GEORGIOS MANDRAKIS

Dr. GEORGIOS MANDRAKIS

Medical school, National and Kapodistrian University of Athens, Athens, Attikí, Greece
orcid
Bachelor degree in Biology / Master degree in Biomedicine

Research Focus & Metrics

Academic Career Length

5Years (2022-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
20 December 2022 in Biomedicines
Verified
Journal Article
Open access
PDF file
Iason PsilopatisIason Psilopatis
Iason Psilopatis
ASAlexandros Sykaras
Alexandros Sykaras
GEORGIOS MANDRAKISGEORGIOS MANDRAKIS
GEORGIOS MANDRAKIS
KVKleio Vrettou
Kleio Vrettou
Stamatios TheocharisStamatios Theocharis
Stamatios Theocharis
Ovarian cancer (OC) is the leading cause of death from gynecological malignancies. Despite great advances in treatment strategies, therapeutic resistance and the gap between preclinical data and actual clinical efficacy justify the necessity of developing novel models for investigating OC. Organoids represent revolutionary three-dimensional cell culture models, deriving from stem cells and reflecting the primary tissue’s biology and pathology. The aim of the current review is to study the current status of mouse- and patient-derived organoids, as well as their potential to model carcinogenesis and perform drug screenings for OC. Herein, we describe the role of organoids in the assessment of high-grade serous OC (HGSOC) cells-of-origin, illustrate their use as promising preclinical OC models and highlight the advantages of organoid technology in terms of disease modelling and drug sensitivity testing.

15 November 2023 in Cells
Verified
Journal Article
Open access
PDF file
SKStefania Kokkali
Stefania Kokkali
EGEleni Georgaki
Eleni Georgaki
GEORGIOS MANDRAKISGEORGIOS MANDRAKIS
GEORGIOS MANDRAKIS
CVClaudia Valverde
Claudia Valverde
Stamatios TheocharisStamatios Theocharis
Stamatios Theocharis
Genomic profiling has improved our understanding of the pathogenesis of different cancers and led to the development of several targeted therapies, especially in epithelial tumors. In this review, we focus on the clinical utility of next-generation sequencing (NGS) to inform therapeutics in soft tissue sarcoma (STS). The role of NGS is still controversial in patients with sarcoma, given the low mutational burden and the lack of recurrent targetable alterations in most of the sarcoma histotypes. The clinical impact of genomic profiling in STS has not been investigated prospectively. A limited number of retrospective, mainly single-institution, studies have addressed this issue using various NGS technologies and platforms and a variety of criteria to define a genomic alteration as actionable. Despite the detailed reports on the different gene mutations, fusions, or amplifications that were detected, data on the use and efficacy of targeted treatment are very scarce at present. With the exception of gastrointestinal stromal tumors (GISTs), these targeted therapies are administered either through off-label prescription of an approved drug or enrollment in a matched clinical trial. Based mainly on anecdotal reports, the outcome of targeted therapies in the different STS histotypes is discussed. Prospective studies are warranted to assess whether genomic profiling improves the management of STS patients.

31 March 2024 in Biomedicines
Verified
Journal Article
Open access
PDF file
ISIoanna STERGIOU
Ioanna STERGIOU
KPKostas Palamaris
Kostas Palamaris
Georgia LevidouGeorgia Levidou
Georgia Levidou
MTMARIA TZIMOU
MARIA TZIMOU
Stavros P. PapadakosStavros P. Papadakos
Stavros P. Papadakos
Stamatios TheocharisStamatios Theocharis
Stamatios Theocharis
Background: Programmed death-ligand 1 (PD-L1) expression in neoplastic and immune cells of the tumor microenvironment determines the efficacy of antitumor immunity, while it can be regulated at the epigenetic level by various factors, including HDACs. In this study, we aim to evaluate the expression patterns of PD-L1 in thymic epithelial tumors (TETs), while we attempt the first correlation analysis between PD-L1 and histone deacetylases (HDACs) expression. Methods: Immunohistochemistry was used to evaluate the expression of PD-L1 in tumor and immune cells of 91 TETs with SP263 and SP142 antibody clones, as well as the expressions of HDCA1, -2, -3, -4, -5, and -6. Results: The PD-L1 tumor proportion score (TPS) was higher, while the immune cell score (IC-score) was lower in the more aggressive TET subtypes and in more advanced Masaoka–Koga stages. A positive correlation between PD-L1 and HDAC-3, -4, and -5 cytoplasmic expression was identified. Conclusions: Higher PD-L1 expression in neoplastic cells and lower PD-L1 expression in immune cells of TETs characterizes more aggressive and advanced neoplasms. Correlations between PD-L1 and HDAC expression unravel the impact of epigenetic regulation on the expression of immune checkpoint molecules in TETs, with possible future applications in combined therapeutic targeting.

6 August 2024 in Biomedicines
Verified
Journal Article
Open access
PDF file
APAlexandros Pergaris
Alexandros Pergaris
Georgia LevidouGeorgia Levidou
Georgia Levidou
GEORGIOS MANDRAKISGEORGIOS MANDRAKIS
GEORGIOS MANDRAKIS
Marianna ChristodoulouMarianna Christodoulou
Marianna Christodoulou
Michalis V KaramouzisMichalis V Karamouzis
Michalis V Karamouzis
Stamatios TheocharisStamatios Theocharis
Stamatios Theocharis
Uveal melanomas (UMs) represent rare malignant tumors associated with grim prognosis for the majority of patients. DAXX (Death Domain-Associated Protein), HJURP (Holliday Junction Recognition Protein) and CENPA (Centromere Protein A) proteins are implicated in epigenetic mechanisms, now in the spotlight of cancer research to better understand the molecular background of tumorigenesis. Herein, we investigated their expression in UM tissues using immunohistochemistry and explored possible correlations with a multitude of clinicopathological and survival parameters. The Cancer Genome Atlas Program (TCGA) was used for the investigation of their mRNA levels in UM cases. Nuclear DAXX expression correlated with an advanced T-stage (p = 0.004), while cytoplasmic expression marginally with decreased disease-free survival (DFS) (p = 0.084). HJURP nuclear positivity also correlated with advanced T-status (p = 0.054), chromosome 3 loss (p = 0.042) and increased tumor size (p = 0.03). More importantly, both nuclear and cytoplasmic HJURP immunopositivity correlated with decreased overall survival (OS) (p = 0.011 and 0.072, respectively) and worse DFS (p = 0.071 and 0.019, respectively). Lastly, nuclear CENPA overexpression was correlated with presence of irido-corneal angle involvement (p = 0.015) and loss of chromosome 3 (p = 0.041). Nuclear and cytoplasmic CENPA immunopositivity associated with decreased OS (p = 0.028) and DFS (p = 0.018), respectively. HJURP and CENPA mRNA overexpression exhibited strong association with tumor epithelioid histology and was linked to worse prognosis. Our results show the compounding role of DAXX, HJURP and CENPA in UM carcinogenesis, designating them as potential biomarkers for assessing prognosis and possible targets for novel therapeutic interventions.

Verified
Journal Article
Open access
PDF file
GEORGIOS MANDRAKISGEORGIOS MANDRAKIS
GEORGIOS MANDRAKIS
CFChristina-Maria Flessa
Christina-Maria Flessa
PKPanoraia Keratsa
Panoraia Keratsa
Apostolos ZaravinosApostolos Zaravinos
Apostolos Zaravinos
Stamatios TheocharisStamatios Theocharis
Stamatios Theocharis
ASAlexandros Sykaras
Alexandros Sykaras
Uveal melanoma (UVM) is a rare cancer that represents the second most common melanoma (after the cutaneous) and the most common primary intraocular malignancy in adults. Despite recent advances in the understanding of UVM pathogenesis, its prognosis remains unchanged, with half of patients dying because of liver metastasis. Erythropoietin-producing human hepatocellular receptors (EPHs) constitute the largest known family of tyrosine receptors, and, along with their ligands, EFNs, regulate key physiological processes and are implicated in cancer pathogenesis. In this study, we used open-access web bioinformatics platforms to explore and analyze big datasets provided by The Cancer Genome Atlas (TCGA) UVM cohort of patients. We profiled the genomic alterations present in a subset of UVM patients, highlighting a likely pathogenic deep deletion of EPHA7. Survival analysis showed that overexpression levels of EPHA4, EPHA5, EPHA8, EPHB2, and EFNB2 are significantly associated with poor overall survival. Additionally, high expression levels of EPHA4, EPHA5, EPHA7, EPHA8, EPHB2, EFNA2, and EFNB2 correlate with reduced progression-free interval and disease-free survival. Finally, we identified the EPHs (EPHA2, EPHA4, EPHA8, and EPHB4) and EFNs (EFNA1, EFNA3, EFNA4, and EFNB2) that are significantly overexpressed in the aggressive epithelioid histological subtype and revealed that the majority of EPHs/EFNs are overexpressed in metastatic disease. In conclusion, our results highlight that a subset of EPHs and EFNs may be associated with worse clinical outcomes (EPHA4, EPHA5, EPHA7, EPHA8, EPHB2, EFNA2, and EFNB2), and an aggressive histological subtype (EPHA2, EPHA4, EPHA8, EPHB4, EFNA1, EFNA3, EFNA4, and EFNB2). The potential correlation of these genes with clinicopathological parameters of UVM need to be evaluated and validated with bioinformatic and experimental approaches in well-characterized cohorts of UVM patients.

23 January 2026 in Cancers
Verified
Journal Article
Open access
PDF file
CYChristina Yfanti
Christina Yfanti
Georgia LevidouGeorgia Levidou
Georgia Levidou
VLVicky Lampropoulou
Vicky Lampropoulou
SKStefania Kokkali
Stefania Kokkali
GEORGIOS MANDRAKISGEORGIOS MANDRAKIS
GEORGIOS MANDRAKIS
Stamatios TheocharisStamatios Theocharis
Stamatios Theocharis
Background: Autophagy, a self-destructive cellular mechanism with a paradoxical nature, plays a part in both tumor suppression and induction by providing cancer cells with metabolic substrates, resulting in cell proliferation and survival. In this study, we aim to investigate the clinical significance of four autophagy pathway components (BECLIN, p62/, LC3b, ATG3) in pathogenetic mechanisms of thymic epithelial tumors (TETs) with possible prognostic importance. Methods: Immunohistochemistry was used to evaluate the cytoplasmic expression of BECLIN, p62, LC3b, and ATG3 in tumor cells of 99 TETs, and possible correlations with clinicopathological parameters were examined. Results: Higher BECLIN and p62 expression was associated with male gender (p = 0.027 and p = 0.014, respectively). B3 thymomas and thymic carcinomas (TCs) displayed higher p62 expression (p = 0.019), while LC3b expression was marginally higher in non-B3/TC TETs (p = 0.098). A positive correlation between higher BECLIN expression and advanced Masaoka–Koga stage was also observed (p = 0.009). ATG3 was not associated with any of the investigated clinicopathological parameters (p > 0.05). There was also no significant correlation between any of the four examined molecules and overall survival or relapse. Conclusions: Our findings indicate autophagy activation in B3/TC and advanced Masaoka–Koga stage cases. Further studies are needed to explore the role of these autophagy related proteins as potential biomarkers and therapeutic targets in TETs.