5-Aminolevulinic Acid-Based Sonodynamic Therapy Induces the Apoptosis of Osteosarcoma in Mice.

Yongning Li,Qingsong Li,Wenwu Cao,Bin Yang,Jinhua Zheng,Zheng Hu,Jianhua Wang,Qi Zhou,Ferenc Gallyas

doi:10.1371/journal.pone.0132074

Abstract

ObjectiveSonodynamic therapy (SDT) is promising for treatment of cancer, but its effect on osteosarcoma is unclear. This study examined the effect of 5-Aminolevulinic Acid (5-ALA)-based SDT on the growth of implanted osteosarcoma and their potential mechanisms in vivo and in vitro.MethodsThe dose and metabolism of 5-ALA and ultrasound periods were optimized in a mouse model of induced osteosarcoma and in UMR-106 cells. The effects of ALA-SDT on the proliferation and apoptosis of UMR-106 cells and the growth of implanted osteosarcoma were examined. The levels of mitochondrial membrane potential (ΔψM), ROS production, BcL-2, Bax, p53 and caspase 3 expression in UMR-106 cells were determined.ResultsTreatment with 5-ALA for eight hours was optimal for ALA-SDT in the mouse tumor model and treatment with 2 mM 5-ALA for 6 hours and ultrasound (1.0 MHz 2.0 W/cm2) for 7 min were optimal for UMR-106 cells. SDT, but not 5-ALA, alone inhibited the growth of implanted osteosarcoma in mice (P<0.01) and reduced the viability of UMR-106 cells (p<0.05). ALA-SDT further reduced the tumor volumes and viability of UMR-106 cells (p<0.01 for both). Pre-treatment with 5-ALA significantly enhanced the SDT-mediated apoptosis (p<0.01) and morphological changes. Furthermore, ALA-SDT significantly reduced the levels of ΔψM, but increased levels of ROS in UMR-106 cells (p<0.05 or p<0.01 vs. the Control or the Ultrasound). Moreover, ALA-SDT inhibited the proliferation of osteosarcoma cells and BcL-2 expression, but increased levels of Bax, p53 and caspase 3 expression in the implanted osteosarcoma tissues (p<0.05 or p<0.01 vs. the Control or the Ultrasound).ConclusionsThe ALA-SDT significantly inhibited osteosarcoma growth in vivo and reduced UMR-106 cell survival by inducing osteosarcoma cell apoptosis through the ROS-related mitochondrial pathway.

Highlights

Osteosarcoma is a malignant tumor threatening young adults worldwide and accounts for 20% of primary bone cancers
Treatment with 5-aminolevulinic acid (5-ALA) for eight hours was optimal for ALA-Sonodynamic therapy (SDT) in the mouse tumor model and treatment with 2 mM 5-ALA for 6 hours and ultrasound (1.0 MHz 2.0 W/cm2) for 7 min were optimal for UMR-106 cells
Sonosensitizers can selectively accumulate in tumor cells, activated by ultrasound in the targeted area and generate reactive oxygen species (ROS) to kill tumor cells [6,7,8,9]. 5-aminolevulinic acid (5-ALA) can metabolize into the biological precursor of protoporphyrin IX (PpIX) in the haeme biosynthesis pathway and 5-ALA has low toxicity and a short dark period in the cells, as compared with other sonosensitizers[10,11]

Summary

Introduction

Osteosarcoma is a malignant tumor threatening young adults worldwide and accounts for 20% of primary bone cancers. There are several therapeutic strategies available for treatment of osteosarcoma. Sonodynamic therapy (SDT) was developed by Umemura et al in 1989 for cancer treatment, and is a non-thermal method utilizing low-intensity ultrasound and sonosensitizers[5]. Sonosensitizers can selectively accumulate in tumor cells, activated by ultrasound in the targeted area and generate reactive oxygen species (ROS) to kill tumor cells [6,7,8,9]. 5-aminolevulinic acid (5-ALA) can metabolize into the biological precursor of protoporphyrin IX (PpIX) in the haeme biosynthesis pathway and 5-ALA has low toxicity and a short dark period in the cells, as compared with other sonosensitizers[10,11]. The PpIX derived from 5-ALA mainly accumulates in the mitochondria of cells[12], where the generated ROS following ultrasound can through the mitochondrial apoptotic pathway trigger vertebrate cell apoptosis[13,14]

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Results

Conclusion