Thyroid cancer remains the most common malignancy of the endocrine system worldwide. The indicators of its morbidity and mortality rates have been increasing rapidly over the last decades. Most cases of differentiated thyroid cancer (follicular and papillary histotypes) are clinically manifested by nodular goiter frequently combined with uncertain results of cytological diagnosis (categories III and IV according to the Bethesda (Bethesda System for Reporting Thyroid Cytopathology) classification). All of that makes it difficult to choose a proper tactic for patient treatment. It is known that the development, progression, invasion, and metastasis of cancer cells are regulated by a variety of molecular mechanisms. This review describes several molecular aspects of thyroid nodules oncogenesis, as well as its most promising diagnostic tumor markers. Following molecular pathways are described in particular: gene mutations, protein tumor markers, and epigenetic effects of micro-RNA, histones, as well as DNA methylation. The study of the pathogenesis of this disease has a prognostic value and contributes to the search for effective therapeutic and diagnostic methods and their improvement. That is why we also reviewed modern test panels aimed at preoperative differential diagnosis of thyroid nodules. Summarizing the results of world research on this topic allows us not only to expand the understanding of the fundamental processes of oncogenesis, but also to outline promising areas for future experimental research projects. All of that together will contribute to developing new prognostic, diagnostic and therapeutic technologies, and as a result, will improve the quality of medical care for patients with thyroid cancer.

Osteopontin is an extracellular matrix protein which is produced by different types of cells and plays an important functional role in many biological processes. This review discusses the main functions of osteopontin, its role in the progression and chemoresistance of malignant neoplasms, in the regulation of epithelial-mesenchymal transition, angiogenesis, and the body’s immune response to the tumor. The article considers the currently known mechanisms by which osteopontin affects to the survival, mobility and invasion of tumor cells, to tumor sensitivity to drug treatment, as well as the prospects for a integrated study of the predictive significance of osteopontin, markers of hypoxia, angiogenesis, epithelial- mesenchymal transition, and immunological tolerance.

Introduction. Nitric oxide (NO) produced by NO synthases (NOS) is involved in the regulation of vital physiological functions. At the same time, NO and NOS are involved in events associated with the tumor process: mutagenesis, proliferation, apoptosis, angiogenesis, etc., exerting a multidirectional effect on the tumor.

Objectives – analyze and summarize literature data concerning the role of NO and endothelial NOS (eNOS) in the initiation and progression of tumors, as well as in the inhibition of tumor growth.

Materials and methods. In preparing the review, publications of information bases of biomedical literature were used: SciVerse Scopus (538), PubMed (1327), Web of Science (905), Russian Science Citation Index (125).

Results. The molecular mechanisms of the action of NO and its derivatives on the initiation and progression of carcinogenesis have been explored. Numerous factors and conditions regulating the activity of eNOS in health and tumor growth have been analyzed. The molecular signaling pathways through which the pro-tumor effects of NO and eNOS, stimulating angiogenesis, lymphangiogenesis, are realized, including through the mobilization of stem cells, are considered.

Conclusion. Nitric oxide produced by activated eNOS promotes tumor progression by increasing the proliferation of tumor cells, enhancing the action of pro-angiogenic factors, stimulating angiogenesis, lymphangiogenesis, and metastasis. Selective inhibition of increased eNOS activity may be a promising therapeutic approach aimed at reducing metastasis and tumor growth.

Introduction. Cancer of the esophagus ranks sixth in mortality among malignant neoplastic diseases. To understand the molecular mechanisms of its progression, it is necessary to study not only tumor cells directly, but also cells of the microenvironment. In this work, we studied tumor-associated macrophages and their different phenotypes using membrane protein, indoleamine 2,3‑dioxygenase-1 (IDO1) as a marker for type 1 macrophages and macrophage scavenger receptor (CD204) as a marker for type 2 macrophages.

The objective of this work was to study the expression of IDO1 and CD204 in tumors of squamous cell carcinoma of the esophagus and to assess its prognostic value.

Materials and methods. The study included tumor samples obtained from 48 patients with squamous cell carcinoma of the esophagus. The expression of CD204 and IDO1 was assessed by immunohistochemistry. Survival analysis was carried out by constructing survival curves using the Kaplan–Meier method. Comparison of the significance of differences was performed using the logarithmic rank test. Differences were considered statistically significant at p <0.05.

Results. We analyzed the expression of CD204 and IDO1 in esophageal squamous cell carcinoma tumors. Expression of CD204 was detected in stromal macrophages in 100 % of cases and was not detected in tumor cells. We have shown that in esophageal cancer, IDO1 is expressed in both stromal and tumor cells. In tumor cells, the expression of IDO1 was found in 44 % of the samples, in stromal cells, IDO1 was expressed in 92 % of cases. No association with clinical and morphological characteristics was observed for CD204 in stromal cells and IDO1 in tumor cells. For IDO1 expressed in stromal cells, an association with the stage of the disease (p = 0.0450) and the presence of regional metastases (p = 0.0279) was observed. Survival analysis showed that CD204 is a marker of a favorable prognosis for esophageal cancer (hazard ratio 0.455, p = 0.0419).

Conclusion. This study has shown that the expression of IDO1 in the tumor stroma is associated with more favorable clinical characteristics. It has also been shown that an increased content of CD204+ macrophages is a marker of a good prognosis for esophageal cancer.

Introduction. There has been a recent trend toward a gradual increase in the incidence of rectal cancer and a decrease in the average age of patients. These changes interpret the need to personalize treatment in each case.

Objective – to evaluate the association of polymorphic variants of some genes with the results of neoadjuvant chemoradiotherapy of rectal cancer.

Materials and methods. We analyzed polymorphic variants of MTHFR, XPD, XRCC1, XRCC1, P53, VEGF, EGFR, TNF, CHEK2 and MMP1 genes in 76 patients with rectal cancer who underwent preoperative chemoradiation therapy followed by surgical treatment. Genotyping was performed by DNA isolation from venous blood leukocytes of the subjects followed by polymerase chain reaction with electrophoretic detection of the result.

Results. Statistical analysis of the association of polymorphic variants of the studied genes with the treatment pathomorphosis revealed significance in relation to the MMP1-1607 gene (1G >2G) (p = 0.033). There was also an association of co-carrying polymorphic variants of TNF (G / A) + MMP1 (2G / 2G) genes with grade III–IV therapeutic pathomorphosis (p = 0.007).

Conclusion. Carriage of recessive allele of MMP1 gene can be a predictor of favorable prognosis of preoperative chemoradiotherapy in patients with rectal cancer.

Background. Microsatellites are short tandem nucleotide repeats, the change in length of which plays a key roles in the pathogenesis of various malignant neoplasms. This change is called microsatellite instability. It is caused by aberrations in the genes of DNA mismatch repair system. Tumors with microsatellite instability are a special subtype regardless of location and are characterized by high sensitivity to immune checkpoint inhibitors.

Objective – determination of characteristic clinical and morphological patterns of tumors of various localizations with microsatellite instability.

Materials and methods. The study included 512 patients with malignant tumors of different localizations. Of these, 359 patients were diagnosed with colorectal cancer, 57 with uterine body cancer, and 57 with stomach cancer. Determination of the status of microsatellite instability was performed by a PCR-based method using 5 mononucleotide markers: BAT-25, BAT-26, NR-21, NR-24, NR-27.

Results. The prevalence of microsatellite instability in colorectal cancer, uterine neoplasm and gastric cancer was 6.4; 22.8 and 1.75 %, respectively. Patients with MSI-positive colorectal cancer are characterized by yonger age (p = 0.023), right-sided localization of the tumor (p <0.0001), presence of multiple primary tumors (p = 0.0299), poorly differentiation (p = 0.0025), mucinous component (p <0.0001), tumor-infiltrating lymphocytes (p <0.0001) and Crohn-like reaction (p = 0.0006). Patients with uterine neoplasms with microsatellite instability are characterized by the presence of endometrial adenocarcinoma (p = 0.047), as well as the presence of tumor-infiltrating lymphocytes (p = 0.0022) and cribriform growth (p = 0.0011).

Conclusion. A common pattern for colorectal cancer and uterine neoplasms is the presence of tumor-infiltrating lymphocytes. Certain clinical and morphological features of tumors of these localizations will more accurately identify candidates for microsatellite instability status determination for further immunotherapy.