Division of Medicine and Clinical Science, Faculty of Medicine, Tottori University, 36-1 Nishi-cho, Yonago 683-8504, Japan.
Department of Gastroenterology and Hepatology, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki 852-8501, Japan.
Photodiagnosis Photodyn Ther. 2018 Jun;22:79-85. doi: 10.1016/j.pdpdt.2018.02.005. Epub 2018 Feb 6.
BACKGROUND/AIM: Laser-based photodynamic endoscopic diagnosis (LPDED) is a type of endoscopic diagnosis that uses the fluorescence caused by the photochemical reaction that occurs when a fluorescent substance is irradiated by a light of a specific wavelength. Although 5-aminolevulinic acid (5-ALA) can detect early gastric cancer (EGC) during LPDED, there is an unresolved issue of the differences in fluorescence intensity among histopathological types of gastric cancer. Thus, the aim of the present study was to assess whether protoporphyrinogen oxidase (PPOX), involved in the activation of protoporphyrin IX, can affect the fluorescence intensity in EGC.
Thirty-three gastric tumor lesions in 30 patients were assessed by LPDED using a prototype endoscope equipped with a blue laser ray to cause excitation following oral 5-ALA administration. The tumors were then resected by endoscopic submucosal dissection or laparoscopic surgery. PPOX expression was examined immunohistochemically in the excised specimens. To explore the mechanisms of histopathological diversity in PPOX and coproporphyrinogen oxidase (CPOX) expression of EGC, immunohistochemical analysis was performed using 75 surgically resected specimens of diverse EGCs.
Among the 33 lesions, 26 tumors were detectable by LPDED, whereas seven were undetectable. Between the LPDED-positive and negative groups, there was a significant difference in histopathology. The expression of PPOX was higher in tubular adenocarcinoma (tub) than in signet-ring cell carcinoma (sig). There were significant differences in PPOX and CPOX expression scores of the surgically resected specimens among tub, poorly differentiated adenocarcinoma (por), and sig.
PPOX protein expression could be involved in the fluorescence intensity of LPDED in EGC, possibly reflecting histopathological features.
背景/目的：基于激光的光动力内镜诊断（LPDED）是一种内镜诊断方法，它利用荧光物质在特定波长的光照射下发生光化学反应产生的荧光。虽然 5-氨基酮戊酸（5-ALA）可在 LPDED 中检测早期胃癌（EGC），但仍存在胃癌组织病理学类型之间荧光强度差异的问题尚未解决。因此，本研究旨在评估原卟啉原氧化酶（PPOX）是否参与原卟啉 IX 的激活，从而影响 EGC 的荧光强度。
30 例患者的 33 个胃肿瘤病变通过 LPDED 进行评估，使用配备蓝色激光射线的原型内镜在口服 5-ALA 后引起激发。然后通过内镜黏膜下剥离术或腹腔镜手术切除肿瘤。在切除的标本中通过免疫组织化学检查 PPOX 表达。为了探索 EGC 中 PPOX 和粪卟啉原氧化酶（CPOX）表达的组织病理学多样性的机制，使用 75 个不同的 EGC 手术切除标本进行免疫组织化学分析。
在 33 个病变中，26 个肿瘤可通过 LPDED 检测到，而 7 个肿瘤不可检测。在 LPDED 阳性和阴性组之间，组织病理学存在显著差异。管状腺癌（tub）的 PPOX 表达高于印戒细胞癌（sig）。在手术切除标本中，PPOX 和 CPOX 表达评分在 tub、低分化腺癌（por）和 sig 之间存在显著差异。
PPOX 蛋白表达可能参与 EGC 的 LPDED 荧光强度，可能反映组织病理学特征。
