Browsing by Author "Nikolić, Aleksandra (57194842918)"

Background. Promoter hypermethylation of the SMAD4 gene has been registered in some cancer types, but in general doesn’t appear to be a frequent event in carcinogenesis. However, only a few published studies deal with this topic and not many cancer types have been analyzed. The aim of this study was to establish SMAD4 gene promoter methylation status in pancreatic and endometrial cancers. Methods. Patients included in the study (62 subjects) were diagnosed and surgically treated at the University of Belgrade, Clinical Center of Serbia. Patients with pancreatic carcinoma (17 subjects) underwent surgical removal of the pancreatic adenocarcinoma at the First Surgical Clinic, while the patients with endometrial carcinoma (45 subjects) underwent hysterectomy with adnexectomy at the Institute for Gynecology and Obstetrics. Extraction of DNA from fresh tissue samples was performed and the methylation status of the SMAD4 gene promoter was studied by a previously designed PCR-based HpaII and MspI restriction enzyme assay. The resulting PCR products were analyzed by electrophoresis in 2% agarose gels. Results. Neither of the analyzed samples was found to be hypermethylated. Conclusion. This is the first report on SMAD4 methylation status in pancreatic and endometrial tumor specimens, and supports the viewpoint that SMAD4 hypermethylation is not a common event in malignant tumors. Nevertheless, promoter hypermethylation remains a candidate mechanism for SMAD4 inactivation in malignant tissue as a potential cause of decreased or lost SMAD4 expression in certain tumor types, and should be further investigated in different tumor types and larger cohorts of patients. © 2018, Institute of Oncology Sremska Kamenica. All rights reserved.

Background: Chronic obstructive pulmonary disease (COPD) is a complex disorder characterized by increased oxidative stress. Functional genetic variants of phase I and II genes are implicated in oxidants-antioxidants imbalance and may be involved in COPD development. In this study, we aimed to investigate the role of cytochrome P450 (CYP), glutathione S-transferase (GST) and microsomal epoxide hydrolase (mEH) functional variants in the pathogenesis of COPD in a Serbian population. Methods: The genotypes of 122 COPD patients and 100 controls with normal lung function were determined for CYP1A1 ∗1A/∗2A, CYP2E1 ∗1A/∗5B, GSTM1 null, GSTT1 null GSTP1 Ile105Val, mEH Tyr113His and mEH His139Arg gene variants. Results: Results obtained showed that GSTM1 null variant was significantly more represented in COPD patients than in controls (61.5% vs. 47.0%; OR=1.80; p=0.042). Also, a significant difference was observed for combinations of GSTM1 null and GSTP1 105Val/(Val) (38.5% vs. 24.0%; OR=1.98; p=0.029), as well as for CYP1A1 ∗1A/∗2A, GSTM1 null and mEH 113His/(His) genotypes (7.4% vs. 1.0%; OR=7.88; p=0.025). Conclusions: These are the first data concerning the analysis of the variants of phase I and II genes in the pathogenesis of COPD in a Serbian population. Results obtained in this study open up the possibility for thorough analyses of the role of genetic factors in COPD on larger cohorts. Also, they implicate the importance of previously described genetic associations with COPD in our population, as well as reveal a new one, not reported so far. © by Marija Stanković 2015.

Background: Chronic obstructive pulmonary disease (COPD) is a complex disorder characterized by increased oxidative stress. Functional genetic variants of phase I and II genes are implicated in oxidants-antioxidants imbalance and may be involved in COPD development. In this study, we aimed to investigate the role of cytochrome P450 (CYP), glutathione S-transferase (GST) and microsomal epoxide hydrolase (mEH) functional variants in the pathogenesis of COPD in a Serbian population. Methods: The genotypes of 122 COPD patients and 100 controls with normal lung function were determined for CYP1A1 ∗1A/∗2A, CYP2E1 ∗1A/∗5B, GSTM1 null, GSTT1 null GSTP1 Ile105Val, mEH Tyr113His and mEH His139Arg gene variants. Results: Results obtained showed that GSTM1 null variant was significantly more represented in COPD patients than in controls (61.5% vs. 47.0%; OR=1.80; p=0.042). Also, a significant difference was observed for combinations of GSTM1 null and GSTP1 105Val/(Val) (38.5% vs. 24.0%; OR=1.98; p=0.029), as well as for CYP1A1 ∗1A/∗2A, GSTM1 null and mEH 113His/(His) genotypes (7.4% vs. 1.0%; OR=7.88; p=0.025). Conclusions: These are the first data concerning the analysis of the variants of phase I and II genes in the pathogenesis of COPD in a Serbian population. Results obtained in this study open up the possibility for thorough analyses of the role of genetic factors in COPD on larger cohorts. Also, they implicate the importance of previously described genetic associations with COPD in our population, as well as reveal a new one, not reported so far. © by Marija Stanković 2015.

Liquid biopsy and cell-free DNA (cfDNA) show great promise in cancer diagnostics. In this study, we designed a custom droplet digital PCR (ddPCR) assay for the quantification and quality control of cfDNA isolated from serum. The assay was validated on a group of locally advanced colorectal cancer (CRC) patients and two control groups—patients with hemorrhoids and healthy individuals. The assay shows a high correlation with Qubit measurement (r = 0.976) but offers a higher dynamic range. Mean concentrations of cfDNA were 12.36 ng/µL, 5.17 ng/µL, and 0.29 ng/µL for CRC, hemorrhoid patients, and healthy controls, respectively. The quality of cfDNA was assessed with the measurement of B-cell DNA contamination. On a subset of CRC patients, we compared the mutation status on KRAS (G12A, G12D, G12V, G13D) and BRAF (V600E) genes in the primary tumor and cfDNA isolated from the serum. A total of 70.6% of primary tumor samples were mutated, and the mean fractional abundance of mutations was 9.50%. The matching serum samples were mutated in 38% cases with an average fractional abundance of 0.23%. We conclude that any decisions based solely on the amount of cfDNA present in patient serum must be inter-preted carefully and in the context of co-morbidities. This study explores the potential of ddPCR somatic mutations detection from liquid biopsy as a supplement to tissue biopsy in targeted per-sonalized CRC patient management. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Liquid biopsy and cell-free DNA (cfDNA) show great promise in cancer diagnostics. In this study, we designed a custom droplet digital PCR (ddPCR) assay for the quantification and quality control of cfDNA isolated from serum. The assay was validated on a group of locally advanced colorectal cancer (CRC) patients and two control groups—patients with hemorrhoids and healthy individuals. The assay shows a high correlation with Qubit measurement (r = 0.976) but offers a higher dynamic range. Mean concentrations of cfDNA were 12.36 ng/µL, 5.17 ng/µL, and 0.29 ng/µL for CRC, hemorrhoid patients, and healthy controls, respectively. The quality of cfDNA was assessed with the measurement of B-cell DNA contamination. On a subset of CRC patients, we compared the mutation status on KRAS (G12A, G12D, G12V, G13D) and BRAF (V600E) genes in the primary tumor and cfDNA isolated from the serum. A total of 70.6% of primary tumor samples were mutated, and the mean fractional abundance of mutations was 9.50%. The matching serum samples were mutated in 38% cases with an average fractional abundance of 0.23%. We conclude that any decisions based solely on the amount of cfDNA present in patient serum must be inter-preted carefully and in the context of co-morbidities. This study explores the potential of ddPCR somatic mutations detection from liquid biopsy as a supplement to tissue biopsy in targeted per-sonalized CRC patient management. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

This study aimed to examine the expression pattern of tumoral and circulating miR-93-5p in patients with colorectal cancer (CRC) liver metastasis (CRLM) and to explore its predictive and prognostic potential. CRLM tissue, surrounding non-tumor liver tissue, and serum were obtained from 35 patients with CRLM. The expression pattern of tissue and circulating miR-93-5p in patients with CRLM was determined using quantitative polymerase chain reaction, using miR-16-5p for normalization. Sample-based cut-off values for CRLM and serum miR-93-5p expression were calculated using Receiver Operating Characteristic curve analysis to stratify the patients into high and low miR-93-5p expression groups which were that compared with patients' clinicopathological data, therapy response, one-year disease-free survival, and disease recurrence. Relative miR-93-5p expression was higher in CRLM in comparison to the non-metastatic liver tissue (p<0.001). CRLM miR-93-5p expression showed moderate negative correlation with carcinoembryonic antigen levels (r=-0.406; p=0.016). There were no differences in high-/low-miR-93-5p expression and therapy responders vs. non-responders, which was confirmed in vitro using metastatic and normal colonic cells SW620 and HCEC-1CT, respectively. No difference was observed in one-year recurrence-free survival in patients with high vs. low miR-93-5p expression in CRLM or serum. However, high miR-93-5p serum levels were significantly associated with early disease recurrence (p=0.035). In conclusion, miR-93-5p serum levels could be potentially used as a prognostic factor for early disease recurrence in CRLM patients.

Aim To analyze the expression of autophagy markers p62, LC3, and Beclin1 in ovarian cancer tissue and evaluate the prognostic potential of these markers. Methods The study enrolled 328 patients: 122 with epithelial ovarian carcinoma, 42 with atypical proliferative tumor, and 164 with benign epithelial ovarian tumor. The expression of p62, LC3, and Beclin1 was analyzed in central and invasive tumor segments with immunohistochemistry combined with tissue microarray. The expression levels of the analyzed markers were correlated with relevant histopathology parameters. Results The expression of all analyzed markers was most remarkable in epithelial ovarian carcinoma. There was a strong positive correlation between the expressions of p62 and LC3, while these two markers negatively correlated with Beclin1. High-grade serous carcinoma had higher p62 and LC3 levels, and lower Beclin1 levels than other tumor types. This expression profile was also observed in more advanced tumor stages. Conclusion Prominent p62 and LC3 expression in combination with weak Beclin1 expression in high-grade serous carcinoma indicates potential for the application of autophagy inhibitors in patients with this tumor subtype. © 2022 Medicinska Naklada Zagreb. All rights reserved.

Introduction Y chromosome microdeletions are the second most frequent genetic cause of male infertility after Klinefelter's syndrome. Objective The aim of the study was to determine the frequency of Y chromosome microdeletions in a group of infertile men with an idiophatic cause of infertility, candidates for microfertilization (Intra-cytoplasmic Sperm Injection - ICSI) in Serbia and to correlate genotype-phenotype in patients with Y chromosome microdeletions. Method One hundred and sixty patients with low sperm count (less than 5x106 spermatozoa/ml) were enrolled in the study. Forty patients were excluded from the study: ten because they were diagnosed with cytogenetic abnormality and thirty patients were diagnosed with other known causes of infertility. The control group consisted of 150 men who fathered at least one child in the last two years. Genomic DNA was extracted from peripheral blood samples and two multiplex polymerase chain reactions (PCR) analyses were performed using specific primers to confirm the presence or absence of Y chromosome microdeletions. Results Microdeletions were detected in 12 of 120 (10%) cases, while no deletions were detected in the control group. Of total number of 12 deletions, nine were detected in AZFc region (75%), one in AZFa (8%), and two in AZFbc (17%). Conclusion Testing for Y chromosome microdeletions should be considered as an important element in diagnosis and genetic counselling of infertile couples in Serbia. Decisions regarding the assisted reproduction should be made based on the detailed clinical, endocrinological and cytogenetic examinations, spermogram, presence or absence and type of AZF microdeletions and CFTR gene mutations.