Background. Caveolin-1 (CAV1) is an integral membrane protein required to generate caveolae and cholesterol-enriched lipid rafts of the plasma membrane. It is widely accepted that loss of CAV-1 correlates with early-stage tumor progression, while its over-expression and phosphorylation are associated with metastatic disease. In particular, it has been shown that CAV-1 cooperates with tumor growth and metastatic potential in rhabdomyosarcoma (RD). Extracellular vesicles (EVs) are lipid-bound vesicles secreted by cells into the extracellular space; it is well-known that EVs have a pivotal role in cancer disease. Aim. The present work aims to investigate if the increased aggressiveness of RD cells overexpressing CAV1 (RD-CAV1) correlates with an altered extracellular vesicle release and cargo and if RD-CAV1 EVs contribute to the cancer dissemination. Methods. RD cells were employed: RD-ctrl cells which are transfected with an empty vector, RD-F0 and RD-F2 which are transfected with a plasmid that allows the overexpression of CAV1, gradually more aggressive based on the number of subcloning steps. EVs were isolated from conditioned media by sequential ultracentrifugation and characterized by Nanoparticle Tracking Analysis (NTA) and Western Blot analysis. Results. The obtained data show that RD-CAV1 cells release more EVs compared to RD-Ctrl cells. Western Blot analysis highlighted that small extracellular vesicles (sEVs) exhibit the exosomal markers Alix, Flot-1, Syntenin-1, and TSG101, whereas large extracellular vesicles (lEVs) are positive for Calnexin. Interestingly, the tetraspanins CD63, CD81, and CD9 were not detectable in RD-CAV1 EVs, which instead are detected in RD-Ctrl EVs, suggesting that CAV1 overexpression induces an alteration of the EV proteomic profile. These data are all supported and extended by the Proteomic Analysis. Moreover, the treatment of HUVEC with RD-CAV1 EVs has been performed: transwell assay shows an increase in cell proliferation and migration, both in a dose-dependent manner. Conclusions. Taken together, these data confirm that CAV1 overexpression critically affects RD-EV release and cargo, allowing them to alter the behaviour of target cells of the tumor microenvironment. In order to further understand other signals involved in this mechanism, future studies will focus on the characterization of RD-EV cargo in terms of lipid- and miRNA-loading and on the evaluation of RD-EV effects in other cell types, tipical of tumor niche. REFERENCES 1. Codenotti et al. Caveolin-1 enhances metastasis formation in a human model of embryonal rhabdomyosarcoma through Erk signaling cooperation. Cancer letters (2019). 2. Ni et al. The Evolving Role of Caveolin-1: A Critical Regulator of Extracellular Vesicles. Medical Sciences (2020). 3. Bebelman et al. Biogenesis and function of extracellular vesicles in cancer. Pharmacology & Therapeutics (2018).
Caveolin-1-overexpression stimulates extracellular vesicle secretion and modulates tumor microenvironment in a model of rhabdomyosarcoma
R. Agostini;E. Polidori;P. Ceccaroli;F. Luchetti;V. Stocchi;M. Guescini
2023
Abstract
Background. Caveolin-1 (CAV1) is an integral membrane protein required to generate caveolae and cholesterol-enriched lipid rafts of the plasma membrane. It is widely accepted that loss of CAV-1 correlates with early-stage tumor progression, while its over-expression and phosphorylation are associated with metastatic disease. In particular, it has been shown that CAV-1 cooperates with tumor growth and metastatic potential in rhabdomyosarcoma (RD). Extracellular vesicles (EVs) are lipid-bound vesicles secreted by cells into the extracellular space; it is well-known that EVs have a pivotal role in cancer disease. Aim. The present work aims to investigate if the increased aggressiveness of RD cells overexpressing CAV1 (RD-CAV1) correlates with an altered extracellular vesicle release and cargo and if RD-CAV1 EVs contribute to the cancer dissemination. Methods. RD cells were employed: RD-ctrl cells which are transfected with an empty vector, RD-F0 and RD-F2 which are transfected with a plasmid that allows the overexpression of CAV1, gradually more aggressive based on the number of subcloning steps. EVs were isolated from conditioned media by sequential ultracentrifugation and characterized by Nanoparticle Tracking Analysis (NTA) and Western Blot analysis. Results. The obtained data show that RD-CAV1 cells release more EVs compared to RD-Ctrl cells. Western Blot analysis highlighted that small extracellular vesicles (sEVs) exhibit the exosomal markers Alix, Flot-1, Syntenin-1, and TSG101, whereas large extracellular vesicles (lEVs) are positive for Calnexin. Interestingly, the tetraspanins CD63, CD81, and CD9 were not detectable in RD-CAV1 EVs, which instead are detected in RD-Ctrl EVs, suggesting that CAV1 overexpression induces an alteration of the EV proteomic profile. These data are all supported and extended by the Proteomic Analysis. Moreover, the treatment of HUVEC with RD-CAV1 EVs has been performed: transwell assay shows an increase in cell proliferation and migration, both in a dose-dependent manner. Conclusions. Taken together, these data confirm that CAV1 overexpression critically affects RD-EV release and cargo, allowing them to alter the behaviour of target cells of the tumor microenvironment. In order to further understand other signals involved in this mechanism, future studies will focus on the characterization of RD-EV cargo in terms of lipid- and miRNA-loading and on the evaluation of RD-EV effects in other cell types, tipical of tumor niche. REFERENCES 1. Codenotti et al. Caveolin-1 enhances metastasis formation in a human model of embryonal rhabdomyosarcoma through Erk signaling cooperation. Cancer letters (2019). 2. Ni et al. The Evolving Role of Caveolin-1: A Critical Regulator of Extracellular Vesicles. Medical Sciences (2020). 3. Bebelman et al. Biogenesis and function of extracellular vesicles in cancer. Pharmacology & Therapeutics (2018).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
