Chromosomal Instability in Gastric Cancer: Role in Tumor Development, Progression, and Therapy.

According to the Cancer Genome Atlas (TCGA), gastric cancers are classified into four molecular subtypes: Epstein-Barr virus-positive (EBV+), tumors with microsatellite instability (MSI), tumors with chromosomal instability (CIN), and genomically stable (GS) tumors. However, the gastric cancer (GC) with chromosomal instability remains insufficiently described and does not have effective markers for molecular and histological verification and diagnosis. The CIN subtype of GC is characterized by chromosomal instability, which is manifested by an increased frequency of aneuploidies and/or structural chromosomal rearrangements in tumor cells. Structural rearrangements in the CIN subtype of GC are not accidental and are commonly detected in chromosomal loci, being abnormal because of specific structural organization. The causes of CIN are still being discussed; however, according to recent data, aberrations in the TP53 gene may cause CIN development or worsen its phenotype. Clinically, patients with the CIN subtype of GC demonstrate poor survival, but receive the maximum benefit from adjuvant chemotherapy. In the review, we consider the molecular mechanisms and possible causes of chromosomal instability in GC, the common rearrangements of chromosomal loci and their impact on the development and clinical course of the disease, as well as the driver genes, their functions, and perspectives on their targeting in the CIN subtype of GC.

Epigenomic Profiling Advises Therapeutic Potential of Leukotriene Receptor Inhibitors for a Subset of Triple-Negative Breast Tumors.

Triple-negative breast cancer (TNBC) is the most aggressive molecular subtype, with a poor survival rate compared to others subtypes. For a long time, chemotherapy was the only systemic treatment for TNBC, and the identification of actionable molecular targets might ultimately improve the prognosis for TNBC patients. We performed a genome-wide analysis of DNA methylation at CpG islands on a collection of one hundred ten breast carcinoma samples and six normal breast tissue samples using reduced representation bisulfite sequencing with the XmaI restriction enzyme (XmaI-RRBS) and identified a subset of TNBC samples with significant hypomethylation at the LTB4R/LTB4R2 genes' CpG islands, including CpG dinucleotides covered with cg12853742 and cg21886367 HumanMethylation 450K microarray probes. Abnormal DNA hypomethylation of this region in TNBC compared to normal samples was confirmed by bisulfite Sanger sequencing. Gene expression generally anticorrelates with promoter methylation, and thus, the promoter hypomethylation detected and confirmed in our study might be revealed as an indirect marker of high LTB4R/LTB4R2 expression using a simple methylation-sensitive PCR test. Analysis of RNA-seq expression and DNA methylation data from the TCGA dataset demonstrates that the expression of the LTB4R and LTB4R2 genes significantly negatively correlates with DNA methylation at both CpG sites cg12853742 (R = -0.4, p = 2.6 × 10-6; R = -0.21, p = 0.015) and cg21886367 (R = -0.45, p = 7.3 × 10-8; R = -0.24, p = 0.005), suggesting the upregulation of these genes in tumors with abnormal hypomethylation of their CpG island. Kaplan-Meier analysis using the TCGA-BRCA gene expression and clinical data revealed poorer overall survival for TNBC patients with an upregulated LTB4R. To this day, only the leukotriene inhibitor LY255283 has been tested on an MCF-7/DOX cell line, which is a luminal A breast cancer molecular subtype. Other studies compare the effects of Montelukast and Zafirlukast (inhibitors of the cysteinyl leukotriene receptor, which is different from LTB4R/LTB4R2) on the MDA-MB-231 (TNBC) cell line, with high methylation and low expression levels of LTB4R. In our study, we assess the therapeutic effects of various drugs (including leukotriene receptor inhibitors) with the DepMap gene effect and drug sensitivity data for TNBC cell lines with hypomethylated and upregulated LTB4R/LTB4R2 genes. LY255283, Minocycline, Silibinin, Piceatannol, Mitiglinide, 1-Azakenpaullone, Carbetocin, and Pim-1-inhibitor-2 can be considered as candidates for the additional treatment of TNBC patients with tumors demonstrating LTB4R/LTB4R2 hypomethylation/upregulation. Finally, our results suggest that the epigenetic status of leukotriene B4 receptors is a novel, potential, predictive, and prognostic biomarker for TNBC. These findings might improve individualized therapy for TNBC patients by introducing new therapeutic adjuncts as anticancer agents.

DNA Methylation and Prospects for Predicting the Therapeutic Effect of Neoadjuvant Chemotherapy for Triple-Negative and Luminal B Breast Cancer.

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.

Histone Modifications and Non-Coding RNAs: Mutual Epigenetic Regulation and Role in Pathogenesis.

In the last few years, more and more scientists have suggested and confirmed that epigenetic regulators are tightly connected and form a comprehensive network of regulatory pathways and feedback loops. This is particularly interesting for a better understanding of processes that occur in the development and progression of various diseases. Appearing on the preclinical stages of diseases, epigenetic aberrations may be prominent biomarkers. Being dynamic and reversible, epigenetic modifications could become targets for a novel option for therapy. Therefore, in this review, we are focusing on histone modifications and ncRNAs, their mutual regulation, role in cellular processes and potential clinical application.

Genetic and Clinical Factors Associated with Olokizumab Treatment in Russian Patients with Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease and its treatment is an urgent problem of rheumatology. Olokizumab (OKZ) is a new humanized monoclonal antibody targeting IL-6 and is one of the few promising drugs for RA therapy. One-hundred-and-twenty-five DNA samples from Russian patients with RA, treated with olokizumab, were genotyped with an NGS panel containing 60 single nucleotide polymorphisms (SNPs) and the whole coding sequences of IL6, IL6R, TNFRSF1A, CTLA4, IL10, IL23R, and PADI4; and by RT-PCR for HLA-DRB1 and HLA-B. Associations of polymorphic variants with olokizumab efficacy according to the scores ACR20, ACR50, and DAS28-CRP were determined. We analyzed the obtained data by using logistic regression, ROC curves, and multivariate ANOVA. A high predictive value of the response to olokizumab therapy at 24 weeks was found for the combination of HLA-DRB1*04 and HLA-B*27 alleles with SNPs located in non-HLA genes (IL1B, IL17A, PADI4, DHODH, GLCCI1, IL23R, and TNFAIP3), and clinical characteristics (age, RA duration, and intensity) according to ACR20. Thus, the comprehensive assessment of polymorphic variants of HLA and non-HLA genes considering population characteristics in combination with clinical parameters allows for the elaboration of an RA prognostic panel.

Parental Origin of the RB1 Gene Mutations in Families with Low Penetrance Hereditary Retinoblastoma.

Our aim was to identify RB1 alterations causing hereditary low penetrance retinoblastoma and to evaluate how the parental origin of an RB1 mutation affects its phenotypic expression. By NGS and MLPA, RB1 mutations were found in 191 from 332 unrelated retinoblastoma patients. Among patients with identified RB1 mutations but without clinical family history of retinoblastoma, 7% (12/175) were found to have hereditary disease with one of the parents being an asymptomatic carrier of an RB1 mutation. Additionally, in two families with retinoblastoma history, mutations were inherited by probands from unaffected parents. Overall, nine probands inherited RB1 mutations from clinically unaffected fathers and five, from mothers. Yet, we gained explanations of maternal "unaffectedness" in most cases, either as somatic mosaicism or as clinical presentation of retinomas in involution, rendering the proportion of paternal to maternal truly asymptomatic mutation carriers as 9:1 (p = 0.005). This observation supports an assumption that parental origin of an RB1 mutation influences the likelihood of developing retinoblastoma. Additionally, our study revealed a relatively high frequency of asymptomatic carriage of the RB1 mutations among the parents of retinoblastoma patients, highlighting the utmost necessity of molecular analysis among the probands' relatives irrespective of their clinical status and family history of retinoblastoma.

Mutations in Epigenetic Regulation Genes in Gastric Cancer.

We have performed mutational profiling of 25 genes involved in epigenetic processes on 135 gastric cancer (GC) samples. In total, we identified 79 somatic mutations in 49/135 (36%) samples. The minority (n = 8) of mutations was identified in DNA methylation/demethylation genes, while the majority (n = 41), in histone modifier genes, among which mutations were most commonly found in KMT2D and KMT2C. Somatic mutations in KMT2D, KMT2C, ARID1A and CHD7 were mutually exclusive (p = 0.038). Mutations in ARID1A were associated with distant metastases (p = 0.03). The overall survival of patients in the group with metastases and in the group with tumors with signet ring cells was significantly reduced in the presence of mutations in epigenetic regulation genes (p = 0.036 and p = 0.041, respectively). Separately, somatic mutations in chromatin remodeling genes correlate with low survival rate of patients without distant metastasis (p = 0.045) and in the presence of signet ring cells (p = 0.0014). Our results suggest that mutations in epigenetic regulation genes may be valuable clinical markers and deserve further exploration in independent cohorts.

Genetic Factors of Predisposition and Clinical Characteristics of Rheumatoid Arthritis in Russian Patients.

Rheumatoid arthritis (RA) is a multifactorial disease caused by a genetic predisposition and environmental factors. Predisposing alleles of various genes have a relatively small influence on the disease risk when they appear separately, but in combination, they predispose an individual to RA development. We genotyped 125 patients with RA including 60 SNPs and sequenced coding part of six genes by next-generation sequencing (NGS) technology on a target panel (IAD177464_185). According to our data, the alleles HLA-DRB1*04, HLA-DRB1*01, HLA-B*27, PTPN22 (rs2476601), TNF (rs1800629), TPMT (rs2842934), and IL4 (rs2243250), and genotypes HLA-DRB1*04:04, HLA-DRB1*01:16, PTPN22 (rs2476601), TPMT (rs2842934), were significantly associated with the RA development. Associations with clinical criteria (DAS28-CRP, HAQ-DI, and CDAI) and biochemical factors were investigated. We have shown that the PADI4 genotypes (rs11203367, rs2240340, rs11203366, and rs874881) are significantly associated with the baseline levels of DAS28-CRP, HAQ-DI, and CDAI; genotypes IL23R (rs7530511) and TNFRSF1A (rs748004, rs2228144) with the level of anti citrullinated peptide antibodies (ACPA); the genotypes DHODH (rs3213422) and MTHFR (rs180113) with the concentration of C-reactive protein (CRP); and the genotypes IL2RA (rs2104286), IRAK3 (rs11541076), and IL4R (rs1801275) with the level of rheumatoid factor (RF). Application of targeted NGS panel contributes to expanded genotyping to identify risk groups among the RA patients.

Long Non-Coding PROX1-AS1 Expression Correlates with Renal Cell Carcinoma Metastasis and Aggressiveness.

Long non-coding RNAs (lncRNAs) can be specifically expressed in different tissues and cancers. By controlling the gene expression at the transcriptional and translational levels, lncRNAs have been reported to be involved in tumor growth and metastasis. Recent data demonstrated that multiple lncRNAs have a crucial role in renal cell carcinoma (RCC) progression-the most common malignant urogenital tumor. In the present study, we found a trend towards increased PROX1 antisense RNA 1 (PROX1-AS1) expression in RCC specimens compared to non-tumoral margins. Next, we found a positive correlation between PROX1-AS1 expression and the occurrence of distant and lymph node metastasis, higher tumor stage (pT1 vs. pT2 vs. pT3-T4) and high-grade (G1/G2 vs. G3/G4) clear RCC. Furthermore, global demethylation in RCC-derived cell lines (769-P and A498) and human embryonic kidney 293 (HEK293) cells induced a significant increase of PROX1-AS1 expression level, with the most remarkable change in HEK293 cells. In line with this evidence, bisulfite sequencing analysis confirmed the specific demethylation of bioinformatically selected CpG islands on the PROX1-AS1 promoter sequence in the HEK293 cell line but not in the tumor cells. Additionally, the human specimen analysis showed the hemimethylated state of CG dinucleotides in non-tumor kidney tissues, whereas the tumor samples presented the complete, partial, or no demethylation of CpG-islands. In conclusion, our study indicated that PROX1-AS1 could be associated with RCC progression, and further investigations may define its role as a new diagnostic marker and therapeutic target.

Secretion of Mutant DNA and mRNA by the Exosomes of Breast Cancer Cells.

Exosomes are the small vesicles that are secreted by different types of normal and tumour cells and can incorporate and transfer their cargo to the recipient cells. The main goal of the present work was to study the tumour exosomes' ability to accumulate the parent mutant DNA or RNA transcripts with their following transfer to the surrounding cells. The experiments were performed on the MCF7 breast cancer cells that are characterized by the unique coding mutation in the PIK3CA gene. Using two independent methods, Sanger sequencing and allele-specific real-time PCR, we revealed the presence of the fragments of the mutant DNA and RNA transcripts in the exosomes secreted by the MCF7 cells. Furthermore, we demonstrated the MCF7 exosomes' ability to incorporate into the heterologous MDA-MB-231 breast cancer cells supporting the possible transferring of the exosomal cargo into the recipient cells. Sanger sequencing of the DNA from MDA-MB-231 cells (originally bearing a wild type of PIK3CA) treated with MCF7 exosomes showed no detectable amount of mutant DNA or RNA; however, using allele-specific real-time PCR, we revealed a minor signal from amplification of a mutant allele, showing a slight increase of mutant DNA in the exosome-treated MDA-MB-231 cells. The results demonstrate the exosome-mediated secretion of the fragments of mutant DNA and mRNA by the cancer cells and the exosomes' ability to transfer their cargo into the heterologous cells.

Abnormal promoter DNA hypermethylation of the integrin, nidogen, and dystroglycan genes in breast cancer.

Cell transmembrane receptors and extracellular matrix components play a pivotal role in regulating cell activity and providing for the concerted integration of cells in the tissue structures. We have assessed DNA methylation in the promoter regions of eight integrin genes, two nidogen genes, and the dystroglycan gene in normal breast tissues and breast carcinomas (BC). The protein products of these genes interact with the basement membrane proteins LAMA1, LAMA2, and LAMB1; abnormal hypermethylation of the LAMA1, LAMA2, and LAMB1 promoters in BC has been described in our previous publications. In the present study, the frequencies of abnormal promoter hypermethylation in BC were 13% for ITGA1, 31% for ITGA4, 4% for ITGA7, 39% for ITGA9, 38% for NID1, and 41% for NID2. ITGA2, ITGA3, ITGA6, ITGB1, and DAG1 promoters were nonmethylated in normal and BC samples. ITGA4, ITGA9, and NID1 promoter hypermethylation was associated with the HER2 positive tumors, and promoter hypermethylation of ITGA1, ITGA9, NID1 and NID2 was associated with a genome-wide CpG island hypermethylated BC subtype. Given that ITGA4 is not expressed in normal breast, one might suggest that its abnormal promoter hypermethylation in cancer is non-functional and is thus merely a passenger epimutation. Yet, this assumption is not supported by our finding that it is not associated with a hypermethylated BC subtype. ITGA4 acquires expression in a subset of breast carcinomas, and methylation of its promoter may be preventive against expression in some tumors. Strong association of abnormal ITGA4 hypermethylation with the HER2 positive tumors (p = 0.0025) suggests that simultaneous presence of both HER2 and integrin α4 receptors is not beneficial for tumor cells. This may imply HER2 and integrin α4 signaling pathways interactions that are yet to be discovered.

Analysis of miRNA Expression in Patients with Rheumatoid Arthritis during Olokizumab Treatment.

Rheumatoid arthritis (RA) is the most common autoimmune disease worldwide. Epigenetic alternations of microRNAs (miRNAs) can contribute to its pathogenesis and progression. As the first line therapy with DMARDs is not always successful, other drugs and therapeutic targets should be applied. This study aims to measure the expression level of plasma miRNAs in RA patients treated with olokizumab and to evaluate their potential as prognostic biomarkers. The expression of 9 miRNAs was quantified in 103 RA patients before treatment and at weeks 12 and 24 of olokizumab therapy by reverse transcription-polymerase chain reaction (RT-PCR) assay and analyzed in groups of responders and non-responders. Almost all miRNAs changed their expression during therapy. The ROC curve analysis of the most prominent of them together with consequent univariate and multivariate regression analysis revealed statistically significant associations with the olokizumab therapy efficiency scores for miR-26b, miR-29, miR-451, and miR-522. Therefore, these miRNAs might be a potential therapeutic response biomarker.

Genetic Polymorphisms Associated with Rheumatoid Arthritis Development and Antirheumatic Therapy Response.

Rheumatoid arthritis (RA) is the most common inflammatory arthropathy worldwide. Possible manifestations of RA can be represented by a wide variability of symptoms, clinical forms, and course options. This multifactorial disease is triggered by a genetic predisposition and environmental factors. Both clinical and genealogical studies have demonstrated disease case accumulation in families. Revealing the impact of candidate gene missense variants on the disease course elucidates understanding of RA molecular pathogenesis. A multivariate genomewide association study (GWAS) based analysis identified the genes and signalling pathways involved in the pathogenesis of the disease. However, these identified RA candidate gene variants only explain 30% of familial disease cases. The genetic causes for a significant proportion of familial RA have not been determined until now. Therefore, it is important to identify RA risk groups in different populations, as well as the possible prognostic value of some genetic variants for disease development, progression, and treatment. Our review has two purposes. First, to summarise the data on RA candidate genes and the increased disease risk associated with these alleles in various populations. Second, to describe how the genetic variants can be used in the selection of drugs for the treatment of RA.

DNA methylation markers panel can improve prediction of response to neoadjuvant chemotherapy in luminal B breast cancer.

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%.

Abnormal Hypermethylation of CpG Dinucleotides in Promoter Regions of Matrix Metalloproteinases Genes in Breast Cancer and Its Relation to Epigenomic Subtypes and HER2 Overexpression.

Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) substantially contribute to the regulation of intercellular interactions and thereby play a role in maintaining the tissue structure and function. We examined methylation of a subset of 5'-cytosine-phosphate-guanine-3' (CpG) dinucleotides in promoter regions of the MMP2, MMP11, MMP14, MMP15, MMP16, MMP17, MMP21, MMP23B, MMP24, MMP25, MMP28, TIMP1, TIMP2, TIMP3, and TIMP4 genes by methylation-sensitive restriction enzyme digestion PCR. In our collection of 183 breast cancer samples, abnormal hypermethylation was observed for CpGs in MMP2, MMP23B, MMP24, MMP25, and MMP28 promoter regions. The non-methylated status of the examined CpGs in promoter regions of MMP2, MMP23B, MMP24, MMP25, and MMP28 in tumors was associated with low HER2 expression, while the group of samples with abnormal hypermethylation of at least two of these MMP genes was significantly enriched with HER2-positive tumors. Abnormal methylation of MMP24 and MMP25 was significantly associated with a CpG island hypermethylated breast cancer subtype discovered by genome-wide DNA bisulfite sequencing. Our results indicate that abnormal hypermethylation of at least several MMP genes promoters is a secondary event not directly functional in breast cancer (BC) pathogenesis. We suggest that it is elevated and/or ectopic expression, rather than methylation-driven silencing, that might link MMPs to tumorigenesis.

Clinical relevance of somatic mutations in main driver genes detected in gastric cancer patients by next-generation DNA sequencing.

Somatic mutation profiling in gastric cancer (GC) enables main driver mutations to be identified and their clinical and prognostic value to be evaluated. We investigated 77 tumour samples of GC by next-generation sequencing (NGS) with the Ion AmpliSeq Hotspot Panel v2 and a custom panel covering six hereditary gastric cancer predisposition genes (BMPR1A, SMAD4, CDH1, TP53, STK11 and PTEN). Overall, 47 somatic mutations in 14 genes were detected; 22 of these mutations were novel. Mutations were detected most frequently in the CDH1 (13/47) and TP53 (12/47) genes. As expected, somatic CDH1 mutations were positively correlated with distant metastases (p = 0.019) and tumours with signet ring cells (p = 0.043). These findings confirm the association of the CDH1 mutations with diffuse GC type. TP53 mutations were found to be significantly associated with a decrease in overall survival in patients with Lauren diffuse-type tumours (p = 0.0085), T3-T4 tumours (p = 0.037), and stage III-IV tumours (p = 0.013). Our results confirm that the detection of mutations in the main driver genes may have a significant prognostic value for GC patients and provide an independent GC-related set of clinical and molecular genetic data.

Epigenetic Changes in the Pathogenesis of Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a systemic autoimmune disease that affects about 1% of the world's population. The etiology of RA remains unknown. It is considered to occur in the presence of genetic and environmental factors. An increasing body of evidence pinpoints that epigenetic modifications play an important role in the regulation of RA pathogenesis. Epigenetics causes heritable phenotype changes that are not determined by changes in the DNA sequence. The major epigenetic mechanisms include DNA methylation, histone proteins modifications and changes in gene expression caused by microRNAs and other non-coding RNAs. These modifications are reversible and could be modulated by diet, drugs, and other environmental factors. Specific changes in DNA methylation, histone modifications and abnormal expression of non-coding RNAs associated with RA have already been identified. This review focuses on the role of these multiple epigenetic factors in the pathogenesis and progression of the disease, not only in synovial fibroblasts, immune cells, but also in the peripheral blood of patients with RA, which clearly shows their high diagnostic potential and promising targets for therapy in the future.

Genome-wide methylotyping resolves breast cancer epigenetic heterogeneity and suggests novel therapeutic perspectives.

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.

Autoantibody against arrestin-1 as a potential biomarker of renal cell carcinoma.

Renal cell carcinoma (RCC) is the second-most common uronephrological cancer. In the absence of specific symptoms, early diagnosis of RCC is challenging. Monitoring of the aberrant expression of tumour-associated antigens (TAAs) and related autoantibody response is considered as a novel approach of RCC diagnostics. The aim of this study was to examine the aberrant expression of arrestin-1 in renal tumours, to investigate the possible epigenetic mechanism underlying arrestin-1 expression, and to assess the frequency of anti-arrestin-1 autoantibody response. Immunohistochemistry was used to assess the presence of arrestin-1 in primary tumours and metastases of 39 patients with RCC and renal oncocytoma. Bisulfite sequencing was employed to analyse the methylation status of the promoter of the SAG gene encoding arrestin-1. Western blot analysis was performed to detect autoantibodies against arrestin-1 in serum samples of 36 RCC and oncocytoma patients. Arrestin-1 was found to be expressed in RCC (58.7% of cases) and renal oncocytoma (90% of cases) cells, while being absent in healthy kidney. The expression of arrestin-1 in RCC metastases was more prominent than in primary tumours. Hypomethylation of the SAG gene promoter is unlikely to be the mechanism for the aberrant expression of arrestin-1. Autoantibodies against arrestin-1 were detected in sera of 75% of RCC patients. Taken together, our findings suggest employment of autoantibody against arrestin-1 as biomarker of RCC.

Loss of heterozygosity and uniparental disomy of chromosome region 10q23.3-26.3 in glioblastoma.

Glioblastoma is the most frequent and aggressive brain tumor in the adult population. Loss of heterozygosity (LOH) at markers of the long arm of chromosome 10 is the most common genetic alteration in glioblastoma, being detectable in up to 80% of cases. We have tested 124 glioblastoma samples for LOH by microsatellite analysis of the 10q23.3-26.3 region which contains the cancer related genes PTEN, FGFR2, MKI67, and MGMT. Then, a real-time quantitative microsatellite analysis (QuMA) was used to qualitatively estimate the change in copy number of this region in the samples with LOH. LOH was detected in 62.1% of the glioblastoma samples. A total of 64 samples with LOH in this region were examined by QuMA. LOH was attributed to a deletion in 37.5% of cases, and uniparental disomy (UPD) in 25% of cases. In 37.5% of cases, deletion and UPD segments alternated within the region: deletions being more frequent than UPD in its proximal part (encompassing PTEN and FGFR2) and both deletions and UPD occurring at the same frequency in its distal part (MGMT). Thus, we have investigated mechanisms of structural alterations of the chromosome region 10q23.3-26.3 in glioblastoma. In addition to a structural deletion of this region, UPD was identified as a frequent cause of LOH. We resume that more detailed studies of glioblastoma at the molecular genetic level are essential in search for potential markers suitable for predicting the disease outcome and the response to treatment.