Caveolin-1 regulates the ASMase/ceramide-mediated radiation response of endothelial cells in the context of tumor–stroma interactions

• Published in: Cell death & disease Vol. 11; no. 4; p. 228
• Main Authors: Ketteler, Julia, Wittka, Alina, Leonetti, Daniela, Roy, Victoria Veas, Estephan, Hala, Maier, Patrick, Reis, Henning, Herskind, Carsten, Jendrossek, Verena, Paris, Francois, Klein, Diana
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 09.04.2020; Springer Nature B.V; Nature Publishing Group
• Subjects: 13; 13/2; 13/51; 13/95; 631/67/1059/2326; 631/80/82/23; 64; 692/308/575; 692/699/67/327; 82; 96; 96/63; 96/95; AKT protein; Angiogenesis; Antibodies; Apoptosis; Biochemistry; Biomedical and Life Sciences; Cancer; Caveolin; Caveolin 1 - biosynthesis; Caveolin 1 - deficiency; Caveolin 1 - metabolism; Caveolin-1; Cell Biology; Cell Communication - physiology; Cell Communication - radiation effects; Cell Culture; Cell Line, Tumor; Ceramide; Ceramides - biosynthesis; Ceramides - metabolism; Ceramides - pharmacology; Endothelial cells; Endothelial Cells - metabolism; Endothelial Cells - pathology; Endothelial Cells - radiation effects; Hsp27 protein; Humans; Immunohistochemistry; Immunology; Kinases; Life Sciences; Male; MAP kinase; MAP Kinase Signaling System - radiation effects; Membrane proteins; Microvasculature; PC-3 Cells; Prostate cancer; Prostatic Neoplasms - metabolism; Prostatic Neoplasms - pathology; Prostatic Neoplasms - radiotherapy; Proteins; Radiation; Radiation Tolerance; Radioresistance; Radiosensitivity; Signal Transduction; Spheroids; Sphingomyelin phosphodiesterase; Sphingomyelin Phosphodiesterase - metabolism; Stroma; Stromal Cells - metabolism; Stromal Cells - pathology; Tumor cells; Tumor Microenvironment; Tumors
• ISSN: 2041-4889; 2041-4889
• DOI: 10.1038/s41419-020-2418-z

The integral membrane protein caveolin-1 (CAV1) plays a central role in radioresistance-mediating tumor–stroma interactions of advanced prostate cancer (PCa). Among the tumor–stroma, endothelial cells (EC) evolved as critical determinants of the radiation response. CAV1 deficiency in angiogenic EC was already shown to account for increased apoptosis rates of irradiated EC. This study explores the potential impact of differential CAV1 levels in EC on the acid sphingomyelinase (ASMase)/ceramide pathway as a key player in the regulation of EC apoptosis upon irradiation and cancer cell radioresistance. Enhanced apoptosis sensitivity of CAV1-deficient EC was associated with increased ASMase activity, ceramide generation, formation of large lipid platforms, and finally an altered p38 mitogen-activated protein kinase (MAPK)/heat-shock protein 27 (HSP27)/AKT (protein kinase B, PKB) signaling. CAV1-deficient EC increased the growth delay of LNCaP and PC3 PCa cells upon radiation treatment in direct 3D spheroid co-cultures. Exogenous C6 and C16 ceramide treatment in parallel increased the growth delay of PCa spheroids and induced PCa cell apoptosis. Analysis of the respective ceramide species in PCa cells with increased CAV1 levels like those typically found in radio-resistant advanced prostate tumors further revealed an upregulation of unsaturated C24:1 ceramide that might scavenge the effects of EC-derived apoptosis-inducing C16 ceramide. Higher ASMase as well as ceramide levels could be confirmed by immunohistochemistry in human advanced prostate cancer specimen bearing characteristic CAV1 tumor–stroma alterations. Conclusively, CAV1 critically regulates the generation of ceramide-dependent (re-)organization of the plasma membrane that in turn affects the radiation response of EC and adjacent PCa cells. Understanding the CAV1-dependent crosstalk between tumor cells and the host-derived tumor microvasculature and its impact on radiosensitivity may allow to define a rational strategy for overcoming tumor radiation resistance improving clinical outcomes by targeting CAV1.