SOCS1 expression in prostate epithelial cells is essential for tissue homeostasis and tumor suppression

Abstract Suppressor of cytokine signaling 1 (SOCS1) negative regulates inflammatory cytokine production and attenuates oncogenic growth factor signaling pathways. Reduced SOCS1 protein expression in human prostate cancer correlates with greater disease severity. To define the physiological functions of SOCS1 functions in the prostate, we conditionally ablated Socs1 in prostate epithelial cells of C57BL/6 mice. These Socs1ΔPE mice exhibited normal prostate development, maturation and lobular architecture. However, adult Socs1ΔPEmice developed progressive epithelial hyperplasia and inflammatory cell infiltration that were temporally and spatially distinct. SOCS1-deficient prostate showed increased epithelial cell proliferation and elevated oxidative stress markers, and prostate organoids recapitulated this hyperplasia phenotype. Diet-induced obesity exacerbated both hyperplasia and inflammation in SOCS1-deficient prostate. Upon transurethral infection with uropathogenic Escherichia coli UPEC1677 expressing the genotoxin colibactin, Socs1ΔPE mice developed invasive prostate cancer with complete loss of lobular architecture, whereas control mice developed hyperplasia and pre-neoplastic lesions. In vitro, SOCS1-deficient prostate organoid–derived epithelial cells exhibited increased DNA damage following exposure to UPEC1677. Deletion of the colibactin biosynthetic gene clbP in UPEC1677 abolished its ability to induce DNA damage in SOCS1-deficient cells and to drive prostate cancer in vivo. Proteomic analysis of prostate organoids revealed dysregulation of basal and luminal epithelial lineage markers and signaling pathway proteins that could promote neoplasia in SOCS1-deficient cells. Collectively, these findings establish an essential, epithelial cell-intrinsic role for SOCS1 in maintaining prostate tissue homeostasis by restraining proliferation, regulating lineage plasticity, limiting inflammation and oxidative stress, and conferring protection against genotoxic injury and neoplastic transformation. Competing Interest Statement The authors have declared no competing interest. Abbreviations - BPH - benign prostate hyperplasia - CFU - colony forming units - FFPE - Formalin-fixed paraffin-embedded - LPS - lipopolysaccharide - MOI - multiplicity of infection - NDP - Nanozoomer Digital Pathology - OFC - organoid formation count - PFA - paraformaldehyde - PIA - proliferative inflammatory atrophy - PIN - prostate intraepithelial neoplasia - αSMA - alpha smooth muscle actin - SOCS1 - suppressor of cytokine signaling 1 - UPEC - uropathogenic Escherichia coli.