结直肠癌中Keap1、Nrf2、Gpx4表达与铁死亡的相关性分析及临床意义

Correlation of Keap1, Nrf2, Gpx4 with ferroptosis in colorectal carcinoma and its clinical significance

目的 探讨结直肠癌中Keap1、Nrf2、Gpx4的表达与铁死亡相关因子PLOOH、MDA、GSH及组织铁含量的相关性及临床意义。方法 收集106例结直肠癌、正常肠黏膜组织,采用免疫组化EnVision法、Western blot、qRT-PCR检测两者中Keap1、Nrf2及Gpx4的表达;应用分光光度法检测PLOOH、组织铁、MDA、GSH的含量,分析其相关性及临床意义。结果 结直肠癌组织中Keap1、Nrf2和Gpx4的阳性率分别为60.5%、35.8%、39.6%,其蛋白相对表达量分别为0.78±0.14、0.70±0.13、0.63±0.10,其mRNA水平分别为0.80±0.018、0.68±0.019、0.52±0.016,各因子在肿瘤中的表达均高于正常肠黏膜组织(P<0.05)。线性回归的对数趋势线分析显示结直肠癌组织中Keap1与Nrf2的表达呈负相关(R2=0.188 1,P<0.05),Nrf2与Gpx4的表达呈正相关(R2=0.252 7,P<0.05)。结直肠癌组织中PLOOH、MDA、GSH及组织铁的平均光密度值分别为0.67±0.07、3.13±0.32、3.32±0.41、102±11.91,其含量均高于正常肠黏膜组织(P<0.05),线性回归的对数趋势线分析显示PLOOH与MDA、组织铁含量呈正相关(P<0.05),而与GSH的表达呈负相关(P<0.05)。PLOOH与Keap1呈正相关(r=0.273,P<0.05),而与Nrf2、Gpx4表达呈负相关(r=-0.304,r=-0.330,P<0.05)。铁死亡、Keap1与结直肠癌患者的预后呈正相关,而Nrf2、Gpx4、浸润深度及淋巴结转移与结直肠癌患者预后呈负相关,是结直肠癌预后的独立危险因素。结论 结直肠癌中存在铁死亡现象,其与Keap1/Nrf2-Gpx4的表达有关,并且与患者预后密切相关。

Purpose To investigate the correlation and clinical significance of the expression of Keap1, Nrf2, Gpx4 with iron death related factors PLOOH, MDA, GSH and tissue iron content in colorectal carcinoma. Methods Immunohistochemistry, Western blot and qRT-PCR were used to detect the expression of Keap1, Nrf2 and GPx4 in 106 cases of colorectal adenocarcinoma and normal mucosa. The contents of PLOOH, Fe2+, MDA and GSH were detected by spectrophotometry, and their correlation and clinical significance were analyzed. Results The positive rates of Keap1, Nrf2 and Gpx4 expression in colorectal carcinoma cases were 60.5%, 35.8% and 39.6%, respectively. The relative protein expression levels were 0.78±0.14, 0.70±0.13 and 0.63±0.10, respectively. The mRNA levels were 0.80±0.018, 0.68±0.019 and 0.52±0.016, respectively. The expression of each factor in tumors was higher than that in normal intestinal mucosa(P<0.05). The analysis of logarithmic trend line of linear regression showed that the expression of Keap1 and Nrf2 was negatively correlated in colorectal cancer tissues(R~2=0.188 1, P<0.05), and the expression of Nrf2 and Gpx4 was positively correlated(R~2=0.252 7, P<0.05). The mean optical density values of PLOOH, MDA, GSH and tissue iron in colorectal cancer were 0.67±0.07, 3.13±0.32, 3.32±0.41 and 102±11.91, respectively, which were higher than those in normal intestinal mucosa(P<0.05). The log trend line analysis of linear regression showed that PLOOH was positively correlated with MDA and Fe2+(P<0.05), but negatively correlated with GSH expression(P<0.05). PLOOH was positively correlated with Keap1(r=0.273, P<0.05), but negatively correlated with Nrf2 and Gpx4(r=-0.304, r=-0.330, P<0.05). Ferroptosis and Keap1 were positively correlated with the prognosis of colorectal carcinoma patients, while Nrf2, Gpx4, depth of invasion and lymph node metastasis were negatively correlated with the prognosis of colorectal cancer patients, and were independent risk factors for the prognosis of colorectal cancer. Conclusion There is ferroptosis in colorectal carcinoma, which is related to the expression of Keap1/Nrf2-Gpx4 and is closely related to the prognosis of patients.