Mild heat shock induces autophagic growth arrest, but not apoptosis in U251-MG and U87-MG human malignant glioma cells
Mild heat shock induces autophagic growth arrest, but not apoptosis in U251-MG and U87-MG human malignant glioma cells
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DOI：
10.1023/b:neon.0000027739.33842.6c
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发表时间：
2004-06-01
影响因子：
3.9
通讯作者：
Tanaka, R
中科院分区：
文献类型：
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作者：
Komata, T;Kanzawa, T;Tanaka, R
虽然热疗已被用作恶性脑肿瘤的治疗，但尚不清楚热休克抑制细胞生长的机制，特别是临床上应用于肿瘤-脑边缘区的温度（42- 43 ℃）。因此，本研究以U251-MG和U87-MG两种人恶性胶质瘤细胞为研究对象，以45 ℃为对照，研究43 ℃热休克后两种细胞的变化。首先，我们观察到在43 ℃热休克3或5天后，分别在U251-MG或U87-MG细胞中细胞生长被短暂抑制，随后再生长。在短暂的生长抑制期间，观察到轻微的G2/M期阻滞。然而，在U251-MG或U87-MG细胞中，在43 ℃加热的细胞中分别仅观察到2.7%或1.5%的凋亡。相反，透射电子显微镜显示空泡形成，线粒体变性和自噬体。此外，在这两种细胞系中，流式细胞仪分析与吖啶橙子揭示了诱导的酸性囊泡细胞器，这是由3-甲基腺嘌呤（3-MA），这表明自噬的参与。此外，虽然3-MA没有增加43 ℃热休克的抗肿瘤作用，但另一种自噬抑制剂巴弗洛霉素A1确实显著增强了U251-MG细胞的作用。总之，轻度热休克（43 ℃，2小时）引起自噬和轻度G2/M期阻滞，但不诱导U251-MG和U87-MG胶质瘤细胞明显的凋亡。巴弗洛霉素A1抑制自噬可能增加轻度热休克对某些恶性胶质瘤细胞的抗肿瘤效果。
Although hyperthermia has been used as a treatment of malignant brain tumors, it is not yet clear what is the mechanism of the cell growth inhibition by heat shock, especially by the temperature which has clinically been applied to tumor-brain border-zone, 42-43degreesC. Therefore, we evaluated the change of U251-MG and U87-MG human malignant glioma cells after 43degreesC-heat shock comparing with that of 45degreesC. First, we observed that cell growth was transiently inhibited after 43degreesC-heat shock for 3 or 5 days, in U251-MG or U87-MG cells, respectively, which was followed by regrowth. During the period of transient growth inhibition, mild G2/M arrest was observed. However, apoptosis was observed in only 2.7% or 1.5%, of 43degreesC-heated cells, in U251-MG or U87-MG cells, respectively. Instead, transmission electron micrography showed the formation of vacuoles, degeneration of mitochondria, and autophagosomes. Moreover, in the both cell lines, flow-cytometric analysis with acridine orange revealed the induction of acidic vesicle organelles, which was blocked by 3-methyladenine (3-MA), suggesting the involvement of autophagy. Furthermore, while 3-MA did not increase the anti-tumor effect of 43degreesC-heat shock, bafilomycin A1, another autophagy inhibitor, did significantly enhance the effect in U251-MG cells. Taken together, mild heat shock (43degreesC for 2 h) causes autophagy and mild G2/M arrest, but does not induce apparent apoptosis in U251-MG and U87-MG glioma cells. Inhibition of autophagy with bafilomycin A1 may increase the anti-tumor efficacy of mild heat shock against some malignant glioma cells.