Zainudin Nh Mohd, R Abdullah, W N Rahman
PhD student, Medical Radiation Programme, School of Health Sciences, Universiti Sains Malaysia, Health Campus, Kubang Kerian, Kelantan, Malaysia.
PhD student, Faculty of Health Sciences, Universiti Sultan Zainal Abidin, Gong Badak Campus, Kuala Terengganu, Malaysia.
J Biomed Phys Eng. 2020 Jun 1;10(3):319-328. doi: 10.31661/jbpe.v0i0.1135. eCollection 2020 Jun.
Radiation induced bystander effects (RIBEs) occurs in unirradiated cells exhibiting indirect biological effect as a consequence of signals from other irradiated cells in the population.
In this study, bystander effects in MCF-7 breast cancer cells and hFOB 1.19 normal osteoblast cells irradiated with gamma emitting HDR Brachytherapy Ir-192 source were investigated.
In this in-vitro study, bystander effect stimulation was conducted using medium transfer technique of irradiated cells to the non-irradiated bystander cells. Cell viability, reactive oxygen species (ROS) generation and colony forming assay was employed to evaluate the effect.
Results indicate that the exposure to the medium irradiated MCF-7 induced significant bystander killing and decreased the survival fraction of bystander MCF-7 and hFOB from 1.19 to 81.70 % and 65.44 %, respectively. A significant decrease in survival fraction was observed for hFOB 1.19 bystander cells (p < 0.05). We found that the rate of hFOB 1.19 cell growth significantly decreases to 85.5% when added with media from irradiated cells. The ROS levels of bystander cells for both cell lines were observed to have an increase even after 4 h of treatment. Our results suggest the presence of bystander effects in unirradiated cells exposed to the irradiated medium.
These data provide evidence that irradiated MCF-7 breast cancer cells can induce bystander death in unirradiated MCF-7 and hFOB 1.19 bystander cells. Increase in cell death could also be mediated by the ROS generation during the irradiation with HDR brachytherapy.
辐射诱导旁观者效应（RIBE）发生在未受照射的细胞中，这些细胞由于群体中其他受照射细胞发出的信号而表现出间接生物学效应。
本研究调查了用发射γ射线的高剂量率近距离放射治疗铱 - 192源照射的MCF - 7乳腺癌细胞和hFOB 1.19正常成骨细胞中的旁观者效应。
在这项体外研究中，采用将受照射细胞的培养基转移至未受照射的旁观者细胞的技术来刺激旁观者效应。采用细胞活力、活性氧（ROS）生成和集落形成试验来评估该效应。
结果表明，暴露于受照射MCF - 7细胞的培养基会诱导显著的旁观者杀伤，并使旁观者MCF - 7细胞和hFOB 1.19细胞的存活分数分别从100%降至81.70%和65.44%。观察到hFOB 1.19旁观者细胞的存活分数显著降低（p < 0.05）。我们发现，当添加来自受照射细胞的培养基时，hFOB 1.19细胞的生长速率显著降低至85.5%。两种细胞系的旁观者细胞在处理4小时后，其ROS水平均有升高。我们的结果表明，暴露于受照射培养基的未受照射细胞中存在旁观者效应。
这些数据提供了证据，证明受照射的MCF - 7乳腺癌细胞可诱导未受照射的MCF - 7和hFOB 1.19旁观者细胞发生旁观者死亡。高剂量率近距离放射治疗照射期间ROS的生成也可能介导细胞死亡的增加。
