Wang, Yin

Abstract TRIM29 (Tripartite Motif-Containing Protein 29), also known as ATDC (Ataxia-Telangiectasia Group D-Complementing Protein), is an E3 ubiquitin ligase frequently upregulated in muscle-invasive bladder cancer (MIBC). We have previously shown that TRIM29 overexpression in a genetically engineered mouse model (GEMM) is sufficient to drive development of MIBC. We have also shown that TRIM29 is enriched in basal bladder cancer subtypes and is part of a TP63-regulated program that promotes migration and invasive progression. Prior studies suggest that Keratin 5/14 (K5+/K14+) expressing basal-stem progenitor cells in the urothelium are the cells of origin for MIBC in mice. However, whether Trim29 expression in these basal urothelial cells is required for MIBC development has not been established. In this study, we find that Trim29 expression in K5+ basal cells is linked to the inflammatory response and is critical for bladder tumor formation and invasive progression. We show that urothelial TRIM29 expression is enhanced during inflammation in humans and under inflammatory and genotoxic stress in mice. Knockout (KO) of Trim29 in the K5+ basal urothelium of a GEMM exposed to a bladder-specific chemical carcinogen blocked MIBC development. Further, urothelial Trim29 KO enriches immune cell recruitment to the bladder and upregulates STING and inflammatory signaling in mouse and human bladder cancers. These data reveal a critical role for TRIM29 in immunomodulation of the bladder tumor microenvironment (TME), which may act in concert with pro-migratory basal gene programs to expedite MIBC development.

Abstract Protein kinase Cι (PKCι) has oncogenic potential and is an attractive therapeutic target for treatment of lung cancer, particularly those tumors that express elevated PKCι. However, whether PKCι is a viable target in ovarian cancer is unknown, and virtually nothing is known about the mechanism by which PKCι drives ovarian tumorigenesis. Here, it is demonstrated that PKCι maintains a tumor-initiating cell (TIC) phenotype that drives ovarian tumorigenesis. A highly tumorigenic population of cells from human ovarian cancer cell lines exhibit cancer stem-like TIC properties, including self-renewal, clonal expansion, expression of stem-related genes, enhanced transformed growth in vitro, and aggressive tumor-initiating activity in vivo. Genetic disruption of PKCι inhibits the proliferation, clonal expansion, anchorage-independent growth, and enhanced tumorigenic properties of ovarian TICs. Biochemical analysis demonstrates that PKCι acts through its oncogenic partner Ect2 to activate a MEK/ERK signaling axis that drives the ovarian TIC phenotype. Genomic analysis reveals that PKCι and Ect2 are coordinately amplified and overexpressed in the majority of primary ovarian serous tumors, and these tumors exhibit evidence of an active PKCι-Ect2 signaling axis in vivo. Finally, this study reveals that auranofin, a potent and selective inhibitor of oncogenic PKCι signaling, inhibits the tumorigenic properties of ovarian TIC cells in vitro and in vivo. These data demonstrate that PKCι is required for a TIC phenotype in ovarian cancer, and that auranofin is an attractive therapeutic option to target deadly ovarian TICs in ovarian cancer patients. Implications: PKCι drives a tumor-initiating cell phenotype in ovarian cancer cells that can be therapeutically targeted with auranofin, a small molecule inhibitor of PKCι signaling. Mol Cancer Res; 11(12); 1624–35. ©2013 AACR.