Citations

AbstractThe AURKA oncogene is associated with abnormal chromosome segregation and aneuploidy and predisposition to cancer. Amplification of AURKA has been detected at higher frequency in tumors from BRCA1 and BRCA2 mutation carriers than in sporadic breast tumors, suggesting that overexpression of AURKA and inactivation of BRCA1 and BRCA2 cooperate during tumor development and progression. The F31I polymorphism in AURKA has been associated with breast cancer risk in the homozygous state in prior studies. We evaluated whether the AURKA F31I polymorphism modifies breast cancer risk in BRCA1 and BRCA2 mutation carriers from the Consortium of Investigators of Modifiers of BRCA1/2. Consortium of Investigators of Modifiers of BRCA1/2 was established to provide sufficient statistical power through increased numbers of mutation carriers to identify polymorphisms that act as modifiers of cancer risk and can refine breast cancer risk estimates in BRCA1 and BRCA2 mutation carriers. A total of 4,935 BRCA1 and 2,241 BRCA2 mutation carriers and 11 individuals carrying both BRCA1 and BRCA2 mutations was genotyped for F31I. Overall, homozygosity for the 31I allele was not significantly associated with breast cancer risk in BRCA1 and BRCA2 carriers combined [hazard ratio (HR), 0.91; 95% confidence interval (95% CI), 0.77-1.06]. Similarly, no significant association was seen in BRCA1 (HR, 0.90; 95% CI, 0.75-1.08) or BRCA2 carriers (HR, 0.93; 95% CI, 0.67-1.29) or when assessing the modifying effects of either bilateral prophylactic oophorectomy or menopausal status of BRCA1 and BRCA2 carriers. In summary, the F31I polymorphism in AURKA is not associated with a modified risk of breast cancer in BRCA1 and BRCA2 carriers. (Cancer Epidemiol Biomarkers Prev 2007;16(7):1416–21)

Abstract Aberrant DNA methylation occurs early in oncogenesis, is stable, and can be assayed in tissues and body fluids. Therefore, genes with aberrant methylation can provide clues for understanding tumor pathways and are attractive candidates for detection of early neoplastic events. Identification of sequences that optimally discriminate cancer from other diseased and healthy tissues is needed to advance both approaches. Using well-characterized specimens, genome-wide methylation techniques were used to identify candidate markers specific for colorectal neoplasia. To further validate 30 of these candidates from genome-wide analysis and 13 literature-derived genes, including genes involved in cancer and others with unknown functions, a high-throughput methylation-specific oligonucleotide microarray was used. The arrays were probed with bisulfite-converted DNA from 89 colorectal adenocarcinomas, 55 colorectal polyps, 31 inflammatory bowel disease, 115 extracolonic cancers, and 67 healthy tissues. The 20 most discriminating markers were highly methylated in colorectal neoplasia (area under the receiver operating characteristic curve > 0.8; P < 0.0001). Normal epithelium and extracolonic cancers revealed significantly lower methylation. Real-time PCR assays developed for 11 markers were tested on an independent set of 149 samples from colorectal adenocarcinomas, other diseases, and healthy tissues. Microarray results could be reproduced for 10 of 11 marker assays, including eight of the most discriminating markers (area under the receiver operating characteristic curve > 0.72; P < 0.009). The markers with high specificity for colorectal cancer have potential as blood-based screening markers whereas markers that are specific for multiple cancers could potentially be used as prognostic indicators, as biomarkers for therapeutic response monitoring or other diagnostic applications, compelling further investigation into their use in clinical testing and overall roles in tumorigenesis. (Mol Cancer Res 2007;5(2):153–63)

Human memory is a polygenic trait. We performed a genome-wide screen to identify memory-related gene variants. A genomic locus encoding the brain protein KIBRA was significantly associated with memory performance in three independent, cognitively normal cohorts from Switzerland and the United States. Gene expression studies showed that KIBRA was expressed in memory-related brain structures. Functional magnetic resonance imaging detected KIBRA allele–dependent differences in hippocampal activations during memory retrieval. Evidence from these experiments suggests a role for KIBRA in human memory.

Abstract Cancer cells secrete matrix metalloproteinases (MMP) that degrade the extracellular matrix and are responsible for some hallmarks of malignant cancer. Many viruses, including a few currently used in oncolytic virotherapy clinical trials, depend on intracellular proteases to process their proteins and activate their particles. We show here for measles virus (MV) that particle activation can be made dependent of proteases secreted by cancer cells. The MV depends on the intracellular protease furin to process and activate its envelope fusion (F) protein. To make F protein activation cancer cell specific, we introduced hexameric sequences recognized by an MMP and identified the mutant proteins most effective in fusing MMP-expressing human fibrosarcoma cells (HT1080). We showed that an MMP inhibitor interferes with syncytia formation elicited by mutant F proteins and confirmed MMP-dependent cleavage by Edman degradation sequence analysis. We generated recombinant MVs expressing the modified F proteins in place of furin-activated F. These viruses spread only in cells secreting MMP. In nude mice, an MMP-activated MV retarded HT1080 xenograft growth as efficiently as the furin-activated MV vaccine strain. In MV-susceptible mice, the furin-activated virus caused lethal encephalitis upon intracerebral inoculation, whereas the MMP-activated did not. Thus, MV particle activation can be made dependent of proteases secreted by cancer cells, enhancing safety. This study opens the perspective of combining targeting at the particle activation, receptor recognition, and selective replication levels to improve the therapeutic index of MV and other viruses in ongoing clinical trials of oncolysis. (Cancer Res 2006; 66(15): 7694-700)

We describe a strategy to “revive” putatively pathogenic T cells from frozen specimens of human inflammatory target organs. To distinguish pathogenic from irrelevant bystander T cells, we focused on cells that were ( i ) clonally expanded and ( ii ) in direct morphological contact with a target cell. Using CDR3 spectratyping, we identified clonally expanded T cell receptor (TCR) β-chains in muscle sections of patients with inflammatory muscle diseases. By immunohistochemistry, we identified those Vβ-positive T cells that fulfilled the morphological criteria of myocytotoxicity and isolated them by laser microdissection. Next, we identified coexpressed pairs of TCR α- and β-chains by a multiplex PCR protocol, which allows the concomitant amplification of both chains from single cells. This concomitant amplification had not been achieved previously in histological sections, mainly because of the paucity of available anti-α-chain antibodies and the great heterogeneity of the α-chain genes. From muscle tissue of a patient with polymyositis, we isolated 64 T cells that expressed an expanded Vβ1 chain. In 23 of these cells, we identified the corresponding α-chain. Twenty of these 23 α-chains were identical, suggesting antigen-driven selection. After functional reconstitution of the αβ-pairs, their antigen-recognition properties could be studied. Our results open avenues for combined analysis of the full TCR α- and β-chain repertoire in human inflammatory tissues.

AbstractA randomized, double-blinded, placebo-controlled 2 × 2 factorial chemoprevention trial was conducted in Linxian, China to assess the effects of selenomethionine and celecoxib on the natural history of esophageal squamous dysplasia. Results from this study indicated that asymptomatic adults with mild dysplasia were more likely to show an improvement when treated with selenomethionine compared with placebo (P = 0.02). Prompted by this finding, we examined the molecular profiles associated with regression and progression of dysplastic lesions in normal mucosa from 29 individuals, a subset of the Linxian cohort, using the Affymetrix U133A chip. Twenty differentially expressed genes were associated with regression and 129 were associated with progression when we compared the change in gene expression over time. Genes associated with immune response (n = 15), cell cycle (n = 15), metabolism (n = 15), calcium transport or calcium ion activity (n = 10), regulation of transcription (n = 9), signal transduction (n = 7), cytoskeleton and microtubules (n = 5), nucleotide processing and biosynthesis (n = 4), G-coupled signaling (n = 4), and apoptosis (n = 3) were present in the list of 149 genes. Using the Expression Analysis Systematic Explorer pathway analysis program, only the immune response pathway was significantly overrepresented among these 149 genes. Individuals whose lesions regressed seemed to have higher expression of genes associated with immune stimulation, such as antigen presentation, survival of T cells, and T-cell activation (HLA-DRA, HLA-DPA1, HLA-DBQ1, CD58, and FCER1A). In contrast, individuals whose lesions progressed had higher expression of genes involved in immune suppression and inflammation (CNR2, NFATC4, NFRKB, MBP, INHBB, CMKLR1, CRP, ORMS, SERPINA7, and SERPINA1). These data suggest that local and systemic immune responses may influence the natural history of esophageal squamous dysplasia. (Cancer Res 2006; 66(13): 6851-60)

Abstract Selenium is a promising cancer chemoprevention agent. A recent randomized controlled chemoprevention trial found that selenomethionine (SeMet) supplementation for 10 months favorably effected a change in esophageal dysplasia grade among participants who started the trial with mild dysplasia. To further explore the role of SeMet in this trial, we compared gene expression profiles by treatment group using Affymetrix HU 133A chips in before/after supplementation paired normal esophageal biopsies from a subset of 29 trial participants, 16 who received SeMet, and 13 who received placebo. Using P < 0.001 as a cutoff, 11 differentially expressed genes were found in the SeMet supplementation group but these genes did not include either known selenoprotein genes or genes previously shown to be modulated by selenium treatment. Because the number of differentially expressed genes (n = 11) was less than expected by chance (n = 18), we concluded that SeMet supplementation had no measurable effect on gene expression in the normal squamous esophagus of these subjects with dysplasia. (Cancer Epidemiol Biomarkers Prev 2006;15(5):1046-7)

Abstract Background: Controversy exists over the association of estrogen and cardiovascular disease. Estrogen receptors (ERs) α and β are expressed in the endothelial cells and vascular smooth muscle cells (VSMCs) of many arteries, but the relative importance of ERα or ERβ in mediating the vascular response to estrogens is not well defined, particularly in humans. We have shown previously that postmenopausal women receiving hormone therapy (HT) had lower mean coronary artery calcium, plaque area, and calcium-to-plaque ratio compared with untreated women. In this study, we examined coronary artery ERα and ERβ expression in pre- and postmenopausal women as a function of plaque area, calcium area, calcium-to-plaque ratio, and estrogen status. Methods: Coronary arteries were obtained at autopsy from a total of 55 women: nine premenopausal women, 13 postmenopausal women on HT and 33 untreated postmenopausal women (non-HT). Coronary calcification was quantified by contact microradiography, and atherosclerotic plaque area was measured histologically. Coronary artery cross-sections were immunostained for ERα and ERβ, and the amount of receptors was estimated semiquantitatively in each arterial wall layer (intima, adventitia, and media). Double immunofluorescence was used to colocalize ERα and ERβ with smooth muscle actin, a marker of VSMCs. Results: ERβ and ERα were expressed in all artery wall layers, but most avidly in the media (P = 0.001), and colocalized with VSMCs. ERβ expression exceeded ERα expression in all wall layers (P < 0.001) and was adjacent to areas of calcium deposition. ERβ expression in the intimal layer correlated with calcium content, plaque area, and calcium-to-plaque ratio (all P < 0.01) and tended to be greater in non-HT than in HT women (P = 0.06). ERα expression did not vary significantly among groups, nor did it correlate with calcium content, plaque area or calcium-to-plaque ratio. Expression of ERα but not ERβ declined with age (P < 0.01) in HT women only. Age had no effect on ERα or ERβ expression in non-HT or premenopausal women. Conclusions: ERβ is the predominant ER in human coronary arteries and correlates with coronary calcification, a marker of severe atherosclerosis. Increased ERβ expression is linked to advanced atherosclerosis and calcification independent of age or hormone status. Future pharmacogenetic studies that target this receptor are needed to confirm causality.