Small-scale variants and large deletions in BRCA1/2 genes in Slovak high-grade serous ovarian cancer.

The role of PARP inhibitors is to prevent the polymerase from repairing the single-strand break that occurred due to tumor growth and thus induce cell apoptosis when the homologous recombination deficiency (HRD) system is disabled. The eliminated system can be monitored especially in patients with serous ovarian epithelial tumors. Current studies still show the highest progression-free survival (PFS) in the examined groups with BRCA mutant status, even though they are also effective in the case of a disrupted HRD system, apart from BRCA genes. The study cohort consists of women diagnosed with high-grade serous ovarian cancer (HGSOC), after at least two lines of chemotherapy and after relapse of the disease, as determined by ESMO standards and guidelines. The commercially available tool SOPHIA DDM™ (SophiaGenetics, Switzerland) was used to classify the variants after sequencing. The most common variants (pathogenic or likely pathogenic) were in BRCA1 c.1067 A>G (rs1799950) and c.5266dupC (rs80357906) and in BRCA2 c.9976 A>T (rs11571833). Large deletions were detected in one and three cases in the BRCA1 and BRCA2 genes, respectively. A mutation in the BRCA1/2 genes was confirmed in 50% of the examined patients. In the study, we focused on the identification of mutated BRCA genes by a commercially available Sophia DDM™ system to identify a pathogenic or probable pathogenic variant in a cohort of patients with HGSOC in the Slovak population, which could result in better management and stratification of the individual.

Cancer stem cell marker expression and methylation status in patients with colorectal cancer.

The number of individuals diagnosed with colorectal cancer (CRC) has been on an alarming upward trajectory over the past decade. In some countries, this cancer represents one of the most frequently diagnosed types of neoplasia. Therefore, it is an important demand to study the pathology underlying this disease to gain insights into the mechanism of resistance to treatment. Resistance of tumors to chemotherapy and tumor aggressiveness have been associated with a minor population of neoplastic cells, which are considered to be responsible for tumor recurrence. These types of neoplastic cells are known as cancer stem cells, which have been previously reported to serve an important role in pathogenesis of this malignant disease. Slovakia has one of the highest incidence rates of CRC worldwide. In the present study, the aim was to classify the abundance of selected stem cell markers (CD133, CD166 and Lgr5) in CRC tumors using flow cytometry. In addition, the methylation status of selected genomic regions of CRC biomarkers (ADAMTS16, MGMT, PROM1 (CD133), LGR5 and ALCAM) was investigated by pyrosequencing in a cohort of patients from Martin University Hospital, Martin, Slovakia. Samples from both primary tumors and metastatic tumors were tested. Analysis of DNA methylation in the genomic regions of indicated five CRC biomarkers was also performed, which revealed the highest levels of methylation in the A disintegrin and metalloproteinase with thrombospondin motifs 16 and O6-methyguanine-DNA methyl transferase genes, whereas the lowest levels of methylation were found in genes expressing prominin-1, leucine-rich repeat-containing G-protein-coupled receptor 5 and activated leukocyte cell adhesion molecule. Furthermore, tumor tissues from metastases showed significantly higher levels of CD133+ cells compared with that in primary tumors. Higher levels of CD133+ cells correlated with TNM stage and the invasiveness of CRC into the lymphatic system. Although relatively small number of samples was processed, CD133 marker was consider to be important marker in pathology of CRC.

High-grade serous ovarian carcinoma and detection of inactivated BRCA genes from biopsy material of Slovak patients.

Ovarian cancer is the leading cause of mortality among all gynecological cancers in developed countries and its most common and most lethal type is the high-grade serous ovarian carcinoma (HGSC). At the molecular level, nearly half of all HGSCs exhibit ineffective homologous DNA recombination and disruption of DNA damage/repair pathway inactivation caused often by BRCA1 and BRCA2 gene mutation. Recently, the detection of BRCA1/2 mutations became important for personalized treatment of HGSC patients with the PARP-inhibitors in the defined clinical setting of relapse after positive adjuvant platinum-based chemotherapeutic response. Based on the selection of patients by regional oncologists, we attempted to verify the possibilities of BRCA1/2 mutation testing on archival formalin-fixed paraffin-embedded (FFPE) biopsy material from regional hospitals. In the study we used: a/ FFPE tumor resections of 97 patients sent to our laboratory, originally stored in archives of regional departments for a period of 1-3 years and retrieved on the principle to contain a maximum of non-necrotic tumor tissue, b/ next-generation sequencing (NGS) assay covering all known mutations in the BRCA1/2 genes on MiSeq (Illumina® platform), and c/ Sophia DDM® bioinformatics platform. After processing of FFPE samples, 5 cases were excluded due to the insufficient genomic DNA quantity. Bioinformatics results of NGS analyses of 92 patients' samples indicated 17.39% pathogenic mutations and 32.61% potentially pathogenic mutations in genes BRCA1/2. Overall, 50% pathogenic and potentially pathogenic mutations were detected in the patient's cohort. The relatively high incidence of BRCA1/2 mutations in our series may be influenced by various indicators including the selection of patients based on adjuvant therapy response as well as regional or population heterogeneity in their frequency. Based on the interdisciplinary cooperation, the use of archival biopsy material processed primarily and stored for a longer period in different laboratories without uniformly defined pre-analytical conditions allows identifying the HGSC patients who might better respond to the PARP-inhibition therapy.

Fluctuations of Histone Chemical Modifications in Breast, Prostate, and Colorectal Cancer: An Implication of Phytochemicals as Defenders of Chromatin Equilibrium.

Natural substances of plant origin exert health beneficiary efficacy due to the content of various phytochemicals. Significant anticancer abilities of natural compounds are mediated via various processes such as regulation of a cell's epigenome. The potential antineoplastic activity of plant natural substances mediated by their action on posttranslational histone modifications (PHMs) is currently a highly evaluated area of cancer research. PHMs play an important role in maintaining chromatin structure and regulating gene expression. Aberrations in PHMs are directly linked to the process of carcinogenesis in cancer such as breast (BC), prostate (PC), and colorectal (CRC) cancer, common malignant diseases in terms of incidence and mortality among both men and women. This review summarizes the effects of plant phytochemicals (isolated or mixtures) on cancer-associated PHMs (mainly modulation of acetylation and methylation) resulting in alterations of chromatin structure that are related to the regulation of transcription activity of specific oncogenes, which are crucial in the development of BC, PC, and CRC. Significant effectiveness of natural compounds in the modulation of aberrant PHMs were confirmed by a number of in vitro or in vivo studies in preclinical cancer research. However, evidence concerning PHMs-modulating abilities of plant-based natural substances in clinical trials is insufficient.

Next Generation Sequencing in Molecular Diagnosis of Lynch Syndrome - a Pilot Study Using New Stratification Criteria.

The development of the new technologies such as the next-generation sequencing (NGS) makes more accessible the diagnosis of genetically heterogeneous diseases such as Lynch syndrome (LS). LS is one of the most common hereditary form of colorectal cancer. This autosomal dominant inherited disorder is caused by deleterious germline mutations in one of the mismatch repair (MMR) genes - MLH1, MSH2, MSH6 or PMS2, or the deletion in the EPCAM gene. These mutations eventually result in microsatellite instability (MSI), which can be easily tested in tumor tissue. According to the actual recommendations, all patients with CRC that are suspect to have LS, should be offered the MSI testing. When the MSI is positive, these patients should be recommended to genetic counseling. Here we report a pilot study about the application of NGS in the LS diagnosis in patients considered to have sporadic colorectal cancer. The inclusion criteria for the NGS testing were MSI positivity, BRAF V600E and MHL1 methylation negativity. We have used 5 gene amplicon based massive parallel sequencing on MiSeq platform. In one patient, we have identified a new pathogenic mutation in the exon 4 of the MSH6 gene that was previously not described in ClinVar, Human Gene Mutation Database, Ensembl and InSight databases. This mutation was confirmed by the Sanger method. We have shown that the implementation of new criteria for colorectal patients screening are important in clinical praxis and the NGS gene panel testing is suitable for routine laboratory settings.