Abstract 5: Activation of PKA Signaling: A Milestone Associated With Bone Progression of Prostate Cancer
Authors: Sanchis Pablo , Anselmino Nicolas , Lage-Vickers Sofia , Sabater Agustina , Lavignolle Rosario , Labanca Estefania , Shepherd Peter , Bizzotto Juan , Pascual Gaston , Seniuk Rocio , Toro Ayelen , Mitrofanova Antonina , Valacco Pia , Navone Nora , Cotignola Javier , Vazquez Elba , Gueron Geraldine 
Published: June 2023

Abstract
Purpose: Metabolic rewiring is critical for the adaptation of tumor cells to the new homing organ. We sought to identify metabolic dysregulations fueling PCa bone metastasis, modulated by bone secreted factors.
Methods: By an indirect co-culture system of PCa (PC3) and bone progenitor cells (MC3T3, pre-osteoblasts, or Raw264.7, pre-osteoclasts), we assessed the transcriptome of PC3 cells modulated by soluble factors released by bone precursors. We validated the transcriptional profile of metabolic genes using open-access transcriptomic datasets. We performed an Ingenuity Pathway Analysis (IPA) to delineate the regulators of these metabolic genes. The bone secretome was profiled in the conditioned media (CM) by ESI-MS/MS. We validated our results using a PDX pre-clinical model comparing gene expression levels in MDA-PCa-183 growing intrafemorally (i.f.) vs. subcutaneously (s.c.).
Results: PC3 cells co-cultured with bone progenitors displayed an activation of lipid metabolism, including the PPAR-signaling and fat absorption/digestion pathways. Accordingly, we observed an accumulation of neutral lipids in PC3 cells treated with the CM from the co-culture (Bodipy 493/503 staining). Unsupervised Clustering analysis using transcriptomic data from human PCa and bone metastatic samples (GSE74685) showed that the metabolic genes deregulated in co-cultured PC3 accurately clustered samples in primary tumor or bone metastasis. Moreover, 5 lipid-associated genes, PPARA, VDR, SLC16A1, PAPSS2 and GPX1, were associated with a 23-fold higher risk of death (SU2C-PCF dataset). This expression signature was validated in a PDX pre-clinical model when comparing MDA-PCa-183 growing i.f. vs. s.c. An IPA revealed that these genes are regulated by the Protein Kinase A (PKA). Accordingly, PKA inhibition led to a downregulation of these genes. Moreover, GSEA showcased an activation of PKA signaling pathways in MDA-PCa-183 i.f. vs. s.c., reinforcing the fact that the bone environment shapes PCa metabolism. Additionally, secretome and protein-protein interaction analyses revealed soluble factors (Col1a1, Fn1, etc.) secreted by bone cells that could regulate PKA activity.
Conclusion: We identified a novel lipid-associated gene signature important for metastatic PCa, triggered by the dialogue with bone cells. This signature is under the regulation of PKA in response to bone-secreted factors, emerging as a potential target for intervention.
Citation Format: Pablo Sanchis, Nicolas Anselmino, Sofia Lage-Vickers, Agustina Sabater, Rosario Lavignolle, Estefania Labanca, Peter Shepherd, Juan Bizzotto, Gaston Pascual, Rocio Seniuk, Ayelen Toro, Antonina Mitrofanova, Pia Valacco, Nora Navone, Javier Cotignola, Elba Vazquez, Geraldine Gueron. Activation of PKA Signaling: A Milestone Associated With Bone Progression of Prostate Cancer [abstract]. In: Proceedings of the 11th Annual Symposium on Global Cancer Research; Closing the Research-to-Implementation Gap; 2023 Apr 4-6. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(6_Suppl):Abstract nr 5.