柳氮磺吡啶通过铁死亡途径增强结直肠癌细胞放射敏感性研究

目的 探究低剂量柳氮磺吡啶（SAS）对结直肠癌细胞的放疗增敏作用。方法 CCK‐8检测不同浓度SAS对结直肠癌细胞的增殖抑制作用,采用凋亡、自噬等抑制剂联合SAS处理结直肠癌细胞,CCK‐8法比较细胞活力。采用锥虫蓝染色、平板克隆形成、细胞生长曲线等实验评价低浓度SAS联合放疗对结直肠癌细胞的体外放疗增敏作用。通过检测细胞内脂质过氧化物、铁死亡蛋白标志物（GPX4、PTGS2）等,探究低浓度SAS联合放疗对细胞铁死亡的促进作用。利用小鼠皮下移植瘤模型,明确SAS的体内放疗增敏效应。结果 高浓度SAS可诱导结直肠癌细胞凋亡与铁死亡。低浓度SAS增强结直肠癌细胞放疗敏感性,该效应可被铁死亡抑制剂（Fer‐1）阻断。低浓度SAS联合放疗显著增加细胞内脂质过氧化物含量与PTGS2表达,降低GPX4表达。皮下移植瘤模型中SAS亦显示显著的放疗增敏效应。结论 低浓度SAS通过铁死亡途径增强结直肠癌细胞放疗敏感性。

Sulfasalazine increases the radiosensitivity of colorectal cancer cells by promoting ferroptosis

Objective To investigate the radiosensitization effect of low‐dose sulfasalazine (SAS) on colorectal cancer (CRC) cells. Methods Proliferation inhibition effect of SAS on CRC cells was detected by CCK‐8 assay, and the concentration of SAS in vitro assays was based on its IC10 value. CRC cells were treated with SAS alone or combined with inhibitors of apoptosis, autophagy, ferroptosis and necroptosis, then cell viability was detected by CCK‐8 assay. Trypan blue staining, clone formation assay and cell growth curves were used to verify the radiosensitization effect of SAS on CRC cells in vitro. CRC cells were treated with SAS and radiotherapy, then the intracellular contents of lipid peroxidation and the protein levels of GPX4, PTGS2, cleaved PARP and active caspase 3 were evaluated, respectively. Subcutaneous xenograft tumor mouse model was established to further verify the radiosensitization effect of SAS in vivo. Results High dose (lethal dose) of SAS could induce apoptosis and ferroptosis in CRC cells. Low dose (non‐lethal dose) of SAS enhanced the radiosensitivity of CRC cells in vitro, and the radiosensitivity effect of SAS could only be abolished by ferroptosis inhibitor (Fer‐1). Low dose of SAS combined with radiotherapy significantly down‐regulated the expression of GPX4, whereas increased the intracellular lipid peroxidation levels and the expression of PTGS2. SAS also showed significant radiosensitization effect in subcutaneous xenograft tumor model. Conclusion Our findings suggest that low‐dose SAS could increase the radiosensitivity of CRC cells by promoting ferroptosis.