Tatiana M. Zavarykina

Triple-negative breast cancer (TNBC) is the most unfavorable subtype of breast cancer. Achieving pathological complete responce (pCR) is an important prognostic factor in patients diagnosed with TNBC, as it is associated with increased overall and disease-free survival. Currently, clinical parameters and pathological examination of resection tissue after surgery are used to evaluate the effectiveness of neoadjuvant drug chemotherapy (NAC). Traditional clinical and instrumental methods used in routine practice (examination, palpation, ultrasound of the mammary glands and regional areas, mammography, and MRI of the mammary glands) often do not allow for an accurate assessment of the treatment effect. The rate of detection of complete responses may be lower with clinical and instrumental assessment of the effect compared to pathological examination. In this regard, there is growing interest in assessing the effect of NAC based on changes in circulating tumor DNA (ctDNA) levels in the blood, which is characterized by the presence of genetic alterations specific to tumor tissue, i.e., liquid biopsy. This study examines two clinical cases of TNBC, determining the dynamics of ctDNA level changes during treatment and comparing these results with the severity of pathological tumor responce after NAC. In one case, pathological complete responce was achieved, while in the second, significant residual tumor was detected. Mutations for tracking ctDNA level dynamics were selected based on bioinformatics analysis of whole-exome sequencing of tumor biopsy samples and patient’s blood. Plasma ctDNA levels were assessed using digital PCR (dPCR). We obtained quantitative results for ctDNA determination in the plasma of patients with TNBC at five points and compared the dynamics of ctDNA level changes with the results of NAC. The study discusses the possible relationship between the observed ctDNA dynamics and treatment response (achievement of complete pathological tumor regression) and the feasibility of using liquid biopsy in predicting tumor response to NAC.

The review discusses main characteristics and analytical features of the circulating tumor DNA (ctDNA), which accounts for a minor fraction of the cell-free DNA (cfDNA) in cancer patients. Currently, ctDNA is considered to be a promising biomarker for assessing treatment efficacy, prognosis, and disease monitoring in oncology, including breast cancer (BC). A significant proportion of BC patients receive neoadjuvant drug therapy, effectiveness of which largely determines necessity and extent of subsequent treatment. Determination of ctDNA could be the most sensitive method for evaluating response to neoadjuvant therapy, as it enables real-time monitoring of molecular changes during the treatment, prediction of therapeutic response, and assessment of recurrence risk. This approach could become an additional tool for personalization of BC therapy.

Ovarian cancer (OC) is the most lethal gynecological cancer worldwide. DNA damage plays an important role in cancer development, and the proteins encoded by XRCC1 and ERCC2 are important components of the DNA repair system. This study aimed to examine the relationship between the rs25487 XRCC1 and rs13181 ERCC2 polymorphisms and the risk of OC development in women from the Moscow region. DNA was isolated from the blood of 129 healthy donors and tissues and blood samples from 125 patients with OC and studied using real-time PCR. An increase in odds ratios (OR) was obtained for OC tissue and blood for both T (OR = 1.46, 95% confidence interval [CI] = 1.22–1.76, P = 0.00005), and for T/T of rs25487 XRCC1. The most significant OR values were found for the T/T genotype using the codominant model (OR = 2.11, 95% CI = 1.44–3.07, P = 0.00006) and dominant model (OR = 3.13, 95% CI = 1.44–6.79, P = 0.0025) for the pooled blood and tissue groups. For rs13181 ERCC2, differences were observed for the T/G genotype in OC tissues (OR = 0.69, 95% CI = 0.51–0.92, P = 0.011) in the codominant model. In this study, the association of allele T and genotypes of rs25487 XRCC1 and T/G of rs13181 ERCC2 with OC was shown. Our results indicate that these polymorphisms may be involved in the pathogenesis of OC and are promising for further studies on therapeutic applications in OC.

Background: The aim of our study was to determine the role of sphingolipids, which control proliferation and apoptosis, in the placenta of pregnant women with pregnancy-associated breast cancer (PABC) after chemotherapy compared with healthy patients. Methods: We analyzed (by the PCR method) the gene expression of key sphingolipid metabolism enzymes (sphingomyelinases (SMPD1 and SMPD3), acid ceramidase (ASAH1), ceramide synthases (CERS 1–6), sphingosine kinase1 (SPHK1), sphingosine-1-phosphate lyase 1 (SGPL1), and sphingosine-1-phosphate receptors (S1PR1, S1PR2, and S1PR3)) and the content of subspecies of ceramides, sphingosine, and sphingosine-1-phosphate in seven patients with PABC after chemotherapy and eight healthy pregnant women as a control group. Results: We found a significant increase in the expression of genes of acid ceramidase (ASAH1), sphingosine-1-phosphate lyase 1 (SGPL1), sphingosine kinase (SPHK1), and ceramide synthases (CERS 1-3, 5, 6) in the samples of patients with PABC during their treatment with cytostatic chemotherapy. The increase in the expression of the enzymes’ genes was not accompanied by changes in the content of the studied sphingolipids. Such significant changes in the expression of genes controlling the level of CER, sphingosine, and S1P may indicate their ability to initiate the metabolism of pro-apoptotic and anti-apoptotic sphingolipids in the placenta of pregnant women with cancer undergoing chemotherapy in order to maintain levels typical of the placenta of healthy women. Conclusions: Our results may indicate the promising mechanism of placenta protection during chemotherapy for pregnant women with breast cancer and, consequently, of the newborn. This protective effect of the placenta and especially for the newborn has been discovered for the first time and requires more careful study.

The spaceflight storage of seeds is known to cause mutations affecting both their quality and the mature plants originating from them. To study the effects of space stress, tomato seeds of two cultivars (Lotus and Autumn rhapsody) were subjected to half a year of storage at the International Space Station (ISS), and then, sown in a greenhouse to produce tomato fruits. The space-treated plants gave smaller fruits with a stable total yield not significantly different from that of the control plants. Space-treated tomatoes showed significantly higher levels of dry matter, dietary fiber, monosaccharides and citric and malic acids and lower values of oxalic acid compared to the control plants. The pulp of space-treated fruits had 1.44–1.70 times lower levels of carotenoids, while their peel contained a 1.27–1.90 times higher pigment amount compared to the control plants. No significant changes in the total antioxidant activity (AOA), photosynthetic pigments and phenolic (TP) and proline content were recorded in the fruits due to seed spaceflight storage. Contrarily, space-treated tomatoes showed decreased levels of Ca, Sr and Mo and increased Se both in the fruit pulp and peel. The concentration of Fe and especially Pb was lower in space-treated fruit pulp. Positive correlations between Se and dry matter, Ca and Sr, Ca and Co, Ca and Fe, and Cr and carotenoids, and negative correlations between Se and Mo, Se and K, and Mo and dry matter were recorded. The results indicate that seed stress caused by long-term spaceflight affects both the biochemical characteristics and mineral composition of tomato fruits and causes the peel/pulp redistribution of carotenoids as well as macro- and micro-elements, improving Se accumulation levels in the fruit peel.

This paper introduces the reader to the field of liquid biopsies and cell-free nucleic acids, focusing on circulating tumor DNA (ctDNA) in breast cancer (BC). BC is the most common type of cancer in women, and progress with regard to treatment has been made in recent years. Despite this, there remain a number of unresolved issues in the treatment of BC; in particular, early detection and diagnosis, reliable markers of response to treatment and for the prediction of recurrence and metastasis, especially for unfavorable subtypes, are needed. It is also important to identify biomarkers for the assessment of drug resistance and for disease monitoring. Our work is devoted to ctDNA, which may be such a marker. Here, we describe its main characteristics and potential applications in clinical oncology. This review considers the results of studies devoted to the analysis of the prognostic and predictive roles of various methods for the determination of ctDNA in BC patients. Currently known epigenetic changes in ctDNA with clinical significance are reviewed. The possibility of using ctDNA as a predictive and prognostic marker for monitoring BC and predicting the recurrence and metastasis of cancer is also discussed, which may become an important part of a precision approach to the treatment of BC.

Цель. Изучение связи полиморфных маркеров генов репарации ДНК ERCC2 (rs13181), ERCC5 (rs17655), транспортного белка ABCB1 (rs1045642, rs2032582) с клиническим ответом и степенью патоморфологической регрессии (ПР) опухоли у беременных женщин с онкологическими заболеваниями после ХТ препаратами платины.

Background. Breast cancer is the most common cancer among women. Triple negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, in which there are no special targets for therapy. Therefore chemotherapy is still leading treatment for TNBC including the regiments with platinum drugs.Aim. To study the association of polymorphic markers of the genes XRCC1 (rs25487), ERCC5 (rs17655), TP53 (rs1042522), CDKN1A1 (rs1801270) with progression-free survival (PFS) and overall survival (OS) of TNBC patients after platinum-based neoadjuvant chemotherapy.Materials and methods. Polymorphic markers of the XRCC1, ERCC5, CDKN1A and TP53 genes were studied in blood samples of 67 patients with stage II–III TNBC by real-time polymerase chain reaction with fluorescent allele-specific probes. The results of determining the markers were compared with PFS and OS using the Kaplan–Meyer method and the log-rank-test.Results. The association was found for the polymorphic marker rs25487 of the XRCC1 gene with PFS (carrying the T/T genotype was associated with a decrease of median PFS: 15.6 months versus 34.3 months, p = 0.013) and OS (carrying the T allele was associated with a decrease of median OS: 24.3 months versus 34.6 months, p = 0.041) without depending on the BRCA status. For the polymorphic marker rs17655 of the ERCC5 gene, significant difference in PFS was obtained in the period from 15.4 to 60.0 months of follow-up (the carrier of the C allele was associated with a decrease of median PFS: 20.0 months versus 35.2 months, p = 0.035). When considering the genotypes of the polymorphic marker of the ERCC5 gene differences were revealed between patients with the C/C genotype (M = 15.9 months) and two other genotypes (M = 33.6 months), p = 0.039. For the polymorphic marker rs1801270 of the CDKN1A gene significant differences in PFS were obtained in the period from 15.4 to 60.0 months of follow-up (for carriers of allele A, a decrease in median PFS was observed: 16.6 months versus 32.0 months, p = 0.046). For the polymorphic marker of the TP53 gene (rs1042522) a tendency to decrease OS for carriers of the C/C genotype was found seems promising for further study.Conclusion. The association of the studied polymorphic markers of the genes XRCC1 (rs25487), ERCC5 (rs17655) and CDKN1A (rs1801270) with PFS was revealed in patients with TNBC. Association with OS was obtained for the polymorphic marker of the XRCC1 gene (rs25487). These data may allow for further validation to individualize the treatment of this category of patients.

The distribution of allele frequencies of polymorphic markers of the genes of the apoptosis and cell cycle control system TP53 (rs1042522), MDM2 (rs2279744), and CDKN1A (rs1801270) was obtained. The relationship of these markers with the risk of ovarian cancer was analyzed in women of the Moscow region. The study included 70 healthy female donors and 66 patients with ovarian cancer. DNA isolated from the blood of healthy donors and tissue and blood of patients with ovarian cancer was studied. The polymorphic markers of genes were analyzed by real-time PCR with fluorescent allele-specific probes. In the work, the odds ratios (OR) of ovarian cancer risk were obtained: OR = 0.94, 95% CI = 0.57–1.65, p = 1.0 for the Pro allele of the Arg72Pro of the TP53 gene; OR = 0.96, 95% CI = 0.49–1.89, p = 0.90 for the G allele of the T(–410)G of the MDM2 gene; OR = 1.53, 95% CI = 0.76–3.09, p = 0.29 for the Arg allele of the Ser31Arg of the CDKN1A gene. Obtained results show no association with ovarian cancer for studied markers. It was revealed that the carriage of minor alleles of the Arg72Pro of the TP53 gene, T(–410)G of the MDM2 gene, and Ser31Arg of the CDKN1A gene did not affect the risk of development of ovarian cancer in women of the Moscow region.

We analyzed associations of polymorphic markers of DNA repair genes (XRCC1, ERCC2), cell cycle control genes (TP53, MDM2, and CDKN1A), methylation of promoter region, and mutation 5382insC of BRCA1 gene in ovarian cancer with effectiveness of platinumbased chemotherapy assessed by the median of progression-free survival time for markers of DNA repair genes and by relapse risk for all studied markers. An increase in the median of progression-free survival time for carriers of the Gln allele (р=0.025) and Gln/Gln genotype (р=0.022) of the Gln399Arg XRCC1 was observed during the 19-months period after chemotherapy. In carriers of C/C genotype of 5382insC mutation of BRCA1 gene (n=6), no relapses were observed (р=0.035), while 17 of 49 patients without this mutation developed relapses. Of 14 patients with BRCA1 gene function inactivation due to promoter methylation or the presence of the C/C genotype of 5382insC, one relapse was observed (p=0.033). Multivariate analysis revealed an association of markers of the XRCC1, TP53, MDM2 genes, BRCA1 gene inactivation, and type of surgery with the risk of relapse during the follow-up period up to 19 months after the end of chemotherapy (р≤0.0007).