Leonidas Antonakis

Leonidas Antonakis

orcid

Research Focus & Metrics

Academic Career Length

16Years (2011-Present)

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

Representative Publications

View All Publications
1 April 2020 in Fertility and Sterility
Verified
Journal Article
Closed access
AKApostolos Kaponis
Apostolos Kaponis
GCGrigoris Chatzopoulos
Grigoris Chatzopoulos
MPMinas Paschopoulos
Minas Paschopoulos
IGIoannis Georgiou
Ioannis Georgiou
VPVaggelis Paraskevaidis
Vaggelis Paraskevaidis
THTasuku Harada
Tasuku Harada

1 October 2023 in Epigenomes
Verified
Journal Article
Open access
PDF file
GAGeorgios Androutsopoulos
Georgios Androutsopoulos
ISIoanna Styliara
Ioanna Styliara
EZEvgenia Zarogianni
Evgenia Zarogianni
NLNadia Lazurko
Nadia Lazurko
George ValasoulisGeorge Valasoulis
George Valasoulis
LALeonidas Antonakis
Leonidas Antonakis
Endometrial cancer (EC) is the second most common malignancy of the female reproductive system worldwide. The updated EC classification emphasizes the significant role of various signaling pathways such as PIK3CA-PIK3R1-PTEN and RTK/RAS/β-catenin in EC pathogenesis. Some of these pathways are part of the EGF system signaling network, which becomes hyperactivated by various mechanisms and participates in cancer pathogenesis. In EC, the expression of ErbB receptors is significantly different, compared with the premenopausal and postmenopausal endometrium, mainly because of the increased transcriptional activity of ErbB encoding genes in EC cells. Moreover, there are some differences in ErbB-2 receptor profile among EC subgroups that could be explained by the alterations in pathophysiology and clinical behavior of various EC histologic subtypes. The fact that ErbB-2 receptor expression is more common in aggressive EC histologic subtypes (papillary serous and clear cell) could indicate a future role of ErbB-targeted therapies in well-defined EC subgroups with overexpression of ErbB receptors.

1 December 2021 in Current Molecular Pharmacology
Verified
Journal Article
Closed access
PDF file
EPEfthymia Papakonstantinou
Efthymia Papakonstantinou
GAGeorgios Androutsopoulos
Georgios Androutsopoulos
SLSouzana Logotheti
Souzana Logotheti
LALeonidas Antonakis
Leonidas Antonakis
IMIoannis Maroulis
Ioannis Maroulis
VTVasiliki Tzelepi
Vasiliki Tzelepi
: Ovarian cancer is an aggressive disease and only a few cases are diagnosed at early stages due to the absence of symptoms. Τhe majority of malignant ovarian tumors (>90%) are of epithelial origin and subdivided in five histological sybtypes with different molecular pathogenesis and clinical behavior. High-grade serous ovarian cancer is the most common subtype (70%), however, the different histotypes of ovarian cancer should be viewed as separate diseases both clinically and in biomarker studies. At present, surgical debulking and platinum/taxane - based chemotherapy is the standard of care for epithelial ovarian cancer. Most patients show initial response to this therapeutic approach, but the majority of them experience disease recurrence at which point cure is no longer possible, due to acquired resistance in those chemotherapeutic regimens. Nevertheless, the current treatment model is still a “one size fits all” approach. Epigenetic modifications represent heritable modifications in gene expression without alteration of the DNA sequence. DNA methylation is the best studied epigenetic mechanism and in epithelial ovarian cancer, the methylenome is widely altered. In addition, patterns of DNA methylation may represent potential diagnostic and prognostic markers as well as markers predictive of chemoresistance and potential therapeutic targets. This article systematically reviews the complicated era of DNA methylation in ovarian carcinoma and summarizes the current implications and future perspectives of its use as a screening, diagnostic, prognostic and predictive tool as well as in personalized cancer therapy.

19 March 2023 in Viruses
Verified
Journal Article
Open access
PDF file
KAKarolina Akinosoglou
Karolina Akinosoglou
Georgios SchinasGeorgios Schinas
Georgios Schinas
ARAngelos Emmanouil Rigopoulos
Angelos Emmanouil Rigopoulos
EPEleni Polyzou
Eleni Polyzou
ATArgyrios Tzouvelekis
Argyrios Tzouvelekis
CGCharalambos Gogos
Charalambos Gogos
The clinical management of COVID-19 in pregnant women, who are considered a vulnerable population, remains uncertain even as the pandemic subsides. SARS-CoV-2 affects pregnant individuals in multiple ways and has been associated with severe maternal morbidity and mortality, as well as neonatal complications. The unique anatomy and physiology of gestation make managing COVID-19 in this population a complex and challenging task, emphasizing the importance of spreading knowledge and expertise in this area. Therapeutic interventions require distinct clinical consideration, taking into account differences in pharmacokinetics, vertical transmission, drug toxicities, and postnatal care. Currently, there is limited data on antiviral and immunomodulating COVID-19 pharmacotherapy in pregnancy. Some medication has been shown to be safe and well tolerated among pregnant women with COVID-19; however, the lack of randomized clinical trials and studies in this patient population is evident. Available vaccines are considered safe and effective, with no evidence of harm to the fetus, embryo development, or short-term postnatal development. Pregnant women should be counseled about the risks of SARS-CoV-2 infection and informed of available ways to protect themselves and their families. Effective treatments for COVID-19 should not be withheld from pregnant individuals, and more research is needed to ensure the best outcomes.

11 October 2023 in Cancers
Verified
Journal Article
Open access
PDF file
EPEfthymia Papakonstantinou
Efthymia Papakonstantinou
IPIoanna Pappa
Ioanna Pappa
GAGeorgios Androutsopoulos
Georgios Androutsopoulos
LALeonidas Antonakis
Leonidas Antonakis
IMIoannis Maroulis
Ioannis Maroulis
VTVasiliki Tzelepi
Vasiliki Tzelepi
Background: Despite recent advances in epithelial ovarian carcinoma (EOC) treatment, its recurrence and mortality rates have not improved significantly. DNA hypermethylation has generally been associated with an ominous prognosis and chemotherapy resistance, but the role of DNA methyltransferases (DNMTs) in EOC remains to be investigated. Methods: In the current study, we systematically retrieved gene expression data from patients with EOC and studied the immunohistochemical expression of DNMTs in 108 primary and 26 relapsed tumors. Results: Our results showed that the DNMT1, DNMT3A, DNMT3B and DNMT3L RNA levels were higher and the DNMT2 level was lower in tumors compared to non-neoplastic tissue, and DNMT3A and DNMT2 expression decreased from Stage-II to Stage-IV carcinomas. The proteomic data also suggested that the DNMT1 and DNMT3A levels were increased in the tumors. Similarly, the DNMT1, DNMT3A and DNMT3L protein levels were overexpressed and DNMT2 expression was reduced in high-grade carcinomas compared to non-neoplastic tissue and low-grade tumors. Moreover, DNMT1 and DNMT3L were increased in relapsed tumors compared to their primaries. The DNMT3A, DNMT1 and DNMT3B mRNA levels were correlated with overall survival. Conclusions: Our study demonstrates that DNMT1 and DNMT3L are upregulated in primary high-grade EOC and further increase in relapses, whereas DNMT3A is upregulated only in the earlier stages of cancer progression. DNMT2 downregulation highlights the presumed tumor-suppressor activity of this gene in ovarian carcinoma.

Verified
Journal Article
Open access
PDF file
EPEvangelia Panagodimou
Evangelia Panagodimou
ITIanthi Terzopoulou
Ianthi Terzopoulou
OTOlga Triantafyllidou
Olga Triantafyllidou
GMGeorgios K Markantes
Georgios K Markantes
NGNeoklis A. A. Georgopoulos
Neoklis A. A. Georgopoulos
AKApostolos Kaponis
Apostolos Kaponis
Successful embryo implantation requires dynamic, bidirectional communication between a developmentally competent blastocyst and a receptive endometrium, integrating hormonal, molecular, and immunologic signals. Increasing evidence indicates that endometrial receptivity is critically dependent on a specialized immune microenvironment that supports trophoblast invasion while maintaining maternal tolerance. This review synthesizes current knowledge on the immunologic regulation of implantation, with emphasis on uterine natural killer (uNK) cells, regulatory T cells (Tregs), macrophages, dendritic cells, and cytokine networks. We further examine intracellular signaling pathways—including JAK/STAT, PI3K/AKT, NF-κB, and MAPK—that integrate immune and decidual responses. The bidirectional embryo–endometrium dialogue is explored through embryo-derived mediators such as human chorionic gonadotropin (hCG), cytokines, growth factors, and extracellular vesicles. The endometrium is increasingly recognized as a biosensor of embryo quality, selectively supporting viable embryos. Disruption of this complex communication network is implicated in recurrent implantation failure and early pregnancy loss. Despite substantial mechanistic advances, clinical translation remains limited. Emerging strategies, including immune profiling, microbiome modulation, and extracellular vesicle-based diagnostics, hold promise for precision reproductive medicine.