Abstract 3076: Clonal dynamics and single cell transcriptomics of prostate luminal epithelial cells in aging and cancer

Age-related prostate diseases are among the most frequently encountered conditions in the male population and age remains a major risk for prostate cancer (PCa) development. Understanding the cellular origins of age-related prostate hyperplasia and dysplasia and finding novel ways to halt progression towards malignancy remain fundamental challenges of PCa treatment, prevention, and patient stratification. Elucidating how aging alters the barriers posed by normal homeostasis to tumor cells expansions is of paramount importance for understanding PCa initiation. To date, it remains elusive how prostate clonal activity maintains the constant prostate size and what homeostatic barriers need to be disrupted for the age-related hyperproliferations to occur and lead to cancer. Moreover, altered aging prostate epithelial cell types and mechanisms that facilitate clonal expansion of tumor cells in aging are not well understood. These unresolved questions hamper the development of anti-proliferative therapies designed to block the deregulated activity of aged prostate epithelial cells. We used in vivo lineage tracing with multicolor reporters, whole organ mapping and single cell transcriptomics to study clonal dynamics of the luminal epithelial layer at single cell resolution. We report here the molecular characterization of a newly identified “intermediate” hybrid state in the luminal compartment with increased basal features. These luminal intermediate cells are associated with increased clonal activity and Wnt signaling, including the atypical and understudied Wnt4 ligand. This cell state becomes dominant in aging mouse and human prostate tissue. Within a set of adult/middle age and advanced age normal human prostate samples, we have identified increased levels of Wnt4 expression in aging luminal cells. Moreover, this “pro-proliferative” state has exacerbated growth in oncogenic set-ups leading to clonal expansions in early stages of prostate cancer. We further delineated the master regulators of these luminal intermediate state and singled out p63 as a putative critical activator. In sum, our results suggest that the luminal lineage is maintained by a balancing act of luminal cells activating a “basal-like” pro-proliferative program in response to cellular loss due to normal turnover. These cells are less dependent on androgens, and thus survive better in the low androgen milieu of aging prostate. This active pro-proliferative program is susceptible to hyperproliferation alterations and potentially contributes to the onset of early prostate cancer and might serve as a cell of origin. Our ongoing studies address the targetable vulnerabilities in the Wnt4-p63 luminal signaling in order to provide new venues for therapeutic interventions against age-related prostate hyperproliferations. Citation Format: Fu Luo, Lara F. Tshering, Karis Tutuska, Mariola Szenk, Diana Rubel, James Rail, Savanah Russ, Gabor Balazsi, Flaminia Talos. Clonal dynamics and single cell transcriptomics of prostate luminal epithelial cells in aging and cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3076.