Li Zhang, Li Ming, Xia Pengcheng, Lu Zhiming
Department of Clinical Laboratory, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China.
Front Oncol. 2022 Mar 24;12:873561. doi: 10.3389/fonc.2022.873561. eCollection 2022.
The advanced grade glioblastomas are characterized by dismal five-year survival rates and are associated with worse outcomes. Additionally, resistance to therapies is an additional burden responsible for glioma associated mortality. We studied the resistance against temozolomide (TMZ) as a surrogate to understand the mechanism of therapy resistance in glioma cancer cells. Screening of three glioma cells lines, A172, LN229 and SF268 revealed that SF268 glioma cells were particularly resistant to TMZ with the IC-50 of this cell line for TMZ ten times higher than for the other two cell lines. A role of lncRNAs in glioma progression has been identified in recent years and, therefore, we focused on lncRNAs for their role in regulating TMZ resistance in glioma cancer cells. lncRNA HOTTIP was found to be particularly elevated in SF268 cells and over-expression of HOTTIP in both A172 and LN229 remarkably increased their TMZ IC-50s, along with increased cell proliferation, migration, clonogenicity and markers of angiogenesis and metastasis. As a mechanism we observed increased expression of miRNA-10b and mesenchymal markers Zeb1/Zeb2 and reduced expression of E-cadherin in SF268 cells indicating a role of EMT in TMZ resistance. A172 and LN229 cells with overexpressed HOTTIP also had similarly induced EMT and the elevated miR-10b levels. Further, silencing of miR-10b in HOTTIP overexpressing cells as well as the SF268 cells reversed EMT with associated sensitization of all the tested cells to TMZ. Our results thus present a case for HOTTIP in native as well as acquired resistance of glioma cells against chemotherapy, with a key mechanistic role of EMT and the miR-10b. Thus, HOTTIP as well as miR-10b are critical targets for glioma therapy, and need to be tested further.
高级别胶质母细胞瘤的特征是五年生存率极低，且预后较差。此外，对治疗的耐药性是导致胶质瘤相关死亡的另一个负担。我们研究了对替莫唑胺（TMZ）的耐药性，以此作为了解胶质瘤癌细胞治疗耐药机制的一个指标。对三种胶质瘤细胞系A172、LN229和SF268进行筛选后发现，SF268胶质瘤细胞对TMZ具有特别的耐药性，该细胞系对TMZ的半数抑制浓度（IC-50）比其他两种细胞系高出十倍。近年来已确定lncRNA在胶质瘤进展中发挥作用，因此，我们重点研究lncRNA在调节胶质瘤癌细胞对TMZ耐药性方面的作用。发现lncRNA HOTTIP在SF268细胞中特别上调，在A172和LN229细胞中过表达HOTTIP显著提高了它们的TMZ IC-50，同时细胞增殖、迁移、克隆形成能力以及血管生成和转移标志物也增加。作为一种机制，我们观察到SF268细胞中miRNA-10b和间充质标志物Zeb1/Zeb2的表达增加，而E-钙黏蛋白的表达减少，这表明上皮-间质转化（EMT）在TMZ耐药中发挥作用。过表达HOTTIP的A172和LN229细胞也同样诱导了EMT和miR-10b水平升高。此外，在过表达HOTTIP的细胞以及SF268细胞中沉默miR-10b可逆转EMT，并使所有测试细胞对TMZ敏感。因此，我们的结果表明HOTTIP在胶质瘤细胞对化疗的天然及获得性耐药中起作用，EMT和miR-10b起关键机制作用。因此，HOTTIP以及miR-10b是胶质瘤治疗的关键靶点，需要进一步进行测试。
