Aleksey V. Kononov

Gastric cancer represents a heterogeneous group of tumors with distinct molecular mechanisms of development. One of the many molecular genetic alterations found in gastric cancer is inactivation of the O6-methylguanine-DNA methyltransferase (MGMT) gene. The aim of the study was to evaluate MGMT protein expression in chronic gastritis as a potential predictive marker for gastric cancer risk. Material and methods . The study material consisted of biopsy and surgical specimens of the gastric mucosa. The first group included 62 cases of sporadic gastric cancer, each represented by one tumor tissue fragment and one fragment from a distant zone of tumor growth. The second group comprised 58 gastric mucosal samples obtained during esophagogastroduodenoscopy from patients with dyspeptic complaints. Immunohistochemical staining was performed on paraffin sections of all specimens using mouse monoclonal antibodies against the MGMT protein (Diagnostic Bio Systems, USA; clone MT3.1, dilution 1:100) and the PolyVuePlus HRP/DAB detection system (Diagnostic Bio Systems, USA). Results . In the gastric cancer samples, a marked decrease in the MGMT protein index was observed, down to 4 [2; 8] points. In the gastric mucosal fragments from the distant zone in the first group, a pronounced reduction in the MGMT protein index was also found, down to 4 [2; 6] points. In the second group of gastric mucosal biopsies, the MGMT protein index value remained at a high level — 9 [9; 12] points. Comparison of the distribution of MGMT protein index values demonstrated no differences between the gastric cancer samples and the distant-zone gastric mucosa (p = 0.56). At the same time, the decrease in the MGMT protein index in the distant-zone samples was statistically significantly different (p < 0.001) from the preserved level of MGMT protein expression in the biopsies of the second group. Conclusion . The statistically significant decrease in the MGMT protein level in the distant zone of tumor growth compared with morphologically comparable gastric mucosa in chronic gastritis may serve as a potential predictor of gastric cancer risk.

The PDCD4 (programmed cell death protein 4) protein is a key target protein, in particular for the well-studied miR-21. By suppressing its synthesis, miR-21 exerts its influence on key cellular biological processes. Furthermore, miR-21 itself is one of the most relevant predictor markers for assessing the risk of developing gastric cancer. Objective. Evaluation of PDCD4 expression as a potential marker for gastric cancer prediction and in the differential diagnosis of gastric mucosal dysplasia. Material and methods. Comparative immunohistochemical analysis of PDCD4 protein was performed in biopsy specimens of the antral gastric mucosa with signs of chronic gastritis and gastric mucosal dysplasia, as well as in surgical specimens from stomachs resected for adenocarcinoma. Results. In gastric mucosa with signs of chronic gastritis, high immunohistochemical expression of PDCD4 was maintained, regardless of the severity of inflammation, atrophy, and type of metaplasia. PDCD4 protein expression in the dysplasia group was significantly lower compared to gastric mucosal biopsy samples with signs of chronic gastritis (p=0.00001) and did not differ from that in adenocarcinoma tissues (p=0.43). A simple logistic regression model demonstrated a significant negative association between PDCD4 protein expression and dysplasia in the gastric mucosa (OR=0.27, CI=[0.16-0.46]). Conclusion. Low PDCD4 protein expression in dysplasia in the gastric mucosa and high levels regardless of the presence and severity of atrophy and inflammation may indicate its high potential for use in the differential diagnosis of indefinite for dysplasia and true dysplasia of the gastric mucosa.

Aim: to present clinical guidelines describing the clinical, laboratory, endoscopic and histological characteristics of autoimmune gastritis (AIG) and to provide information support for decision-making on diagnosis, prognosis assessment and choice of management tactics for patients with AIG. Key points. AIG is an organ-specific autoimmune disease characterized by the presence of antibodies to parietal cells and/or intrinsic factor, in which inflammation and atrophy are limited to the gastric mucosa, functionally manifesting as hypo- and achlorhydria. There is evidence of an increase in the incidence of AIG worldwide. AIG is often associated with autoimmune thyroiditis (up to 40 % of cases), type 1 diabetes mellitus, and autoimmune polyglandular syndrome. Data on laboratory diagnostic methods, esophagogastroduodenoscopy, and histological examination of biopsies are presented, with an analysis of the endoscopic and histological picture typical of AIG. When AIG is combined with H. pylori infection, eradication therapy is recommended. In addition to symptomatic treatment and treatment of anemia, long-term rebamipide therapy is recommended to potentiate the protective properties of the gastric mucosa. Endoscopic monitoring of patients with AIG is recommended at intervals of once every 3 years.

Aim: to assess the microsatellite instability status in gastric mucosa to determine the possibility of its use as a predictive marker of carcinogenesis.Material and methods. The study included two groups of gastric mucosa specimens: Group 1 — 155 mucosa fragments of the distant tumor growth zone obtained from stomachs resected for malignant neoplasms; Group 2 — 100 fragments with chronic gastritis taken from patients with dyspeptic complaints. Gastrobiopsy specimens were examined histologically, immunohistochemically using mouse monoclonal antibodies (Diagnostic BioSystems, USA) to the MMR system proteins: MLH-1 (clone G168-15, dilution 1:50), MSH2 (clone DBM15.82, dilution 1:100), MSH6 (clone 44, dilution 1:50), PMS2 (clone A16-4, ready to use). MSI was studied with multiplex PCR evaluation of DNA microsatellites (NR-21, NR-24, NR-27, BAT-25, BAT-26) from paraffin sections, their analysis with capillary electrophoresis. The obtained data were processed with the Statistica 10.0 (StatSoft Inc., USA), presented using descriptive, analytical statistics.Results. Immunohistochemical examination revealed 8 microsatellite-unstable cases in gastric mucosa specimens of Group 1 and 0 cases in Group 2 (statistically significant differences, p = 0.024). All studied gastric tissue samples were assessed as microsatellite-stable based on PCR results.Conclusion. Detection of MMR deficiency in gastric mucosa of the distant tumor growth zone and its absence in morphologically comparable specimens obtained from patients with chronic gastritis may be considered as confirmation of the hypothesis of disturbances in the MMR system as an early event in carcinogenesis. This, in turn, may indicate the potential for studying MMR status as a component of a decision support system for assessing the risk of developing microsatellite-associated gastric cancer.

Objective. To evaluate the MMR system proteins and the MSI status of regenerative (indefinite for dysplasia) and pronounced (epithelial dysplasia) gastric mucosa precancerous lesions in the comparison with cancer to determine their possible potential as a diagnostic markers of gastric mucosa dysplasia. Material and methods. The study included 2 groups of gastric mucosa specimens: (1) 150 biopsy gastric mucosa specimens: 43 with low-grade dysplasia, 32 with high-grade dysplasia, 75 — indefinite for dysplasia; (2) 155 cancer tissue specimens from resected stomachs. Gastric mucosa specimens were examined histologically, immunohistochemically using mouse monoclonal antibodies to the MMR system proteins: MLH-1, MSH2, MSH6, PMS2 (Diagnostic BioSystems, USA). MSI was studied with multiplex PCR evaluation of DNA microsatellites (NR-21, NR-24, NR-27, BAT-25, BAT-26) from paraffin sections, their analysis with capillary electrophoresis. The obtained data were processed with the Statistica 10.0 (StatSoft, USA), presented using descriptive, analytical statistics. Results. MSI was detected by immunohistochemistry in 8% (n=6) of the studied cases of low/high grade dysplasia, which does not have statistically significant differences from the distribution of MSI in the gastric cancer group (12% of microsatellite-unstable cases (n=18)) (p=0.49). MSI was not detected in any indefinite for dysplasia case. Conclusion. Detection of microsatellite instability in gastric mucosa dysplasia indicates the likelihood of its occurrence at the early stages of the carcinogenesis cascade and makes it possible to use it to assess the risk of gastric cancer associated with microsatellite instability. The absence of instability in cases indefinite for dysplasia determines the possibility of its use for differential diagnosis of truly neoplastic and regenerative/reactive changes in the gastric mucosa.

INTRODUCTION: Disorder in the function of the ARID1A gene is associated with the initiation and progression of many malignant tumors. In gastric cancer, ARID1A loss is noted in approximately 31% of all adenocarcinomas, in particular, in the subtype with microsatellite instability, indicating a probable potential for assessment of ARID1A protein for early diagnosis of early and pronounced precancerous alterations and gastric cancer. AIM: To compare the characteristics of ARID1A protein production in tissues of gastric adenocarcinoma and gastric mucosa in the distant zone of tumor growth to assess diagnostic and predictive potential of this marker. MATERIALS AND METHODS: Fragments of gastric mucosa of 43 patients with gastric adenocarcinoma were studied: group 1 — fragments of adenocarcinoma tissue (n = 43), group 2 — fragments of mucosa at 1 cm and more distance from tumor (distant zone, n = 43). The samples were subjected to immunohistochemical examination using ARID1A (ab182560, 1:1000; Abcam, UK). The intensity of nuclei staining (0 — none, 1 — weak, 2 — moderate, 3 — pronounced) and spread of immunohistochemical marks (0 — < 50% of stained nuclei, 1 — 50%–75%, 2 — 75–90%, 3 — 90%–95%, 4 — 95%–98%, 5 — more than 98%). were assessed. The evidence and spread scores were interpreted as ARID1A index. The data were presented as median and interquartile range. Mann-Whitney U test and Wilcoxon matched-pairs test were used to compare groups. RESULTS: ARID1A index demonstrated lower values in adenocarcinoma (4 [2–6]) compared to the distant zone (5 [3–6], p = 0.0447). However, the interquartile range of both groups partially overlapped, due to which, when using Wilcoxon test, no statistically significant difference (р = 0.0697) was found between matched pairs. CONCLUSION: The absence of statistically significant differences between the tumor tissue and distant zone of tumor growth in the assessment of matched samples can indicate the early involvement of pathways leading to loss of AID1A in the gastric mucosa, in carcinogenesis, and makes it a possible marker of the risk of development and early diagnosis of gastric cancer.

The participation of PDCD4 protein in molecular mechanisms of key importance in carcinogenesis makes the assessment of the level of its synthesis in tissues important for assessing the early diagnosis of malignant tumors. The aim of the presented study was to develop a method for evaluation of the results of immunohistochemical staining of the PDCD4 protein. Material and methods. The material for the study included 49 samples of human gastric adenocarcinoma tissue and 80 cases of endoscopic biopsy examination of the gastric mucosa of patients with dyspeptic complaints. Morphological changes in biopsies corresponded to chronic gastritis with varying degrees of inflammation. Rabbit monoclonal anti-PDCD4 antibodies (clone EP 102, abcam, USA) and a detection system (Diagnostic BioSystems, USA) were used to detect PDCD4 protein by immunohistochemical method. Results. The developed can be used for semi-quantitative visual assessment of synthesis of regulatory protein PDCD4 in histological sections of tissue by immunohistochemical method with detection in nucleus and cytoplasma. That is ensured by calculating an expression index of PDCD4 in tissues when summing up the nuclei expression and cytoplasm expression. Nuclear expression represents a product of staining frequency of nuclei (0–3 points) and semi-quantitative visual assessment of intensity of coloring nuclei (0–3 points). Cytoplasmic expression represents semi-quantitative visual assessment of intensity of cytoplasm (0–3 points). Conclusion. The proposed method makes it possible to evaluate the synthesis of the PDCD4 regulatory protein in tissues with greater sensitivity and specificity, which makes it possible to detect a violation of PDCD4 expression in epithelial cells at the early stages of tumor cell transformation.

   Aim: to evaluate the possibility of the MMR-system status, microsatellite instability (MSI) usage in the differential diagnosis of gastric mucosa dysplasia, determination of the gastric adenocarcinoma development risk.   Material and methods. The study included gastric mucosa specimens of 75 patients: 25 with high-grade dysplasia, 25 with low-grade dysplasia, 25 were indefinite for dysplasia. Gastrobiopsy specimens were examined histologically, immunohistochemically using mouse monoclonal antibodies (Diagnostic BioSystems, USA) to the MMR system proteins: MLH-1 (clone G168-15, dilution 1:50), MSH2 (clone DBM15.82, dilution 1:100), MSH6 (clone 44, dilution 1:50), PMS2 (clone A16-4, ready to use). MSI was studied with multiplex PCR evaluation of DNA microsatellites (NR-21, NR-24, NR-27, BAT-25, BAT-26) from paraffin sections, their analysis with capillary electrophoresis. The obtained data were processed with the Statistica 10.0 (StatSoft, USA), presented using descriptive, analytical statistics. VOSviewer (1.6.20) was used to visualize the bibliometric analysis.   Results. MMR-deficient cases were found in low (2.8 %) and high-grade (2.8 %) dysplasia with the immunohistochemical evaluation of MMR-system proteins in gastric mucosa specimens. In all indefinite for dysplasia cases MMR-system proteins remained unaffected. Three MSI-positive cases (6.5 %) were detected by PCR with two low-grade dysplasia, one high-grade dysplasia cases. All identified cases were also immunohistochemically MSI-positive.   Conclusion. Determination of MSI can be used as an auxiliary study within a panel of biomarkers aimed to support the decision-making of a pathologist in the alternative of “indefinite for dysplasia” or “definite dysplasia — obligate precancer”.

Aim. To evaluate the activity of autophagy and apoptosis in the myocardium of rats with differentstress resistance after the modeling of myocardial contusion.Materials and Methods. The study was performed on 106 white male rats weighing 250-300 g. The rats were ranked according to stress tolerance, and medium-resistant individuals (n = 42) were excluded from the experiment. Control (n = 16) and experimental (n = 48) groups were formed from the remaining animals; the control group included subgroups with high and low stress resistance, and the experimental group included 6 subgroups (rats with high and low stress resistance; 6, 12, and 24-hour time points). Each of the subgroups included 8 animals. Myocardial contusion was modeled in the experimental group. At 6-, 12- and 24-hour time point, rat hearts have been excised and 5×5 mm myocardial fragments were dissected from the areas with the most prominent traumatic effects (interventricular septum, anterior walls of the left and right ventricles). Tissues were then sectioned and stained with antibodies to Beclin-1 and caspase-3.Results. We have documented a significant expression of Beclin-1 and Caspase 3 expression in rat hearts after myocardial contusion. From 6 to 24 hours upon the myocardial contusion, Beclin-1 expression has been increased in rats with high stress resistance but was reduced in rats with low stress resistance. Expression of caspase-3 expression was registered exclusively at 24-hour time point in rats with high stress resistant but increased along the time points in rats with low stress resistance.Conclusion. Expression of Beclin-1 and caspase-3 in rat myocardium indicated autophagy and apoptosis upon the myocardial contusion. Temporal patterns of Beclin-1 and caspase-3 expression were opposite in rats with high and low stress resistance.

For more than a century, physicians have noted the relationship of chronic gastritis with the development of gastric cancer, which prompted great interest in the study and systematization of chronic gastritis in order to better understand the prognosis and develop approaches for cancer prevention. The accumulated knowledge about the etiology, pathogenesis and morphology of gastritis has made it possible to coordinate the general ideas about gastritis in the classifications used by practicing physicians today, and the systems developed and implemented into practice for assessing atrophy/intestinal metaplasia (OLGA/OLGIM) undoubtedly can help the doctor in determining the tactics of curation of the patient.