Gergana Stancheva

Dr. Gergana Stancheva

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Research Focus & Metrics

Academic Career Length

13Years (2014-Present)

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

Representative Publications

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1 January 2014 in BioMed Research International
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GSGergana Stancheva
Gergana Stancheva
TGTeodora Goranova
Teodora Goranova
MLMaria Laleva
Maria Laleva
MKMargarita Kamenova
Margarita Kamenova
AMAtanaska Mitkova
Atanaska Mitkova
NGNikolay Gabrovsky
Nikolay Gabrovsky
Mutations in genes encoding isocitrate dehydrogenase isoforms 1 (IDH1) and 2 (IDH2) have been associated with good prognosis for patients with brain neoplasias and have been commonly found together with mutatedTP53gene. To determine the prevalence ofIDH1,IDH2, andTP53mutations and their impact on overall survival 106 glioblastoma patients were analysed.IDH1mutations were detected in 13 andIDH2mutation in one patient. Two homozygous samples with R132H mutation inIDH1gene and a novel aberration K129R inIDH2gene were found. Sixty-four percent ofIDH1/IDH2mutated tumours harboured also a mutation inTP53gene. Genetic aberrations inTP53were present in 37 patients. Statistical analysis of the impact of the studied factors on the overall survival showed that the mutations inIDH1/IDH2, but not the ones inTP53, were associated with longer survival. Also, the impact of age on prognosis was confirmed. This is the first comprehensive study on glioblastomas in Bulgaria. Our results suggest thatIDH1/IDH2but notTP53mutations together with other prognostic factors such as age might be applied in clinical practice for prediction of outcome in patients with glioblastomas.

19 August 2022 in Medicine
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VPVeronika Petkova
Veronika Petkova
DMDora Marinova
Dora Marinova
SKSilva Kyurkchiyan
Silva Kyurkchiyan
GSGergana Stancheva
Gergana Stancheva
EMEvgeni Mekov
Evgeni Mekov
RKRadka Kaneva
Radka Kaneva
The current study investigated the expression signatures of miRNAs in lung adenocarcinoma (LUAD) and squamous cell lung carcinoma (LUSC). miRNA profiling was performed using microarray in 12 LUAD and 12 LUSC samples and adjacent normal tissues. In LUAD, 107 miRNAs were significantly deregulated, whereas 235 miRNAs were deregulated in LUSC. Twenty-six miRNAs were common between the 2 cancer subtypes and 8 were prioritized for validation, in addition to 6 subtype-specific miRNAs. The RT-qPCR validation samples included 50 LUAD, 50 LUSC, and adjacent normal tissues. Eight miRNAs were validated in LUAD: 3 upregulated - miR-7-5p, miR-375-5p, miR-6785-3p, and 5 downregulated - miR-101-3p, miR-139-5p, miR-140-3p, miR-144-3p, miR-195-5p. Ten miRNAs were validated in the LUSC group: 3 upregulated - miR-7-5p, miR-21-3p, miR-650, and 7 downregulated - miR-95-5p, miR-140-3p, miR-144-3p, miR-195-5p, miR-375, miR-744-3p, and miR-4689-3p. Reactome pathway analysis revealed that the target genes of the deregulated miRNAs in LUAD were significantly enriched in cell cycle, membrane trafficking, gene expression processes, and EGFR signaling, while in LUSC, they were enriched in the immune system, transcriptional regulation by TP53, and FGFR signaling. This study identified distinct miRNA profiles in LUSC and LUAD, which are common and specific miRNAs that could be further investigated as biomarkers for diagnosis and prognosis.

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LDLyuben Dimitrov Dimitrov
Lyuben Dimitrov Dimitrov
GSGergana Stancheva
Gergana Stancheva
SKSilva Kyurkchiyan
Silva Kyurkchiyan
MMMilena Mitkova
Milena Mitkova
ISIglika Petrova Stancheva
Iglika Petrova Stancheva
TPTodor Popov
Todor Popov
Field cancerization is a fundamental paradigm in tumorigenesis, emphasizing that carcinogenesis begins long before the appearance of clinically detectable lesions and often precedes recognizable premalignant changes. A direct manifestation of this process is the molecular dysregulation observed in the peritumoral mucosa—histologically normal-appearing tissue that nonetheless exhibits genetic and epigenetic alterations similar to those of the adjacent tumor. This review summarizes current evidence on the molecular alterations shared between tumor tissue and peritumoral mucosa in HNSCC and evaluates their potential as biomarkers for defining molecular margins and improving surgical precision. A literature search was conducted in PubMed using combinations of the keywords “peritumor,” “laryngeal”, “HNSCC,” and “field cancerization.” Studies were included if they directly compared tumor tissue with peritumoral mucosa and, preferably, a third set of distant normal control samples. Only nine studies met the inclusion criteria, highlighting the scarcity of focused research in this area. Reported biomarkers exhibiting comparable dysregulation in both tumor and peritumor tissues include MDM2, E2F2, CDKN2A/p16, ETS-1, MGMT, and multiple microRNAs (e.g., miR-21, miR-96-5p, miR-145-5p). These molecular signatures demonstrate the presence of a biologically altered field extending beyond histologically defined tumor margins. Peritumoral mucosal dysregulation, as a consequence of field cancerization, underscores the need to redefine surgical margins at the molecular level. The identification and validation of biomarkers reflecting this continuum could enable the establishment of molecular margins—improving risk assessment, reducing local recurrence, and advancing personalized oncologic surgery in HNSCC. Standardizing definitions and sampling protocols for “normal adjacent tissue” remains essential for future translational research.

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KKKristina Stoyanova Komitova
Kristina Stoyanova Komitova
LDLyuben Dimitrov Dimitrov
Lyuben Dimitrov Dimitrov
GSGergana Stancheva
Gergana Stancheva
SKSilva Kyurkchiyan
Silva Kyurkchiyan
VPVeronika Petkova
Veronika Petkova
TPTodor Popov
Todor Popov
During the past decade, a vast number of studies were dedicated to unravelling the obscurities of non-coding RNAs in all fields of the medical sciences. A great amount of data has been accumulated, and consequently a natural need for organization and classification in all subfields arises. The aim of this review is to summarize all reports on microRNAs that were delineated as prognostic biomarkers in laryngeal carcinoma. Additionally, we attempt to allocate and organize these molecules according to their association with key pathways and oncogenes affected in laryngeal carcinoma. Finally, we critically analyze the common shortcomings and biases of the methodologies in some of the published papers in this area of research. A literature search was performed using the PubMed and MEDLINE databases with the keywords “laryngeal carcinoma” OR “laryngeal cancer” AND “microRNA” OR “miRNA” AND “prognostic marker” OR “prognosis”. Only research articles written in English were included, without any specific restrictions on study type. We have found 43 articles that report 39 microRNAs with prognostic value associated with laryngeal carcinoma, and all of them are summarized along with the major characteristics and methodology of the respective studies. A second layer of the review is structural analysis of the outlined microRNAs and their association with oncogenes and pathways connected with the cell cycle (p53, CCND1, CDKN2A/p16, E2F1), RTK/RAS/PI3K cascades (EGFR, PI3K, PTEN), cell differentiation (NOTCH, p63, FAT1), and cell death (FADD, TRAF3). Finally, we critically review common shortcomings in the methodology of the papers and their possible effect on their results.

23 September 2024 in Biomolecules and Biomedicine
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SKSilva Garo Kyurkchiyan
Silva Garo Kyurkchiyan
VPVeronika Petkova
Veronika Petkova
GSGergana Stancheva
Gergana Stancheva
ISIglika Petrova Stancheva
Iglika Petrova Stancheva
SDStoyan Dimitrov
Stoyan Dimitrov
TPTodor Popov
Todor Popov
Advanced laryngeal squamous cell carcinoma (LSCC) is the second most prevalent type of head and neck squamous cell carcinoma (HNSCC). Identifying microRNAs (miRNAs) related to key regulatory molecules or mechanisms could offer an alternative approach to developing new treatment strategies. The aim of our study is to evaluate significant correlations among deregulated miRNAs in advanced laryngeal carcinoma and to analyze, in silico, their strength of association, targets, and the most deregulated pathways. Several miRNAs demonstrated promising co-expression results, specifically miR-93-5p, miR-145-5p, and miR-210-3p. Their expressions were explored and further validated in a large set of in vivo advanced LSCC samples, which were subsequently used for bioinformatics and enrichment analyses. Our results highlight the significant roles of miR-93-5p, miR-145-5p, and miR-210-3p in regulating major pathways linked to the cell cycle via epithelial-to-mesenchymal transition (EMT), PI3K/Akt signaling, hypoxia, metabolism, apoptosis, angiogenesis, and metastasis. The associations between the expressions of these miRNAs and patients' clinical features could be central to the progression of advanced LSCC. Overall, our study provides important insights into the co-expression and regulatory networks of miR-93-5p, miR-145-5p, and miR-210-3p in advanced laryngeal carcinoma, underscoring their potential as therapeutic targets or biomarkers for this aggressive cancer. Further research is needed to elucidate the specific mechanisms through which these miRNAs contribute to the pathogenesis and progression of laryngeal carcinoma.

5 April 2024 in Cells
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SKSilva Kyurkchiyan
Silva Kyurkchiyan
GSGergana Stancheva
Gergana Stancheva
VPVeronika Petkova
Veronika Petkova
SPStiliana Panova
Stiliana Panova
VDVenera Dobriyanova
Venera Dobriyanova
TPTodor Popov
Todor Popov
The field cancerization theory is an important paradigm in head and neck carcinoma as its oncological repercussions affect treatment outcomes in diverse ways. The aim of this study is to assess the possible interconnection between peritumor mucosa and the process of tumor neoangiogenesis. Sixty patients with advanced laryngeal carcinoma were enrolled in this study. The majority of patients express a canonical HIF-upregulated proangiogenic signature with almost complete predominancy of HIF-1α overexpression and normal expression levels of the HIF-2α isoform. Remarkably, more than 60% of the whole cohort also exhibited an HIF-upregulated proangiogenic signature in the peritumoral benign mucosa. Additionally, the latter subgroup had a distinctly shifted phenotype towards HIF-2α upregulation compared to the one in tumor tissue, i.e., a tendency towards an HIF switch is observed in contrast to the dominated by HIF-1α tumor phenotype. ETS-1 displays stable and identical significant overexpression in both the proangiogenic phenotypes present in tumor and peritumoral mucosa. In the current study, we report for the first time the existence of an abnormal proangiogenic expression profile present in the peritumoral mucosa in advanced laryngeal carcinoma when compared to paired distant laryngeal mucosa. Moreover, we describe a specific phenotype of this proangiogenic signature that is significantly different from the one present in tumor tissue as we delineate both phenotypes, quantitively and qualitatively. This finding is cancer heterogeneity, per se, which extends beyond the “classical” borders of the malignancy, and it is proof of a strong interconnection between field cancerization and one of the classical hallmarks of cancer—the process of tumor neoangiogenesis.