Use of Fluorescence In Situ Hybridization (FISH) in Diagnosis and Tailored Therapies in Solid Tumors.

Fluorescence in situ hybridization (FISH) is a standard technique used in routine diagnostics of genetic aberrations. Thanks to simple FISH procedure is possible to recognize tumor-specific abnormality. Its applications are limited to designed probe type. Gene rearrangements e.g., ALK, ROS1 reflecting numerous translocational partners, deletions of critical regions e.g., 1p and 19q, gene fusions e.g., COL1A1-PDGFB, genomic imbalances e.g., 6p, 6q, 11q and amplifications e.g., HER2 are targets in personalized oncology. Confirmation of genetic marker is frequently a direct indication to start specific, targeted treatment. In other cases, detected aberration helps pathologists to better distinguish soft tissue sarcomas, or to state a final diagnosis. Our main goal is to show that applying FISH to formalin-fixed paraffin-embedded tissue sample (FFPE) enables assessing genomic status in the population of cells deriving from a primary tumor or metastasis. Although many more sophisticated techniques are available, like Real-Time PCR or new generation sequencing, FISH remains a commonly used method in many genetic laboratories.

Chromosome Conformation Capture Reveals Two Elements That Interact with the PTBP3 (ROD1) Transcription Start Site.

The long-range control of gene expression is facilitated by chromatin looping and can be detected using chromosome conformation capture-3C. Here we focus on the chromatin architecture of the PTBP3 (Polypyrimidine tract binding protein 3) locus to evaluate its potential role in regulating expression of the gene. PTBP3 expression in prostate cancer cell lines is found significantly higher compared to skin fibroblasts using real-time PCR (p < 0.05) and digital droplet PCR (p < 0.01). Exploration of the chromatin spatial architecture of a nearly 200-kb fragment of chromosome 9 encompassing the PTBP3 gene identified two elements located 63 kb upstream and 48 kb downstream of PTBP3, which looped specifically to the PTBP3 promoter. These elements contain histone acetylation patterns characteristic of open chromatin regions with active enhancers. Our results reveal for the first time that long-range chromatin interactions between the -63 kb and +48 kb loci and the PTBP3 promoter regulate the expression of this gene in prostate cancer cells. These interactions support an open chromatin form for the PTBP3 locus in cancer cells and the three-dimensional structural model proposed in this paper.

Detection of somatic mutations in ctDNA derived from adenocarcinoma patients - EGFR tyrosine kinase inhibitor monitoring preliminary study.

AIM OF THE STUDY: The main purpose of this study was to assess detection of mutations in the epidermal growth factor receptor (EGFR) gene in circulating tumor DNA (ctDNA) as a tool for EGFR tyrosine kinase inhibitor (TKI) monitoring therapy. MATERIAL AND METHODS: The study was conducted using 20 samples from 7 adenocarcinoma patients treated with TKIs. Blood samples for ctDNA analysis were collected in 2015-2016. ctDNA was isolated using the QIAamp Circulating Nucleic Acid Kit (Qiagen) and analyzed using the ctEGFR Mutation Detection Kit (EntroGen). RESULTS: The most common exon 19 deletion and p.Leu858Arg mutation in exon 21 of the EGFR gene were detected. We observed a correlation between stabilization of patient condition and the lack of p.Thr790Met mutation detection in ctEGFR during TKI treatment (2 out of 7 patients). We also observed a correlation between progression of the disease and p.Thr790Met mutation detection in ctEGFR (3 out of 7 cases). We did not detect ctDNA p.Thr790Metp in two patients in whom progression occurred shortly thereafter. Last but not least, we noticed that good organization during plasma collection and transportation (average time of 6 minutes and 30 seconds) allows to use K2EDTA tubes. CONCLUSIONS: When tissue is limited or insufficient, analysis of the ctEGFR mutational status can be considered as an alternative tool for qualifying patients with non-small cell lung cancer (NSCLC) for TKI therapy, also as a potential monitoring tool. The plasma p.Thr790Met-negative result needs to be verified for the presence of p.Thr790Met-positive tumor tissue.

Clinical Validation of GenBody COVID-19 Ag, Nasal and Nasopharyngeal Rapid Antigen Tests for Detection of SARS-CoV-2 in European Adult Population.

Accurate and rapid identification of COVID-19 is critical for effective patient treatment and disease outcomes, as well as the prevention of SARS-CoV-2 transmission. Rapid antigen tests (RATs) for identifying SARS-CoV-2 are simpler, faster and less expensive than molecular assays. Any new product to be considered a medical device is subject to evaluation and data analysis to verify the in vitro diagnostic ability to achieve its intended purpose. Clinical validation of such a test is a prerequisite before clinical application. This study was a clinical validation on adult Europeans of GenBody COVID-19 Ag, nasal and nasopharyngeal RATs. A set of 103 positive and 301 negative from nose and nasopharynx samples confirmed by RT-qPCR were examined. The tests were safe to use and showed 100% specificity in both specimens, and high sensitivity of 94.17% (95%CI 87.75% to 97.83%) and 97.09% (95%CI 91.72% to 99.4%), respectively. The parameters were significantly better for samples with higher virus loads (the highest for CT ≤ 25). The GenBody COVID-19 Ag RATs are inexpensive (compared to RT-qPCR), reliable and rapid with high sensitivity and specificity, making them suitable for diagnosis and timely isolation and treatment of COVID-19 patients, contributing to the better control of virus spread.

An Alu-derived intronic splicing enhancer facilitates intronic processing and modulates aberrant splicing in ATM.

We have previously reported a natural GTAA deletion within an intronic splicing processing element (ISPE) of the ataxia telangiectasia mutated (ATM) gene that disrupts a non-canonical U1 snRNP interaction and activates the excision of the upstream portion of the intron. The resulting pre-mRNA splicing intermediate is then processed to a cryptic exon, whose aberrant inclusion in the final mRNA is responsible for ataxia telangiectasia. We show here that the last 40 bases of a downstream intronic antisense Alu repeat are required for the activation of the cryptic exon by the ISPE deletion. Evaluation of the pre-mRNA splicing intermediate by a hybrid minigene assay indicates that the identified intronic splicing enhancer represents a novel class of enhancers that facilitates processing of splicing intermediates possibly by recruiting U1 snRNP to defective donor sites. In the absence of this element, the splicing intermediate accumulates and is not further processed to generate the cryptic exon. Our results indicate that Alu-derived sequences can provide intronic splicing regulatory elements that facilitate pre-mRNA processing and potentially affect the severity of disease-causing splicing mutations.

BRCA1/2 Mutation Detection in the Tumor Tissue from Selected Polish Patients with Breast Cancer Using Next Generation Sequencing.

(1) Background: Although, in the mutated BRCA detected in the Polish population of patients with breast cancer, there is a large percentage of recurrent pathogenic variants, an increasing need for the assessment of rare BRCA1/2 variants using NGS can be observed. (2) Methods: We studied 75 selected patients with breast cancer (negative for the presence of 5 mutations tested in the Polish population in the prophylactic National Cancer Control Program). DNA extracted from the cancer tissue of these patients was used to prepare a library and to sequence all coding regions of the BRCA1/2 genes. (3) Results: We detected nine pathogenic variants in 8 out of 75 selected patients (10.7%). We identified one somatic and eight germline variants. We also used different bioinformatic NGS software programs to analyze NGS FASTQ files and established that tertiary analysis performed with different tools was more likely to give the same outcome if we analyzed files received from secondary analysis using the same method. (4) Conclusions: Our study emphasizes (i) the importance of an NGS validation process with a bioinformatic procedure included; (ii) the importance of screening both somatic and germline pathogenic variants; (iii) the urgent need to identify additional susceptible genes in order to explain the high percentage of non-BRCA-related hereditary cases of breast cancer.

Prognostic and Predictive Epigenetic Biomarkers in Oncology.

Epigenetic patterns, such as DNA methylation, histone modifications, and non-coding RNAs, can be both driver factors and characteristic features of certain malignancies. Aberrant DNA methylation can lead to silencing of crucial tumor suppressor genes or upregulation of oncogene expression. Histone modifications and chromatin spatial organization, which affect transcription, regulation of gene expression, DNA repair, and replication, have been associated with multiple tumors. Certain microRNAs (miRNAs), mainly those that silence tumor suppressor genes and occur in a greater number of copies, have also been shown to promote oncogenesis. Multiple patterns of these epigenetic factors occur specifically in certain malignancies, which allows their potential use as biomarkers. This review presents examples of tests for each group of epigenetic factors that are currently available or in development for use in early cancer detection, prediction, prognosis, and response to treatment. The availability of blood-based biomarkers is noted, as they allow sampling invasiveness to be reduced and the sampling procedure to be simplified. The article stresses the role of epigenetics as a crucial element of future cancer diagnostics and therapy.

Somatic Mutations in miRNA Genes in Lung Cancer-Potential Functional Consequences of Non-Coding Sequence Variants.

A growing body of evidence indicates that miRNAs may either drive or suppress oncogenesis. However, little is known about somatic mutations in miRNA genes. To determine the frequency and potential consequences of miRNA gene mutations, we analyzed whole exome sequencing datasets of 569 lung adenocarcinoma (LUAD) and 597 lung squamous cell carcinoma (LUSC) samples generated in The Cancer Genome Atlas (TCGA) project. Altogether, we identified 1091 somatic sequence variants affecting 522 different miRNA genes and showed that half of all cancers had at least one such somatic variant/mutation. These sequence variants occurred in most crucial parts of miRNA precursors, including mature miRNA and seed sequences. Due to our findings, we hypothesize that seed mutations may affect miRNA:target interactions, drastically changing the pool of predicted targets. Mutations may also affect miRNA biogenesis by changing the structure of miRNA precursors, DROSHA and DICER cleavage sites, and regulatory sequence/structure motifs. We identified 10 significantly overmutated hotspot miRNA genes, including the miR-379 gene in LUAD enriched in mutations in the mature miRNA and regulatory sequences. The occurrence of mutations in the hotspot miRNA genes was also shown experimentally. We present a comprehensive analysis of somatic variants in miRNA genes and show that some of these genes are mutational hotspots, suggesting their potential role in cancer.

The relationship between HER2 overexpression and angiogenesis in gastric cancer.

In gastric cancer, HER2 protein overexpression is considered to be conducive to the higher proliferation activity of the tumor cells. Tumor formation is associated with angiogenesis in order to secure an abundant supply of oxygen and glucose to cancer cells. The aim of the study was to assess if HER2 overexpression is related to higher microvessel density (MVD) in the tumor stroma.The archival samples of primary tumor from 144 consecutive patients that underwent gastric resection for cancer between August 1, 2006 and December 31, 2013 in the Department of Oncological Surgery of Medical University of Gdansk were analyzed. CD34 was used as a marker of MVD in the tumor stroma. Both CD34 and HER2 protein expressions were tested by immunohistochemistry.The assays were unsuccessful to estimate HER2 in 10 cases and CD34 in 14 cases due to technical reasons. The results were obtained for 128 patients. HER2 0 and HER2 1+ were considered negative, while HER2+ and HER2 3+ were recognized as positive. Mean MVD (mean number of vessels in the visual field) was 32.4 (median 29.5). Microvessel density was insignificantly higher in HER2 positive tumors. The slight difference was also seen between IHC 2+ and 3+ groups. The differences did not reach the level of statistical significance.Statistical analysis performed in our study did not reveal the significant relationship between HER2 overexpression on the tumor cells and MVD in the tumor stroma.

Can chromatin conformation technologies bring light into human molecular pathology?

Regulation of gene expression in eukaryotes involves many complex processes, in which chromatin structure plays an important role. In addition to the epigenetic effects, such as DNA methylation and phosphorylation or histone modifications, gene expression is also controlled by the spatial organization of chromatin. For example, distant regulatory elements (enhancers, insulators) may come into direct physical interaction with target genes or other regulatory elements located in genomic regions of up to several hundred kilobases in size. Such long-range interactions result in the formation of chromatin loops. In the last several years, there has been a rapid increase in our knowledge of the spatial organization of chromatin in the nucleus through the chromosome conformation capture (3C) technology. Here we review and compare the original 3C and 3C-based methods including chromosome conformation capture-on-chip (4C), chromosome conformation capture carbon copy (5C), hi-resolution chromosome confomation capture (HiC). In this article, we discuss different aspects of how the nuclear organization of chromatin is associated with gene expression regulation and how this knowledge is useful in translational medicine and clinical applications. We demonstrate that the knowledge of the chromatin 3D organization may help understand the mechanisms of gene expression regulation of genes involved in the development of human diseases, such as CFTR (responsible for cystic fibrosis) or IGFBP3 (associated with breast cancer pathogenesis). Additionally, 3C-derivative methods have been also useful in the diagnosis of some leukemia subtypes.

High copy number variation of cancer-related microRNA genes and frequent amplification of DICER1 and DROSHA in lung cancer.

A growing body of evidence indicates that miRNAs may be a class of genetic elements that can either drive or suppress oncogenesis. In this study we analyzed the somatic copy number variation of 14 miRNA genes frequently found to be either over- or underexpressed in lung cancer, as well as two miRNA biogenesis genes, DICER1 and DROSHA, in non-small-cell lung cancer (NSCLC). Our analysis showed that most analyzed miRNA genes undergo substantial copy number alteration in lung cancer. The most frequently amplified miRNA genes include the following: miR-30d, miR-21, miR-17 and miR-155. We also showed that both DICER1 and DROSHA are frequently amplified in NSCLC. The copy number variation of DICER1 and DROSHA correlates well with their expression and survival of NSCLC and other cancer patients. The increased expression of DROSHA and DICER1 decreases and increases the survival, respectively. In conclusion, our results show that copy number variation may be an important mechanism of upregulation/downregulation of miRNAs in cancer and suggest an oncogenic role for DROSHA.

The use of a two-tiered testing strategy for the simultaneous detection of small EGFR mutations and EGFR amplification in lung cancer.

Lung cancer is the leading cause of cancer-related death worldwide. Recent progress in lung cancer diagnosis and treatment has been achieved due to a better understanding the molecular mechanisms of the disease and the identification of biomarkers that allow more specific cancer treatments. One of the best known examples of personalized therapy is the use of tyrosine kinase inhibitors, such as gefitinib and erlotinib, for the successful treatment of non-small-cell lung cancer patients selected based on the specific EGFR mutations. Therefore, the reliable detection of mutations is critical for the application of appropriate therapy. In this study, we tested a two-tiered mutation detection strategy using real-time PCR assays as a well-validated high-sensitivity method and multiplex ligation-dependent probe amplification (MLPA)-based EGFRmut+ assay as a second-tier standard-sensitivity method. One additional advantage of the applied MLPA method is that it allows the simultaneous detection of EGFR mutations and copy-number alterations (i.e., amplifications) in EGFR, MET and ERBB2. Our analysis showed high concordance between these two methods. With the use of this two-tier strategy, we reliably determined the frequency of EGFR mutations and EGFR, MET and ERBB2 amplifications in over 200 lung cancer samples. Additionally, taking advantage of simultaneous copy number and small mutation analyses, we showed a very strong correlation between EGFR mutations and EGFR amplifications and a mutual exclusiveness of EGFR mutations/amplifications with MET and ERBB2 amplifications. Our results proved the reliability and usefulness of the two-tiered EGFR testing strategy.

Transdifferentiation of Bone Marrow Mesenchymal Stem Cells into the Islet-Like Cells: the Role of Extracellular Matrix Proteins.

Pancreatic islet implantation has been recently shown to be an efficient method of treatment for type 1 diabetes. However, limited availability of donor islets reduces its use. Bone morrow would provide potentially unlimited source of stem cells for generation of insulin-producing cells. This study was performed to evaluate the influence of extracellular matrix proteins like collagen, laminin, and vitronectin on bone marrow mesenchymal stem cells (BM-MSCs) transdifferentiation into islet-like cells (ILCs) in vitro. To our knowledge, this is the first report evaluating the importance of vitronectin in transdifferentiation of BM-MSCs into ILCs. Rat BM-MSCs were induced to ILCs using four-step protocol on plates coated with collagen type IV, laminin type I and vitronectin type I. Quantitative real-time PCR was performed to detect gene expression related to pancreatic ß cell development. The induced cells expressed islet-related genes including: neurogenin 3, neurogenic differentiation 1, paired box 4, NK homeobox factor 6.1, glucagon, insulin 1 and insulin 2. Laminin but not collagen type IV or vitronectin enhanced expression of insulin and promoted formation of islet-like structures in monolayer culture. Laminin triggered transdifferentiation of BM-MSCs into ILCs.

The efficacy of EGFR gene mutation testing in various samples from non-small cell lung cancer patients: a multicenter retrospective study.

INTRODUCTION: Testing for the epidermal growth factor receptor (EGFR) gene mutations requires considerable multidisciplinary experience of clinicians (for appropriate patient selection), pathologists (for selection of appropriate cytological or histological material) and geneticists (for performing and reporting reliable molecular tests). We present our experience on the efficacy of routine EGFR testing in various types of tumor samples and the frequency of EGFR mutations in a large series of Polish non-small cell lung cancer (NSCLC) patients. METHODS: Deletions in exon 19 and substitution L858R in exon 21 of EGFR gene were assessed using real-time PCR techniques in 1,138 small biopsies or cytological specimens and in 1,312 surgical samples. RESULTS: Out of 2,450 diagnostic samples (containing >10% of tumor cells), the occurrence of EGFR gene mutations was 9%; more frequently in women (13.9%) and adenocarcinoma patients (10%), particularly with accompanying expression of TTF1 (13.0%). The frequency of EGFR gene mutations was similar in cytological and histological specimens, and in primary and metastatic lesions, and did not depend on the percentage of tumor cells and quality of isolated DNA. Cytological or small biopsy, compared to surgical specimens showed lower percentage of tumor cells, with no impact on the quality of real-time PCR assay. CONCLUSION: Cytological and small biopsy samples with low (10-20%) content of tumor cells and specimens from metastatic lesions are a sufficient source for EGFR mutation testing in NSCLC patients. The incidence of EGFR gene mutations in examined population was similar to those reported in other Caucasian populations.

Prognostic and predictive biomarkers: tools in personalized oncology.

Oncology indispensably leads us to personalized medicine, which allows an individual approach to be taken with each patient. Personalized oncology is based on pharmacogenomics and the effect of genetic differences in individuals (germline and somatic) on the way cancer patients respond to chemotherapeutics. Biomarkers detected using molecular biology tools allow the molecular characterization of cancer signatures and provide information relevant for personalized treatment. Biomarkers can be divided into two main subgroups: prognostic and predictive. The aim of the application of prognostic biomarkers, which provide information on the overall cancer outcome in patients, is to facilitate cancer diagnosis, usually with no need for putting invasive methods into use. Predictive biomarkers help to optimize therapy decisions, as they provide information on the likelihood of response to a given chemotherapeutic. Among the prognostic factors that identify patients with different outcome risks (e.g., recurrence of the disease), the following factors can be distinguished: somatic and germline mutations, changes in DNA methylation that lead to the enhancement or suppression of gene expression, the occurrence of elevated levels of microRNA (miRNA) capable of binding specific messenger RNA (mRNA) molecules, which affects gene expression, as well as the presence of circulating tumor cells (CTCs) in blood, which leads to a poor prognosis for the patient. Biomarkers for personalized oncology are used mainly in molecular diagnostics of chronic myeloid leukemia, colon, breast and lung cancer, and recently in melanoma. They are successfully used in the evaluation of the benefits that can be achieved through targeted therapy or in the evaluation of toxic effects of the chemotherapeutic used in the therapy.

Impact of specific KRAS mutation in exon 2 on clinical outcome of chemotherapy- and radiotherapy-treated colorectal adenocarcinoma patients.

BACKGROUND AND OBJECTIVES: Knowledge obtained via high-throughput technologies, used for tumor genome sequencing or identifying gene expression and methylation signatures, is clinically applicable thanks to molecular characterization in the context of tumor development and progression. This study was conducted to assess the impact of specific KRAS mutation in codons 12 and 13 on clinical outcome of chemotherapy and radiotherapy in colorectal cancer patients. METHODS: A total of 239 samples of colorectal adenocarcinoma underwent histological evaluation and DNA isolation. RESULTS AND CONCLUSIONS: Patients with a mutation in KRAS codon 13 experienced worse outcome than those with a mutation in KRAS codon 12. Moreover, the cases of mutations in KRAS codons 12 or 13 were associated with a significantly higher mortality than the cases of wild-type KRAS, and some patients with KRAS mutated in codon 12 had an exceptionally long overall survival. Finally, primary preoperative radiation therapy followed by surgery significantly increased overall survival more efficiently than surgery followed by chemotherapy. This should be investigated in further studies. The fact that all patients treated with radiotherapy + surgery were alive, again focused our attention on the effect of preoperative radiation therapy on the prognosis for colorectal cancer patients. However, the number of patients in this subgroup is too small to allow any specific explanation for this observation. We should, rather, point out a problem for further investigation.

An analysis of the prognostic value of IDH1 (isocitrate dehydrogenase 1) mutation in Polish glioma patients.

BACKGROUND AND OBJECTIVE: IDH1 (isocitrate dehydrogenase 1) is a potential biomarker and drug target. Genomic and epigenetic data on astrocytoma have demonstrated that the IDH1 mutation is sufficient to establish the glioma hypermethylator phenotype. Furthermore, recent studies have also indicated that a mutant IDH1 inhibitor induced demethylation of histone H3K9me3 and expression of genes associated with gliogenic differentiation. As the presence of the p.R132H mutation in the IDH1 gene seems to be a more powerful prognostic marker than O(6)-methylguanine-DNA methyltransferase promoter status, we evaluated the presence of IDH1 mutation in Polish patients with astrocytoma, glioblastoma, oligoastrocytoma, ganglioglioma, oligodendroglioma, and ependymoma. METHODS: The IDH1 mutation status at codon 132 was determined using a mouse monoclonal antibody specific for the R132H mutation, direct sequencing, and Co-amplification at Lower Denaturation Temperature (COLD) polymerase chain reaction (PCR) high-resolution melting-curve analysis (HRM). RESULTS: Wild-type (WT) IDH1 was detected in cases with a World Health Organization (WHO) grade I astrocytoma. The IDH1 c.G395A; p.R132H mutation was observed in 56 and 94 % of grade II and grade III astrocytoma cases, respectively. Significant differences in the median overall survival were observed in astrocytoma patients grouped on the basis of the presence of IDH1 mutation: survival was 24 months longer in grade II astrocytoma and 12 months longer in glioblastoma. Overall survival was compared between grade II astrocytoma patients with low or high expression of the mutant protein. Interestingly, lower R132H expression correlated with better overall survival. CONCLUSION: Our results indicate the usefulness of assessing the R132H IDH1 mutation in glioma patients: the presence or absence of the R132H mutation can help pathologists to distinguish pilocytic astrocytomas (IDH1 WT) from diffuse ones (R132H IDH1/WT). Moreover, low IDH1 p.R132H expression was related to better prognosis. This clinical implication appears to be important for personalization of prognosis and treatment by oncologists.

KRAS and BRAF mutation analysis in colorectal adenocarcinoma specimens with a low percentage of tumor cells.

BACKGROUND AND OBJECTIVE: The rapid development of molecular biology techniques allows for the introduction of real-time polymerase chain reaction (PCR) methods with a limit of mutation detection at 1% in a background of wild-type DNA. Analysis of KRAS mutations in codons 12, 13, and 61, together with analysis of BRAF mutations in codon 600, are predictive biomarkers for anti-epidermal growth factor receptor (EGFR) treatment in colorectal cancer. Our aim was to compare PCR methods for KRAS mutations and BRAF mutation analysis using DNA isolated from tissue samples previously evaluated for presence of tumor cells using a quantitative scale and the percentage of tumor cells (PTC) scale. We addressed the question of whether a low number of tumor cells can be qualified for somatic mutation testing. RESULTS: Our study showed that PTC as low as 10% was good enough to detect KRAS G12D, G13D, and Q61L mutations in formalin-fixed paraffin-embedded (FFPE) material. Furthermore, our results indicate that up to 20% of colorectal cancer may carry mutations in the KRAS codon 61 and BRAF codon 600, which suggests the value of these mutation analyses because patients carrying them are unlikely to respond to cetuximab or panitumumab. A low level of KRAS somatic mutation detection has not been studied in depth in the context of clinical outcomes in patients; therefore, we compared new PCR methods, (KRBR-RT 50 Entrogen; ViennaLab StripAssay) and re-evaluated KRAS and BRAF status in patients with relapse after targeted therapy. CONCLUSIONS: The importance of molecular results was confirmed by clinical observation of a patient with relapse who had qualified for targeted therapy with KRAS WT status (but was diagnosed by less sensitive single-stranded conformation polymorphisms method). Interestingly, during anti-EGFR treatment, it came to the selection of cells with KRAS G12C mutation which were present from the beginning in the tumor but at a low level (detected by PCR methods) only and led consequently to the metastasis. Taking into consideration the limit of detection, labor time, and assay cost, the real-time PCR method seems to be very promising especially for FFPE material with the PTC below 15%.

Application of PCR methods to evaluate EGFR, KRAS and BRAF mutations in a small number of tumor cells in cytological material from lung cancer patients.

The epidermal growth factor receptor (EGFR) mutation status in the tyrosine kinase domain is known to be a predictor of the response to gefitinib or erlotinib in lung cancer; thus, a non-surgical procedure of tumor specimen collection is critical for mutation analysis. The aim of the present study was to analyze the EGFR, KRAS and BRAF status in limited cytological material. To the best of our knowledge, this is the first time that the quantitative scale of tumor cells and the percentage of tumor cells in cytological material were evaluated at the early stages of pathomorphological material qualification for EGFR, KRAS and BRAF mutation analysis. Our results revealed that even 100-1,000 tumor cells from fine needle aspiration (FNA) samples provided reliable results of mutation analysis when sensitive real-time polymerase chain reaction (PCR) methods were used. EGFR mutations were detected in 10% (7/71) and KRAS mutations were detected in 35% (19/54) of the lung adenocarcinoma cases. In addition, we reported the most common inhibiting mutation (p.T790M) found in coexistence with p.L858R in an FNA sample from a patient, for whom short-term improvement after erlotinib treatment was observed before further progression of the disease. Subsequently, mutual exclusion of EGFR and KRAS mutations was observed. Cytological samples with a small number of tumor cells obtained via FNA, endobronchial ultrasound (EBUS)-transbronchial needle aspiration (TBNA) or brushing are suggested to be used for diagnostic purposes after careful selection by cytopathologists and analysis using a validated, sensitive real-time PCR method.

Characterization of MRP RNA-protein interactions within the perinucleolar compartment.

The perinucleolar compartment (PNC) forms in cancer cells and is highly enriched with a subset of polymerase III RNAs and RNA-binding proteins. Here we report that PNC components mitochondrial RNA-processing (MRP) RNA, pyrimidine tract-binding protein (PTB), and CUG-binding protein (CUGBP) interact in vivo, as demonstrated by coimmunoprecipitation and RNA pull-down experiments. Glycerol gradient analyses show that this complex is large and sediments at a different fraction from known MRP RNA-containing complexes, the MRP ribonucleoprotein ribozyme and human telomerase reverse transcriptase. Tethering PNC components to a LacO locus recruits other PNC components, further confirming the in vivo interactions. These interactions are present both in PNC-containing and -lacking cells. High-resolution localization analyses demonstrate that MRP RNA, CUGBP, and PTB colocalize at the PNC as a reticulated network, intertwining with newly synthesized RNA. Furthermore, green fluorescent protein (GFP)-PTB and GFP-CUGBP show a slower rate of fluorescence recovery after photobleaching at the PNC than in the nucleoplasm, illustrating the different molecular interaction of the complexes associated with the PNC. These findings support a working model in which the MRP RNA-protein complex becomes nucleated at the PNC in cancer cells and may play a role in gene expression regulation at the DNA locus that associates with the PNC.