A genetically defined disease model reveals that urothelial cells can initiate divergent bladder cancer phenotypes

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 117; no. 1; pp. 563 - 572
• Main Authors: Wang, Liang, Smith, Bryan A., Balanis, Nikolas G., Tsai, Brandon L., Nguyen, Kim, Cheng, Michael W., Obusan, Matthew B., Esedebe, Favour N., Patel, Saahil J., Zhang, Hanwei, Clark, Peter M., Sisk, Anthony E., Said, Jonathan W., Huang, Jiaoti, Graeber, Thomas G., Witte, Owen N., Chin, Arnold I., Park, Jung Wook
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 07.01.2020
• Subjects: Animals; Antineoplastic Agents, Immunological - pharmacology; Antineoplastic Agents, Immunological - therapeutic use; B7-H1 Antigen - antagonists & inhibitors; B7-H1 Antigen - metabolism; Biological Sciences; Bladder; Bladder cancer; Cancer; Carcinoma, Small Cell - genetics; Carcinoma, Small Cell - pathology; Carcinoma, Small Cell - therapy; Carcinoma, Transitional Cell - genetics; Carcinoma, Transitional Cell - pathology; Carcinoma, Transitional Cell - therapy; Cell surface; Cell Transformation, Neoplastic - drug effects; Cell Transformation, Neoplastic - genetics; Cells, Cultured; Cystectomy; Datasets as Topic; Epithelial Cells; Gene Expression Regulation, Neoplastic; Genetic Engineering; Humans; Immune checkpoint inhibitors; Lymphocytes; Lymphocytes, Tumor-Infiltrating - metabolism; Mice; Pathogenesis; PD-L1 protein; Phenotypes; Primary Cell Culture; Proteins; RNA-Seq; Squamous cell carcinoma; Transcription; Tumor cells; Tumor-infiltrating lymphocytes; Tumors; Urinary Bladder - cytology; Urinary Bladder - pathology; Urinary Bladder - surgery; Urinary Bladder Neoplasms - genetics; Urinary Bladder Neoplasms - pathology; Urinary Bladder Neoplasms - therapy; Urothelial carcinoma; Urothelium - cytology; Urothelium - pathology; Xenograft Model Antitumor Assays; Xenografts; Xenotransplantation; preclinical model; cell surface protein; urothelial cell; cancer phenotypes
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1915770117

Small cell carcinoma of the bladder (SCCB) is a rare and lethal phenotype of bladder cancer. The pathogenesis and molecular features are unknown. Here, we established a genetically engineered SCCB model and a cohort of patient SCCB and urothelial carcinoma samples to characterize molecular similarities and differences between bladder cancer phenotypes. We demonstrate that SCCB shares a urothelial origin with other bladder cancer phenotypes by showing that urothelial cells driven by a set of defined oncogenic factors give rise to a mixture of tumor phenotypes, including small cell carcinoma, urothelial carcinoma, and squamous cell carcinoma. Tumor-derived single-cell clones also give rise to both SCCB and urothelial carcinoma in xenografts. Despite this shared urothelial origin, clinical SCCB samples have a distinct transcriptional profile and a unique transcriptional regulatory network. Using the transcriptional profile from our cohort, we identified cell surface proteins (CSPs) associated with the SCCB phenotype. We found that the majority of SCCB samples have PD-L1 expression in both tumor cells and tumor-infiltrating lymphocytes, suggesting that immune checkpoint inhibitors could be a treatment option for SCCB. We further demonstrate that our genetically engineered tumor model is a representative tool for investigating CSPs in SCCB by showing that it shares a similar a CSP profile with clinical samples and expresses SCCB–up-regulated CSPs at both the mRNA and protein levels. Our findings reveal distinct molecular features of SCCB and provide a transcriptional dataset and a preclinical model for further investigating SCCB biology.