Abstract 2975: Vitamin D receptor signaling limits DNA damage at early stage of prostate tumorigenesis and prevents tumor aggressiveness
Authors: Len Kateryna , Gantzer Justine , May Nicolas Le , Thibault-Carpentier Christelle , Metzger Daniel , Laverny Gilles 
Published: March 2024

Abstract
Prostate cancer (PCa) is the most common visceral neoplasm and the second leading cause of cancer-related deaths in male of western societies. Low circulating vitamin D levels and reduced expression of its receptor (VDR) correlate with PCa risk and severity, but the clinical use of vitamin D is limited by its pro-calcemic activities. To characterize the role of VDR in PCa, PTEN(i)pe-/− mice, that recapitulate the human disease and in which the tumor suppressor gene PTEN is selectively inactivated in prostatic epithelial cells (PECs) at adulthood, were compared to PTEN/VDR(i)pe-/− mice in which PECs are PTEN and VDR-deficient. Histological analysis showed that prostatic intraepithelial neoplasia (PIN) are formed between 1-3 months after gene inactivation (AGI). Importantly, VDR-deficiency increased by 2-fold the PECs proliferation rate as early as 1-month AGI. At this stage, RNA-seq and immunohistochemistry analysis revealed the presence of oxidative DNA damage selectively in VDR-deficient PINs. Moreover, a 4-week supplementation with the antioxidant N-acetyl cysteine reduced oxidative DNA damage in PTEN/VDR(i)pe-/- prostates, and normalized the number of Ki-67+ cells to the levels of PTEN(i)pe-/- ones. After 3 months AGI, both PTEN(i)pe-/- and PTEN/VDR(i)pe-/- tumors entered in a latency phase characterized by cellular senescence. However, the prostate weight in PTEN/VDR(i)pe-/− mice was 2-fold higher than in PTEN(i)pe-/− mice 12 months AGI. In addition, tumors of PTEN(i)pe-/− were mostly composed of non-invasive PIN-like adenocarcinoma, whereas invasive adenocarcinoma, sarcomatoid and squamous-cell carcinoma were observed in those of PTEN/VDR(i)pe-/- mice. Using single cell and spatial transcriptomics, we unraveled the presence of epithelial cells with epithelial-mesenchymal transition (EMT) hallmarks in PTEN/VDR(i)pe-/− prostate 10 months AGI. In addition, immunophenotyping revealed a higher infiltration of neutrophils, also termed as myeloid-derived suppressive cells and implicated in EMT and metastasis dissemination, in PTEN/VDR(i)pe-/− prostates compared to PTEN(i)pe-/− ones. Moreover, pan-cytokeratin-positive micro-metastasis were detected in lymph nodes and livers of PTEN/VDR(i)pe-/− mice, but not in those of PTEN(i)pe-/- mice, demonstrating that VDR-deficiency in PECs promotes aggressive PCa. Thus, VDR signaling exerts a protective role on PTEN-deficient PECs by limiting the oxidative-stress and proliferation during PINs initiation, and prevents PCa progression.
Citation Format: Kateryna Len, Justine Gantzer, Nicolas Le May, Christelle Thibault-Carpentier, Daniel Metzger, Gilles Laverny. Vitamin D receptor signaling limits DNA damage at early stage of prostate tumorigenesis and prevents tumor aggressiveness [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2975.