Abstract 316: Engineering large chromosomal deletions to advance precision oncology for prostate cancer

Human prostate cancer is notable for its high number of somatic copy number alterations (CNAs), which include both focal and broad arm-level amplifications and deletions. Up to 90% of prostate tumors harbor aberrant CNAs, and genomic deletions affect about 40% of these tumors. Many chromosomal deletions are highly recurrent and occur in more than 10% of prostate tumors, including 8p (40~50%), 6q14-16, 10q23, 13q14, and 16q22-24 (20~30% each). Most of these deletions are large, often including hundreds of genes. Notably, several large deletions, including 6q14-16 and 16q22-24, are significantly associated with poor patient outcomes, suggesting that these large chromosomal deletions play a functional role in prostate tumorigenesis, and highlighting the critical need for elucidation of the mechanisms underlying large-deletion driven tumorigenesis. However, due to the limited cloning capacity of targeting vectors and the rarity of on-target homologous recombination events in traditional gene-targeting technology, modelling large chromosomal deletions has proven highly challenging, and the role of such lesions in tumorigenesis has therefore been significantly understudied. Here, we developed an innovative approach to engineering the chromosome over large genetic distances through CRISPR/Cas9 technology in both mouse embryonic stem (ES) cells and human prostate cancer cells. Upon completion of the desired genome edits, the resulting mouse ES clones make possible the creation of conditional knockout mice that accurately mimic prostate cancer-associated large deletions, while the engineered human cancer cell clones serve as an indispensable in vitro model to validate the biological relevance of large chromosomal deletions in prostate tumorigenesis. Further characterization of the human prostate cell line bearing 10q23 deletion revealed that 10q23 loss conferred RWPE1 cells growth advantage. The development and characterization of these in vivo and in vitro models will contribute greatly to the implementation of precision oncology research, open new opportunities for modelling human diseases associated with large chromosomal deletions, and lead to novel insights into the biology of prostate cancer-associated large deletions, which will facilitate the identification of deletion-specific vulnerabilities that can be exploited for prostate cancer treatment. Citation Format: Jinjin Wu, Chen Wu, Joel A. Lawitts, Cheryl B. Bock, Jiaoti Huang, Ming Chen. Engineering large