Bladder cancer (urothelial cancer of the bladder) is the most common malignancy affecting the urinary system with increasing incidence and mortality. Treatment of bladder cancer has not advanced in the past 30 years. Therefore, there is a crucial unmet need for novel therapies, especially for advanced disease. We have recently reported Secreted Protein Acidic and Rich in Cysteine (SPARC) as a tumor suppressor in urinary bladder cancer that inhibits the multistep cascades on tumor initiation, progression and metastasis. SPARC gene and protein expression was among candidates associated with the tumorigenicity of the isogenic T24/T24t cell lines. We reported that SPARC depletion in human bladder cancer cell lines including T24 cells increased their tumorigenicity and metastatic potential. In addition, SPARC protein and transcript expression are significantly downregulated in advanced urothelial cancer. To gain insight on the molecular mechanisms of the tumor suppressor effects of SPARC in urothelial cancer, we did whole transcriptome profiling of T24 cells depleted of SPARC to identify SPARC-signature associated with bladder cancer invasiveness, progression, and metastasis. Subsequently, we used gene signature enrichment analysis (GSEA) pathway enrichment tools to define functionally related genes that are consistently up- or down- regulated as a function of loss of SPARC. We found that loss of SPARC expression is associated with enrichment of multiple oncogenic signaling pathways that are enriched in muscle invasive urothelial cancer and have been associated with poor prognosis. These pathways include K-ras, Myc-oncogene, p53 pathways as well as DNA damage/repair. Consistent with our earlier reports, loss of SPARC is associated with genes and proteins involved in angiogenesis, inflammation and hypoxia. In addition, we have identified novel signatures involved in unfolded protein response, mTOR signaling, glycolysis and cholesterol metabolism. These comprehensive signatures not only reveal SPARC-dependent networks that cooperate to elicit its biological responses but enables coherent understanding of the etiology of complex bladder cancer disease. Importantly, these signatures identify novel therapeutic opportunities for bladder cancer.
Citation Format: Bincy Anu John, Neveen Said. Systematic enrichment analysis of gene expression profiling studies identifies SPARC dependent consensus pathways implicated in bladder cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2839. doi:10.1158/1538-7445.AM2017-2839