A different prognostic value of BRAFV600E mutation positivity in various age groups of patients with papillary thyroid cancer.

The aim of the retrospective single-center study was to assess the prognostic value of BRAFV600E mutation positivity (BRAFV600E+) on disease persistence/recurrence in patients with papillary thyroid cancer (PTC). A total of 199 patients having had initial surgery with neck dissection in our hospital between 6/2009-6/2012 were included in the cohort. Excluded were patients with unifocal microcarcinoma ≤1cm. BRAFV600E mutation was tested from formalin-fixed paraffin-embedded surgicaly removed tumors. All included patients were postoperatively treated with radioiodine. The median duration of follow-up was 43 months, quartiles range 30 - 58 months. Variables included in the final model: BRAFV600E+, categorised age, sex, and high-risk status, or alternatively lymph node status. Based on differences in persistence/recurrence rates, patients were divided into three age categories (<35, 35-60, ≥60). Multiple regression analysis showed a significant interaction between BRAFV600E+ and age, modifying the effect of BRAFV600E+ on persistence/recurrence. BRAFV600E+ in low-risk patients of any age and in high-risk middle-aged patients did not confer additional hazard compared with BRAFV600E mutation negative (BRAFV600E-) low-risk and BRAFV600E- high-risk patients, respectively. However, younger (<35 years) and older (≥60 years) high-risk BRAFV600E+ patients had 17.28 and 33.49-fold increased hazard of persistence/recurrence, respectively, compared with low-risk BRAFV600E- patients. The alternative model including lymph node status yielded similar results for the prognostic significance of BRAFV600E+ in younger and older patients. In conclusion, the prognostic value of BRAFV600E+ depends on high-risk status and likely on age-associated factors. Such additional knowledge could change clinical decision-making in treatment modality.

Molecular analysis of EGFR gene in different types of tumor material from NSCLC patients.

Lung carcinoma is the most frequently occurring cancer worldwide and the Non-small Cell Lung Cancer (NSCLC) subtype represents 80% of all diagnosed cases. Epidermal growth factor receptor (EGFR) has an important dual role in NSCLC patients. On one hand, EGFR is frequently mutated in many types of tumors, which leads to deregulation of important downstream pathways including those affecting cell proliferation, differentiation and migration. On the other hand, presence of certain activating mutation leads to increased sensitivity of EGFR to tyrosine kinase inhibitors (TKIs) treatment. Detection of these mutations is essential for identification of NSCLC patients who would profit from such therapy. However, due to the nature of available tumor material and the relatively high number of mutation hot spots, such DNA analysis may be challenging and time consuming. Here we present an approach combining direct sequencing and SNaPshot assay for identification of EGFR mutations in FFPE tissues as well as in rarely analyzed cytological smears. Using this strategy on the set of 450 tested NSCLC samples; we have identified 29 activating mutations and 14 variants, which might be interesting in predicting the efficiency of TKI therapy.

The detection of circulating tumor cells expressing E6/E7 HR-HPV oncogenes in peripheral blood in cervical cancer patients after radical hysterectomy.

The aim of this study was to establish the sensitive, specific and clinically acceptable method for detection of tumor cells (TCs) circulating in peripheral blood (PB) of cervical cancer patients without the clinically detectable risk of disease progression. The 7.5 ml of PB of healthy donor was spiked with 5 to 100 cells from SiHa or HeLa cell lines. The spiked tumor cells were collected without gradient centrifugation, by standard gradient centrifugation or by modified gradient centrifugation combined with immunomagnetic separation using EpCAM antibody with affinity for epithelial cell adhesion molecule. The number of collected TCs was determined by EpCAM-FITC-staining and their viability was detected by nested RT-PCR amplifying E6/E7 HR-HPV 16 or HR-HPV 18 oncogenes. For the technical validation of this approach the TCs separation and RT-PCRs were repeated several times. The recovery of viable TCs was reproducibly higher using modified gradient centrifugation combined with immunomagnetic separation in comparison with standard approach. The recovery of TCs in low number of spiked TCs (range from 5 - 20 TCs in 7.5 ml of PB) using modified gradient centrifugation was not reproducible. The recovery of TCs in higher number of spiked TCs (25 TCs and more in 7.5 ml of PB) was reproducible with average recovery about 50 %. The sensitivity of nested RT-PCR amplifying E6/E7 oncogenes was decisively influenced by the number of recovered TCs and the amount of cDNA introduced to RT-PCR, as well. Using this approach we were allowed to detect circulating TCs (CTCs) in cervical cancer patients without metastases, thus this procedure might become a tool to early estimation of disease progression. According to our knowledge, this is the first report describing the use of EpCAM antibody for CTCs detection in cervical cancer patients.

Genetic analysis of KRAS mutation status in metastatic colorectal cancer patients.

Colorectal carcinoma (CRC) represents a serious problem worldwide: in the Slovak republic are diagnosed about 2600 new CRC cases annually and its incidence is increasing. Colorectal cancer patients may succumb to the disease because of local recurrence or local formation of metastasis. Therefore, it is necessary to modulate therapeutic algorithm with new methods, leading to early diagnostic of CRC or changing the existing therapeutic procedures. Recent progresses have been made in understanding of EGFR pathway involved in CRC carcinogenesis, especially the role of Ras protein. Mutations in KRAS oncogene are frequently found in human cancers, particularly colorectal, pancreatic, billiary tract and lung tumors. The presence of the KRAS mutations in metastatic colorectal cancer patients correlates with lack of response to the certain epidemal growth factor receptor (EGFR) inhibitor therapies, such as Panitumumab and Cetuximab. Consequently, screening for KRAS mutations status may be used as a prognostic marker, because the CRC patients with KRAS positive tumors have a worse prognosis. The aim of our study was to establish the methods for rapid and sensitive detection of KRAS mutation status in formalin fixed paraffin embedded (FFPE) tissues DNA. We applied Real Time PCR analysis (TheraScreen KRAS Mutation Test Kit) and sequencing analysis (optimised for the analysis of FFPE tissues) to detect somatic mutations in codon 12 and 13 of KRAS gene. Both methods were used concurrently in the panel of DNA isolated from 25 colorectal FFPE tissues tumor. The positive or negative results from all 25 samples were identified by both methods independently. The KRAS mutations were presented in 8 of 25 patients (32%). Our results demonstrate that the Real Time PCR analysis can be used for detection of somatic KRAS mutations in FFPE clinical samples. However, we also recognize that the sequencing analysis of approximately 200bp amplicons may be used for mutations status screening, but with care of method sensitivity.

The role of clinical criteria, genetic and epigenetic alterations in Lynch-syndrome diagnosis.

Lynch syndrome (hereditary nonpolyposis colorectal cancer, HNPCC) represents 1-3% of all diagnosed colorectal cancers (CRCs). This study aimed to evaluate the benefit of clinical criteria and several molecular assays for diagnosis of this syndrome. We examined tumors of 104 unrelated clinically characterized colorectal cancer patients for causal mismatch repair (MMR) deficiency by several methods: microsatellite instability (MSI) and loss of heterozygosity (LOH) presence, MMR protein absence, hypermethylation of MLH1 promoter and germline mutation presence. Twenty-five (24%) patients developed CRCs with a high level of MSI (MSI-H). Almost all (96%) had at least one affected relative, while this simple criterion was satisfied in only 22% (17/79) of individuals with low level MSI or stable cancers (MSI-L, MSS). Using strict Amsterdam criteria, the relative proportion of complying individuals in both sets of patients (MSI-H vs. MSI-L and MSS) decreased to 68% and 9%, respectively. The right-sided tumors were located in 54% of MSI-H persons when compared to 14% of cancers found in MSI-L or MSS patients. In 16 MSI positive patients with identified germline mutation by DNA sequencing, the gene localization of mutation could be indicated beforehand by LOH and/or immunohistochemistry (IHC) in four (25%) and 14 cases (88%), respectively. The IHC findings in MSI-H cancers with methylation in distal or both regions of MLH1 promoter have not confirmed the epigenetic silencing of the MLH1 gene. None of the patients with MSIL or MSS tumors was a carrier of the MLH1 del616 mutation, despite seven of them meeting Amsterdam criteria. The effective screening algorithm of Lynch-syndrome-suspected patients consists of evaluation of Bethesda or Revised Bethesda Guidelines fulfilling simultaneous MSI, LOH and IHC analyses before DNA sequencing. Variable methylation background in MLH1 promoter does not affect gene silencing and its role in Lynch-syndrome tumorigenesis is insignificant.

STK11/LKB1 germline mutations in the first Peutz-Jeghers syndrome patients identified in Slovakia.

Peutz-Jeghers syndrome (PJS) is characterized by number of hamartomatous polyps in the gastrointestinal tract and by mucocutaneous hypermelanocytic lesions at different sites. Older patients have an increased risk of the cancers of small intestine, stomach, pancreas, colon, esophagus, ovary, testis, uterus, breast and lung. In majority of PJS cases, the germline mutations in serine/threonine kinase STK11/LKB1 gene were found to be associated with disease. Here we report the results of a first mutational screen of STK11/LKB1 in PJS patients characterized in Slovak population. The first patient with unusual carcinoma of duodenum was a sporadic case and carried c.842delC change residing in a mutational C6 repeat hotspot. Neither the polyp nor the tumor of the patient displayed the loss of heterozygosity at the site of mutation suggesting different mechanism involved in the formation of polyp and tumor in this case. The second patient belonged to a three-generation family with typical PJS features but not cancers. Interestingly, the patient displayed concomitant occurrence of adenomatous and hamartomatous polyps. Molecular analysis revealed an IVS2+1A>G mutation that alters the second intron 5' splice site and was shown to lead to aberrant splicing mediated by the U12-dependent spliceosome. The same mutation was present in the 9 affected members of the family but in none of their normal relatives. We also observed novel c. IVS2+61G>A unclassified variant, and recurrent IVS2+24G>T and 3UTR+129C>T polymorphisms. Based on the achieved results, we could offer predictive genetic testing and counseling to other members of the patient's families.

Natural microbial polysaccharide sulphoethyl glucan as antigenotoxic and cancer preventing agent.

Naturally occurring polysaccharides isolated from the yeasts are the substances with versatile intriguing biomodulatory activities. One of the novel derivatives prepared from the (1 --> 3)-beta-D-glucan isolated from the cell walls of baker's yeast Saccharomyces cerevisiae is sulfoethyl glucan (SEG). Its DNA-protective, antimutagenic, anticlastogenic and cytotoxic/cytostatic enhancing effect was evaluated using five eukaryotic systems. SEG showed bioprotective effect in recombination- repair-deficient strain of alga Chlamydomonas reinhardtii against methyl methanesulfonate-induced genotoxicity, antimutagenic effect against ofloxacin-induced genetic changes in yeast Saccharomyces cerevisiae assay and anticlastogenic activity in plants Vicia sativa and Vicia faba assays against maleic hydrazide-induced clastogenicity. In the combined application with cytostatic drug vumon, SEG exerted enhancement of the drug's cytotoxic/cytostatic effect in the cell revitalization assay using mouse leukemia cells. The study sheds light on the possible mechanisms of actions and utilization of this microbial polysaccharide derivative in the cancer prevention and therapy.

Novel and recurrent germline alterations in the MLH1 and MSH2 genes identified in hereditary nonpolyposis colorectal cancer patients in Slovakia.

Hereditary non-polyposis colorectal cancer (HNPCC) is associated with germline mutations in DNA mismatch repair genes, predominantly MSH2 and MLH1. Mutation carriers develop cancers in the colorectum, endometrium, ovary, stomach, small intestine and the upper urinary tract. We describe here the results of a mutational analysis of 11 unrelated HNPCC patients by direct genomic sequencing of MLH1 and MSH2. The alterations found include 7 novel changes and 4 different pathogenic mutations described previously in Poland, Moldavia, Finland, Germany, France and USA. Four novel pathogenic mutations in the MLH1 gene include two frameshift mutations (c.1150delG and c.1210_1211delCT), one missense mutation (c.793C>A) and one intron-exon border mutation (c.546- 2A>C). The last change resulted in the skipping of exon 7, as shown by sequencing of RT-PCR products. The only novel MSH2 pathogenic change was a nonsense mutation c.1129C>T. The novel intronic change c.381-41A>G in MLH1 was found in a patient carrying a previously-described mutation in the MSH2 gene. Interestingly, two unrelated patients carried also a novel change in the promoter region of MLH1 in one of the CpG islands (c.-269C>G). However, this alteration does not abrogate transcription, as shown by RT-PCR analysis. In summary, most (approximately 80%) pathogenic germline mutations detected in the studied group of patients by direct genomic sequencing of MLH1 and MSH2 were located in the MLH1 gene. These and previous data indicate that the majority of germline point mutations and small deletions/insertions in HNPCC families in Slovakia affect the MLH1 locus.