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Purpose: Previous research has shown, that ABC transporters gene expression level can predict the efficacy of therapy. However, other mechanisms of gene activity are rarely considered, especially in non-small cell lung cancer (NSCLC). Thus, the purpose of the work was to assess chromosomal aberrations of all 49 ABC transporters genes and the expression levels of some ABC genes, as well as their correlation with survival., Materials and Methods: The surgical material of 104 patients with NSCLC was used in this study. Treatment included surgery and 3 courses of adjuvant chemotherapy with "platinum doublets". DNA and RNA were isolated from the samples, followed by microarray analysis to assess the expression and chromosomal aberrations (deletions and amplifications) of ABC genes., Results: Metastatic-free survival (MFS) was higher with ABCC1, ABCC2, and ABCG1 hypoexpression at a statistically significant level (p=0.01). The presence of deletion in ABCB1 correlates with 100% MFS (p=0.001). The survival rates with ABCG1 amplification are not higher than 45% (p<0.0001). ABCA11 deletion is associated with a low MFS rate (38%) versus 91% with normal copy number (p=0.006). ABCB9 analysis showed opposite results, with survival rates of 55% and 91% in the presence of amplification and normal copy number, respectively (p=0.006). ABCC subfamily genes showed a similar result in the presence of amplification, where ABCC3 and ABCC10 account for 64% and 60% survival, respectively (p=0.005, p=0.01)., Conclusion: Thus, not only expression but also chromosomal aberrations were found to be associated with patient survival. These findings could be a potential marker of metastatic-free survival., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

We propose an original strategy for metastasis prevention using a combination of three microRNAs that blocks the dedifferentiation of cancer cells in a metastatic niche owing to the downregulation of stemness genes. Transcriptome microarray analysis was applied to identify the effects of a mixture of microRNAs on the pattern of differentially expressed genes in human breast cancer cell lines. Treatment of differentiated CD44 - cancer cells with the microRNA mixture inhibited their ability to form mammospheres in vitro. The combination of these three microRNAs encapsulated into lipid nanoparticles prevented lung metastasis in a mouse model of spontaneous metastasis. The mixture of three microRNAs (miR-195-5p/miR-520a/miR-630) holds promise for the development of an antimetastatic therapeutic that blocks tumor cell dedifferentiation, which occurs at secondary tumor sites and determines the transition of micrometastases to macrometastases.

Background: Peritoneal carcinomatosis (PC) is one of the most unfavorable sites of metastasis for malignant tumors of various localizations, especially gastric cancer (GC). According to the literature, synchronous PC in GC is common in 15-52% of patients. The purpose of this study was to examine the long-term results using personalized systemic and intraperitoneal chemotherapy as part of the combined treatment of stomach cancer presenting with synchronous PC., Methods: Cytoreductive surgical treatment was performed for 70 patients at the first stage. The control group (n = 35) received standard postoperative chemotherapy according to the FOLFOX scheme. Personalized postoperative systemic and intraperitoneal chemotherapy was administered in the basic group (n = 35), based on the expression levels of the eight genes in the primary tumor, lymph node, and peritoneal metastases., Results: The median progression-free survival was 14.9 months in the basic group, and in the control group it was 11.2 months (P < 0.001). The median life expectancy in the basic group was 16.8 (13.7 - 18.8) months, in the control group it was 12.5 (11.3 - 13.1) months (P < 0.001)., Conclusions: Developing algorithms of personalized systemic and intraperitoneal chemotherapy in patients with GC with synchronous carcinomatosis, based on the analysis of molecular genetic characteristics of the tumor and metastases, allows to improve the long-term results of combined treatment., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright 2024, Markovich et al.)

To date, numerous mechanisms have been identified in which one cell engulfs another, resulting in the creation of 'cell-in-cell' (CIC) structures, which subsequently cause cell death. One of the mechanisms of formation of these structures is entosis, which is presumably associated with possible carcinogenesis and tumour progression. The peculiarity of the process is that entotic cells themselves actively invade the host cell, and afterwards have several possible variants of fate. Entotic formations are structures where one cell is engulfed by another cell, creating a cell-in-cell structure. The nucleus of the outer cell has a crescent shape, while the inner cell is surrounded by a large entotic vacuole. These characteristics differentiate entosis from cell cannibalism. It's worth noting that entotic formations are not necessarily harmful and may even be beneficial in some cases. In this article we will consider the mechanism of entosis and variants of entotic cell death, and also put forward hypothesis about possible variants of participation of this process on the formation and progression of cancer. This article also presents our proposed classification of functional forms of entosis., (© 2024. The Author(s).)

Breast cancer (BC) remains one of the most common malignancies among women worldwide. Breast cancer shows metastatic heterogeneity with priority to different organs, which leads to differences in prognosis and response to therapy among patients. The main targets for metastasis in BC are the bone, lung, liver and brain. The molecular mechanism of BC organ-specificity is still under investigation. In recent years, the appearance of new genomic approaches has led to unprecedented changes in the understanding of breast cancer metastasis organ-specificity and has provided a new platform for the development of more effective therapeutic agents. This review summarises recent data on molecular organ-specific markers of metastasis as the basis of a possible therapeutic approach in order to improve the diagnosis and prognosis of patients with metastatically heterogeneous breast cancer.

The involvement of human papillomavirus (HPV) in the prostate carcinogenesis is a controversial issue. The presented meta-analysis was carried out to systematize the currently available research results regarding this question. The meta-analysis includes case-control studies from 1991 to 2022, which were collected from publicly available bibliometric databases. The meta-analysis was performed using Meta-Essentials&#95;1.5 software. We used Begg's and Egger's methods to assess publication bias. Cochran's Q test was used to assess heterogeneity and the I 2 index was employed for calculating the variation in the pooled estimations. The analysis was based on data from 27 case-control studies, which in total yielded 1607 tumour tissue samples of prostate and 1515 control samples (317 samples of normal tissue, 1198 samples of benign prostatic hyperplasia (BPH)). According to the data obtained, there was high risk of prostate cancer by HPV infection in both cases. HPV was found in prostate cancer in 25.8% of cases, while in normal tissue samples the virus was detected in 9.2% of cases and in 17.4% with BPH as a control. In particular, more studies on the association of HPV and prostate cancer are needed to prove the role of HPV in the development of prostate cancer. In addition to the controversial question of whether HPV infection is associated with prostate cancer risk, it is worth considering whether the samples used as a control have an impact on the results. The impact of HPV in prostate tumour tissue samples on outcome should also be investigated., (© 2023. Springer Nature Limited.)

It has been shown that the loss of function of the BRCA1 , BRCA2 , and PALB2 genes due to a number of hereditary mutations or chromosomal aberrations can affect the effectiveness of chemotherapy treatment and disease prognosis in patients with various types of cancer, and in particular in breast cancer. Thus, the aim of the work was to evaluate the predictive and prognostic potential of DNA copy number aberrations and mutations in the BRCA1 , BRCA2 , and PALB2 genes in breast tumors., Materials and Methods: The study included 66 patients with breast cancer. DNA copy number aberrations (CNA) were assessed by high-density CytoScanHD™ Array micro matrix analysis. Gene mutations were assessed by sequencing on the MiSeq™ Sequencing System using the Accel-Amplicon BRCA1 , BRCA2 , and PALB2 Panel., Results: It has been established that the presence of a normal copy number of PALB2 is associated with a lack of response to chemotherapy in Taxotere-containing treatment regimens ( p = 0.05). In addition, the presence of a PALB2 deletion is associated with 100% metastatic survival rates (log-rank test p = 0.04). As a result of sequencing, 25 mutations were found in the BRCA1 gene, 42 mutations in BRCA2 , and 27 mutations in the PALB2 gene. The effect of mutations on the effectiveness of treatment is controversial, but an effect on the survival of patients with breast cancer has been shown. So, in the presence of pathogenic mutations in the BRCA2 gene, 100% metastatic survival is observed (log-rank test p = 0.05), as well as in the elimination of PALB2 mutations during treatment (log-rank test p = 0.07)., Conclusion: Currently, there is little data on the effect of chromosomal aberrations and mutations in the BRCA1/2 and PALB2 genes on the effectiveness of treatment and prognosis of the disease. At the same time, the study of these genes has great potential for testing focused on a personalized approach to the treatment of patients with breast cancer.

Critical evaluation of how and when to include anthracyclines in preoperative chemotherapy is becoming more relevant in an era when the molecular genetic approach not only allows for the development of biologically targeted therapeutics, but also implies the ability to select the patients likely to benefit from certain cytotoxic agents. Changes in the copy number aberration (CNA) landscape of luminal B HER2- negative (HER2-) breast cancer (BC) during anthracycline-based neoadjuvant chemotherapy (NAC) regimens were studied in order to identify groups of potential CNA markers of objective response and CNA markers for predicting the development of hematogenous metastasis. Comparison of CNA frequencies depending on the response to NAC showed that objective response was observed in a larger number of deletions in the 11q22.3 and 11q23.1 loci ( p = 0.004). Comparison of CNA frequencies in groups of patients after treatment showed that hematogenous metastasis was observed with a greater number of amplifications in the 9p22.2 locus ( p = 0.003) and with a greater number of deletions in the 9p21.3 locus ( p = 0.03). Potential predictive CNA markers of objective response and prognostic CNA markers of hematogenous metastasis in anthracycline- based NAC regimens have been identified., (Copyright ® 2023 National Research University Higher School of Economics.)

Background: the present study aims to prove or disprove the hypothesis that the state of copy number aberration (CNA) activation of WNT signalling pathway genes accounts for the ability of differentiated tumour cells to emerge from postchemotherapy shock., Methods: In the first step, the CNA genetic landscape of breast cancer cell lines BT-474, BT-549, MDA-MB-231, MDA-MD-468, MCF7, SK-BR-3 and T47D, which were obtained from ATCC, was examined to rank cell cultures according to the degree of ectopic activation of the WNT signalling pathway. Then two lines of T47D with ectopic activation and BT-474 without activation were selected. The differentiated EpCAM+CD44-CD24-/+ cells of these lines were subjected to IL6 de-differentiation with formation of mammospheres on the background of cisplatin and WNT signalling inhibitor ICG-001., Results: it was found that T47D cells with ectopic WNT signalling activation after cisplatin exposure were dedifferentiated to form mammospheres while BT-474 cells without ectopic WNT-signalling activation did not form mammospheres. The dedifferentiation of T47D cells after cisplatin exposure was completely suppressed by the WNT signalling inhibitor ICG-001. Separately, ICG-001 reduced, but did not abolish, the ability to dedifferentiate in both cell lines., Conclusions: these data support the hypothesis that the emergence of differentiated tumour cells from postchemotherapy shock after chemotherapy is due to ectopic activation of WNT signalling pathway genes., Competing Interests: The authors declare no conflict of interest.

Our genome consists not only of protein-coding DNA, but also of the non-coding part that plays a very important role in the regulation of all cellular processes. A part of the non-coding genome comes with non-coding RNAs (ncRNAs), and disruption of the functional activity of these RNAs may be associated with oncogenesis in various cancer types. There exist two types of ncRNAs: small and long non-coding RNAs, which are classified according to their transcript length. Long non-coding metastasis-associated lung adenocarcinoma transcript 1, MALAT1 RNA ( NEAT2 ), is a long non-coding RNA of particular interest. The aforementioned transcript takes part in the regulation of numerous cellular processes and pathogenesis of different malignant tumors, including breast tumors. This review focuses on experimental and clinical studies into the role of MALAT1 in carcinogenesis and the progression of breast cancer., (Copyright ® 2023 National Research University Higher School of Economics.)

Despite advances in the diagnosis and treatment of breast cancer (BC), the main cause of deaths is resistance to existing therapies. An approach to improve the effectiveness of therapy in patients with aggressive BC subtypes is neoadjuvant chemotherapy (NACT). Yet, the response to NACT for aggressive subtypes is less than 65% according to large clinical trials. An obvious fact is the lack of biomarkers predicting the therapeutic effect of NACT. In a search for epigenetic markers, we performed genome-wide differential methylation screening by XmaI-RRBS in cohorts of NACT responders and nonresponders, for triple-negative (TN) and luminal B tumors. The predictive potential of the most discriminative loci was further assessed in independent cohorts by methylation-sensitive restriction enzyme quantitative PCR (MSRE-qPCR), a promising method for the implementation of DNA methylation markers in diagnostic laboratories. The selected most informative individual markers were combined into panels demonstrating cvAUC = 0.83 ( TMEM132D and MYO15B markers panel) for TN tumors and cvAUC = 0.76 ( TTC34 , LTBR and CLEC14A ) for luminal B tumors. The combination of methylation markers with clinical features that correlate with NACT effect (clinical stage for TN and lymph node status for luminal B tumors) produces better classifiers, with cvAUC = 0.87 for TN tumors and cvAUC = 0.83 for luminal B tumors. Thus, clinical characteristics predictive of NACT response are independently additive to the epigenetic classifier and in combination improve prediction., Competing Interests: The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

The significance of the role of human papillomavirus (HPV) in the development of lung cancer remains an open question. The data from the literature do not provide conclusive evidence of HPV being involved in the pathogenesis of lung cancer. The aim of this work was to detect the presence of HPV infections with a high carcinogenic risk in patients with non-small cell lung cancer (NSCLC)., Materials and Methods: the study involved 274 patients with stage IIA-IIIB non-small cell lung cancer. We analyzed normal and tumor tissues as well as blood from each patient. DNA was extracted from patients' specimens, and HPV detection and genotyping was carried out using commercially available kits by PCR., Results: HPV was detected in 12.7% of the patients (35/274 of all cases). We detected nine different types of human papillomavirus in the patients, namely, types 16, 18, 31, 35, 45, 51, 52, 56, and 59. The HPV-positive samples had a clinically insignificant viral load and were predominantly integrated. The relationship between the presence of HPV and its virological parameters and the clinical and pathological parameters of the patients was established. A metastatic-free survival analysis showed that all patients with HPV in the tumor tissue had a higher 5-year survival rate (94%) compared with the HPV-negative patients (78%). The result was not statistically significant ( p = 0.08)., Conclusions: data showing a 12.7% human papillomavirus representation among patients with non-small cell lung cancer were obtained. The presence/absence of a viral component in patients with lung cancer was a clinically significant parameter. HPV types 16, 18, and 56, which are the most oncogenic, were most often detected.

The concept of BRCAness was developed because of similarities between sporadic and hereditary breast cancer. BRCAness defines the pathogenesis and treatment sensitivity of many types of cancer, as well as the presence of a defect in the homologous recombination repair of tumor cells simulating the loss of BRCA1 or BRCA2 , as in the presence of germline mutations. The question of treatment effectiveness for BRCA-like tumors is controversial and open. Thus, the aim of this work was to study the effectiveness of neoadjuvant chemotherapy (NAC) in BRCA-deficient breast cancer patients without germline mutations. The study involved 130 patients with breast cancer in stages IIA-IIIB. The treatment regimen included neoadjuvant chemotherapy, surgery, and adjuvant chemotherapy. The materials used were tumor samples from before and after chemotherapy. DNA and RNA were isolated from the tumor material. RNA was used to assess the expression level of BRCA1 , while DNA was used for methyl-sensitive PCR. A microarray analysis was performed on high-density DNA chips from an Affymetrix CytoScan TM HD Array to assess DNA copy number aberration (CNA status) and loss of heterozygosity. A statistical analysis was performed using the Statistica 8.0 application package. It was noted that the existence of copy number aberrations in genes was statistically significantly associated with tumor treatment response and disease prognosis. Patients with partial regression had a statistically significantly higher amount of deletion than patients without an objective response (5/25 patients; 16%), as shown in the general sample of patients (52.9% versus 27.1%, respectively) at p = 0.0001 and in patients treated with anthracycline-containing regimen ( p = 0.0001). In addition, it was shown that patients with BRCA1 deletion had higher rates of metastatic-free survival (log rank test, p = 0.009). BRCAness patients had a higher rate of 5-year metastatic survival, but not of treatment efficacy. The prospective study showed the positive effect of assessing the BRCAness phenotype of a tumor before treatment and of prescribing personalized NAC regimens. The objective response rate was statistically significantly more often observed in the group of patients with personalized chemotherapy (85.0% (34/40 patients) versus 62.3% (56/90 patients); p = 0.007). Despite the controversial effectiveness of BRCA-like tumor treatment, our data showed high predictive and prognostic significance of the BRCAness phenotype for the personalization of platinum and taxane regimens.

The assessment of molecular genetic landscape changes during NAC and the relationship between molecular signatures in residual tumors are promising approaches for identifying effective markers of outcome in breast cancer. The majority of the data in the literature present the relationship between the molecular genetic landscape and the response to NAC or are simply descriptive. The present study aimed to determine changes in expression profiles during NAC and assess the relationship between gene expression and the outcome of patients with luminal B HER2 breast cancer depending on distant hematogenous metastasis. The study included 39 patients with luminal B HER2-BC. The patients received 6-8 courses of NAC, and paired samples consisting of biopsy and surgical materials were analyzed. A full transcriptome microarray analysis was performed using the human Clariom™ S Assay platform (Affymetrix, 3450 Central Expy, Santa Clara, CA, 95051, USA). A comparison of the expression profiles of patients with breast cancer before and after NAC, depending on the status of hematogenous metastasis, was conducted. It was shown that the amount of DEGs in the tumor was reduced by more than six times after NAC. The top 10 signaling pathways were also found, the activity of which varied depending on the status of hematogenous metastasis before and after NAC. In addition, the association of DEGs with hematogenous metastasis in patients with breast cancer was evaluated: MFS was assessed depending on the expression level of 21 genes. It was shown that MFS was significantly associated with the expression level and pattern of nine genes. The expression levels of nine DEGs in the tumors of patients with breast cancer after NAC were significantly correlated with MFS when the status of hematogenous metastasis was taken into account.

Objectives: A growing body of evidence suggests the important role of chemosensitive gene expression in the prognosis of patients with lung cancer. However, studies on combined gene expression assessments for personalized prescriptions of chemotherapy regimens in patients have not yet been conducted. The aim of this work was to conduct a prospective study on the appointment of personalized chemotherapy in patients with non-small-cell lung cancer. Materials and methods: The present study analyzed 85 patients with lung cancer (stage IIB-IIIB). Within this group, 48 patients received individualized chemotherapy, and 37 patients received classical chemotherapy. In the individualized chemotherapy group, the mRNA expression levels of ERCC1, RRM1, TUBB3, TYMS, TOP1, TOP2α, BRCA1, and GSTP1 in lung tissues were measured by quantitative real-time PCR (qPCR), and an individual chemotherapy regimen was developed for each patient according to the results. Patients in the classical chemotherapy group received the vinorelbine/carboplatin regimen. Survival analyses were performed using the Kaplan−Meier method. Prognostic factors of metastasis-free survival (MFS) and overall survival (OS) of patients were identified via Cox’s proportional hazards regression model. Results: MFS and OS were significantly better in the personalized chemotherapy group compared to the classic chemotherapy group (MFS, 46.22 vs. 22.9 months, p = 0.05; OS, 58.6 vs. 26.9 months, p < 0.0001). Importantly, the best metastasis-free survival rates in the group with personalized ACT were achieved in patients treated with the paclitaxel/carboplatin regimen. Based on an assessment of chemosensitivity gene expression in the tumors, the classical chemotherapy strategy also increased the risk of death (HR = 14.82; 95% CI: 3.33−65.86; p < 0.000) but not metastasis (HR = 1.95; 95% CI: 0.96−3.98; p = 0.06) compared to the group of patients with chemotherapy. Conclusions: The use of combined ERCC1, RRM1, TUBB3, TYMS, TOP1, TOP2α, BRCA1, and GSTP1 gene expression results for personalized chemotherapy can improve treatment efficacy and reduce unnecessary toxicity.

One of the important reasons for the ineffectiveness of chemotherapy in breast cancer (BC) is considered to be the formation of a multidrug resistance phenotype in tumour cells, which is caused by the expression of energy-dependent ABC transporters. The aim of this work was to assess chromosomal aberrations and the level of transcripts of all 49 known ABC transporter genes in breast tumours., Materials and Methods: The study included 129 patients with breast cancer. A microarray study of all tumour samples was carried out on microchips., Results: This study established that the presence of a deletion in genes ABCB1, ABCB4, ABCB8, ABCC7, ABCC11, ABCC12, ABCF2, and ABCG4 is associated with an objective response to treatment ( p ≤ 0.05). A decrease in the expression of genes was associated with a good response to chemotherapy, whereas an increase in expression caused the progression and stabilization of the tumour. Analysis of metastatic-free survival rates showed that the presence of ABCB1/4 and ABCC1/6 deletions was associated with 100% survival (log-rank test p = 0.01 and p = 0.03)., Conclusions: The study showed that the aberrant state of ABC transporter genes, as well as a decrease in the expression of these genes, is a predictor of the effectiveness of therapeutic treatment and a potential prognostic marker of metastatic survival.

Increasingly, many researchers are focusing on the sensitivity in breast tumors (BC) to certain chemotherapy drugs and have personalized their research based on the assessment of this sensitivity. One such personalized approach is to assess the chemotherapy's gene expression, as well as aberrations in the number of DNA copies-deletions and amplifications with the ability to have a significant effect on the gene's activity. Thus, the aim of this work was to study the predictive and prognostic significance of the expression and chromosomal aberrations of eight chemosensitivity genes in breast cancer patients., Material and Methods: The study involved 97 patients with luminal B breast cancer IIB-IIIB stages. DNA and RNA were isolated from samples of tumor tissue before and after treatment. Microarray analysis was performed for all samples on high-density microarrays (DNA chips) of Affymetrix (USA) CytoScanTM HD Array and Clariom™ S Assay, human. Detection of expression level of seven chemosensitivity genes- RRM1 , ERCC1 , TOP1 , TOP2a , TUBB3 , TYMS , and GSTP1 -was performed using PCR real-time (RT-qPCR)., Results: The expression of the RRM1 (AC scheme), TOP2α , TYMS , and TUBB3 genes in patients with an objective response to treatment (complete and partial regression) is higher than in patients with stabilization and progression ( p < 0.05). According to our results, the presence of a high level of GSTP1 in a tumor biopsy is associated with the low efficiency of the NAC CP scheme ( p = 0.05). The presence of RRM1 deletion is associated with complete and partial regression, as for the TOP1 and TUBB3 genes ( p < 0.05). Higher rates of metastatic survival are associated with a high level of expression and amplification of the GSTP1 gene (log-rank test p = 0.02 and p = 0.05)., Conclusion: Thus, a complex assessment of the chemotherapy's gene expression is important not only for understanding the heterogeneity and molecular biology of breast cancer but also to obtain a more accurate disease prognosis.

Introduction: In this research, we studied how the expression of 14 stem genes (TERT; OCT3; SMO; MYC; SNAI2; MOB3B; KLF4; BMI1; VIM; FLT3; LAT; SMAD2; LMNB2; KLF1), as well as the TGF-β1 cytokine gene and its TGFBR1 receptor in breast tumors before and after NAC is associated with clinical and morphological parameters and the disease outcome., Materials and Methods: The study included 82 patients with the morphologically verified diagnosis of T1-4N0-3M0 breast cancer (stages IIA - IIIB). The material was paired biopsy samples of tumor and surgical material for each patient. The stem genes expression was analyzed via qPCR., Results: As a result, we found that increased level of stem genes expression in breast tumors is associated with lymphogenic metastasis, young age, small tumor size, expression of estrogen and progesterone receptors, and the luminal B molecular subtype. NAC stimulates the expression of 7 out of 16 stem genes. Patients who further developed hematogenic metastases have twice as many hyperexpressed stem genes in their tumors before the treatment and after NAC than patients with no hematogenic metastases. The expression level of three genes - OCT3, LAT, and LMNB2 - in a residual tumor allows us to predict metastasis-free survival of patients with breast cancer of various molecular subtypes with a 79% accuracy., Conclusion: Thus, stem genes hyperexpression is associated with tumor progression., Competing Interests: None

This review is devoted to a rare in clinical practice, but promising phenomenon of regression distant non-irradiated metastases in combination therapy of cancer patients. R. H. Mole in 1953 suggested introducing the term "abscopal effect" to denote the effect of ionizing radiation "at a distance from the irradiated volume but within the same organism." Currently, it is a hypothesis in the treatment of metastatic cancer, when there is a regression of untreated areas simultaneously with a decrease in the tumor. After the discovery of immune checkpoint cases were increase with patients treated with check-point blockade (especially lymphocyte associated protein 4, programmed cell death 1/programmed cell death 1 ligand 1) and which have an abscopal effect. This review systematizes works covering the time period from 1969 to 2019, which give cases of the abscopal effect at different localizations. However, abscopal effect is a poorly understood phenomenon. In this review, the authors tried to collect all information about the possible mechanisms of the abscopal effect, possible role in antitumor response and frequency abscopal effect at radio/immunotherapy or combined both.

Many factors are involved in carcinogenesis of the ovary, such human genetic and physiological characteristics as lifestyle, existing diseases of the reproductive system, and, as suggested, the human papillomavirus (HPV). It is well known that the human papillomavirus virus of high carcinogenic risk (HCR) plays a crucial role in the onset and development of cervical cancer, as well as cases of HPV positive breast cancer and endometrial cancer. The data on the presence of HPV in ovarian cancer are ambiguous: the researchers claim that there is no complete effect of the virus on the development of this type of cancer, and the detection of HPV in 60-80% of tumors. In this regard, there is a need to systematize the currently available research results on this controversial issue and conduct a meta-analysis of the association of HPV infection with the risk of ovarian cancer., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Understanding of the genetic mechanisms and identification of the biological markers of tumor progression that form the individual molecular phenotype of transformed cells can characterize the degree of tumor malignancy, the ability to metastasize, the hormonal sensitivity, and the effectiveness of chemotherapy, etc. Breast cancer (BC) is a genetically heterogeneous disease with different molecular biological and clinical characteristics. The available knowledge about the genetic heterogeneity of the most aggressive molecular subtype of breast cancer-triple-negative (TN)-has led to discoveries in drug treatment, including the use of DNA damaging agents (platinum and PARP inhibitors) for these tumors, as well as the use of immunotherapy. Most importantly, the ability to prescribe optimal drug treatment regimens for patients with TNBC based on knowledge of the molecular-genetic characteristics of this subtype of BC will allow the achievement of high rates of overall and disease-free survival. Thus, identification of the molecular-genetic phenotype of breast cancer is an important prognostic factor of the disease and allows personalization of the patient's treatment.

Aim: To study the peculiarities of ecological relationships of breast cancer (BC) cell lines MCF-7, BT-474 and MDA-MD-231 under co-culturing conditions., Materials and Methods: Three BC cell lines: luminal A - MCF-7, luminal B - BT-474 and triple-negative - MDA-MD-231 were co-cultured pairwise. Immunocytochemistry was used to differentiate the cell lines in the wells. The effect of the cell-free culture medium on the growth rate of the alternate cell line in the pair was also evaluated., Results: It was shown that when BT-474 cells were co-cultured with MCF-7 and BT-474 cells were co-cultured with MDA-MD-231, two types of ecological interactions could be observed: commensalism and amensalism, respectively. While the cells do not interact with each other in contact, the supernatants of single cultures of MCF-7 and MDA-MD-231 exert the same effect on BT-474 as co-cultivation of BT-474 with these cells., Conclusions: The paracrine mechanism of intercellular interaction between different human BC cell lines has been demonstrated. The models used in population ecology can be applicable to identify the types of interaction between cell lines.

In this prospective study, a new strategy for the prescription of neoadjuvant chemotherapy (NAC) was prospectively tested and depended on the presence of stemness gene amplifications in the tumor before treatment, which in our early studies showed a connection with metastasis. The study included 92 patients with grade IIA-IIIB luminal B breast cancer. Patients underwent a biopsy before treatment, and with the use of a CytoScan HD Array microarray (Affymetrix, Santa Clara, CA, USA), the presence of stemness gene amplifications (3q, 5p, 6p, 7q, 8q, 13q, 9p, 9q, 10p, 10q21.1, 16p, 18chr, 19p) in the tumor was determined. In group 1 ( n = 41), in the presence of two or more amplifications, patients were prescribed a personalized NAC regimen. In group 2 ( n = 21), if there was no amplification of stemness genes in the tumor, then patients were not prescribed NAC, and treatment began with surgery. Group 3 ( n = 30) served as a historical control. The frequency of an objective response to NAC in groups 1 and 3 was 79%. Nonmetastatic survival was found in 100% of patients in group 2, who did not undergo NAC. In patients in group 1, the frequency of metastasis was 10% (4/41). At the same time, in patients in group 3, who received NAC, the rate of metastasis was 47% (14/30). The differences between group 1 and group 3 and between group 2 and group 3 were statistically significant, both by Fisher's criterion and a log-rank test. The appointment of NAC was most feasible in patients with clones with stemness gene amplifications in the primary tumor, while in the absence of amplifications, preoperative chemotherapy led to a sharp decrease in metastasis-free survival. This strategy of NAC prescription allowed us to achieve 93% metastatic survival in patients with breast cancer.

Background: Amplification of chromosome 8q with locus 8q24 is the most common copy number aberration, and is associated with tumour progression and chemoresistance., Materials and Methods: The study used paired samples of biopsy and surgical material from 60 patients with breast cancer. The amplification status of 8q was determined using a CytoScan HD Array microarray; complete transcriptomic analysis was performed using a Human Clariom S Assays microarray (Affymetrix, USA)., Results: It was shown that in 65% of cases, amplification of 8q was preserved in the tumour after neoadjuvant chemotherapy (NAC). NAC significantly enhanced the heterogeneity of the transcriptome between tumours with and without amplification of 8q. Compared with a good response, a poor response to NAC also led to increased heterogeneity of the transcriptome of residual tumours. Eight differentially expressed genes of patients with different amplification status of 8q before and after NAC overlapped., Conclusion: Amplification of 8q leads to a significant shift in the level of transcription of a large number of genes after exposure to chemotherapy., (Copyright© 2021, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

The MYC and OCT4 genes are known factors associated with maintaining pluripotency and are linked with a more aggressive course, progression, and resistance to therapy in cancer. Determining the subpopulations of tumour cells expressing the Myc and Oct4 proteins will provide an opportunity to understand which tumour cell subpopulations expressing MYC and OCT4 are associated with metastasis and resistance and which subpopulations can be targeted by anti-MYC and anti-OCT4 therapy. The study included paraffin-embedded tissue from tumours from 27 patients with luminal B breast cancer obtained after neoadjuvant chemotherapy (NACT). Immunofluorescence staining was used to identify subpopulations of tumour cells expressing Myc, Oct4 and Snai2 (Opal™ 7-Color Kit (PerkinElmer, Hopkinton, MA). The following tumour cell subpopulations were identified with the Myc and Oct4 proteins and the Snai2 EMT marker: stem/progenitor tumour cells with/without Myc, Oct4 or Snai2 expression; differentiated tumour cells with/without Myc, Oct4 or Snai2 expression; and other nontumour cells (CK7 - EpCAM - CD44 +/- Myc +/- (Oct4, Snai2) +/- ) within the inflammatory infiltrate in the tumour parenchyma and stroma. The circulating tumour cell subpopulations with Oct4 protein expression in the bloodstream were studied by flow cytometry. It was found that in patients with partial regression (PR) in response to NACT, the frequency of tumour stem cells was 3.6-fold increased (p = 0.038) in the non-EMT state (CK7 + EpCam + CD44 + Snai2 - ). In patients with metastases, there was a statistically significant 2.5-fold increase in the frequency of differentiated tumour cells with Myc expression (CK7 + EpCam + CD44 - Myc + ) and a 2.7-fold increase in the frequency of cells with Oct4 expression (CK7 + EpCam + CD44 - OCT4 + ). In the next stage, the frequencies of subpopulations with expression of the Oct4 protein and signs of EMT among circulating tumour cells (CTCs) were determined. In patients with metastases, the frequency of tumour stem cells in the EMT state (CD326 + CD44 + CD24 - CD325 + ) (p = 0.015) was more than fourfold increased, and the frequency of progenitor tumour cells with expression of the Oct4 stem protein (CD326 + CD44 + CD24 + Oct4 + ) (p = 0.016) was almost sixfold higher than that in patients without metastases. Nonstem (differentiated) tumour cells with expression of the stemness proteins Myc and Oct4 were present in the breast tumour. Their content was significantly higher in residual tumours after NACT in patients who subsequently developed metastases compared with that in patients without metastases. Such cells are a new in situ marker of metastasis.

The NF-kB1 gene belongs to the family of transcription factors that are involved in the regulation of a wide range of biological reactions. It has been established that NF-kB1 plays an important role in the regulation of immune responses, but more and more studies indicate that this gene is involved in the processes of oncogenesis and DNA repair. The product of this gene regulates the expression of genes involved in the development and progression of cancer. In recent years, numerous studies have been aimed at elucidating the functional consequences of the activation of NF-kB1, as well as its signaling mechanisms. In this regard, NF-kB1 is an interesting therapeutic target for a possible personalized approach in the treatment of cancer. This article provides an overview of modern clinical studies of the NF-kB1 gene, which acts as a predictive and prognostic marker in the treatment of cancer.

In 5 patients, a change in the genetic landscape from HPV16 positive high-grade squamous intraepithelial lesion (HSIL) to squamous cervical cancer was traced, which occurred in these patients within the period from 7 months to 5 years after diagnosing HSIL., Materials and Methods: The DNA from paraffin blocks of dysplasia tissue and the tumor that emerged afterwards was used for the study, which was analyzed using the OncoScan FFPE microarray Assay Kit Affymetrix (USA) for genome-wide determination of gene abundance and 65 key somatic driver mutations of oncogenes and tumor suppressor genes., Results: In the study of HSIL material, somatic mutations were observed in 4/5 cases, 18 different somatic driver mutations of the NRAS, EGFR, BRAF, KRAS, IDH2 oncogenes and TP53 suppressor genes were found and almost no CNA-Copy Number Aberration was identified. HSIL malignization is associated with the appearance of secondary driver mutations in oncogenes and tumor suppressor genes and a large number of structural and numerical CNA, the frequency of which correlates with the time of dysplasia malignization into cancer with a very high correlation coefficient r = 0.98, P = 0.004. The trees of dysplasia evolution into tumor were constructed for each patient., Conclusion: According to the results of the work, it is assumed that the initiation of the development of mucosa dysplastic changes is due to primary driver mutations. The formation of secondary driver mutations and CNA are genetic mechanisms of malignant transformation, while the scenarios of the evolution of dysplasia into a tumor are individual and very diverse., (Copyright © 2020. Published by Elsevier Inc.)

Despite the advantages of neoadjuvant chemotherapy (NACT), associated toxicity is a serious complication that renders monitoring of the patients' response to NACT highly important. Thus, prediction of tumor response to treatment is imperative to avoid exposure of potential non-responders to deleterious complications. We have performed genome-wide analysis of DNA methylation by XmaI-RRBS and selected CpG dinucleotides differential methylation of which discriminates luminal B breast cancer samples with different sensitivity to NACT. With this data, we have developed multiplex methylation sensitive restriction enzyme PCR (MSRE-PCR) protocol for determining the methylation status of 10 genes (SLC9A3, C1QL2, DPYS, IRF4, ADCY8, KCNQ2, TERT, SYNDIG1, SKOR2 and GRIK1) that distinguish BC samples with different NACT response. Analysis of these 10 markers by MSRE-PCR in biopsy samples allowed us to reveal three top informative combinations of markers, (1) IRF4 and C1QL2; (2) IRF4, C1QL2, and ADCY8; (3) IRF4, C1QL2, and DPYS, with the areas under ROC curves (AUCs) of 0.75, 0.78 and 0.74, respectively. A classifier based on IRF4 and C1QL2 better meets the diagnostic panel simplicity requirements, as it consists of only two markers. Diagnostic accuracy of the panel of these two markers is 0.75, with the sensitivity of 75% and specificity of 75%.

The review is devoted to assessing the prevalence of human papillomavirus (HPV) in combination with other viral agents for head and neck tumors (HNT). HPV is recognized as an etiological factor in the development of cervical cancer, but there is evidence that it may be involved in carcinogenesis in other locations, in particular the upper respiratory tract. However, HPV is not the most important factor in tumor growth and progression. Recently, many researchers have reported the presence of concomitant co-infection, affecting tumor progression. Of all the studies analyzed, only 3 studies showed the absence or low rates of co-infection in HNT: from the Czech Republic (0%), China (0.6%) and Japan (3%). Most often, HPV infection was detected together with the Epstein-Barr virus (EBV) - from 12.5 to 34.1% of cases. In Russia, the prevailing combination of viral co-infection was a combination of EBV and cytomegalovirus (9.5%) and a combination of EBV and herpes simplex virus (6.7%). Thus, the degree of incidence of HPV in HNT varies greatly, and the mechanisms of coinfection are poorly understood, which raises the question of whether HPV and concomitant infection can be involved in tumor progression. This makes further research in this direction relevant and promising.

Background: In this study, we examined the CNA-genetic landscape (CNA - copy number aberration) of breast cancer prior to and following neoadjuvant chemotherapy (NAC) and correlated changes in the tumor landscape with chemotherapy efficiency as well as metastasis-free survival., Objective: Breast cancer patients (n = 30) with luminal B molecular subtypes were treated with anthracycline- based therapy., Methods: To study CNAs in breast tumors, microarray analysis was performed., Results: Three effects of NAC on tumor CNA landscape were identified: 1 - the number of CNAbearing tumor clones decreased following NAC; 2 - there were no alterations in the number of CNAcontaining clones after NAC; 3 - the treatment with NAC increased the number of CNA-bearing clones (new clones appeared). All NAC-treated patients who had new tumor clones with amplification (20%) had a 100% likelihood of metastasis formation. In these cases, NAC contributed to the emergence of potential metastatic clones. Our study identified the following loci - 5p, 6p, 7q, 8q, 9p, 10p, 10q22.1, 13q, 16p, 18Chr and 19p - that were amplified during the treatment with NAC and maybe the markers of potential metastatic clones. In other patients who showed total or partial elimination of CNA-bearing cell clones, no new amplification clones were observed after NAC, and no evidence of metastases was found with follow-up for 5 years (р = 0.00000)., Conclusion: Our data suggest that the main therapeutic result from NAC is the elimination of potential metastatic clones present in the tumor before treatment. The results showed the necessity of an intelligent approach to NAC to avoid metastasis stimulation., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: According to our previous studies, the presence of amplifications of stem genes can lead to their ectopic expression and this is associated with an increased activity of tumor stem cells in these patients. This leads to a high aggressiveness of the tumor and the development of metastatic disease. The aim was to evaluate the prognostic significance of the presence of amplifications of stem genes and their expression in patients with early breast cancer (BC)., Methods: The study included 28 patients with T₁NxM₀ BC. We used surgical specimens, including formalin-fixed paraffin-embedded archive materials, for 8 patients. A microarray analysis was performed on high-density DNA chips from CytoScanHDArray to assess the status of copy number aberration (CNA) of stem genes locus. Gene expression was assessed using RT-qPCR., Results: CNA analysis of the studied tumors of patients without chemotherapy showed that 17/18 patients without metastases did not have two or more amplifications of chromosomal regions. Ten patients had visceral metastases. In 9/10 of these patients in the primary tumor there were two or more amplifications of the stem genes locus. Two or more amplifications of stem genes locus were found in 12 patients with stage I. Hematogenous metastases did not develop in all patients. Comparison of metastasis-free survival rates in groups of patients with 1 or without amplifications and with two or more amplifications showed statistically significant differences ( P = 0.01)., Conclusion: Our studies have shown that the presence of clones with two or more amplifications of stem gene in patients with BC T₁NxM₀ has a significant prognostic value and determines an unfavorable prognosis for distant metastasis., Competing Interests: The authors have no potential conflicts of interest to disclose., (© 2019 The Korean Academy of Medical Sciences.)

Purpose: This review is devoted to assessing the prevalence of human papillomavirus (HPV) in lung cancer (LC) in the world. HPV is recognized as the etiological factor of cervical cancer, however, there is widespread evidence that this virus is detected not only in gynecological carcinomas, but also in tumors of other organs, in particular the upper respiratory tract and digestive tract., Materials and Methods:  A search was conducted to a depth of 29 years in the PubMed, Web of Science, Scopus, databases. The review includes 95 articles., Results: Of all the analyzed studies (9195 patients), 12 works showed a complete absence of HPV in the biological material in patients with LC. The absence of a virus among lung cancer patients has been established for Canada, the Netherlands and Singapore. The highest average percent of occurrence of this virus is shown for such countries as: Brazil, Korea, Greece and Taiwan (more than 40%). But the highest percentage of HPV occurrence by region is observed in Latin America (33.5%), followed by the Asian countries (31%), in European countries the frequency is 18%. Interestingly, the highest occurrence of high oncogenic types (16 and 18) is observed in Asia (40.3%), then in Latin America (33.6%), Europe (25.6%) and North America (15.4%). Low-oncogenic types (6 and 11) are also predominantly observed in Asia (39.9%), while in Europe and North America 30% and 12.8%, respectively. A meta-analysis of the prevalence of HPV was conducted using Comprehensive Meta-Analysis 3.0. Program, which included 26 studies, the results of which revealed: the prevalence of HPV infection in tumor lung tissue was compared with normal lung tissue OR (95% CI) = 5.38 (3.21-9.00) p < 0.0001, significance was also found for Chinese studies OR = 6.3, 95% CI 3.42-11.53, p < 0.0001, I2 = 71.8% and for nine studies in Europe OR = 6.3, 95% CI 1.8-22.18, p = 0.004, I2 = 51.0%. However, given the fact that the frequency of occurrence of HPV in lung tumor tissue varies greatly, a question may arise about the real role of HPV in LC carcinogenesis, which makes further research relevant and promising.

Aim: To provide a breast cancer (BC) methylotype classification by genome-wide CpG islands bisulfite DNA sequencing. Materials & methods: XmaI-reduced representation bisulfite sequencing DNA methylation sequencing method was used to profile DNA methylation of 110 BC samples and 6 normal breast samples. Intrinsic DNA methylation BC subtypes were elicited by unsupervised hierarchical cluster analysis, and cluster-specific differentially methylated genes were identified. Results & conclusion: Overall, six distinct BC methylotypes were identified. BC cell lines constitute a separate group extremely highly methylated at the CpG islands. In turn, primary BC samples segregate into two major subtypes, highly and moderately methylated. Highly and moderately methylated superclusters, each incorporate three distinct epigenomic BC clusters with specific features, suggesting novel perspectives for personalized therapy.

The involvement of human papillomavirus in carcinogenesis of colorectal cancer is a contentious issue. The presented meta-analysis was performed to systematize the currently available research results on the matter. The analysis was based on the data from 19 studies to assess the association of HPV infection with colorectal cancer. According to the obtained data, researchers determined the statistically significant level of HPV infection in tumor tissue of CRC and the resulting relative risk of developing CRC with HPV infection to be RR (95% CI) = 2.97 (1.42-6.22) with p = 0.0039.

Purpose: We aimed to investigate the association between the polymorphism and expression patterns of multiple drug resistance genes (MDR) in breast cancer (BC)., Materials and Methods: The MDR gene expression levels were measured in tumor tissues of 106 breast cancer patients using quantitative real-time PCR. Affymetrix CytoScan™ HD Array chips were used to assess genotypes. Pairwise correlation analysis for ABCB1, ABCC1, ABCC2 and ABCG2 gene expression levels was carried out to reveal co-expression clusters. Associations between SNPs of MDR genes and their preoperative expression levels were assessed using analysis of covariance adjusting for covariates., Results: The SNPs associated with the expression of the ABCB1, ABCC1, ABCC2 and ABCG2 genes before NAC were detected. In addition, 21 SNPs associated with the expression of four ABC-transporter genes and involved in the expression regulation were identified. Validation in an independent sample confirmed the association between the MDR cluster genes and 11 SNPs., Conclusions: Four MDR genes: ABCB1, ABCC1, ABCC2 and ABCG2 were shown to form the functional expression cluster in breast tumor. Further studies are required to discover precise mechanisms of the cluster regulation, thereby providing new approaches and targets to combat the development of the MDR phenotype during chemotherapy.

One of the factors providing the diversity and heterogeneity of malignant tumors, particularly breast cancer, are genetic variations, due to gene polymorphism, and, especially, the phenomenon of loss of heterozygosity (LOH). It has been shown that LOH in some genes could be a good prognostic marker., Aim: To perform genome-wide study on LOH in association with metastasis-free survival in breast cancer., Materials and Methods: The study involved 68 patients with breast cancer. LOH status was detected by microarray analysis, using a high density DNA-chip CytoScanTM HD Array (Affymetrix, USA). The Chromosome Analysis Suite 3.1 (Affymetrix, USA) software was used for result processing., Results: 13,815 genes were examined, in order to detect LOH. The frequency of LOH varied from 0% to 63%. The association analysis identified four genes: EDA2R, PGK1, TAF9B and CYSLTR1 that demonstrated the presence of LOH associated with metastasis-free survival (log-rank test, p < 0.03)., Conclusions: The presence of LOH in EDA2R, TAF9B, and CYSLTR1 genes is associated with metastasis-free survival in breast cancer patients, indicating their potential value as prognostic markers.

Evolution and natural selection of tumoral clones in the process of transformation and the following carcinogenesis can be called natural clonal evolution. Its main driving factors are internal: genetic instability initiated by driver mutations and microenvironment, which enables selective pressure while forming the environment for cell transformation and their survival. We present our overview of contemporary research dealing with mechanisms of carcinogenesis in different localizations from precancerous pathologies to metastasis and relapse. It shows that natural clonal evolution establishes intratumoral heterogeneity and enables tumor progression. Tumors of monoclonal origin are of low-level intratumoral heterogeneity in the initial stages, and this increases with the size of the tumor. Tumors of polyclonal origin are of extremely high-level intratumoral heterogeneity in the initial stages and become more homogeneous when larger due to clonal expansion. In cases of chemotherapy-induced clonal evolution of a tumor, chemotherapy becomes the leading factor in treatment. The latest research shows that the impact of chemotherapy can radically increase the speed of clonal evolution and lead to new malignant and resistant clones that cause tumor metastasis. Another option of chemotherapy-induced clonal evolution is formation of a new dominant clone from a clone that was minor in the initial tumor and obtained free space due to elimination of sensitive clones by chemotherapy. As a result, in ~20% of cases, chemotherapy can stimulate metastasis and relapse of tumors due to clonal evolution. The conclusion of the overview formulates approaches to tumor treatment based on clonal evolution: in particular, precision therapy, prediction of metastasis stimulation in patients treated with chemotherapy, methods of genetic evaluation of chemotherapy efficiency and clonal-oriented treatment, and approaches to manipulating the clonal evolution of tumors are presented.

The study involved 500 patients with LSIL (low grade squamous intraepithelial lesion), HSIL (high grade squamous intraepithelial lesion), stage I-IV cervical cancer, infected with human papillomavirus (HPV), as well as 235 women without pathological changes in cervical mucosa. The comprehensive survey included colposcopy, cytological and histological analysis, detection and genotyping of high-risk human papillomavirus. Viral load and physical status of HPV16 DNA was evaluated in cases of mono-infection (n = 148). The prevalence of virus-positive cases among the patients with LSIL/NSIL, cervical cancer patients and healthy women was 69.2%, 76.7% and 51.9%, respectively. An association between the severity of disease and high viral load was revealed. The frequency of integrated DNA was strongly increased in patients with a high viral load. The frequency of episomal forms was either reduced or not detecteable in patients with high viral load as compared to patients with low viral load. It is reasonable to suggest that a high HPV16 viral load may cause an increase in the frequency of integration of virus DNA into the cellular/host genome. This suggests that a high HPV16 viral load may be considered as a risk factor for prognosis of cervical intraepithelial neoplasia and cervical cancer.

An etiological role of high risk human papillomavirus (HPV) in the development of cervical cancer has been well established. Hence, attention of researchers has been focused on the role of HPV in pathogenesis of other malignancies, such as head and neck cancers. An analysis of epidemiological data on the prevalence of HPV infection among healthy people and patients with precancerous lesions and/or cancer is an important step in understanding the role of HPV in head and neck carcinogenesis. More and more data de-monstrate the impact of HPV infection on disease outcome. HPV-positive patients have been shown to have better responses to radiotherapy and better overall and disease-free survival than HPV-negative patients. This review presents data of the meta-analysis based on a large number of original studies on HPV prevalence in patients with precancerous lesions and in patients with oral, oropharyngeal and laryngeal cancers as well as findings on the impact of HPV infection on survival of these patients.

Neoadjuvant chemotherapy (NAC) is intensively used for the treatment of primary breast cancer. In our previous studies, we reported that clinical tumor response to NAC is associated with the change of multidrug resistance (MDR) gene expression in tumors after chemotherapy. In this study we performed a combined analysis of MDR gene locus deletions in tumor DNA, MDR gene expression and clinical response to NAC in 73 BC patients. Copy number variations (CNVs) in biopsy specimens were tested using high-density microarray platform CytoScanTM HD Array (Affymetrix, USA). 75%-100% persons having deletions of MDR gene loci demonstrated the down-regulation of MDR gene expression. Expression of MDR genes was 2-8 times lower in patients with deletion than in patients having no deletion only in post-NAC tumors samples but not in tumor tissue before chemotherapy. All patients with deletions of ABCB1 ABCB 3 ABCC5 gene loci--7q21.1, 6p21.32, 3q27 correspondingly, and most patients having deletions in ABCC1 (16p13.1), ABCC2 (10q24), ABCG1 (21q22.3), ABCG2 (4q22.1), responded favorably to NAC. The analysis of all CNVs, including both amplification and deletion showed that the frequency of 13q14.2 deletion was 85% among patients bearing tumor with the deletion at least in one MDR gene locus versus 9% in patients with no deletions. Differences in the frequency of 13q14.2 deletions between the two groups were statistically significant (p = 2.03 × 10(-11), Fisher test, Bonferroni-adjusted p = 1.73 × 10(-8)). In conclusion, our study for the first time demonstrates that deletion MDR gene loci can be used as predictive marker for tumor response to NAC.