Modeling neuroendocrine bladder cancer for studying the pathogenesis and improving chemotherapy responses

This proposal addresses PAR-24-306 (Research Projects to Enhance Applicability of Mammalian Models for Translational Research) by developing and credentialling NeuroEndocrine Bladder Carcinoma (NEBC) models for cross-species comparison and evaluating innovative treatment approaches. Most bladder cancer (BC) are conventional urothelial carcinomas (UC) that originate from urothelial cells, the lining of the bladder. Histology variants/subtypes can be found in up to 30% of bladder cancer patients and often co-exist with UC tumors. NEBC significantly contributes to BC death because NEBC is incurable and often relapses after the standard etoposide and cisplatin (EP) chemotherapy. A clear unmet need is to understand the different pathogenesis of NEBC tumors and develop novel treatment strategies for overcoming chemotherapy resistance. However, no studies have systemically investigated NEBC, due to a lack of relevant genetically engineered mouse models (GEMMs) and patient derived organoid/allograft (PDO/PDX). Genomic studies of NEBC tumors have revealed 3 common altered pathways: TP53/RB1/PTEN(PIK3CA). Inactivating mutations of TP53 RB1, and PTEN are more enriched in NEBC tumors (n=47, TP53 83%, RB1 79%, PTEN 13%) than in muscle invasive BC (MIBC) tumors. Therefore, we developed two complementary triple knockout (TKO: Trp53-/-; Pten-/-; Rb1-/-) NEBC GEMMs. These include the UP2-Cre;TKO model, driven by the bladder-specific Uroplakin 2 promoter (UP2-Cre), and the Ad-Cre;TKO model, by intravesical injection of adenovirus-Cre (Ad-Cre) driven by a CMV promoter. The UP2-Cre;TKO model developed pure NEBC tumors, while the Ad-Cre;TKO model developed mixed NEBC/UC tumors. These mouse NEBC (mNEBC) tumors exhibited resistance to EP chemotherapy and a marked activation of the ATM pathway following EP treatment. Additionally, we established PDOs/PDXs from NEBC patients who exhibited resistance to EP chemotherapy. Based on these NEBC GEMMs and PDOs/PDXs, we are ideally positioned to test the hypothesis that NEBC GEMMs faithfully recapitulate human NEBC (hNEBC) biology, particularly in the molecular mechanism and their therapeutic resistance to EP chemotherapy. Our hypotheses will be tested in two specific aims: 1) Aim 1: Develop and credential novel syngeneic NEBC GEMMs and mixed NEBC/UC GEMMs. 2) Determine whether mNEBC GEMMs replicate hNEBC treatment responses and assess the efficacy of ATM inhibitors (ATMi) in enhancing EP chemotherapy responses. This proposal leverages our team expertise in the clinical management of BC and NEBC, as well as the GEMMs/PDXs pathological and bioinformatic characterization, and bladder cancer therapeutics. Our approach is innovative, utilizing novel immune-competent NEBC GEMMs, human NEBC PDXs, and incorporating advanced technologies such as single-cell ATAC/RNA- seq and CHIP-seq. This research is significant as it seeks to develop innovative treatment strategies to overcome chemotherapy resistance. Project Number: 1R01CA308972-01 | Fiscal Year: 2026 | NIH Institute/Center: National Cancer Institute (NCI) | Principal Investigator: Qiang Li | Institution: ROSWELL PARK CANCER INSTITUTE CORP, BUFFALO, NY | Award Amount: $639,379 | Activity Code: R01 | Study Section: Special Emphasis Panel[ZRG1 CTH-B (55)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11269431