DNA Strand Break Properties of Protoporphyrin IX by X-ray Irradiation against Melanoma
DNA Strand Break Properties of Protoporphyrin IX by X-ray Irradiation against Melanoma
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DOI：
10.3390/ijms21072302
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发表时间：
2020-04-01
影响因子：
5.6
通讯作者：
Iwahashi, Hitoshi
中科院分区：
文献类型：
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作者：
Hasegawa, Takema;Takahashi, Junko;Iwahashi, Hitoshi
最近的报道表明，5-氨基乙酰丙酸（5-ALA）是原卟啉IX （PpIX）的前体，可导致PpIX在肿瘤细胞中选择性积累，并在黑色素瘤、胶质瘤和结肠癌的小鼠模型中作为辐射增敏剂。在这项研究中，我们研究了PpIX在x射线照射下通过ROS生成和DNA损伤的影响。采用3′-（对氨基苯基）荧光素（APF）检测羟基自由基（中心点OH），双氢乙啶（DHE）检测超氧化物（O-2（中心点-））两种探针评价PpIX与x射线相互作用产生的ROS。与溶解氧无关，中心点OH均增加。同时，O-2（中心点-）的增加与溶解氧成正比。用凝胶电泳法测定DNA分子的链断裂（SBs），并观察PpIX处理对SBs的增强作用。我们还研究了PpIX对x射线照射下B16黑色素瘤培养细胞DNA损伤的影响。x射线照射诱导γ - H2AX， DNA双链断裂（DSBs），并影响细胞存活。由于PpIX即使在缺氧状态下也能增强ROS的生成并诱导DNA损伤，因此5-ALA联合放疗有望提高放射耐药肿瘤的治疗效果。
Recent reports have suggested that 5-aminolevulinic acid (5-ALA), which is a precursor to protoporphyrin IX (PpIX), leads to selective accumulation of PpIX in tumor cells and acts as a radiation sensitizer in vitro and in vivo in mouse models of melanoma, glioma, and colon cancer. In this study, we investigated the effect of PpIX under X-ray irradiation through ROS generation and DNA damage. ROS generation by the interaction between PpIX and X-ray was evaluated by two kinds of probes, 3 '-(p-aminophenyl) fluorescein (APF) for hydroxyl radical (center dot OH) detection and dihydroethidium (DHE) for superoxide (O-2(center dot-)). center dot OH showed an increase, regardless of the dissolved oxygen. Meanwhile, the increase in O-2(center dot-) was proportional to the dissolved oxygen. Strand breaks (SBs) of DNA molecule were evaluated by gel electrophoresis, and the enhancement of SBs was observed by PpIX treatment. We also studied the effect of PpIX for DNA damage in cells by X-ray irradiation using a B16 melanoma culture. X-ray irradiation induced gamma H2AX, DNA double-strand breaks (DSBs) in the context of chromatin, and affected cell survival. Since PpIX can enhance ROS generation even in a hypoxic state and induce DNA damage, combined radiotherapy treatment with 5-ALA is expected to improve therapeutic efficacy for radioresistant tumors.