Ultrasound modulates fluorescence strength and ABCG2 mRNA response to aminolevulinic acid in glioma cells.
Ultrasound modulates fluorescence strength and ABCG2 mRNA response to aminolevulinic acid in glioma cells.
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DOI：
10.1272/jnms.jnms.2020_87-601
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发表时间：
2020-03
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影响因子：
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通讯作者：
T. Higuchi;F. Yamaguchi;T. Asakura;D. Yoshida;Y. Oishi;A. Morita
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作者：
T. Higuchi;F. Yamaguchi;T. Asakura;D. Yoshida;Y. Oishi;A. Morita
背景5-氨基乙酰丙酸（5-ALA）光诊断（PD）是神经胶质瘤手术期间检测残留肿瘤的有效方法。然而，即使在最恶性的神经胶质瘤（例如胶质母细胞瘤）中，每种情况下的荧光强度也不同。此外，假阴性荧光也可能导致肿瘤残留。我们研究了超声对细胞内原卟啉 IX (PpIX) 水平和 ATP 结合盒转运蛋白 2 (ABCG2) 表达水平的影响，后者被认为充当 PpIX 从细胞质中的膜外排泵。方法采用建立的恶性胶质瘤细胞系SNB19、U87MG和T98G进行体外实验。给予5-ALA后，对培养细胞照射超声波（1MHz、3W/cm2、占空比10%）。观察肿瘤细胞的形态变化。评估了 PpIX 水平和 ABCG2 的表达。结果胶质瘤细胞表现出短暂的形态变化并附着在培养皿上，而大多数细胞存活并在6小时内恢复到原来的形态。超声照射后胶质瘤细胞中 PpIX 表达水平增加，比单独使用 5-ALA 更早且更高。同时，在超声照射的神经胶质瘤细胞中，ABCG2 的表达在给予 5-ALA 后增加，但表达相对减少。结论 恶性胶质瘤的超声照射通过提高细胞内 PpIX 水平来增强 5-ALA 诱导的荧光。超声对ABCG2表达的抑制可能是导致胶质瘤细胞中PpIX积累的因素之一。
BACKGROUND 5-Aminolevulinic Acid (5-ALA) Photodiagnosis (PD) is an effective method to detect residual tumors during glioma surgery. However, the strength of fluorescence differs in every case even in the most malignant glioma such as glioblastoma. Also, false-negative fluorescence may result in tumor residue. We investigated the effect of ultrasound on the intracellular level of protoporphyrin IX (PpIX) and the expression level of ATP-binding cassette transporter 2 (ABCG2), which is thought to act as a membrane efflux pump of PpIX from cytosol. METHODS The malignant glioma established cell line, SNB19, U87MG and T98G were used for in vitro experiments. Ultrasound (1MHz, 3W/cm2, Duty cycle 10%) was irradiated on the cultured cells after administration of 5-ALA. The morphological changes of tumor cells were observed. The PpIX levels and the expression of ABCG2 were evaluated. RESULTS The glioma tumor cells showed transient morphological changes and attachment to the culture dish, while most cells survived and were restored to their original morphology within 6 hours. The PpIX expression levels increased in glioma cells after ultrasound irradiation, earlier and higher than 5-ALA alone. Concurrently the expressions of ABCG2, that increased after 5-ALA administration, were relatively reduced in ultrasound irradiated glioma cells. CONCLUSIONS The ultrasound irradiation of the malignant gliomas contributes to the stronger 5-ALA induced fluorescence by elevating intracellular PpIX levels. The suppression of ABCG2 expression by ultrasound may be one of the factors which contributes to the PpIX accumulation in glioma cells.