背景：光动力疗法（PDT）用于包括脑肿瘤在内的癌症治疗。但是表观遗传过程在正常脑组织光动力损伤中的作用尚不清楚。
方法：5-氨基乙酰丙酸（ALA），原卟啉IX（PpIX）的前体，用于光敏小鼠大脑皮层。用荧光分光光度法测量皮质组织中的PpIX积累。苏木精/伊红,gallocyanin-chromalum和免疫组织化学染色用于研究PDT处理的大脑皮层的形态学变化。蛋白质组抗体微阵列用于评估参与表观遗传调控的112种蛋白质的表达。
结果:与未处理的小鼠相比,ALA给药诱导小鼠大脑皮层中PpIX积累增加2.5倍。组织学研究表明PDT诱导的一些神经元和皮质血管的损伤。ALA-PDT诱导组蛋白H3的二甲基化，组蛋白脱乙酰酶HDAC-1和HDAC-11的上调，以及抑制转录活性的DNA甲基化依赖性蛋白Kaiso。免疫组化证实HDAC-1和H3K9me2上调。转录因子FOXC2,PABP,和hBrm/hsnf2a负调控转录。磷酸化组蛋白H2AX的过表达表明DNA修复的激活，但下调MTA1/MTA1L1和PML-损伤DNA修复。精氨酸甲基转移酶PRMT5的过表达与转录因子E2F4和导入蛋白α5/7的上调相关。
结论：ALA-PDT损伤并杀死一些但不是全部神经元，并在小鼠大脑皮层中引起有限的微血管改变。它改变了一些参与转录表观遗传调控的蛋白质的表达，组蛋白修饰，DNA修复,核蛋白进口，和扩散。
结论：这些数据表明了正常脑组织光氧化损伤的表观遗传标记。
BACKGROUND: Photodynamic therapy (PDT) is used for cancer treatment including brain tumors. But the role of epigenetic processes in photodynamic injury of normal brain tissue is unknown.
METHODS: 5-Aminolevulinic acid (ALA), a precursor of protoporphyrin IX (PpIX), was used to photosensitize mouse cerebral cortex. PpIX accumulation in cortical tissue was measured spectrofluorometrically. Hematoxylin/eosin, gallocyanin-chromalum and immunohistochemical staining were used to
study morphological changes in PDT-treated cerebral cortex. Proteomic antibody microarrays were used to evaluate expression of 112 proteins involved in epigenetic regulation.
RESULTS: ALA administration induced 2.5-fold increase in the PpIX accumulation in the mouse brain cortex compared to untreated mice. Histological
study demonstrated PDT-induced injury of some neurons and cortical vessels. ALA-PDT induced dimethylation of histone H3, upregulation of histone deacetylases HDAC-1 and HDAC-11, and DNA methylation-dependent protein Kaiso that suppressed transcriptional activity. Upregulation of HDAC-1 and H3K9me2 was confirmed immunohistochemically. Down-regulation of transcription factor FOXC2, PABP, and hBrm/hsnf2a negatively regulated transcription. Overexpression of phosphorylated histone H2AX indicated activation of DNA repair, but down-regulation of MTA1/MTA1L1 and PML - impairment of DNA repair. Overexpression of arginine methyltransferase PRMT5 correlated with up-regulation of transcription factor E2F4 and importin α5/7.
CONCLUSIONS: ALA-PDT injures and kills some but not all neurons and caused limited microvascular alterations in the mouse cerebral cortex. It alters expression of some proteins involved in epigenetic regulation of transcription, histone modification, DNA repair, nuclear protein import, and proliferation.
CONCLUSIONS: These data indicate epigenetic markers of photo-oxidative injury of normal brain tissue.
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