Angelika Stein

Genetic Variability of the mTOR Pathway and Prostate Cancer Risk in the European Prospective Investigation on Cancer (EPIC)

The mTOR (mammalian target of rapamycin) signal transduction pathway integrates various signals, regulating ribosome biogenesis and protein synthesis as a function of available energy and amino acids, and assuring an appropriate coupling of cellular proliferation with increases in cell size. In addition, recent evidence has pointed to an interplay between the mTOR and p53 pathways. We investigated the genetic variability of 67 key genes in the mTOR pathway and in genes of the p53 pathway which interact with mTOR. We tested the association of 1,084 tagging SNPs with prostate cancer risk in a study of 815 prostate cancer cases and 1,266 controls nested within the European Prospective Investigation into Cancer and Nutrition (EPIC). We chose the SNPs (n = 11) with the strongest association with risk (p<0.01) and sought to replicate their association in an additional series of 838 prostate cancer cases and 943 controls from EPIC. In the joint analysis of first and second phase two SNPs of the PRKCI gene showed an association with risk of prostate cancer (ORallele = 0.85, 95% CI 0.78–0.94, p = 1.3×10−3 for rs546950 and ORallele = 0.84, 95% CI 0.76–0.93, p = 5.6×10−4 for rs4955720). We confirmed this in a meta-analysis using as replication set the data from the second phase of our study jointly with the first phase of the Cancer Genetic Markers of Susceptibility (CGEMS) project. In conclusion, we found an association with prostate cancer risk for two SNPs belonging to PRKCI, a gene which is frequently overexpressed in various neoplasms, including prostate cancer.

Association Between TAS2R38 Gene Polymorphisms and Colorectal Cancer Risk: A Case-Control Study in Two Independent Populations of Caucasian Origin

Molecular sensing in the lingual mucosa and in the gastro-intestinal tract play a role in the detection of ingested harmful drugs and toxins. Therefore, genetic polymorphisms affecting the capability of initiating these responses may be critical for the subsequent efficiency of avoiding and/or eliminating possible threats to the organism. By using a tagging approach in the region of Taste Receptor 2R38 (TAS2R38) gene, we investigated all the common genetic variation of this gene region in relation to colorectal cancer risk with a case-control study in a German population (709 controls and 602 cases) and in a Czech population (623 controls and 601 cases). We found that there were no significant associations between individual SNPs of the TAS2R38 gene and colorectal cancer in the Czech or in the German population, nor in the joint analysis. However, when we analyzed the diplotypes and the phenotypes we found that the non-taster group had an increased risk of colorectal cancer in comparison to the taster group. This association was borderline significant in the Czech population, (OR = 1.28, 95% CI 0.99–1.67; Pvalue = 0.058) and statistically significant in the German population (OR = 1.36, 95% CI 1.06–1.75; Pvalue = 0.016) and in the joint analysis (OR = 1.34, 95% CI 1.12–1.61; Pvalue = 0.001). In conclusion, we found a suggestive association between the human bitter tasting phenotype and the risk of CRC in two different populations of Caucasian origin.

Risk of advanced gastric precancerous lesions in Helicobacter pylori infected subjects is influenced by ABO blood group and cagA status

A higher incidence of stomach cancer in ABO blood type A individuals than in those with blood type O has been known for a long time. We studied this association in relation to Helicobacter pylori (Hp) of different cagA status. For our study, we used baseline gastric histopathology data and DNAs from frozen gastric biopsies of 2,077 subjects enrolled in a chemoprevention trial for gastric precancerous lesions in Venezuela. We analyzed six single nucleotide polymorphisms in the ABO gene, and we assessed the presence of the Hp cagA gene. Odds ratios (ORs) for risk of advanced precancerous gastric lesions were calculated using individuals with normal gastric epithelium or non‐atrophic gastritis as a reference. Among individuals carrying a cagA negative Hp infection or no Hp infection, those with blood type A had a lower risk of intestinal metaplasia (IM) and dysplasia than those with blood type O (OR=0.60; 95% CI 0.38–0.94). In carriers of cagA positive Hp strains, individuals with blood type A had a higher risk of IM or dysplasia than those with blood type O (OR=1.42, 95% CI 1.09–1.86) and a higher risk if compared to subjects carrying cagA negative strain and non‐A blood group (OR=3.82, 95% CI=2.80–5.20). The interaction between Hp cagA status and blood type was statistically significant (p=0.0006). We showed that SNPs in the ABO gene, predictive of ABO blood groups, are associated with risk of advanced precancerous gastric lesions in individuals infected with Hp, but the assessment of the risk is strictly dependent on cagA status.

Interaction between functional polymorphic variants in cytokine genes, established risk factors and susceptibility to basal cell carcinoma of skin

Basal cell carcinoma (BCC) of the skin is the most common neoplasm among the Caucasian population of the Western world. Inflammation may result in oxidative stress and contribute to promotion and progression of tumors, including BCC. The role of cytokines, which are inflammatory modulators, in the biology of tumors has been extensively studied and it is well known that they are aberrantly produced by cancer cells, macrophages and other phagocytic cells. Genetic polymorphisms are known in several cytokine genes, which result in altered expression. In the present association study, we investigated the association of 14 functional polymorphisms in 11 cytokines genes with BCC risk in 529 BCC cases and 532 healthy controls. We have also tested the possible interactions between the genetic variants and three known risk factors for BCC: skin complexion, sun effect and skin response to sun exposure. We did not observe any statistically significant association between SNPs and BCC risk. However, we found that, in a subgroup of subjects more prone to skin burns, carriers of at least one copy of the G allele of rs1800629 (TNF) had an increased risk of BCC [odds ratio (OR) = 2.40, 95% confidence interval (CI) 1.38-4.16, P = 0.0005]. Moreover, in subjects less prone to sunburns, we observed that carriers of the C allele of rs1143627 (IL1B) showed a decreased risk (OR = 0.53, 95% CI 0.34-0.82, P = 0.0019). In conclusion, we found that two polymorphisms in inflammatory genes interacting with environmental risk factors could modulate BCC risk.

Variation in genes coding for AMP-activated protein kinase (AMPK) and breast cancer risk in the European Prospective Investigation on Cancer (EPIC)

AMP-activated protein kinase (AMPK) is an energy sensing/signalling intracellular protein which is activated by an increase in the cellular AMP:ATP ratio after ATP depletion. Once activated, AMPK inhibits fatty acid synthesis and the Akt-mTOR pathway, and activates the p53-p21 axis. All these molecular mechanisms are thought to play a key role in breast carcinogenesis. We investigated the genetic variability of four genes encoding AMPK (PRKAA1, PRKAA2, PRKAB1 and PRKAB2). Using a tagging approach and selecting SNPs we covered all the common genetic variation of these genes. We tested association of tagging SNPs in our four candidate genes with breast cancer (BC) risk in a study of 1340 BC cases and 2536 controls nested into the European Prospective Investigation into Cancer and Nutrition (EPIC). Given the relevance of AMPK on fatty acid synthesis and the importance of body fatness as a BC risk factor, we tested association of SNPs and body-mass index as well. We observed no statistically significant association between the SNPs in the PRKAs genes and BC risk and BMI after correction for multiple testing.

Polymorphisms in regulators of xenobiotic transport and metabolism genes PXR and CAR do not affect multiple myeloma risk: a case–control study in the context of the IMMEnSE consortium

The exposure to pesticides and toxic compounds in xenobiotic transport and metabolism genes has been shown to affect risk of developing multiple myeloma (MM). Therefore, we hypothesized that genetic variations in xenobiotic transport and metabolism regulator genes PXR (NR1I2) and CAR (NR1I3) could determine a difference in MM susceptibility. Ten tagging single-nucleotide polymorphisms (SNPs) for PXR and seven for the CAR genes were selected and genotyped in 627 MM cases and 883 controls collected in the context of the International Multiple Myeloma rESEarch (IMMEnSE) consortium. None of the 17 SNPs investigated showed significant association with MM risk either alone or when combined in haplotypes. Significant SNP–SNP interactions were not found, neither with 58 previously genotyped polymorphisms in ABC transporters. We can therefore exclude that common genetic variants in the xenobiotic transport and metabolism regulator genes PXR and CAR affect MM risk.

Polymorphisms in xenobiotic transporters ABCB1 , ABCG2 , ABCC2 , ABCC1 , ABCC3 and multiple myeloma risk: a case–control study in the context of the International Multiple Myeloma rESEarch (IMMEnSE) consortium

Polymorphisms in xenobiotic transporters ABCB1 , ABCG2 , ABCC2 , ABCC1 , ABCC3 and multiple myeloma risk: a case–control study in the context of the International Multiple Myeloma rESEarch (IMMEnSE) consortium

Genetic variability of the forkhead box O3 and prostate cancer risk in the European Prospective Investigation on Cancer.

Forkhead box O3 (FOXO3) has a wide range of functions: it promotes tumor suppression, cell cycle arrest, repair of damaged DNA, detoxification of reactive oxygen species, apoptosis and plays a pivotal role in promoting longevity. FOXO3 is a key downstream target of the PI3K-Akt pathway in response to cellular stimulation by growth factors or insulin and has been proposed as a bridge between ageing and tumor suppression. Three SNPs in the FOXO3 gene (rs3800231, rs9400239 and rs479744) that have been shown to be strongly and consistently associated with longevity, were examined in relation to PC risk in a case control study of 1571 incident PC cases and 1840 controls nested within the European Prospective Investigation into Cancer and Nutrition (EPIC). There was no statistically significant association between the SNPs and PC risk regardless of the model of inheritance (dominant, codominant and recessive). The associations were not modified by disease aggressiveness, circulating levels of steroid sex hormones, or IGFs or BMI. We conclude that polymorphisms in the FOXO3 gene that are associated with longevity are not major risk factors for PC risk, in this population of Caucasian men.

Erratum: Polymorphisms in xenobiotic transporters ABCB1, ABCG2, ABCC2, ABCC1, ABCC3 and multiple myeloma risk: A case - Control study in the context of the International Multiple Myeloma rESEarch (IMMEnSE) consortium (Leukemia (2012) 26 (1419-1422) DOI: 10.1038/leu.2011.352)

Multiple myeloma (MM) is a hematological neoplasm that arises from a single clone of malignant plasma cells in the bone marrow. In Europe, 4.6/100 000 males and 3.2/100 000 females every year develop MM, with a median age at diagnosis around 60 years. The observation of a higher risk to develop MM among firstdegree relatives of MM patients in several population-based case -control studies supports the idea that genetic factors are involved in MM pathogenesis. Therefore, several studies focusing on various genes and pathways have tried to identify singlenucleotide polymorphisms (SNPs) associated with the susceptibility to the disease. The detoxification and elimination of xenobiotic compounds is one of the most investigated processes in cancer susceptibility, with several evidences of its association with cancer risk. ATPbinding cassette (ABC) subfamily B, member 1 (ABCB1 or MDR1); subfamily G, member 2 (ABCG2 or BCRP); subfamily C, member 2 (ABCC2 or MRP2); subfamily C, member 1 (ABCC1 or MRP1) and subfamily C, member 3 (ABCC3 or MRP3) are efflux pumps that have a key role in determining the intracellular levels of xenobiotic and toxic compounds, thus protecting cells. ABC transporters are expressed in many tissues, including the blood, and they have been recently showed to be characteristically expressed in hematopoietic stem cells (HSCs). Beside, the exposure to pesticides and toxic compounds, most of which are substrates of ABC transporters, has been shown to increase MM and MGUS Q4 risk. Therefore, it is a reasonable hypothesis that genetic variation within these genes can affect the exposure of hematopoietic cells to toxic compounds resulting in an increased/decreased risk of MM. Despite the large number of studies investigating the role of variants in ABC transporters in cancer susceptibility, including hematological malignancies, to date only one investigated the role of three variants in ABCB1 gene and MM susceptibility. Therefore, we performed a two-phase candidate gene association study to comprehensively evaluate the role of genetic variants of ABCs transporter genes in relation to MM risk. We selected 54 SNPs in ABCB1, ABCG2 and ABCC2 genes using a tagging approach to take into account for all the common genetic variability within these genes and four additional functional polymorphisms in ABCC1 and ABCC3 to test their impact on MM susceptibility (a complete list of the selected SNPs is available in Supplementary Table I). In the context of an International Consortium named IMMEnSE (International Multiple Myeloma rESEarch), we collected more of 700 MM cases and 900 controls from Italy, Spain, Poland, Portugal and France. A subset of 633 MM patients and 835 healthy controls with a similar distribution between gender and age (w P1⁄4 0.753, Kruskal -Wallis P1⁄4 0.307) was available for this study and was used for the initial screening of the 58 genetic variants selected. Baseline characteristics of the population are reported in Table 1. The IMMEnSE biobank is set up at the German Cancer Research Center (DKFZ) in Heidelberg, where genotyping has been conducted using both TaqMan (ABI, Applied Biosystems, Foster City, CA, USA) and KASPar (KBioscence, Hoddesdon, UK) technologies and adequate quality control procedures (as described in the Supplementary methods). All the SNPs were in Hardy -Weinberg Equilibrium (HWE) among controls (P40.001) with the exception of the ABCC2 SNP rs3740073 (Po0.001) that was therefore excluded from further analysis. Logistic regression was used to assess the main effects of the genetic polymorphisms on MM risk using a co-dominant and a dominant inheritance model adjusted for age, gender and region of origin. For each SNP, the more common allele in the controls was assigned as the reference category (for detailed material and methods see Supplementary Information). Of the 58 variants screened, 13 SNPs resulted associated with MM risk in the IMMEnSE population at the conventional P-value level of Po0.05 (Supplementary Table II). Haplotype analysis (Supplementary Table III) and gene -gene interaction analysis did not add any significant information to the single SNP analysis. With the aim to further investigate the associations found in the first phase, an independent case -control set of German origin was collected through the collaboration with the Heidelberg Myeloma Group. Using the same methodology described above, we genotyped the 13 SNPs associated in the first phase in 564 MM cases and 1471 healthy controls from Germany (Table 1) with a similar distribution between genders (w P1⁄4 0.141), although age was significantly higher for the controls (Kruskal -Wallis P1⁄4 0.0001). All the SNPs resulted in HWE among controls (P40.001). The two ABCB1 SNPs rs2235013 and rs10256836 were replicated in the Heidelberg population (Supplementary Table IV). We analyzed the results for the whole population of 1197 MM cases and 2306 controls (Supplementary Tables V, VI). Interestingly, the ABCB1 SNPs rs10264990 and rs17327442 resulted associated with MM risk reaching the P-value threshold adjusted for multiple testing (Po0.0014; Table 2). To evaluate heterogeneity of the findings between populations, we performed a meta-analysis across all the different regions in the IMMEnSE and Heidelberg populations. Results showed the absence of statistically significant heterogeneity among different case -control sets and confirmed the associations (Supplementary Figure 1). To further asses the robustness of our findings, we performed 100 000 permutations to compare P-values from randomly generated empirical distributions for the SNPs rs10264990 and rs17327442 with the observed ones. We confirmed in this way the statistically significant associations of the T carriers for the rs10264990 with a decreased risk of MM (P1⁄4 0.015) and of the T/T homozygous for the rs17327442 with an increased risk of MM (P1⁄4 0.009; Table 2). At the best of our knowledge, this is the largest study on genetic susceptibility of MM and has a sufficient statistical power (over 0.80 for a co-dominant model) to detect an odds ratio1⁄4 1.57 at a1⁄4 0.0014 (study-wise significance P-threshold) for a SNP with a MAF1⁄4 0.05 in the overall population. Beside, this is the first comprehensive study that captures all the common genetic Leukemia (2011) 1 3 & 2011 Macmillan Publishers Limited All rights reserved 0887-6924/11