Inhibition of Cathepsin D (CTSD) enhances radiosensitivity of glioblastoma cells by attenuating autophagy
Inhibition of Cathepsin D (CTSD) enhances radiosensitivity of glioblastoma cells by attenuating autophagy
复制标题
抑制组织蛋白酶 D (CTSD) 通过减弱自噬增强胶质母细胞瘤细胞的放射敏感性
DOI：
10.1002/mc.23194
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发表时间：
2020
影响因子：
4.6
通讯作者：
Shao Chunlin
中科院分区：
文献类型：
--
作者：
Zheng Wang;Chen Qianping;Wang Chen;Yao Dan;Zhu Lin;Pan Yan;Zhang Jianghong;Bai Yang;Shao Chunlin
术后放疗联合化疗是治疗胶质母细胞瘤(GBM)的常用方法，但由于肿瘤的放射抵抗，放疗往往达不到预期效果。在本研究中，我们从人脑胶质瘤细胞系U251中建立了一个放射抗性亚系，发现与胶质瘤临床恶性程度和预后密切相关的基因组织蛋白酶D(CTSD)在放射抵抗克隆中的表达水平高于亲代细胞，并且用小干扰RNA(SiRNA)或其抑制剂Pepstatin-A敲除CTSD会增加放射敏感性。抗辐射的GBM细胞自噬水平高于亲本细胞，轻链3(Lc3)siRNA沉默自噬可显著增强GBM细胞对电离辐射的敏感性。放射抵抗细胞中CTSD蛋白表达水平与自噬标记物Lc3 II/I呈正相关，与p62呈负相关。正如预期的那样，通过Western印迹和免疫荧光分析相结合，CTSD的抑制增加了自噬小体的形成，而减少了自溶酶体的形成，这表明自噬水平减弱，最终导致放射增敏。我们的结果首次揭示了CTSD通过影响自噬小体和溶酶体的融合来调节胶质母细胞瘤的放射敏感性。CTSD可能成为胶质母细胞瘤潜在的分子生物学标志物和新的治疗靶点。
Postoperative radiotherapy combined with chemotherapy is a commonly used treatment for glioblastoma (GBM) but radiotherapy often fails to achieve the expected results mainly due to tumor radioresistance. In this study, we established a radioresistant subline from human glioma cell line U251 and found that Cathepsin D (CTSD), a gene closely related to the clinical malignancy and prognosis in glioma, had higher expression level in radioresistant clones than that in parental cells, and knocking down CTSD by small interfering RNA (siRNA) or its inhibitor Pepstatin‐A increased the radiosensitivity. The level of autophagy was enhanced in the radioresistant GBM cells compared with its parent cells, and silencing autophagy by light chain 3 (LC3) siRNA significantly sensitized GBM cells to ionizing radiation (IR). Moreover, the protein expression level of CTSD was positively correlated with the autophagy marker LC3 II/I and negatively correlated with P62 after IR in radioresistant cells. As expected, through the combination of Western blot and immunofluorescence assays, inhibition of CTSD increased the formation of autophagosomes, while decreased the formation of autolysosomes, which indicating an attenuated autophagy level, leading to radiosensitization ultimately. Our results revealed for the first time that CTSD regulated the radiosensitivity of glioblastoma by affecting the fusion of autophagosomes and lysosomes. In significance, CTSD might be a potential molecular biomarker and a new therapeutic target in glioblastoma.