Hawk, Ernest T.

Abstract Chromosomal aberrations occur frequently during malignant progression from Barrett's esophagus (BE) to esophageal adenocarcinoma (EAC). In this study, we applied Illumina's 317K high-density SNP arrays to profile chromosomal aberrations at each of the four sequential stages of progression - Barrett's metaplasia (BM), low-grade dysplasia (LGD), high-grade dysplasia (HGD), and EAC. We observed significant trends of increasing LOH/deletion associated with the degree of progression. The average numbers of chromosome arms with LOH/deletion per sample were 0.30, 3.21, 7.70, and 11.90 for BM, LGD, HGD, and EAC, respectively (p-for trend=4.82×10−7). The mean percentages of SNPs with LOH/deletion events were 0.1%, 1.8%, 6.6%, and 17.2% for BM, LGD, HGD, and EAC, respectively (p-for trend=2.64×10−6). In BM, there were scattered chromosome deletions at 3p14.2 (10%), 16q23.1 (5%), and 9p21 (5%), which became predominant aberrations in LGD. More importantly, the 3p14.2 (68.4%) and 16q23.1 (50%) LOH/deletion in LGD was exclusively limited to narrow regions within the FHIT (3p14.2) and WWOX (16q23.1) genes, the two most frequent common fragile sites in the human genome. In contrast, the 9p21 deletion (68.4%) occurred in larger regions (encompassing p16 gene), often involving the whole 9p arm. A significant increase in LOH/deletion of other chromosomes was seen in HGD and there was widespread LOH/deletion across the whole genome in EAC. 17p (47.6%) LOH was the most frequent event in EAC, which mostly spanned the entire 17p arm with only one focal site of LOH at 17p13.1. There were many recurrent small regions of LOH/deletion that disrupted a single gene, most of which are common fragile sites in the human genome. RUNX1 is a potential tumor suppressor gene in EAC. Amplifications were rarer than LOH/deletions. The average numbers of chromosome arms with amplification per sample were 0.30, 0.42, 1.90, and 8.50 for BM, LGD, HGD, and EAC, respectively (p-for trend=1.35×10−9). The mean percentages of SNPs with amplification were 0.5%, 0.4%, 1.5%, and 8.0% for BM, LGD, HGD, and EAC, respectively (p-for trend=1.26×10−8). The most frequent chromosome amplifications in EAC were 8q24.21 (36.6%, MYC), 8p23.1 (31.7%, CTSB), 7q21 (30.8%, CDK6), 20q13.2 (28.6%, ZNF217), and 7p11.2 (25.6%, EGFR). We then analyzed the associations of chromosomal aberrations with clinical features and pathological response in EAC patients treated with neoadjuvant chemoradiation. The number and size of LOH/deletion were significantly associated with pathological response. Non-responders had a greater number (16.4 vs. 8.5, p=0.060) and larger size (662.2 Mb vs. 290.7 Mb, p=0.034) of LOH/deletions, and higher percentage of aberrant SNPs (25.2% vs. 11.2%, p=0.030) than responders. This study provides a genome-wide catalogue of chromosome aberrations occurring during the malignant progression from BE to EAC with the highest resolution to date. Our data support genetic instability and p16 loss as drivers of early neoplastic progression from metaplasia to dysplasia, and p53 aberrations as late events critical for progression to adenocarcinoma. Chromosomal aberrations can predict malignant progression and treatment response in EAC, which may have important clinical implications for cancer prevention and personalized treatment of EAC. Citation Information: Cancer Prev Res 2010;3(1 Suppl):A14.

Abstract The Eighth Annual Frontiers in Cancer Prevention Research meeting was held in Houston, Texas, in November 2009. This report highlights significant presentations that advance the fields of chemoprevention, clinical trial recruitment and retention, cancer screening including optical imaging, energy balance, and nutritional epidemiology, and health communications and decision making. In findings from the randomized Reduction by Dutasteride of Prostate Cancer Events trial, dutasteride reduced the risk of biopsy-detectable prostate cancer in high-risk men by 23% compared with placebo. Important clues about the dosing and window of susceptibility for supplementation with choline, vitamin D, and folate were revealed from epigenetic research that has implications for future nutritional epidemiology research. Noninvasive optical imaging techniques using endoscopic ultrasound and autofluorescence for the early detection of cancers in the lung, pancreas, and oral cavity are being studied. The report also addresses the challenges of promoting cancer prevention. Understanding how individuals process risk information and make sustained behavior changes and the effect of socioeconomic status on health disparities were identified as critical areas of research. This multidisciplinary research meeting of basic, clinical, and behavioral scientists and epidemiologists continues to play a major role in identifying the research priority areas of cancer prevention, elucidating new mechanisms of carcinogenesis for targeted chemoprevention therapies and delivering a comprehensive strategy for engaging individuals in the unifying goal to reduce cancer incidence. Cancer Prev Res; 3(8); 1044–8. ©2010 AACR.

Abstract To better understand the molecular mechanisms behind esophageal adenocarcinoma (EAC) tumorigenesis, we used high-density single nucleotide polymorphism arrays to profile chromosomal aberrations at each of the four sequential progression stages, Barrett's metaplasia (BM), low-grade dysplasia (LGD), high-grade dysplasia (HGD), and EAC, in 101 patients. We observed a significant trend toward increasing loss of chromosomes with higher progression stage. For BM, LGD, HGD, and EAC, respectively, the average numbers of chromosome arms with loss per sample were 0.30, 3.21, 7.70, and 11.90 (P for trend = 4.82 × 10−7), and the mean percentages of single nucleotide polymorphisms with allele loss were 0.1%, 1.8%, 6.6%, and 17.2% (P for trend = 2.64 × 10−6). In LGD, loss of 3p14.2 (68.4%) and 16q23.1 (47.4%) was limited to narrow regions within the FHIT (3p14.2) and WWOX (16q23.1) genes, whereas loss of 9p21 (68.4%) occurred in larger regions. A significant increase in the loss of other chromosomal regions was seen in HGD and EAC. Loss of 17p (47.6%) was one of the most frequent events in EAC. Many recurrent small regions of chromosomal loss disrupted single genes, including FHIT, WWOX, RUNX1, KIF26B, MGC48628, PDE4D, C20orf133, GMDS, DMD, and PARK2, most of which are common fragile site regions in the human genome. However, RUNX1 at 21q22 seemed to be a potential tumor suppressor gene in EAC. Amplifications were less frequent than losses and mostly occurred in EAC. 8q24 (containing Myc) and 8p23.1 (containing CTSB) were the two most frequently amplified regions. In addition, a significant trend toward increasing amplification was associated with higher progression stage. Cancer Prev Res; 3(9); 1176–86. ©2010 AACR.

Abstract Aberrant crypt foci (ACF) are the earliest visible neoplastic lesions in the colorectum. The natural history of these lesions and their role in the adenoma-carcinoma sequence are unknown. We studied ACF in a subset of patients randomized to placebo (n = 17), celecoxib (200 mg twice daily; n = 15), or celecoxib (400 mg twice daily; n = 13) in the Adenoma Prevention with Celecoxib (APC) trial. Magnification chromoendoscopy was done to identify, count, and biopsy ACF within the rectum at baseline and after 8 to 12 months of treatment. A total of 655 ACF were identified in 45 patients. We examined 70 of these ACF histologically, and all 70 were nondysplastic. Cohort characteristics and APC trial treatment results for substudy patients were similar to those of the overall APC trial. There was no significant modulation of ACF by celecoxib (versus placebo; P = 0.77). Immunohistochemical comparison of ACF with adjacent normal mucosa showed that ACF had an increased proliferative index as determined by Ki-67 (P < 0.0001), but lacked other features of neoplasia such as increased cyclooxygenase-2 expression and microvessel density, nuclear localization of β-catenin, or decreased expression of the tumor suppressors SMAD4, Estrogen Receptor α, or MGMT. Only baseline SMAD4 expression in ACF correlated with posttreatment adenoma recurrence (independent of treatment arm; P = 0.01). The presence or number of nondysplastic ACF did not correlate with a higher risk of synchronous advanced or recurrent adenomas. Our overall results indicated that nondysplastic ACF were not accurate surrogate endpoint biomarkers of recurrent colorectal adenomas in the APC trial.

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)

AbstractThis article reviews progress in chemopreventive drug development, especially data and concepts that are new since the 2002 AACR report on treatment and prevention of intraepithelial neoplasia. Molecular biomarker expressions involved in mechanisms of carcinogenesis and genetic progression models of intraepithelial neoplasia are discussed and analyzed for how they can inform mechanism-based, molecularly targeted drug development as well as risk stratification, cohort selection, and end-point selection for clinical trials. We outline the concept of augmenting the risk, mechanistic, and disease data from histopathologic intraepithelial neoplasia assessments with molecular biomarker data. Updates of work in 10 clinical target organ sites include new data on molecular progression, significant completed trials, new agents of interest, and promising directions for future clinical studies. This overview concludes with strategies for accelerating chemopreventive drug development, such as integrating the best science into chemopreventive strategies and regulatory policy, providing incentives for industry to accelerate preventive drugs, fostering multisector cooperation in sharing clinical samples and data, and creating public-private partnerships to foster new regulatory policies and public education.

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)