Introduction: Glutathione reductase (GSR) provides reduced glutathione (GSH) to maintain redox homeostasis. Inhibition of GSR disrupts this balance, resulting in cell damage, which benefits cancer therapy. However, the effect of GSR inhibition on the tumorigenicity of human cervical cancer is not fully understood.
Materials and Methods: Tissue microarray analysis was employed to determine GSR expression in cervical cancer tissues by immunohistochemical staining. Cell death was measured with PI/FITC-annexin V staining. mRNA levels were measured via quantitative RT-PCR. Protein expression was measured by Western blotting and flow cytometry. STAT3 deletion was performed with CRISPR/Cas9 technology. GSR knockdown was achieved by RNA interference. Reactive oxygen species (ROS) levels were measured by DCF staining. GSR enzymatic activity was measured with a GSR assay kit. The effect of GSR inhibition on the growth of tumors formed by cervical cancer cells was investigated using a xenograft model.
Results: The expression of GSR was increased in human cervical cancer tissues, as shown by immunohistochemical staining. GSR knockdown by RNA interference in human cervical cancer cell lines resulted in cell death, suggesting the ability of GSR to maintain cancer cell survival. The STAT3 inhibitor 6-nitrobenzo[b]thiophene 1,1-dioxide (Stattic) also inhibited the enzymatic activity of GSR and induced the death of cervical cancer cells. More importantly, Stattic decreased the growth of xenograft tumors formed by cervical cancer cells in nude mice. Mechanistically, tumor cell death induced by Stattic-mediated GSR inhibition was ROS-dependent, since the ROS scavengers GSH and N-acetyl cysteine (NAC) reversed the effect of Stattic. In contrast, pharmacological and molecular inhibition of STAT3 did not induce the death of cervical cancer cells, suggesting a STAT3-independent activity of Stattic.
Conclusion: Stattic inhibits the enzymatic activity of GSR and induces STAT3-independent but ROS-dependent death of cervical cancer cells, suggesting its potential application as a therapeutic agent for human cervical cancers.

Keywords: Stattic, glutathione reductase, cell death, cervical cancer, reactive oxygen species, tumor growth


中文翻译：

---

STAT3 抑制剂 Stattic 通过 ROS 依赖性途径抑制谷胱甘肽还原酶和抑制人宫颈癌细胞致瘤性的新生物学活性

简介：谷胱甘肽还原酶 (GSR) 提供还原型谷胱甘肽 (GSH) 以维持氧化还原稳态。抑制 GSR 会破坏这种平衡，导致细胞损伤，这有利于癌症治疗。然而，GSR抑制对人宫颈癌致瘤性的影响尚不完全清楚。
材料和方法：组织微阵列分析用于通过免疫组织化学染色确定宫颈癌组织中的 GSR 表达。用 PI/FITC-annexin V 染色测量细胞死亡。通过定量RT-PCR测量mRNA水平。通过蛋白质印迹和流式细胞术测量蛋白质表达。状态3使用 CRISPR/Cas9 技术进行删除。GSR 敲低是通过 RNA 干扰实现的。通过 DCF 染色测量活性氧 (ROS) 水平。GSR酶活性用GSR测定试剂盒测量。使用异种移植模型研究了 GSR 抑制对宫颈癌细胞形成的肿瘤生长的影响。
结果：免疫组化染色显示，人宫颈癌组织中 GSR 的表达增加。在人宫颈癌细胞系中通过 RNA 干扰敲低 GSR 会导致细胞死亡，这表明 GSR 具有维持癌细胞存活的能力。STAT3 抑制剂 6-nitrobenzo[b]thiophene 1,1-dioxide (Stattic) 也抑制 GSR 的酶活性并诱导宫颈癌细胞死亡。更重要的是，Stattic 减少了裸鼠体内由宫颈癌细胞形成的异种移植肿瘤的生长。从机制上讲，由 Stattic 介导的 GSR 抑制诱导的肿瘤细胞死亡是 ROS 依赖性的，因为 ROS 清除剂 GSH 和 N-乙酰半胱氨酸 (NAC) 逆转了 Stattic 的作用。相反，STAT3的药理学和分子抑制没有诱导宫颈癌细胞死亡，表明 Stattic 具有不依赖 STAT3 的活性。
结论： Stattic 抑制 GSR 的酶活性并诱导宫颈癌细胞不依赖于 STAT3 但依赖于 ROS 的死亡，表明其作为人类宫颈癌治疗剂的潜在应用。

关键词： Stattic，谷胱甘肽还原酶，细胞死亡，宫颈癌，活性氧，肿瘤生长