Androgen and Notch Signaling Gene Signatures Are Associated with Progression in Superfically Invasive Urothelial Carcinomas.
David M Berman, Brandt William, Schultz Luciana, Ross Ashley, Fan Jinshui, Cheadle Christopher, Netto Georges, Schaeffer Edward, Marchionni Luigi, Malmstrom Per-Uno. Johns Hopkins University, Baltimore, MD; Uppsala University, Sweden
Background: Androgen receptor (AR) and Notch signaling may mediate aspects of urothelial carcinoma (UroCa) progression and thus serve as useful biomarkers for titrating therapy. UroCa occurs far more often in males, and AR signaling is required for bladder cancer formation and growth. Notch signaling maintains stem cells and regulates cell fate in development and cancer.
Design: We comprehensively profiled gene expression from cancer cells laser-captured from formalin-fixed paraffin-embedded (FFPE) bladder biopsies from 38 patients with pT UroCa. 19 patients progressed (Prog; median 22 mos) and 19 did not (NProg; median follow-up 84 mos). 14 received intravesical therapy (mitomycin C or BCG) after sampling. FFPE blocks were stored 8 to 26 years prior to sectioning. 22,000 gene profiling used the cDNA-mediated Annealing, Selection, Extension, and Ligation (DASL) system (Illumina, San Diego, CA). Bioinformatic analyses used R/Bioconductor. After quantile normalization, moderated t statistics and adjusted p values were obtained after fitting a linear model that accounted for progression and intravescical treatment effects. Functional themes were obtained from www.NetPath.org. Enrichment analysis was performed by ranking genes by their t-statistics, and testing the hypothesis that each functional gene set is more or less highly ranked (one-sided Wilcoxon rank-sum).
Results: To our knowledge, this is the first array profiling study using LCM FFPE material in UroCa patients. Of 38 samples, 30 (15 Prog, 15 Nprog) showed excellent hybridization characteristics as demonstrated by wide dynamic signal range across probes. Sample age had no effect on assay parameters (p>0.87). 145 genes were differentially expressed (adj. p<0.05) between Prog and NProg. Overall, Notch pathway components were most significantly associated with progression (p<.04). Among treated patients, components of the androgen receptor signaling pathway were most significantly associated with progression (adj. p<0.006), including sorbitol dehydrogenase (SORD), a well established direct target of AR. This observation held despite Prog and NProg being being overwhelmingly male (88%, 84%, respectively, n.s.).
Conclusions: Comprehensive gene expression profiling on LCM samples is feasible, even after long periods of follow-up. OUr data implicate signaling by the Notch and AR pathways in bladder cancer progression and suggest molecular targets for risk stratification and therapeutic intervention. Confirmatory studies in larger cohorts are ongoing.
Tuesday, March 1, 2011 1:00 PM
Platform Session: Section H, Tuesday Afternoon