title: Nanosecond pulsed electric field inhibits proliferation and induces apoptosis in human osteosarcoma.
abstract: OBJECTIVE
  Recent studies suggest that nanosecond pulsed electric field (nsPEF) is a novel minimal invasive and non-thermal ablation method that can induce apoptosis in different solid tumors. But the efficacy of nsPEF on bone-related tumors or bone metastasis is kept unknown. The current study investigates antitumor effect of nsPEF on osteosarcoma MG-63 cells in vitro.
  
  
  METHODS
  MG-63 cells were treated with nsPEF with different electric field strengths (0, 10, 20, 30, 40, and 50 kV/cm) and different pulse numbers (0, 6, 12, 18, 24, and 30 pulses). The inhibitory effect of nsPEF on the growth of MG-63 cells was measured by Cell Counting Kit-8 (CCK-8) assay at different time points (0, 3, 12, 24, and 48 h post nsPEF treatment). The apoptosis was analyzed by Hoechst stain, in situ terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL), and flow cytometric analysis. The expression of osteoprotegerin (OPG), receptor activator of NF-κB ligand (RANKL), and tumor necrosis factor α (TNF-α) was examined by reverse-transcription polymerase chain reaction (RT-PCR) and western blot.
  
  
  RESULTS
  The CCK-8 assay showed that nsPEF induced a distinct electric field strength- and pulse number-dependent reduction of cell proliferation. For treatment parameter optimizing, the condition 40 kV/cm and 30 pulses at 24 h post nsPEF achieved the most significant apoptotic induction rate. Hoechst, TUNEL, and flow cytometric analysis showed that the cell apoptosis was induced and cells were arrested in the G0/G1 phase. PCR and western blot analysis demonstrated that nsPEF up-regulated OPG expression had no effect on RANKL, increased OPG/RANKL ratio.
  
  
  CONCLUSIONS
  NsPEF inhibits osteosarcoma growth, induces apoptosis, and affects bone metabolism by up-regulating OPG, indicating nsPEF-induced apoptosis in osteosarcoma MG-63 cells. NsPEF has potential to treat osteosarcoma or bone metastasis. When nsPEF is applied on metastatic bone tumors, it might be beneficial by inducing osteoblastic differentiation without cancer proliferation. In the future, nsPEF might be one of the treatments of metastatic bone tumor.
authors.affiliation: The Department of Orthopedics, the Second Affiliated Hospital, Zhejiang University, Hangzhou, Zhejiang Province, 310003, China.
authors.forename: Xudong
authors.initials: X
authors.lastname: Miao
authors.affiliation: The Department of Hepatobiliary and Pancreatic Surgery, the First Affiliated Hospital, Zhejiang University, Collaborative Innovation Center for Diagnosis Treatment of Infectious Diseases, 79 Qinchun Road, Hangzhou, Zhejiang Province, 310003, China.
authors.forename: Shengyong
authors.initials: S
authors.lastname: Yin
authors.affiliation: The Department of Hepatobiliary and Pancreatic Surgery, the First Affiliated Hospital, Zhejiang University, Collaborative Innovation Center for Diagnosis Treatment of Infectious Diseases, 79 Qinchun Road, Hangzhou, Zhejiang Province, 310003, China.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Shao
authors.affiliation: The Department of Gynecology, The First Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, Zhejiang Province, 310000, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: The Department of Hepatobiliary and Pancreatic Surgery, the First Affiliated Hospital, Zhejiang University, Collaborative Innovation Center for Diagnosis Treatment of Infectious Diseases, 79 Qinchun Road, Hangzhou, Zhejiang Province, 310003, China. xinhua_chen@zju.edu.cn.
authors.forename: Xinhua
authors.initials: X
authors.lastname: Chen
mesh_terms: D055011:Ablation Techniques; D017209:Apoptosis; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004574:Electromagnetic Fields; D005434:Flow Cytometry; D006801:Humans; D053244:Osteoprotegerin / Q000378:metabolism; D012516:Osteosarcoma / Q000378:metabolism / Q000601:surgery*; D053245:RANK Ligand / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D053244:Osteoprotegerin; D053245:RANK Ligand; C505688:TNFSF11 protein, human; D014409:Tumor Necrosis Factor-alpha