family in cancer and its involvement in the initiation and progression of malignant transformation has been well demonstrated. The metastasis suppressive role of the miR-200 members is strongly associated with a pathologic EMT. This review describes the most recent advances regarding the influence of miRNAs in EMT and the control they exert in major signaling pathways in various cancers. The ability of the autocrine TGF-β/ZEB/miR-200 signaling regulatory network to control cell plasticity between the epithelial and mesenchymal state is further discussed. Various miRNAs are reported to directly target EMT transcription factors and components of the cell architecture, as well as miRNAs that are able to reverse the EMT process by targeting the Notch and Wnt signaling pathways. The link between cancer stem cells and EMT is also reported and the most recent developments regarding clinical trials that are currently using anti-miRNA constructs are further discussed.
Journal Article
RNA editing in the forefront of epitranscriptomics and human health
2019
Post-transcriptional modifications have been recently expanded with the addition of RNA editing, which is predominantly mediated by adenosine and cytidine deaminases acting on DNA and RNA. Here, we review the full spectrum of physiological processes in which these modifiers are implicated, among different organisms. Adenosine to inosine (A-to-I) editors, members of the ADAR and ADAT protein families are important regulators of alternative splicing and transcriptional control. On the other hand, cytidine to uridine (C-to-U) editors, members of the AID/APOBEC family, are heavily implicated in innate and adaptive immunity with important roles in antibody diversification and antiviral response. Physiologically, these enzymes are present in the nucleus and/or the cytoplasm, where they modify various RNA molecules, including miRNAs, tRNAs apart from mRNAs, whereas DNA editing is also possible by some of them. The expansion of next generation sequencing technologies provided a wealth of data regarding such modifications. RNA editing has been implicated in various disorders including cancer, and neurological diseases of the brain or the central nervous system. It is also related to cancer heterogeneity and the onset of carcinogenesis. Response to treatment can also be affected by the RNA editing status where drug efficacy is significantly compromised. Studying RNA editing events can pave the way to the identification of new disease biomarkers, and provide a more personalised therapy to various diseases.
Journal Article
Current Perspectives in Cancer Immunotherapy
by
Christofi, Theodoulakis
,
Zaravinos, Apostolos
,
Baritaki, Stavroula
in
Antigens
,
Cancer
,
Cancer immunotherapy
2019
Different immunotherapeutic approaches have proved to be of significant clinical value to many patients with different types of advanced cancer. However, we need more precise immunotherapies and predictive biomarkers to increase the successful response rates. The advent of next generation sequencing technologies and their applications in immuno-oncology has helped us tremendously towards this aim. We are now moving towards the realization of personalized medicine, thus, significantly increasing our expectations for a more successful management of the disease. Here, we discuss the current immunotherapeutic approaches against cancer, including immune checkpoint blockade with an emphasis on anti-PD-L1 and anti-CTLA-4 monoclonal antibodies. We also analyze a growing list of other co-inhibitory and co-stimulatory markers and emphasize the mechanism of action of the principal pathway for each of these, as well as on drugs that either have been FDA-approved or are under clinical investigation. We further discuss recent advances in other immunotherapies, including cytokine therapy, adoptive cell transfer therapy and therapeutic vaccines. We finally discuss the modulation of gut microbiota composition and response to immunotherapy, as well as how tumor-intrinsic factors and immunological processes influence the mutational and epigenetic landscape of progressing tumors and response to immunotherapy but also how immunotherapeutic intervention influences the landscape of cancer neoepitopes and tumor immunoediting.
Journal Article
Genomic landscape of the immunogenicity regulation in skin melanomas with diverse tumor mutation burden
by
Zaravinos, Apostolos
,
Georgoulias, George
in
Biomarkers, Tumor - genetics
,
Cancer therapies
,
CD8 antigen
2022
Skin melanoma cells are tightly interconnected with their tumor microenvironment (TME), which influences their initiation, progression, and sensitivity/resistance to therapeutic interventions. An immune-active TME favors patient response to immune checkpoint inhibition (ICI), but not all patients respond to therapy. Here, we assessed differential gene expression in primary and metastatic tumors from the TCGA-SKCM dataset, compared to normal skin samples from the GTEx project and validated key findings across 4 independent GEO datasets, as well as using immunohistochemistry in independent patient cohorts. We focused our attention on examining the expression of various immune receptors, immune-cell fractions, immune-related signatures and mutational signatures across cutaneous melanomas with diverse tumor mutation burdens (TMB). Globally, the expression of most immunoreceptors correlated with patient survival, but did not differ between TMB high and TMB low tumors. Melanomas were enriched in “naive T-cell”, “effector memory T-cell”, “exhausted T-cell”, “resting Treg T-cell” and “Th1-like” signatures, irrespective of their BRAF , NF1 or RAS mutational status. Somatic mutations in IDO1 and HLA-DRA were frequent and could be involved in hindering patient response to ICI therapies. We finally analyzed transcriptome profiles of ICI-treated patients and associated their response with high levels of IFNγ, Merck18, CD274, CD8, and low levels of myeloid-derived suppressor cells (MDSCs), cancer-associated fibroblasts (CAFs) and M2 macrophages, irrespective of their TMB status. Overall, our findings highlight the importance of pre-existing T-cell immunity in ICI therapeutic outcomes in skin melanoma and suggest that TMB low patients could also benefit from such therapies.
Journal Article
Angiogenesis-Related Genes Predict Outcomes and Immune Traits in Skin Melanoma
by
Zaravinos, Apostolos
,
Georgakopoulos-Soares, Ilias
,
Vladova, Latchezara
in
Analysis
,
Angiogenesis
,
Biomarkers
2025
The interplay between angiogenesis and the immune system is intricate, with the potential to either enhance or repress the immune response. Angiogenesis-related genes (ARGs) are significant for the development, growth, and immune response of tumors. Understanding their prognostic significance and molecular characteristics in skin melanoma can guide and refine therapeutic strategies. Here, we analyzed the TCGA-SKCM dataset and explored the ARG expression between skin melanoma and normal skin, as well as between primary and metastatic tumors. Kaplan–Meier analyses were conducted to assess the overall, disease-specific, and progression-free survival. Additionally, comprehensive immune profiling was carried out utilizing advanced bioinformatics tools to evaluate immune checkpoint gene expression and immune cell infiltration. Our findings highlighted strong prognostic associations for S100A4, ITGAV, and COL3A1. Molecular characterization showed a significant upregulation of PTK2, CXCL6, COL3A1, COL5A2, PF4, TNFRSF21, LRPAP1, VTN, TIMP1, SPP1, and OLR1 in SKCM compared to that in normal skin. Immune analyses, including Immune Checkpoint Gene Analysis, Immune Infiltration Analysis, Immune Cell Analysis, and Immune Cell Profiling, demonstrated both positive and negative correlations between ARGs expression and immune cell infiltration, emphasizing the multifaceted role of these genes in immune modulation. The study underscores the prognostic relevance of ARGs in skin melanoma and their contribution to tumor immunity. Overall, our findings expand our understanding of melanoma immunogenetics, suggesting the use of angiogenesis-related genes not merely as vascular regulators, but also as immune modulators.
Journal Article
RKIP: A Key Regulator in Tumor Metastasis Initiation and Resistance to Apoptosis: Therapeutic Targeting and Impact
2018
RAF-kinase inhibitor protein (RKIP) is a well-established tumor suppressor that is frequently downregulated in a plethora of solid and hematological malignancies. RKIP exerts antimetastatic and pro-apoptotic properties in cancer cells, via modulation of signaling pathways and gene products involved in tumor survival and spread. Here we review the contribution of RKIP in the regulation of early metastatic steps such as epithelial–mesenchymal transition (EMT), migration, and invasion, as well as in tumor sensitivity to conventional therapeutics and immuno-mediated cytotoxicity. We further provide updated justification for targeting RKIP as a strategy to overcome tumor chemo/immuno-resistance and suppress metastasis, through the use of agents able to modulate RKIP expression in cancer cells.
Journal Article
NAA40 contributes to colorectal cancer growth by controlling PRMT5 expression
by
Stylianopoulos, Triantafyllos
,
Zaravinos, Apostolos
,
Demetriadou, Christina
in
13/1
,
13/106
,
13/109
2019
N-alpha-acetyltransferase 40 (NAA40) catalyzes the transfer of an acetyl moiety to the alpha-amino group of serine 1 (S1) on histones H4 and H2A. Our previous studies linked NAA40 and its corresponding N-terminal acetylation of histone H4 (N-acH4) to colorectal cancer (CRC). However, the role of NAA40 in CRC development was not investigated. Here, we show that NAA40 protein and mRNA levels are commonly increased in CRC primary tissues compared to non-malignant specimens. Importantly, depletion of NAA40 inhibits cell proliferation and survival of CRC cell lines and increases their sensitivity to 5-Fluorouracil (5-FU) treatment. Moreover, the absence of NAA40 significantly delays the growth of human CRC xenograft tumors. Intriguingly, we found that NAA40 knockdown and loss of N-acH4 reduce the levels of symmetric dimethylation of histone H4 (H4R3me2s) through transcriptional downregulation of protein arginine methyltransferase 5 (
PRMT5
). NAA40 depletion and subsequent repression of PRMT5 results in altered expression of key oncogenes and tumor suppressor genes leading to inhibition of CRC cell growth. Consistent with this,
NAA40
mRNA levels correlate with those of
PRMT5
in CRC patient tissues. Taken together, our results establish the oncogenic function of the epigenetic enzyme NAA40 in colon cancer and support its potential as a therapeutic target.
Journal Article
ILK silencing inhibits migration and invasion of more invasive glioblastoma cells by downregulating ROCK1 and Fascin-1
2020
Glioblastoma multiforme (GBM) is the most aggressive type of brain tumor and it is associated with poor survival. Integrin-linked kinase (ILK) is a serine/threonine protein pseudo-kinase that binds to the cytoplasmic domains of β1 and β3 integrins and has been previously shown to promote invasion and metastasis in many cancer types, including GBM. However, little is known regarding the exact molecular mechanism implicating ILK in GBM aggressiveness. In this study, we used two brain cell lines, the non-invasive neuroglioma H4 cells, and the highly invasive glioblastoma A172 cells, which express ILK in much higher levels than H4. We studied the effect of ILK silencing on the metastatic behavior of glioblastoma cells in vitro and elucidate the underlying molecular mechanism. We showed that siRNA-mediated silencing of ILK inhibits cell migration and invasion of the highly invasive A172 cells while it does not affect the migratory and invasive capacity of H4 cells. These data were also supported by respective changes in the expression of Rho-associated kinase 1 (ROCK1), fascin actin-bundling protein 1 (FSCN1), and matrix metalloproteinase 13 (MMP13), which are known to regulate cell migration and invasion. Our findings were further corroborated by analyzing the Cancer Genome Atlas Glioblastoma Multiforme (TCGA-GBM) dataset. We conclude that ILK promotes glioblastoma cell invasion through activation of ROCK1 and FSCN1 in vitro, providing a more exact molecular mechanism for its action.
Journal Article
Pan-Cancer Computational Analysis of RKIP (PEBP1) and LKB1 (STK11) Co-Expression Highlights Distinct Immunometabolic Dynamics and Therapeutic Responses Within the Tumor Microenvironment
by
Zaravinos, Apostolos
,
Panagopoulou, Maria
,
Dovrolis, Nikolas
in
AMP-Activated Protein Kinase Kinases
,
Angiogenesis
,
Biomarkers, Tumor - genetics
2025
RKIP and LKB1, encoded by PEBP1 and STK11, respectively, have emerged as key regulators of cancer pathophysiology. However, their role in shaping tumor progression through modulation of the tumor microenvironment (TME) is not yet fully understood. To address this, we performed a comprehensive pan-cancer analysis using TCGA transcriptomic data across 33 cancer types, grouped by their tissue of origin. We investigated PEBP1/STK11 co-expression and its association with transcriptomic reprogramming in major TME components, including immune, mechanical, metabolic, and hypoxic subtypes. Our results revealed both positive and inverse correlations between PEBP1/STK11 co-expression and TME-related molecular signatures, which did not align with classical cancer categorizations. In a subset of tumors, PEBP1/STK11 co-expression was significantly associated with improved overall survival and reduced mortality (HR < 1). Notably, we predominantly observed inverse correlations with pro-inflammatory and immunosuppressive chemokines, immune checkpoints, extracellular matrix components, and key regulators of epithelial-to-mesenchymal transition. In contrast, we found positive associations with anti-inflammatory chemokines and their receptors. Importantly, PEBP1/STK11 co-expression was consistently linked to reduced expression of drug resistance genes and greater chemosensitivity across multiple tumor types. Our findings underscore the co-expression of PEBP1 and STK11 as a promising target for future studies aimed at elucidating its potential as a biomarker for prognosis and therapeutic response in precision oncology.
Journal Article
Gravitational Influence on Human Living Systems and the Evolution of Species on Earth
by
Zaravinos, Apostolos
,
Lambrou, George I.
,
Adamopoulos, Konstantinos
in
Astrobiology
,
Astronauts
,
Chemical reactions
2021
Gravity constituted the only constant environmental parameter, during the evolutionary period of living matter on Earth. However, whether gravity has affected the evolution of species, and its impact is still ongoing. The topic has not been investigated in depth, as this would require frequent and long-term experimentations in space or an environment of altered gravity. In addition, each organism should be studied throughout numerous generations to determine the profound biological changes in evolution. Here, we review the significant abnormalities presented in the cardiovascular, immune, vestibular and musculoskeletal systems, due to altered gravity conditions. We also review the impact that gravity played in the anatomy of snakes and amphibians, during their evolution. Overall, it appears that gravity does not only curve the space–time continuum but the biological continuum, as well.
Journal Article