Ionizing Radiation-Induced Extracellular Vesicle Release Promotes AKT-Associated Survival Response in SH-SY5Y Neuroblastoma Cells.

Flavia Tortolici,Anna Giovanetti,Katia Aquilano,Renu Dayal,Stefano Rufini,Bernadette Incocciati,Simone Vumbaca

doi:10.3390/cells10010107

Abstract

Radiation therapy is one of the most effective methods of tumor eradication; however, in some forms of neuroblastoma, radiation can increase the risk of secondary neoplasms, due to the ability of irradiated cells to transmit pro-survival signals to non-irradiated cells through vesicle secretion. The aims of this study were to characterize the vesicles released by the human neuroblastoma cell line SH-SY5Y following X-ray radiations and their ability to increase invasiveness in non-irradiated SH-SY5Y cells. We first purified the extracellular vesicles released by the SH-SY5Y cells following X-rays, and then determined their total amount, dimensions, membrane protein composition, and cellular uptake. We also examined the effects of these extracellular vesicles on viability, migration, and DNA damage in recipient SH-SY5Y cells. We found that exposure to X-rays increased the release of extracellular vesicles and altered their protein composition. These vesicles were readily uptaken by non-irradiated cells, inducing an increase in viability, migration, and radio-resistance. The same results were obtained in an MYCN-amplified SK-N-BE cell line. Our study demonstrates that vesicles released from irradiated neuroblastoma cells stimulate proliferation and invasiveness that correlate with the epithelial to mesenchymal transition in non-irradiated cells. Moreover, our results suggest that, at least in neuroblastomas, targeting the extracellular vesicles may represent a novel therapeutic approach to counteract the side effects associated with radiotherapy.

Highlights

Neuroblastoma is the second most common solid tumor in childhood, characterized by a highly aggressive behavior and poor prognosis
We identify a key role of extracellular vesicles (EVs) released after X-ray exposure in activating cell survival pathways and inducing radio-resistance, which is associated with an increased capacity to repair DNA damage
EVs from both neuroblastoma cell lines irradiated with X-rays at 0 (EVs0), 0.1 (EVs0.1), 1 (EVs1)

Summary

Introduction

Neuroblastoma is the second most common solid tumor in childhood, characterized by a highly aggressive behavior and poor prognosis. Due to the subtle and heterogeneous nature of its symptoms (e.g., weight loss, anemia, fever), most neuroblastomas have already metastasized at diagnosis to secondary sites such as the pelvis, neck, abdomen, or chest [1]. Therapeutic approaches include tumor resection, often combined with chemo and/or radiotherapy [2]. The 21.6 Gy at 1.8 Gy per day, and the 21 Gy at 1.5 Gy per day represent the standard doses used in the clinic [2]. Despite slowing the course of the disease, the therapeutic use of ionizing radiations (IRs) has been frequently associated with an increased risk of developing secondary neoplasms [2].

Objectives

Methods

Results

Discussion

Conclusion