BACKGROUND: Cervical cancer (CC) is the fourth most common cancer among women worldwide in terms of incidence and mortality. High-risk human papillomaviruses (HPVs) are etiologic factor of CC in more than 90% of cases, with type 16 HPV (HPV16) revealed in 50% of cancers. Dysregulation of expression of viral oncogenes E6 and E7 is the main cause of malignant transformation in infected cervical epithelial cells. The mechanisms of impaired expression of these genes are still underexplored. The dysfunction of viral microRNAs may be among the underlying factors. AIM: To analyze the expression of HPV16-associated microRNA-H1 and microRNA-H2 in cervical cancer specimens, evaluate the correlation of their expression to viral load and overall patient survival, and analyze in silico their potential viral and cellular targets. MATERIALS AND METHODS: The expression of HPV16 microRNA-H1 and HPV16 microRNA-H2 was evaluated in the real-time polymerase chain reaction. With this purpose, small RNAs were isolated from 36 specimens of HPV16-positive squamous cell carcinomas of the cervix. Further, the viral load was assessed after calculating the value of HPV16 DNA copies per cell. The association between microRNA expression and the viral load was evaluated using the nonparametric Spearman’s correlation coefficient. Kaplan-Meier curves were plotted to analyze the dependence of 5-year overall survival on the level of viral microRNA expression. The miRanda algorithm and online services mirDB, MR-microT and TargetScan Custom 5.2 were used for in silico search of theoretical microRNA targets. RESULTS: MicroRNA-H1 expression was revealed in 33 of 38 specimens (86.8%), microRNA-H2 was detected in 37 of 38 specimens (97.4%) of HPV16-positive cervical cancer. There was a positive correlation between both microRNA-H1 (r=0.36, p=0.042) and microRNA-H2 (r=0.51, p=0.001) expression and HPV16 viral load. Higher level of expression of viral microRNA-H1 and microRNA-H2 tended to correlate with better overall patient survival. The theoretical microRNA-H1 (E7, E2, E5, L2 and URR) and microRNA-H2 (E1, E2, E5, L2, L1, URR) targets in the HPV16 genome were identified in silico, as well as theoretical cellular targets indicating possible regulation of cellular signaling pathways by means of viral microRNAs, both controlling normal viral cycle and promoting tumor transformation. CONCLUSION: The results of this study demonstrate promising further investigation of the functions of viral microRNAs in relation with the infectious process and virus-induced malignant transformation, and their potential importance in the diagnosis of HPV16-associated cancers.

Introduction. Human papillomavirus (HPV) infection with high-risk HPVs is an etiological factor in the development of cervical cancer, with HPV type 16 (HPV16) being the most common. The mechanisms leading to disruption of viral oncogene expression and initiation of epithelial cell transformation are poorly understood. Epigenetic regulatory factors, including cellular miRNAs, may play an important role in HPV-induced carcinogenesis, and aberrantly expressed miRNAs may be promising markers for the diagnosis of HPV-associated lesions.Aim. To search for miRNAs involved in the pathogenesis of HPV16-associated cervical cancer and to evaluate their diagnostic potential for the detection of cervical cancer and precancerous lesions.Materials and methods. MiRNA expression in clinical samples was assessed by both next generation sequencing and quantitative stem-loop polymerase chain reaction (sl-qPCR). Plasma miRNAs from patients with precancerous and cancerous lesions and healthy donors were analyzed using sl-qPCR. Loss of heterozygosity in cervical cancer samples was assessed by copy number ratio of MIR135A1 and ACTB genes. A total of 67 patients with cervical cancer, 21 with precancerous cervical lesions and 24 healthy donors were included in the study. The effect of DNA methylation on miRNA-135A1 expression was evaluated after treatment with a demethylating agent of the cervical HPV16-positive SiHa cell line. Changes in the expression of the HPV16 E6 oncogene were analyzed after transfection with synthetic analogues of the mature forms of miRNA-135А1 (miRNA-135a-3p and miRNA-135a-5p).Results. A significant decrease in the expression of miRNA-135A1 and miRNA-135A2 was detected in tumor tissue samples from HPV16-positive cervical cancer, which was confirmed by sl-qPCR in an independent panel of tumor samples. A decrease in miRNA-135A1 expression was shown to result from both loss of heterozygosity of the gene and aberrant DNA methylation. Transfection of mature forms of miRNA-135A1 into SiHa cells resulted in decreased expression of the E6 oncogene of HPV16. Blood plasma samples from patients with cervical cancer and precancerous lesions showed lower levels of miRNA-135a-3p than healthy donors, and ROC analysis indicated its high diagnostic potential.Conclusion. Levels of miRNA-135A1 are significantly reduced in cervical lesions, both in tumor tissue and plasma, and the ability of this miRNA to suppress the expression of the HPV16 E6 oncogene suggests its oncosuppressive properties. Thus, miRNA-135A1 can be used as a promising new marker for the diagnosis of HPV-associated lesions.

Aim: Resistance to hormonal and targeted therapies in breast cancer limits treatment efficacy. Epigenetic alterations, including changes mediated by DNA methyltransferases, play a key role in this process. Previously, we identified that resistance to tamoxifen and rapamycin is associated with the suppression of DNMT3A. This study aims to further explore the mechanisms underlying this suppression, with a focus on identifying NR6A1 as a novel regulatory factor. Methods: Acquisition of resistant breast cancer cell sublines, MTT-test, immunoblotting, transient transfection and reporter analysis, lentiviral infection, qRT-PCR, and analysis of methylation using bisulfite pyrosequencing. Results: Our findings indicate that the development of cross-resistance in breast cancer cells to hormonal and targeted therapies involves a shift in cell signaling to alternative AKT pathways, marked by a localized suppression of the NR6A1/DNMT3A axis and associated DNA methylation changes. We demonstrated the critical role of NR6A1 downregulation in resistance development. Additionally, we observed activation of Snail - a key regulator in the epithelial-mesenchymal transition - as a mediator of the effects of NR6A1 depletion, establishing a direct link between Snail expression and resistance formation. Conclusion: The coordinated suppression of NR6A1 and DNMT3A may contribute to sustaining the resistant phenotype in breast cancer cells. This pathway could serve as a predictive marker, helping guide the selection of optimal therapeutic strategies for breast cancer treatment in the future.

Introduction . Rearrangement of molecular pathways and activation of bypass signaling determine the progression of tumor cell resistance to various drugs. Study of the common features of resistant formation mechanisms is essential for breast and other cancer beneficial treatments. Materials and methods . The present work was performed on estrogen receptor α ERα-positive (ERα – estrogen receptor α) McF-7 breast cancer cells, established sublines resistant to the mTOR inhibitor rapamycin or antiestrogen tamoxifen, and ERα-negative MDA-MB-231 breast cancer cells. Methods used include MTT test, transient transfection, immunoblotting, real-time polymerase chain reaction and methylation analysis by bisulfite pyrosequencing. Results . We have shown that the resistance of breast cancer cells to targeted and hormonal drugs is associated with the suppression of DNA methyltransferase 3A (DNMT3A) and respective changes in DNA methylation; DNMT3A knockdown results in the partial resistance to both drugs demonstrating the pivotal role of DNMT3A suppression in the progression of cell resistance. Conclusion . Totally, the results obtained highlight the possible mechanism of tumor cell resistance to targeting/hormonal drugs based on the deregulation of DNMTs expression and demonstrate direct connection between DNMT3A suppression and resistance progression.

Introduction. Retinoic acid (RA) is a key regulator of cell differentiation and a critical player in such systemic processes in the body as embryonic development, immune system cell maturation and functioning, tissue remodeling and several others. This compound displays an antitumor activity due to its ability to stimulate differentiation, induce apoptosis and inhibit proliferation of malignant cells. The rapid acquisition of resistance to RA and its analogues by solid tumor cells is one of the main problems limiting the widespread use of retinoids in the therapy of malignant neoplasms. The mechanisms of RA-resistance are still poorly understood. The study objective – assessment of the relationship between the basal expression level of the nuclear RARα receptor and the RA-induced expression of the cytochromes CYP26A1 and CYP26B1 with the resistance of breast cancer cells to the action of all-trans-retinoic acid. Materials and methods. Cell lines were cultured, the sensitivity of breast cancer cells to the action of fully trans-retinoic acid, RNA isolation, reverse transcription reaction and real-time polymerase chain reaction were analyzed). Results. In present study, using an experimental model represented by 9 breast cancer cell lines with different level of sensitivity to RA, we showed that the expression of the RA nuclear receptor RARα , as well as the level of mRNA induction of CYP26A1 and CYP26B1 cytochromes in response to RA treatment correlate with RA-sensitivity. Conclusion. Thus, a decrease of RARα expression as well as the reduced ability to catabolize RA are factors associated with RA-resistance of breast cancer cells.

Extracellular vesicles (EVs), including exosomes, are key factors of intercellular communication, performing both local and distant transfers of bioactive molecules. The increasingly obvious role of EVs in carcinogenesis, similarity of molecular signatures with parental cells, precise selection and high stability of cargo molecules make exosomes a promising source of liquid biopsy markers for cancer diagnosis. The uterine cavity fluid, unlike blood, urine and other body fluids commonly used to study EVs, is of local origin and therefore enriched in EVs secreted by cells of the female reproductive tract. Here, we show that EVs, including those corresponding to exosomes, could be isolated from individual samples of uterine aspirates (UA) obtained from epithelial ovarian cancer (EOC) patients and healthy donors using the ultracentrifugation technique. First, the conducted profiling of small RNAs (small RNA-seq) from UA-derived EVs demonstrated the presence of non-coding RNA molecules belonging to various classes. The analysis of the miRNA content in EVs from UA performed on a pilot sample revealed significant differences in the expression levels of a number of miRNAs in EVs obtained from EOC patients compared to healthy individuals. The results open up prospects for using UA-derived EVs as a source of markers for the diagnostics of gynecological cancers, including EOC.

INTRODUCTION:High carcinogenic-risk human papillomaviruses (hrHPVs) are recognized as etiological agents of cervical cancer. Constant expression of the viral oncoproteins, E6 and E7, is required for maintenance of the malignant phenotype of tumor cells. The exact mechanism of regulation of viral oncogenes expression in tumor cells is not fully elucidated.THE PURPOSE:identification of viral noncoding RNAs (ncRNAs) in HPV16-positve cervical cancer.MATERIALS AND METHODS:The reverse transcription polymerase chain reactions were used to detect viral ncRNAs in HPV16-positve primary cervical squamous cell carcinomas and SiHa and CasKi cell lines. The knockdown technique with oligonucleotides complementary to ncRNAs was used to elucidate their functions.RESULTS:We have identified ncRNAs transcribed in the upstream regulatory region of HPV16 in the cervical carcinoma cell lines and in 32 out 32 cervical squamous cell carcinomas with episomal or integrated forms of HPV16 DNA. Knockdown of sense or antisense strains of ncRNAs by oligonucleotides results in a decrease or increase of the E6 and E7 oncogenes mRNA levels in cells, respectively. These changes of oncogenes mRNA levels are accompanied by the modulation of the levels of the p53 protein, the main target of the E6 oncoprotein.CONCLUSION:The presence of regulatory ncRNAs in all examined tumors and cell lines revealed for the first time indicates their necessity for maintenance of constant expression of E6 and E7 oncogenes in them. The findings can be useful for understanding of the fundamental aspects of the viral expression regulation in HPV16-positive tumors.

Secreted extracellular vesicles (EVs) contain active biomolecules, including miRNAs, composition of which reflects epigenetic changes occurring in cells during pathological processes, in particular, malignant transformation. The accumulated pool of data on the role of EVs in carcinogenesis has stimulated investigations of the EV-derived cancer markers. The most important factor limiting development of this scientific direction is lack of "gold standards" both for methods of EV isolation from biological fluids and for analyzing their molecular content, including composition of miRNAs. Here we first examined efficacy of various methods for small RNA isolation from EVs contained in ascitic fluid for subsequent miRNA analysis. Comparison of different commercial kits showed advantages of the methods based on phenol-chloroform extraction: Total Exosome RNA & Protein Isolation Kit and miRNeasy Serum/Plasma Kit. Analysis of the small RNA transcriptome showed presence of various classes of molecules in the EVs, among which proportion of miRNAs averaged 6% and reaching 10% with the Total Exosome RNA & Protein Isolation Kit. The PureLink miRNA Isolation Kit demonstrated the lowest efficiency. The miRNeasy Advanced Serum/Plasma Kit showed the highest concentration of the small RNA fraction, miRNA proportion of which, however, did not exceed that obtained with the miRNeasy Serum/Plasma Kit and Total Exosome RNA & Protein Isolation Kit. Moreover, RT-PCR analysis of the individual molecules showed lower levels of each of investigated miRNAs (miR-1246, miR-200b-5p, miR-200c-3p, and miR-23a-3p) when using the miRNeasy Advanced Serum/Plasma Kit. In conclusion, Total Exosome RNA & Protein Isolation Kit and miRNeasy Serum/Plasma Kit can be considered as optimal kits in terms of performance based on combination of the studied characteristics, including small RNA concentration, percentage of microRNA according to bioanalyzer and sequencing results, and levels of individual miRNAs detected by RT-PCR.

The recombinant proteins E6-CBD and E7-CBD, which are antigens E6 and E7 of human papillomavirus type 16 (HPV16), were connected by a glycine-serine spacer with the cellulose-binding domain (CBD) of Anaerocellum thermophilum in preparations obtained via synthesis in a heterologous expression system in Escherichia coli. A simple, effective, one-step technology for the isolation and purification of recombinant proteins E6-CBD and E7-CBD has been developed. The presence of antigenic properties in the obtained protein preparations was confirmed via Western blot. Three variants of immunogenic compositions with the recombinant proteins E6-CBD and E7-CBD and a three-dose immunization scheme have been developed. The immunogenicity was assessed in the BALB/c mice, and the antitumor effect of immunogenic compositions was studied on an experimental model of BALB/c mice with HPV16-associated tumors. It is shown that E6-CBD and E7-CBD are highly immunogenic and have antitumor effects in vivo. Both proteins, E6-CBD and E7-CBD, must be present to achieve the highest efficiency as part of the immunogenic composition. The obtained HPV16 recombinant antigens E6-CBD and E7-CBD can be used in two ways: (a) in clinical practice as the main specific components of therapeutic vaccines for the treatment of HPV16-associated neoplastic lesions of various localizations (cervical cancer, carcinoma of the anogenital tract, oropharynx) and (b) in diagnostics for the development of diagnostic kits to detect antibodies to E6 and E7 oncoproteins in patients with HPV16-associated malignant neoplasms.