A pleiotropy scan to discover new susceptibility loci for pancreatic ductal adenocarcinoma.

Pleiotropic variants (i.e., genetic polymorphisms influencing more than one phenotype) are often associated with cancer risk. A scan of pleiotropic variants was successfully conducted ten years ago in relation to pancreatic ductal adenocarcinoma susceptibility. However, in the last decade, genetic association studies performed on several human traits have greatly increased the number of known pleiotropic variants. Based on the hypothesis that variants already associated with a least one trait have a higher probability of association with other traits, 61,052 variants reported to be associated by at least one genome wide association study (GWAS) with at least one human trait were tested in the present study consisting of two phases (discovery and validation), comprising a total of 16,055 pancreatic ductal adenocarcinoma (PDAC) cases and 212,149 controls. The meta-analysis of the two phases showed two loci (10q21.1-rs4948550 (P=6.52×10-5) and 7q36.3-rs288762 (P=3.03×10-5) potentially associated with PDAC risk. 10q21.1-rs4948550 shows a high degree of pleiotropy and it is also associated with colorectal cancer risk while 7q36.3-rs288762 is situated 28,558 base pairs upstream of the Sonic Hedgehog (SHH) gene, which is involved in the cell differentiation process and PDAC etiopathogenesis. In conclusion, none of the single nucleotide polymorphisms (SNPs) showed a formally statistically significant association after correction for multiple testing. However, given their pleiotropic nature and association with various human traits including colorectal cancer, the two SNPs showing the best associations with PDAC risk merit further investigation through fine mapping and ad hoc functional studies.

Introducing in vivo pancreatic cancer models for the study of new therapeutic regimens

Introduction: Pancreatic cancer is a severe oncological disease with an ever-increasing incidence and a high rate of morbidity and mortality. Therapeutic options are limited and the five-year overall survival rate is 7­20%, depending on the possibility of surgical resection and the earliness of detection. Most patients with this diagnosis die due to the resistance of tumour cells and their microenvironment to the used treatment regimes. Methods: In our study, we focused on the implementation of two in vivo models, which are the cell-line derived xenograft (CDX) and the patient-derived xenograft (PDX). These two models differ significantly from each other methodologically, technically, financially, but also in their achieved results. Results: In a pilot study, we managed to successfully implement the CDX model with a very aggressive and resistant PaCa-44 line of pancreatic cancer in a total of 30 NU/NU strain mice. Furthermore, we created three PDX models with various subtypes of pancreatic cancer from patients operated at the University Hospital Kralovske Vinohrady, Department of General Surgery. These tumours were re-transplanted into subsequent generations of 23 individuals of NOD/SCID strain and 47 NU/NU strain mice. The established CDX and PDX models are then used to compare conventional and experimental chemotherapy regimens. Conclusion: The next steps will be to evaluate the effects of treatment regimens by using imaging and molecular genetic methods and to optimise the entire process for further use in precise personalised medicine for patients with pancreatic cancer. The upcoming goal is to create a library of PDX models of the most common pancreatic ductal adenocarcinoma and other rare subtypes of pancreatic cancer.

Germline BRCA2 K3326X and CHEK2 I157T mutations increase risk for sporadic pancreatic ductal adenocarcinoma.

Rare truncating BRCA2 K3326X (rs11571833) and pathogenic CHEK2 I157T (rs17879961) variants have previously been implicated in familial pancreatic ductal adenocarcinoma (PDAC), but not in sporadic cases. The effect of both mutations in important DNA repair genes on sporadic PDAC risk may shed light on the genetic architecture of this disease. Both mutations were genotyped in germline DNA from 2,935 sporadic PDAC cases and 5,626 control subjects within the PANcreatic Disease ReseArch (PANDoRA) consortium. Risk estimates were evaluated using multivariate unconditional logistic regression with adjustment for possible confounders such as sex, age and country of origin. Statistical analyses were two-sided with p values <0.05 considered significant. K3326X and I157T were associated with increased risk of developing sporadic PDAC (odds ratio (ORdom ) = 1.78, 95% confidence interval (CI) = 1.26-2.52, p = 1.19 × 10-3 and ORdom = 1.74, 95% CI = 1.15-2.63, p = 8.57 × 10-3 , respectively). Neither mutation was significantly associated with risk of developing early-onset PDAC. This retrospective study demonstrates novel risk estimates of K3326X and I157T in sporadic PDAC which suggest that upon validation and in combination with other established genetic and non-genetic risk factors, these mutations may be used to improve pancreatic cancer risk assessment in European populations. Identification of carriers of these risk alleles as high-risk groups may also facilitate screening or prevention strategies for such individuals, regardless of family history.

KRAS pathway expression changes in pancreatic cancer models by conventional and experimental taxanes.

The KRAS signalling pathway is pivotal for pancreatic ductal adenocarcinoma (PDAC) development. After the failure of most conventional cytotoxic and targeted therapeutics tested so far, the combination of taxane nab-paclitaxel (Abraxane) with gemcitabine recently demonstrated promising improvements in the survival of PDAC patients. This study aimed to explore interactions of conventional paclitaxel and experimental taxane SB-T-1216 with the KRAS signalling pathway expression in in vivo and in vitro PDAC models in order to decipher potential predictive biomarkers or targets for future individualised therapy. Mouse PDAC PaCa-44 xenograft model was used for evaluation of changes in transcript and protein levels of the KRAS signalling pathway caused by administration of experimental taxane SB-T-1216 in vivo. Subsequently, KRAS wild-type (BxPc-3) and mutated (MiaPaCa-2 and PaCa-44) cell line models were treated with paclitaxel to verify dysregulation of the KRAS signalling pathway gene expression profile in vitro and investigate the role of KRAS mutation status. By comparing the gene expression profiles, this study observed for the first time that in vitro cell models differ in the basal transcriptional profile of the KRAS signalling pathway, but there were no differences between KRAS mutated and wild-type cells in sensitivity to taxanes. Generally, the taxane administration caused a downregulation of the KRAS signalling pathway both in vitro and in vivo, but this effect was not dependent on the KRAS mutation status. In conclusion, putative biomarkers for prediction of taxane activity or targets for stimulation of taxane anticancer effects were not discovered by the KRAS signalling pathway profiling in various PDAC models.

Hedgehog pathway overexpression in pancreatic cancer is abrogated by new-generation taxoid SB-T-1216.

The Hedgehog pathway is one of the major driver pathways in pancreatic ductal adenocarcinoma. This study investigated prognostic importance of Hedgehog signaling pathway in pancreatic cancer patients who underwent a radical resection. Tumors and adjacent non-neoplastic pancreatic tissues were obtained from 45 patients with histologically verified pancreatic cancer. The effect of experimental taxane chemotherapy on the expression of Hedgehog pathway was evaluated in vivo using a mouse xenograft model prepared using pancreatic cancer cell line Paca-44. Mice were treated by experimental Stony Brook Taxane SB-T-1216. The transcript profile of 34 Hedgehog pathway genes in patients and xenografts was assessed using quantitative PCR. The Hedgehog pathway was strongly overexpressed in pancreatic tumors and upregulation of SHH, IHH, HHAT and PTCH1 was associated with a trend toward decreased patient survival. No association of Hedgehog pathway expression with KRAS mutation status was found in tumors. Sonic hedgehog ligand was overexpressed, but all other downstream genes were downregulated by SB-T-1216 treatment in vivo. Suppression of HH pathway expression in vivo by taxane-based chemotherapy suggests a new mechanism of action for treatment of this aggressive tumor.

Molecular profile of 5-fluorouracil pathway genes in colorectal carcinoma.

BACKGROUND: This study addresses involvement of major 5-fluorouracil (5-FU) pathway genes in the prognosis of colorectal carcinoma patients. METHODS: Testing set and two validation sets comprising paired tumor and adjacent mucosa tissue samples from 151 patients were used for transcript profiling of 15 5-FU pathway genes by quantitative real-time PCR and DNA methylation profiling by high resolution melting analysis. Intratumoral molecular profiles were correlated with clinical data of patients. Protein levels of two most relevant candidate markers were assessed by immunoblotting. RESULTS: Downregulation of DPYD and upregulation of PPAT, UMPS, RRM2, and SLC29A1 transcripts were found in tumors compared to adjacent mucosa in testing and validation sets of patients. Low RRM2 transcript level significantly associated with poor response to the first-line palliative 5-FU-based chemotherapy in the testing set and with poor disease-free interval of patients in the validation set irrespective of 5-FU treatment. UPP2 was strongly methylated while its transcript absent in both tumors and adjacent mucosa. DPYS methylation level was significantly higher in tumor tissues compared to adjacent mucosa samples. Low intratumoral level of UPB1 methylation was prognostic for poor disease-free interval of the patients (P = 0.0002). The rest of the studied 5-FU genes were not methylated in tumors or adjacent mucosa. CONCLUSIONS: The observed overexpression of several 5-FU activating genes and DPYD downregulation deduce that chemotherapy naïve colorectal tumors share favorable gene expression profile for 5-FU therapy. Low RRM2 transcript and UPB1 methylation levels present separate poor prognosis factors for colorectal carcinoma patients and should be further investigated.

[Clinical and Functional Importance of Selected CASP8 and CASP9 Polymorphisms in Breast Carcinoma]. / Klinický a funkcní význam vybraných polymorfizmu CASP8 a CASP9 u karcinomu prsu.

BACKGROUND: Caspase-8 and caspase-9 (encoded by CASP8 and CASP9) are executive caspases of programmed cell death (apoptosis). Dysregulation of apoptosis plays an important role in cancer development, progression, and resistance to anticancer therapy. The goal of this work was to evaluate potential associations between polymorphisms in CASP8 and CASP9, previously linked to breast cancer risk, and the transcript levels of these genes (including their alternative anti-apoptotic variants) in tumor tissues and the clinical characteristics of the patients. MATERIAL AND METHODS: Sanger sequencing, high resolution melting (HRM) analysis, and allelic discrimination were used to identify polymorphisms in DNA samples isolated from tumor tissues and peripheral blood lymphocytes of 60 breast carcinoma patients. Total transcript levels of CASP8 and CASP9, and levels of alternative splicing variants CASP8L and CASP9B, were quantified by real-time PCR in tumor tissues. Clinically interesting associations were validated in DNA from lymphocytes of 615 breast carcinoma patients. RESULTS: A haplotype in CASP9 composed of three polymorphisms rs4645978-rs2020903-rs4646034 was significantly associated with CASP9 expression in tumors, with the expression of the progesterone receptor and ERBB2, and with the TNBC subtype of breast carcinoma in the validation study. The associations between the rs3834129 polymorphism in CASP8 and stage of disease, rs6435074 with grade, expression of estrogen receptor and ERBB2, and rs6723097 with ERBB2 expression have not yet been validated. However, rs6723097 was associated with disease-free survival in patients treated with hormonal therapy. CONCLUSION: This study reveals a previously unknown and presumably functional (in silico) association between a haplotype in CASP9 and molecular and clinical phenotypes of breast carcinoma. The potential clinical utility of this association for prognostication of breast carcinoma should be evaluated by independent studies.Key words: breast carcinoma - caspases - polymorphisms - functional - clinical - importanceThis work was supported by grant of the CU Grant Agency No. 1444313, and grant of the Internal Grant Agency of the Czech Ministry of Health No. 15-25618A.The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study.The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 3. 3. 2016Accepted: 26. 10. 2016.

[PALB2 as Another Candidate Gene for Genetic Testing in Patients with Hereditary Breast Cancer in Czech Republic]. / PALB2 jako dalsí kandidátní gen pro genetické testování u pa-cientu s hereditárním karcinomem prsu v Ceské republice.

BACKGROUND: The PALB2 (FANCN) gene was identified as a component of endogenous BRCA2 complex that encodes a DNA repair protein participating along with BRCA1 and BRCA 2 proteins in DNA double-strand break repair. Hereditary PALB2 mutations are associated with an increased risk of breast and pancreatic cancers in heterozygotes. Breast cancer risk for PALB2 mutation carriers has recently been estimated at 33-58% depending on family history of breast cancer; pancreatic cancer risk in carriers of PALB2 mutations has not been precisely quantified, yet. MATERIALS AND RESULTS: Results of a study identifying PALB2 mutations in high-risk, BRCA1/2-negative, breast and/or ovarian cancer patients in the Czech Republic indicate that the frequency of hereditary PALB2 mutations in our population is quite high. Interestingly, almost 20% of all recognized mutations comprised large genomic rearrangements. The highest proportion of PALB2 mutations (comparable with the number of mutations reported for BRCA2) was found in a subgroup of hereditary breast cancer patients (5.5%). Frequency of mutations in an independent group of Czech unselected pancreatic cancer patients was approximately 1.3%. CONCLUSION: Considering the frequency of pathogenic, hereditary PALB2 mutations in our population, their phenotypic similarity to BRCA2, and expected risk of breast cancer associated with PALB2 mutations, its screen-ing (including large genomic rearrangements) should be encouraged in patients from hereditary breast cancer families. The follow-up of pathogenic PALB2 mutation carriers should be similar to that in BRCA2 mutation carriers, enabling early diagnosis, prevention, and possible targeted therapy. Preventive surgical interventions for the carriers could be considered in case of strong family cancer history and evident segregation of a pathogenic mutation with a tumor phenotype. Additional analysis of various cancer patient populations and further meta-analyses will be necessary for accurate assessment of PALB2 gene penetrance and its significance for the risk of pancreatic and other cancers.

Fusobacterium nucleatum associates with stages of colorectal neoplasia development, colorectal cancer and disease outcome.

Commensal bacteria in the colon may play a role in colorectal cancer (CRC) development. Recent studies from North America showed that Fusobacterium nucleatum (Fn) infection is over-represented in disease tissue versus matched normal tissue in CRC patients. Using quantitative real-time polymerase chain reaction (qPCR) of DNA extracted from colorectal tissue biopsies and surgical resections of three European cohorts totalling 122 CRC patients, we found an over-abundance of Fn in cancerous compared to matched normal tissue (p < 0.0001). To determine whether Fn infection is an early event in CRC development, we assayed Fn in colorectal adenoma (CRA) tissue from 52 Irish patients. While for all CRAs the Fn level was not statistically significantly higher in disease versus normal tissue (p = 0.06), it was significantly higher for high-grade dysplasia (p = 0.015). As a secondary objective, we determined that CRC patients with low Fn levels had a significantly longer overall survival time than patients with moderate and high levels of the bacterium (p = 0.008). The investigation of Fn as a potential non-invasive biomarker for CRC screening showed that, while Fn was more abundant in stool samples from CRC patients compared to adenomas or controls, the levels in stool did not correlate with cancer or adenoma tissue levels from the same individuals. This is the first study examining Fn in the colonic tissue and stool of European CRC and CRA patients, and suggests Fn as a novel risk factor for disease progression from adenoma to cancer, possibly affecting patient survival outcomes. Our results highlight the potential of Fn detection as a diagnostic and prognostic determinant in CRC patients.

The role of ABC transporters in progression and clinical outcome of colorectal cancer.

Worldwide, colorectal cancer (CRC) is the third most common cancer, with the highest mortality rates occurring in Central Europe. The use of chemotherapy to treat CRC is limited by the inter-individual variability in drug response and the development of cancer cell resistance. ATP-binding cassette (ABC) transporters play a crucial role in the development of resistance by the efflux of anticancer agents outside of cancer cells. The aim of this study was to explore transcript levels of all human ABCs in tumours and non-neoplastic control tissues from CRC patients collected before the first line of treatment by 5-fluorouracil (5-FU)-containing regimen. The prognostic potential of ABCs was evaluated by the correlation of transcript levels with clinical factors. Relations between transcript levels of ABCs in tumours and chemotherapy efficacy were also addressed. The transcript profile of all known human ABCs was assessed using real-time polymerase chain reaction with a relative standard curve. The majority of the studied ABCs were down-regulated or unchanged between tumours and control tissues. ABCA12, ABCA13, ABCB6, ABCC1, ABCC2 and ABCE1 were up-regulated in tumours versus control tissues. Transcript levels of ABCA12, ABCC7 and ABCC8 increased in direction from colon to rectum. Additionally, transcript levels of ABCB9, ABCB11, ABCG5 and ABCG8 followed the reverse significant trend, i.e. a decrease in direction from colon to rectum. The transcript level of ABCC10 in tumours correlated with the grade (P = 0.01). Transcript levels of ABCC6, ABCC11, ABCF1 and ABCF2 were significantly lower in non-responders to palliative chemotherapy in comparison with responders. The disease-free interval of patients treated by adjuvant chemotherapy was significantly shorter in patients with low transcript levels of ABCA7, ABCA13, ABCB4, ABCC11 and ABCD4. In conclusion, ABCC11 may be a promising candidate marker for a validation study on 5-FU therapy outcome.

Ornithine decarboxylase G316A genotype and colorectal cancer risk.

AIM: Ornithine decarboxylase (ODC) is a modifier of adenomatous polyposis coli-dependent tumourigenesis. The G316 > A polymorphism in intron 1 of the ODC gene lies between two myc-binding domains and alters the expression of the gene to affect polyamine metabolism. This variant may be associated with recurrence of colorectal adenoma. We examined whether this variant also modified the susceptibility to sporadic colorectal cancer (CRC). METHOD: The G316 > A variant was analysed in a large (n = 754) CRC case-controlled series of hospital patient volunteers (n = 627) in the Czech Republic, and the relationship with cancer risk was estimated by conditional logistic regression. RESULTS: After adjusting for age and sex, G316 > A was associated with no decrease in CRC risk for either heterozygotes [odds ratio 0.98, 95% confidence interval (CI) 0.77-1.23] or rare allele homozygotes (odds ratio 0.92, 95% CI 0.61-1.37). CONCLUSION: The G316 > A functional variant in the ODC gene is unlikely to make much impact on reducing CRC risk regardless of the reduction in risk found for the recurrence of colorectal adenoma.

Genotype and haplotype analysis of TP53 gene and the risk of pancreatic cancer: an association study in the Czech Republic.

Pancreatic carcinoma is the fourth leading cause of cancer-related deaths in the Czech Republic, with only a minimum of patients surviving 5 years. The aetiology and molecular pathogenesis are still weakly understood. TP53 has a fundamental role in cell cycle and apoptosis and is frequently mutated in solid tumours, including pancreatic cancer. Based on the assumption that genetic variation may affect susceptibility to cancer development, the role of TP53 polymorphisms in modulating the risk of pancreatic cancer may be of major importance. We investigated four selected polymorphisms in TP53 (rs17878362:A(1)>A(2), rs1042522:G>C, rs12947788:C>T and rs17884306:G>A) in association with pancreatic cancer risk in a case-control study, including 240 cases and controls (for a total of 1827 individuals) from the Czech Republic. Carriers of the variant C allele of rs1042522 polymorphism were at an increased risk of pancreatic cancer [odds ratio (OR) 1.73; 95% confidence interval (CI) 1.26-2.39; P = 0.001]. Haplotype analysis showed that in comparison with the most common haplotype (A(1)GCG), the A(2)CCG haplotype was associated with an increased risk (OR 1.39; 95% CI 1.02-1.88; P = 0.034) and the A(1)CCG with a reduced risk (OR 0.30; 95% CI 0.12-0.76; P = 0.011) for this cancer. These results reflect previous findings of a recent association study, where haplotypes constructed on the same TP53 variants were associated with colorectal cancer risk [Polakova et al. (2009) Genotype and haplotype analysis of cell cycle genes in sporadic colorectal cancer in the Czech Republic. Hum. Mutat., 30, 661-668.]. Genetic variation in TP53 may contribute, alone or in concert with other risk factors, to modify the inherited susceptibility to pancreatic cancer, as well as to other gastrointestinal cancers.

CYP1B1 gene polymorphism modifies pancreatic cancer risk but not survival.

UNLABELLED: Pancreatic cancer represents one of the biggest problems of current oncology. The risk factors of pancreatic cancer development, as well as factors affecting survival are poorly understood. Since biotransformation enzymes modify detoxification of carcinogens, we supposed, that arelationship between their polymorphism and the risk of pancreatic cancer development and eventually its clinical outcome may exist.
Associations of so far not studied cytochrome P450 1B1 (CYP1B1) polymorphisms with pancreatic cancer risk were investigated by case-control study. Atotal of 754 participants were recruited during study period. All patients were followed to determine their treatment and overall survival.
Carriers of rare genotype Val/Val in codon 432 of CYP1B1 (rs1056836) were under significantly lower risk of pancreatic cancer than wild type carriers (p=0.035). Carriers of heterozygous genotype (p=0.033) and rare allele Val (p=0.015) were also under lower risk than wild type carriers. When histology-verified patients were analyzed separately, even more significant associations were found (p=0.016, p=0.009, p=0.003, respectively). On the contrary, CYP1B1 polymorphism in codon 453 (rs1800440) did not significantly associate with pancreatic cancer risk. Median survival of patients with rare homozygous genotype Val/Val in CYP1B1-codon 432 was longer but not significantly different from those with wild-type homozygotes. The same was true for CYP1B1-codon 453 wild-type homozygotes in comparison with Ser/Ser rare homozygotes.
CYP1B1 polymorphism in codon 432 seems to modify the risk of pancreatic cancer development and should be further studied. KEYWORDS: Pancreatic cancer, CYP1B1, polymorphism, risk, survival.

Polymorphisms in metabolizing enzymes and the risk of head and neck squamous cell carcinoma in the Slavic population of the central Europe.

The question of susceptibility to squamous cell carcinoma of head and neck (SCCHN) in the environmental context was addressed by analysis of functional polymorphisms in enzymes metabolizing smoke constituents and/or alcohol (CYP2A13, CYP1B1, EPHX1, NQO1, GSTM1, GSTP1, GSTT1, ADH1B and ADH1C). Case-control study of 122 age- and sex-matched pairs of subjects was performed using so far unexplored Central European Slavic population with high level of tobacco and alcohol abuse. Age-, gender-, smoking- and alcohol-adjusted logistic regression failed to demonstrate any significant association of the analyzed polymorphisms with the SCCHN risk. When interactions between potential modifiers of effect, i.e. smoking and alcohol were tested, drinkers seemed to be at lower risk than nondrinkers when carrying the heterozygous genotype Ile/Val in codon 432 of CYP1B1 (OR=0.42; 95% CI=0.21-0.83; p=0.013 vs. OR=1.02; 95% CI=0.34-2.94; p=0.977). Similarly, drinkers were at lower risk than nondrinkers when carrying the heterozygous genotype Pro/Ser in codon 187 of NQO1 (OR=0.41; 95% CI=0.19-0.88; p=0.022 vs. OR=0.96; 95% CI=0.29-3.12; p=0.948). More interestingly, drinkers carrying the rare homozygous genotype Val/Val in codon 350 of ADH1C were at significantly higher risk than nondrinkers carrying this genotype (OR=4.01; 95% CI=1.61-10.01; p=0.003 vs. OR=0.93; 95% CI=0.25-3.57; p=0.919). This result confirmed findings of previously published studies. Smoking did not significantly modify the effect of genotypes. Our data thus demonstrate that genetic susceptibility to SCCHN shall be further followed on populations with different genetic background and lifestyle.

Population-based study of BRCA1/2 mutations: family history based criteria identify minority of mutation carriers.

The two major susceptibility genes, BRCA1 and BRCA2, are involved in hereditary breast and ovarian cancer syndrome. Early detection of mutation carriers has crucial clinical importance, as it allows identification of women who may benefit from intensive clinical follow-up or prophylactic surgery. Generally accepted inclusion criteria for BRCA1/2 mutation testing are based either upon family history of breast or ovarian cancer or young age at cancer diagnosis. In order to analyze the impact of BRCA1/2 mutations on breast cancer development in the Czech population and to confront the clinical and histopathological data of mutation carriers with current criteria for mutation testing we examined the frequency of mutations in unselected breast cancer cases. Mutational analysis of BRCA1/2 genes performed in 679 unselected female breast cancer patients included all recurrent deleterious alterations previously identified in the Prague area and truncating mutations in the whole exon 11 of BRCA1. Within analyzed gene sequences more than 80% of mutations were identified previously in high-risk patients. A total of 16 breast cancer patients (2.4%) carried a mutation. BRCA1 mutations were identified in 14 (2.1%) whereas BRCA2 in 2 (0.3%) women. Family history of ovarian cancer was a strong predictor of a BRCA1/2 mutation (OR = 8.3; p = 0.01), however, family history of breast cancer was not indicative of carrier status. A significant association between medullary breast cancer and mutation status was observed. Current criteria for BRCA1/2 mutation testing would distinguish only 6 out of 16 (37.5%) carriers identified in our study. Ten breast cancer patients with confirmed BRCA1/2 germ-line mutation exhibited no clinical characteristics that would predict their carrier status. Therefore, we believe that the testing for BRCA1/2 mutations in the Czech Republic may not be restricted only to high-risk patients. Our results indicate that analysis of locally prevalent BRCA1/2 mutations in all breast cancer patients might extend substantially the percentage of identified mutation carriers.

[The role of membrane transporters in cellular resistance of pancreatic carcinoma to gemcitabine]. / Role membránových transportéru v chemorezistenci karcinomu pankreatu pri terapii gemcitabinem.

BACKGROUNDS: Pancreatic carcinoma is one of the most serious forms of cancer, with a very high mortality rate, and is the fourth leading cause of cancer-related death in the Czech Republic. The etiology and molecular pathogenesis of the disease is still poorly understood. Gemcitabine is a cytotoxic nucleoside analog, which is widely used in the treatment of malignancies, and in particular in pancreatic carcinoma. Interindividual differences in gemcitabine pharmacokinetics and pharmacodynamics have been demonstrated, which can significantly influence the outcome of the therapy in thus treated patients. Resistance developed to nucleoside analogs limits their clinical use, just like in the case of any other cytostatics. AIM: This review summarizes available data concerning the membrane proteins involved in the transport mechanism of gemcitabine through cellular membrane, and their role in the cellular resistance of pancreatic carcinoma to gemcitabine.

The association between glutathione S-transferase gene polymorphisms and pancreatic cancer in a central European Slavonic population.

In the first case-control study on pancreatic cancer conducted on 253 cases and 403 controls in the Czech Republic we observed that the GSTP1-codon 105 Val variant allele and the GSTT1-null genotype were associated with an elevated risk for pancreatic cancer (OR = 1.38; 95%CI = 0.96-1.97 and OR = 1.56; 95%CI = 0.93-2.61, respectively). Combination of GSTT1-null and GSTP1-codon 105 Val variants further increased the risk for pancreatic cancer (OR = 2.50; 95%CI = 1.20-5.20). In conclusion, this study suggests population-specific associations of polymorphisms in key biotransformation genes with elevated risk for pancreatic cancer.

[Monitoring of anti-tumour cell-mediated response in patients with renal cell carcinoma, disturbance of T cell proliferation]. / Sledování protinádorové bunecné imunitní odezvy u nemocných s renálním karcinomem, porucha proliferace T-lymfocytu.

INTRODUCTION: When checking tumour growth, a number of observations indicate that the immune system plays a significant role in patients with renal cell carcinoma (,,RCC"). Infiltration by lymphocytes (tumour infiltrating lymphocytes, "TILs") is more prevalent in RCC than any other tumours. T lymphocytes are the dominant population of TIL cells. Views concerning the role ofT lymphocytic subpopulations, B lymphocytes and NK cells in an anti-tumour response are not established. AIM: The aim is to determine the phenotype and activation of lymphocytic cells and to compare their representation in tumour stroma (TIL), peripheral blood (PBL) and renal vein blood in patients with RCC. PATIENTS AND METHODS: The samples of peripheral blood taken from the cubital and renal veins and tumour stroma cells were obtained from 60 patients in the course of their surgeries carried out due to primary RCC. TILs were isolated from mechanically disintegrated tumour tissue. Immunophenotype multiparametric analysis of PBL and TILs was carried out. Their surface and activation characteristics were determined by means of flow cytometer. RESULTS: CD3+ T lymphocytes (70.4%) were the main population of TILs. The number of CD3+/CD8+ T lymphocytes was significantly higher in TILs, 39.7% (p < 0.01), while CD4+ T lymphocytes were the majority population in peripheral blood, 41.35% (p < 0.001). The representation of CD3+/69+ T lymphocytes was significantly higher in TILs, 32.05%, compared to PBL (p < 0.001). On the contrary, the numbers of CD3+/CD25+, CD8+/57+ and CD4+/RA+ (naive CD4+ T lymphocytes) were higher in PBL (p < 0.001). The differences in representation of (CD3+/16+ 56+) NK cells and CD3+/DR+ T cells in TILs and PBL were not significant. CONCLUSION: The above-mentioned results prove that the characteristics and intensity of anti-tumour responses are different in compared compartments (tumour/PBL). CD3+/CD8+ T lymphocytes are the dominant lymphocytic population of TILs. The knowledge of phenotype and functions ofeffector cells, which are responsible for anti-tumour response, are the basic precondition for understanding the anti-tumour immune response and the cause of its failure.

Importance of genetic background of oxysterol signaling in cancer.

Oxysterols, oxygenated derivatives of cholesterol, are formed in the human body or ingested. Experimental evidence suggests that due to their diverse functions, e.g. modulating the activity of receptors such as liver X receptors, oxysterol-binding and metabolizing proteins, and several ATP binding cassette transporters, oxysterols may contribute to a number of human disorders including cancer. Genetic variability of oxysterol pathways represents another side of this process, affecting carcinogenesis and cancer progression. This review summarizes information about both the physiological role of oxysterol pathway genes and observed associations between their genetic variability and cancer incidence, progression, and therapy outcome. Besides candidate gene studies, results of genome-wide association studies are presented as well. The survey of available data shows some potential genetic biomarkers that, if clinically validated, may allow the stratification of individuals into genetically defined groups for prediction of individual cancer risk and subsequent screening strategies for early diagnosis.

Relationship between the capacity to repair 8-oxoguanine, biomarkers of genotoxicity and individual susceptibility in styrene-exposed workers.

Genotoxic effects related to exposure to styrene have been a matter of investigation for many years by employing markers of exposure, effect and susceptibility. The role of individual DNA-repair capacity in response to exposure to styrene may explain the controversial results so far obtained, but it is still scarcely explored. In the present study, we measured capacity to repair oxidative DNA damage in cell extracts obtained from 24 lamination workers occupationally exposed to styrene and 15 unexposed controls. The capacity to repair oxidative DNA damage was determined by use of a modified comet assay, as follows: HeLa cells, pre-treated with photosensitizer and irradiated with a halogen lamp in order to induce 7,8-dihydroxy-8-oxoguanine, were incubated with cell extracts from mononuclear leukocytes of each subject. The level of strand breaks reflects the removal of 7,8-dihydroxy-8-oxoguanine from substrate DNA by the enzymatic extract. In styrene-exposed subjects a moderate, non-significant increase in oxidative DNA repair was observed. Stratification for sex and smoking habit showed that unexposed males (P=0.010) and unexposed smokers (P=0.037) exhibited higher DNA-repair rates. The repair capacity did not correlate with parameters of styrene exposure and biomarkers of genotoxic effects (DNA strand breaks, N1-styrene-adenine DNA adducts, chromosomal aberrations and mutant frequencies at the HPRT locus). Significantly higher levels of DNA-repair capacity were observed in carriers of GSTM1-plus, compared to those with a deletion in GSTM1. The DNA-repair capacity was significantly lower in individuals with variant Gln/Gln genotype in XRCC1 Arg399Gln than in those with heterozygous Arg/Gln and wild-type Arg/Arg genotypes. Significantly lower repair capacity was also found in individuals with the wild-type Lys/Lys genotype in XPC Lys939Gln as compared with those homozygous for the Gln/Gln variant genotype.