Identification of PEPT2 as an important candidate molecule in 5-ALA-mediated fluorescence-guided surgery in WHO grade II/III gliomas
Identification of PEPT2 as an important candidate molecule in 5-ALA-mediated fluorescence-guided surgery in WHO grade II/III gliomas
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DOI：
10.1007/s11060-019-03158-3
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发表时间：
2019-06-01
影响因子：
3.9
通讯作者：
Houkin, Kiyohiro
中科院分区：
文献类型：
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作者：
Hou, Chongxian;Yamaguchi, Shigeru;Houkin, Kiyohiro
目的5-氨基乙酰丙酸(5-ALA)荧光引导手术(FGS)是一种很有前途的脑胶质瘤治疗方法。然而，在II/III级胶质瘤中并不总是检测到5-ALA介导的荧光。我们假设原卟啉IX(PpIX)合成途径的基因表达模式可能与II/III级胶质瘤的术中荧光状态有关，并试图确定5-ALA介导的荧光的关键分子。方法根据术中5-ALA介导的荧光状态，分析50例手术获得的II级和III级胶质瘤标本中PpIX合成途径的基因表达，以确定候选分子。筛选出最可能的候选基因，并进行蛋白质表达分析。结果在参与卟啉合成途径的基因中，FGS荧光阳性的胶质瘤细胞中肽转运蛋白2(PEPT2)的表达显著高于荧光阴性的胶质瘤。免疫印迹分析和免疫荧光分析证实，在荧光阳性的胶质瘤中，PEPT2的蛋白表达也明显升高。荧光光谱分析证实，siRNA介导的PEPT2mRNA和蛋白表达下调导致PpIX荧光强度降低。结论PEPT2是5-ALA介导的II/III级胶质瘤FGS的重要候选分子。由于PEPT2的过度表达与较高的PPIX荧光强度相关，PEPT2可能会改善II/III级胶质瘤的荧光引导切除。
Purpose5-aminolevulinic acid (5-ALA) fluorescence-guided surgery (FGS) appears to be a promising treatment for glioma. However, 5-ALA-mediated fluorescence cannot always be detected in grade II/III gliomas. We hypothesized that gene expression patterns in the Protoporphyrin IX (PpIX) synthesis pathway may be associated with intraoperative fluorescence status of grade II/III gliomas, and then attempted to identify the key molecule of 5-ALA-mediated fluorescence.MethodsUsing 50 surgically obtained specimens, which were diagnosed as grade II and III gliomas, we analyzed gene expression within the PpIX synthesis pathway to identify candidate molecules according to intraoperative 5-ALA-mediated fluorescence status. The most likely candidate gene was selected and confirmed by protein expression analysis. To evaluate the biological function of the molecule in PpIX synthesis, functional analysis was performed using specific, small interference (si)RNA in the SW-1783human grade III glioma cell line.ResultsAmong the genes involved in the porphyrin synthesis pathway, the mRNA expression of Peptide transporter 2 (PEPT2) in FGS fluorescence-positive gliomas was significantly higher than that in fluorescence-negative gliomas. Protein expression of PEPT2 was also significantly higher in the fluorescence-positive gliomas, which was confirmed by western blot analysis and immunofluorescence analysis. The siRNA-mediated downregulation of the mRNA and protein expression of PEPT2 led to decreased PpIX fluorescence intensity, as confirmed by fluorescence spectrum analysis.ConclusionsThe results suggest PEPT2 is an important candidate molecule in 5-ALA-mediated FGS in grade II/III gliomas. As the overexpression of PEPT2 was associated with higher PpIX fluorescence intensity, PEPT2 may improve fluorescence-guided resection in grade II/III gliomas.