IBCN 2017: Bladder Cancer Progression

Lisbon, Portugal (UroToday.com) Kirsten Junker from Saarland University, Germany presented her abstract ‘Tumor-associated exosomes play a crucial role in the cell-cell communication in bladder cancer’. miRNAs packed in exosomes (Exo) can affect cell-cell communication in the tumor microenvironment and play a crucial role in tumorigenesis. Exo were isolated from invasive (T24,253J-BV,J82), non-invasive (RT112,5637) BC and normal bladder (HCV29) cell lines by ultracentrifugation. MiRNA expression of BC cells and their Exo were analyzed by microarray and qPCR. Uptake of labeled BC-Exo by hTERT-immortalized fibroblasts (hTERT-FB) was shown by LSM. Exo-mediated miRNA transfer between BC and hTERT-FB was shown by transfection of BC cells with cel-miR-39, co-cultivation with hTERT-FB and qPCR. Proliferation and migration of Exo-treated primary BF was measured by BrdU and Boyden Chamber assay. Exo of invasive BC cells are characterized by a specific miRNA signature of 15 miRNAs. Validation of 6 selected miRNAs confirms a significant different expression between both invasive and non-invasive cells and their Exo. In conclusion, Exo secreted by BC cells are characterized by a specific miRNA pattern depending on their invasiveness. Future studie include assessing fibroblasts induced by Exo and their miRNAs correlated with survival outcomes according to treatment.

Bertrand Czerniak from MD Anderson, Houston, TX presented his abstract ‘Molecular Characterization of Field Effects and Their Progression to Clinically Evident Bladder Cancer’. They used a whole organ microscopic strategy coupled with exome sequencing, genome-wide copy number analysis and whole genome methylation to define the genomic profile of bladder cancer progression from field effects to clinically evident disease. They identified complex genomic alterations that involved areas of microscopically normal bladder mucosa adjacent to dysplasia and carcinoma in situ which were hypermethylated. Copy number variations were minimal in the field effects, but involved up to 200 genes including important oncogenes such as SEPT14, GBAS, EPHB4 and CUX1 among others and increased dramatically in parallel to the disease progression. In summary, this strategy has significant implications for understanding the initiating events of bladder carcinogenesis and may provide novel targets for early cancer detection, treatment and prevention.

Charles Guo from MD Anderson, Houston, TX presented his abstract ‘Progression to Sarcomatoid Bladder Cancer is Associated with Dysregulation of Chromatin Remodeling and Cell Cycle Circuits’. Variant pathology portends to increased clinical aggressiveness compared to conventional urothelial carcinoma. They analyzed expression profile of sarcomatoid carcinoma (SARC) in 28 patients with SARC and a reference set of 89 conventional urothelial carcinomas (UC) using Illumina HT-12v4 DASL chips. They showed that SARC was characterized by the genome-wide dysregulation of the expression pattern affecting more than 6000 genes. Among the top upregulated genes were FAM101B, UHRF1, and PHC2, all of which were members of a chromatin remodeling super family. SARC was also characterized by upregulation of multiple oncogenic pathways including RhoA, cell cycle, molecular mechanisms of cancer, and CBX5 targets. Consistent with their epithelial to mesenchymal transition (EMT) SARC demonstrated striking loss of genes associated with epithelial/urothelial differentiation and the activation of EMT genes including SNAIL, TWIST, and ZEB. SARC could be dichotomized into two groups characterized by distinctive expression of basal markers. A subset of SARC, negative for both luminal and basal markers, exhibited the most aggressive behavior when compared to conventional UC and those SARCS that expressed basal markers. In conclusion, progression to SARC is associated with widespread dysregulation of chromatin remodeling and cell cycle circuits. SARCs, which are purely mesenchymal, represent the most aggressive variant of the disease.

Eleonora Lapi from the Spanish National Cancer Research Centre (CNIO), Madrid, Spain presented her abstract ‘Shedding light into the role of STAG2 in urothelial bladder cancer’. Prior data suggests that STAG2 might contribute to bladder cancer. TCGA expression data from 413 samples of muscle-invasive bladder cancer (MIBC) were analyzed. STAG2 loss of expression was associated with the luminal subtype of UBC (UroA and UroB subtypes). Among TCGA MIBC cases, STAG2 mutations were associated with subtypes I and II. Luminal-like/Urothelial tumors were significantly enriched in the PPARg pathway. Using global transcriptomic analyses, we identified Egfr and the ROS pathway as differentially regulated in Stag2 knockdown cells, further supporting a mechanistic role of Stag2 in the tumor phenotype. These results support the notion that STAG2 inactivation contributes to bladder cancer development through the regulation of stemness, differentiation, and growth factor signaling.

Speaker(s): Kirsten Junker, Saarland University, Germany; Bertrand Czerniak, MD Anderson, Houston, TX; Charles Guo, MD Anderson, Houston, TX; Eleonora Lapi, the Spanish National Cancer Research Centre (CNIO), Madrid, Spain

Written by: Stephen B. Williams, M.D., Associate Professor, Division of Urology, The University of Texas Medical Branch, Galveston, TX. and Ashish M. Kamat, M.D. Professor, Department of Urology, Division of Surgery, The University of Texas MD Anderson Cancer Center, Houston, TX., at the International Bladder Cancer Network - October 21, 2017- Lisbon, Portugal