Abstract

Background

Glioblastoma (GBM) is the most common aggressive primary cancer occurring in the brain tissue. GBM accounts 16% of primary brain tumors and half of gliomas. Additionally, the incidence of GBM is increases with aging, and reaches the peak at the age of 75 to 84 years. The survival of patients with GBM remains at a low level, only less than 5% patients diagnosed with GBM survive for 5 years. Temozolomide (TMZ) is a DNA alkylating agent and is currently a first line chemotherapeutic treatment for GBM. TMZ combined with radiation therapy has been shown to prolong the overall survival (OS) to 14.6 months compared with 12.1 months for radiation therapy alone. NF-E2-related factor 2 (Nrf2) is a transcription factor that contains seven functional domains. The binding of Keap1 to Nrf2 is a central regulator of the cellular defense mechanism against environmental stresses.

Methods

First, Nrf2 overexpression and inhibition models were constructed in U251 cells using transfection. The percentage of viable cells was detected using the MTT assay. Then, the expression of the HO-1 regulator was detected using qPCR, and the concentrations of oxidative stress related factors were detected using ELISAs. The levels of proteins related to oxidative stress and the Ras/Raf/MEK signaling pathway was detected using western blotting analysis.

Results

We initially established Nrf2 inhibition and activation cell models in U251 cells and found that the inhibition of Nrf2 expression decreased the mRNA and protein levels of the anti-oxidative enzymes, as well as the secretion of these enzymes into the cellular microenvironment. These effects might be mediated by the inhibition of Ras/Raf/MEK signaling pathway, leading to the inhibition of cellular proliferation.

Conclusions

Inhibition of Nrf2 expression might enhance the effect of TMZ on the treatment of GBM and might be a new therapeutic strategy.

中文翻译：

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抑制Nrf2可能通过抑制Ras/Raf/MEK信号通路增强替莫唑胺对胶质瘤细胞的抗肿瘤作用

摘要

背景

胶质母细胞瘤 (GBM) 是脑组织中最常见的侵袭性原发性癌症。GBM 占原发性脑肿瘤的 16%，占胶质瘤的一半。此外，GBM的发病率随着年龄的增长而增加，并在75～84岁达到高峰。GBM 患者的存活率仍然很低，只有不到 5% 的确诊 GBM 患者存活 5 年。替莫唑胺 (TMZ) 是一种 DNA 烷化剂，目前是 GBM 的一线化疗药物。TMZ 联合放射治疗已被证明可将总生存期 (OS) 延长至 14.6 个月，而单独的放射治疗则为 12.1 个月。NF-E2 相关因子 2 (Nrf2) 是一种包含七个功能域的转录因子。

方法

首先，使用转染在 U251 细胞中构建 Nrf2 过表达和抑制模型。使用MTT测定法检测活细胞的百分比。然后，使用qPCR检测HO-1调节因子的表达，并使用ELISA检测氧化应激相关因子的浓度。使用蛋白质印迹分析检测与氧化应激和 Ras/Raf/MEK 信号通路相关的蛋白质水平。

结果

我们最初在 U251 细胞中建立了 Nrf2 抑制和激活细胞模型，发现抑制 Nrf2 表达降低了抗氧化酶的 mRNA 和蛋白质水平，以及这些酶分泌到细胞微环境中。这些作用可能是通过抑制 Ras/Raf/MEK 信号通路介导的，从而导致细胞增殖的抑制。

结论

抑制 Nrf2 表达可能会增强 TMZ 对 GBM 治疗的影响，并可能成为一种新的治疗策略。