Retinoic acid being the most active metabolite of vitamin A (retinol) regulates the wide spectrum of physiological processes including embryonic development, development of immune response, hematopoiesis, glucose and lipids metabolism, etc. Retinoic acid participates in the regulation of such important aspects of life-sustaining activity as cell differentiation, proliferation and programmed cell death. This review is focused on comparison of two highly homological members of lipid-binding proteins family, CRABP1 and CRABP2. Although binding of retinoic acid is the only known function of these proteins the physiological meaning this interaction seems to be rather different. CRABBP2 binding of retinoic acid leads to the activation of RAR / RXR nuclear receptors, that act as transcription factors, and further stimulation of expression of numerous retinoic responsive genes. The meaning of CRABP1 binding of retinoic acid is less clear. Some data evidences for the similar action of CRABP1 and CRABP2 in regard to the potentiation of the retinoic acid effect, while the majority of data points on the opposite role of CRABP1, that is reduction of intracellular concentration of retinoic acid and / or decrease of retinoic acid bioavailability through the potentiation of its catabolism or sequestration in the cytosol. The most recent publications also suggest some additional functions of these proteins that could be independent of retinoic acid signalling. The data concerning the roles of these proteins in carcinogenesis and tumor progression are contradictive as well.

This review covers the functions of retinoic acid as well as the molecular mechanisms mediating its activity including the different aspects of retinoic acid receptors activity. The review also comprises the comparative structural-functional analysis of CRABP proteins and probable mechanisms of their intracellular activity including those associated with retinoic acid signalling and retinoic acid-independent. A special attention is drawn to the analysis of the data on the involvement of CRABP proteins in the carcinogenesis and tumor progression. The data pointing on either oncogenic or tumor-suppressive functions are given for each protein.

Prostate cancer (PC) represents the second most frequent type of tumor in men worldwide. Proteomics represents a promising approach for the discovery of new biomarkers able to improve the management of PC patients. Markers more specific and sensitive than prostate-specific antigen are needed for PC diagnosis, prognosis and response to treatment. Moreover, proteomics could represent an important tool to identify new molecular targets for PC tailored therapy. Now several possible PC biomarkers sources, each with advantages and limitations, are under investigation, including tissues, urine, serum, plasma and prostatic fluids. Innovative high-throughput proteomic platforms are now identifying and quantifying new specific and sensitive biomarkers for PC detection, stratification and treatment. Nevertheless, many putative biomarkers are still far from being applied in clinical practice.

This review aims to discuss the recent advances in PC proteomics, emphasizing biomarker discovery and their application to clinical utility for diagnosis and patient stratification.

Gastrointestinal stromal tumors (GISTs) are the most spread mesenchymal tumors located within the gastrointestinal tract that have particular clinico-morphological, immunohistochemical and molecular characteristics. The distinguishing mark of GISTs is the presence of the cell-surface antigen CD117 (KIT receptor tyrosine kinase), identified by immunohistochemistry. GISTs consist of tumors with various activating mutations in KIT (75–80 %) or PDGFRA (5–15 %) receptor tyrosine kinases. Numerous KIT and PDGFRA mutations are associated with specific GIST morphology, histologic phenotype, metastasizing and prognosis. 10–15 % of GISTs contain KIT and PDGFRA wild type genes, some of them have driver BRAF, IGF1R or PIK3CA mutations. The other GISTs patients have familial syndromes (neurofibromatosis type 1, Carney–Stratakis syndrome, Carney triad) and contain germline mutations of NF1 or the genes coding for the succinate dehydrogenase subunits SDHA, SDHB, SDHC, and SDHD. GISTs are first and the most studied model for development of principles and methods of personalized targeted therapy of solid tumors with tyrosine kinase inhibitors.

Trabectedin (ET-743, Yondelis) is an alkaloid that was originally isolated from the Caribbean Sea squirt, Ecteinascidia turbinata and is now produced synthetically. Its chemical structure consists in three fused tetrahydroisoquinoline rings. Two of them, A and B, binds covalently to guanine residues in the minor groove of the DNA double helix to bend the molecule toward the major groove and the third ring C protrudes from the DNA duplex, apparently allowing interactions with several nuclear proteins. Binding to the minor groove of DNA, trabectedin trigger a cascade of events that interfere with several transcription factors, DNA binding proteins, and DNA repair pathways in particular nucleotide excision repair. It acts both as a DNA-alkylating drug and topoisomerase poison. Trabectedin-DNA adduct traps the nucleotide excision repair proteins repairing the DNA damage in transcribing genes and induces DNA strand breaks. Cells deficient in homologous recombination pathway which repairs these double-strand breaks show increased sensitivity to trabectedin. The most sensitive of them were myxoid liposarcomas. Trabectedin is also effective in chemotherapy-experienced patients with advanced, recurrent liposarcoma or leiomyosarcoma as well as in women with ovarian cancer and breast cancer with BRCAness phenotype. Besides of tumor cells Trabectedin inhibits inflammatory cells by affecting directly monocytes and tumorassociated macrophages and indirectly by inhibiting production of inflammatory mediators, the cytokines and chemokines. It inhibits also the MDR-1 gene, which is responsible for the resistance of cancer cells to chemotherapeutic agents and strikes tumor angiogenesis.

The main goal of the study is the analysis of the role of cell-cell interactions in the formation of the tumor cell resistance to hormonal drugs. About 70 % of breast tumors contain estrogen receptor (ER), a key molecular target for hormone (endocrine) therapy. However, the efficiency of endocrine therapy of breast cancer is limited by the development of hormone resistance which leads to progression of tumor cells to hormone-independent phenotype, increase in tumor malignancy and worse prognosis. Hormonal independence may be accompanied with the loss of the receptors, as well as with the another mechanisms including ligand-independent receptor activation, disbalance between receptor activators and repressors, stimulation of hormone-independent pathways. It is less known about the role of the intercellular interactions in the progression of hormonal resistance. Several studies demonstrate the involvement of cell junctions in the mediating of cell response to (anti) estrogens, however the significance of cell-cell contacts in the formation of hormonal resistance still not clear. Here we have hypothesized that the formation of the hormone resistance of tumors may be based, at least in part, on the transferring of the resistant phenotype from the resistant to hormone-sensitive cells – as a result of the secretion of the specific factors acting in the paracrine manner or via the direct cell-cell contacts. Using the estrogen-dependent breast cancer cells MCF-7 and the resistant subline MCF-7 / T developed by long-term cultivation of MCF-7 cells in the presence of antiestrogen tamoxifen, we investigated the possible changes in the hormonal sensitivity of these cells caused by the co-cultivation in vitro. To discern the cell cultures, the MCF-7 / T cells were previously transfected with the plasmid containing the gene of the green fluorescent protein (GFP), and GFP-positive hormone-resistant subline MCF-7 / T / GFP+ was developed. We showed that the co-cultivation of the parent and resistant cells lead to increase in the resistance of the parent cell to tamoxifen. To further explore the mechanism of such resistance, the analysis of the biological activity of exosomes prepared from the estrogen-sensitive and resistant cells was performed. The exosome preparations isolated from the resistant MCF-7 / T cells were found to induce the similar resistance in the recipient MCF-7 cells – in contrast to the control exosomes isolated from the MCF-7 cells. The subsequent cloning of these newly formed resistant cells showed that the cells retain the resistant phenotype for at least 80 days of cultivation. Totally, the results presented demonstrate the important role of cell-cell interactions in the progression of hormonal resistance, opening a new perspectives in the development of probable targets for breast cancer therapy.

Epstein–Barr virus (EBV), a representative of the herpesvirus family, is the etiological agent for a number of benign and malignant human neoplasms. Among the latter, the nasopharyngeal carcinoma (NPC) occupies a special place. In NPC development EBV plays a key role stimulating the progression of the pathological process from precancerous lesions to the cancer development. For most NPC patients, elevated levels of humoral IgG and IgA antibodies against capsid and early EBV antigens are characteristic and their antibody titers rise to high levels long before the diagnosis of cancer. Using this phenomenon, virus-specific antibodies are used for many years as markers for NPC screening, especially in cases of undiagnosed primary lesion. In recent years, in endemic for NPC regions (South China, South-East Asia) a great attention has been paid to the use of quantitative determination of EBV DNA copies in the blood plasma of patients with NPC as a method of early cancer detection and monitoring.

The aim of this study was to compare clinical significance of EBV DNA and humoral antibodies levels in blood plasma of NPC patients in non-endemic region, Russia. The results obtained indicate that both markers DNA / EBV and IgA antibodies against capsid EBV antigens can be successfully used for diagnosis of NPC in non-endemic region. However, in comparison with the virus-specific antibody titers, the viral DNA levels in the patients plasma are more sensitive and specific as NPC marker reflecting the efficacy of the therapy, and the state of remission or relapse.

Leptin is a multifunctional hormone with the activity of cytokines, which regulates critical signaling pathways that can induce cell proliferation, invasion, angiogenesis and tumor growth. Leptin plays an important role in the regulation of metabolism, energy exchange, functions of the neuro-endocrine system, including the pituitary, hypothalamus, adrenals, and immune system functions. Recently, some evidences have been appeared concerning the role of leptin in induction of chronic inflammatory processes, autoimmune pathologies, type 2 diabetes and cancer. An elevated blood level of the hormone is considered as a risk factor for different neoplasm development

Objective. Analysis of the hormone leptin (Lep), the long and short isoforms of its receptor (LepR1 and LepR2) expression in blood, tumor cells and normal skin fibroblasts in the patients with metastatic cutaneous melanoma (CM) with various clinico-pathological characteristics for prognostic assessment.

Materials and methods. 15 patients with metastatic CM (10 women and 5 men, aged 22 to 67 years with body mass from normal to obese) have been studied. The expression of Lep / LepR in the patient and donor blood sera, tumor and normal skin fibroblasts were determined using enzyme-linked immunosorbent assay (ELISA) and RT PCR using total RNAs isolated from pairs of tumor samples and normal tissue.

Results. Average level of leptin in the blood of CM patients and in tumor cells exceeds the normal one. Concentration of lepin in female CM patients was higher than in male patients. The expression level of Lep and LepR1 genes (but not LepR2) in tumor cells was relatively higher than in normal skin fibroblasts of these patients, and above the level of GAPDH gene expression. In the female patients with overweight (body mass index = 25,00–29,99 kg/m2 ) there was a trend to higher concentrations of leptin in the blood in comparison of the patients with normal body mass and leptin level in the sera of male CM patients. Earlier revealed relationship between the concentration of leptin in blood and the level of expression of the long isoform of its receptor in tumor cells is confirmed.