Joshi, Nina

Abstract A61 Background Patients with Barrett's esophagus (BE) and dysplasia are ideal candidates for chemopreventive strategies to reduce cancer risk. Difluoromethylornithine (DMFO) is a promising chemopreventive agent that inhibits polyamine synthesis involved in the regulation of cell growth and differentiation. We conducted a pilot study to examine the effects of DFMO on esophageal histopathology, mucosal polyamine content, and gene expression. Materials and Methods Patients (n=10) with histologically confirmed BE and low grade dysplasia were enrolled in a single-arm study of DFMO (0.5 g/m2/d) given continuously for 6 months. Esophagoscopy with biopsies (4 quadrants every 1 cm) was performed at baseline, 3 and 6 months, and at 12 months (where available). Grading of dysplasia was performed by a GI pathologist blinded to clinical/biomarker data. Audiology was also performed. Mucosal polyamine content was measured by high-performance liquid chromatography, and analyzed using paired t-tests. Gene expression profiling was performed using a cDNA two-color chip, and was compared between baseline and 6 months. Expression data was normalized using the two-channel fastlo routine and differential expression was computed using a Wilcoxon signed-rank test. Results After 6 months of DFMO treatment, histopathological response data demonstrate regression of dysplasia (n= 1), stable disease (n= 8), and progression of dysplasia (n= 1). Within the stable category, 2 patients with extensive low grade dysplasia showed only focal dysplasia based upon 4 or more biopsies at 6 months. Histolopathological improvements seen at 6 months were maintained at 12 months. Overall, DFMO was well tolerated. One patient had subclinical, unilateral ototoxicity. Modulation of polyamines (spermine, spermidine, putrescine, histamine) was shown only for putrescine which decreased with treatment (6 mo., p=0.07) and showed recovery to baseline at 12 months (p= 0.01). Gene expression profiling revealed modulated genes of potential biological importance (KLF5, KAL1, RFC5, TIMM8a, TC10) and of these, Krüppel-like factor 5 (KLF5) was downregulated whereas the others were upregulated. Conclusion >Further study of the chemopreventive effect of DFMO upon BE with dysplasia is suggested. DFMO treatment suppressed mucosal putrescine levels and downregulated KLF5, an important mediator of cell proliferation. Citation Information: Cancer Prev Res 2008;1(7 Suppl):A61.

Abstract Patients with Barrett's esophagus (BE) and dysplasia are candidates for chemopreventive strategies to reduce cancer risk. We determined the effects of difluoromethylornithine (DMFO) on mucosal polyamines, gene expression, and histopathology in BE. Ten patients with BE and low-grade dysplasia participated in a single-arm study of DFMO (0.5 g/m2/d) given continuously for 6 months. Esophagoscopy with biopsies was conducted at baseline, 3, 6, and 12 months. Dysplasia was graded by a gastrointestinal pathologist. Audiology was assessed (at baseline and at 6 months). Mucosal polyamines were measured by high-performance liquid chromatography. Microarray-based gene expression was analyzed using a cDNA two-color chip. DFMO suppressed levels of the polyamines putrescine (P = 0.02) and spermidine (P = 0.02) and the spermidine/spermine ratio (P < 0.01) in dysplastic BE (6 months vs. baseline) that persisted at 6 months following drug cessation. Among the top 25 modulated genes, we found those regulating p53-mediated cell signaling (RPL11), cell-cycle regulation (cyclin E2), and cell adhesion and invasion (Plexin1). DFMO downregulated Krüppel-like factor 5 (KLF5), a transcription factor promoting cell proliferation, and suppressed RFC5 whose protein interacts with proliferating cell nuclear antigen. Histopathology showed regression of dysplasia (n = 1), stable disease (n = 8), and progression to high-grade dysplasia (n = 1). Polyamines were suppressed in the responder to a greater extent than in stable cases. DFMO was well tolerated, and one patient had subclinical, unilateral ototoxicity. DFMO suppressed mucosal polyamines and modulated genes that may be mechanistically related to its chemopreventive effect. Further study of DFMO for the chemoprevention of esophageal cancer in BE patients is warranted. Cancer Prev Res; 4(6); 829–39. ©2011 AACR.

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)