Abstract 2510: An atlas of single-cell and spatial transcriptomics reveals alterations that correlate with human prostate cancer progression
Authors: Hirz Taghreed , Mei Shenglin , Sarkar Hirak , Kfoury Youmna , Wu Shulin , Wu Chin-Lee , Chen Fei , Macosko Evan Z. , Dahl Douglas M. , Baryawno Ninib , Scadden David T. , Saylor Philip J. , Kharchenko Peter V. , Sykes David B. 
Published: June 2022

Abstract
Most systemic therapies for prostate cancer target androgen receptor signaling. Given the ongoing disease burden and mortality from advanced prostate cancer that persist despite available therapies, novel therapeutic targets are clearly needed.
To this end, we conducted a high-resolution analysis of primary prostate cancer samples across a spectrum of tumor stage using 10x Chromium scRNAseq. Within each patient, we compared the prostate tumor to its adjacent normal tissue. These samples were also compared to healthy prostate samples collected from patients whose prostates were removed in the setting of bladder cancer surgery.
Joint analysis revealed a rich repertoire of immune and non-immune stroma cells. Significant alterations were apparent in the prostate tumor microenvironment compared to adjacent normal and healthy samples. One striking difference was an expansion of T-cell cluster characterized by decreased cytotoxic and an increased exhaustion gene signatures. Another difference was the significantly higher regulatory T cell (Treg) activity.
There was a substantial population shift within the myeloid compartment. Specifically, tumor tissue showed a selective enrichment in M2-like macrophages which was validated by multiplex immunohistochemistry. In addition, tumor tissue showed a significant increase in the myeloid-derived suppressor cell scoring in tumor inflammatory monocytes that strongly correlated with Treg activity. The changes in both myeloid and T cell gene expression suggest an immune suppressive environment within the tumor.
In addition, we performed Slide-seqV2 to generate high spatial resolution maps of cellular organization of prostate tissues. The highly detailed spatial configuration of the healthy prostate tissue showed well-organized prostate epithelial glands surrounded by immune and non-immune stromal cells. This tissue architecture was severely disrupted within the cancerous prostate. Endothelial and fibroblast populations were disorganized and dispersed throughout the invading tumor. Context-dependent differential expression gene analysis on endothelial cells showed significant upregulation of sprouting angiogenesis and vascular endothelial growth factor pathways in the tumor context. In addition, we developed an approach to characterize the coordination between tumor cells and stromal compartment via spatial ligand-receptor (L/R) interaction. Data revealed 405 significant potential communication channels with many of these interactions known to have a role in prostate tumor angiogenesis and progression.
These data provide a high resolution landscape of localized prostate cancer via 10x and Slide-seq. Data showed an immunosuppressive milieu in addition to highly active endothelial angiogenic program. L/R interaction analysis revealed interactions that may serve as potential therapeutic targets.
Citation Format: Taghreed Hirz, Shenglin Mei, Hirak Sarkar, Youmna Kfoury, Shulin Wu, Chin-Lee Wu, Fei Chen, Evan Z. Macosko, Douglas M. Dahl, Ninib Baryawno, David T. Scadden, Philip J. Saylor, Peter V. Kharchenko, David B. Sykes. An atlas of single-cell and spatial transcriptomics reveals alterations that correlate with human prostate cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2510.