lncRNA SNHG4通过EP300-SNHG4-GPX4轴抑制乳腺癌细胞铁死亡

LncRNA SNHG4 inhibits ferroptosis of breast cancer through EP300-SNHG4-GPX4 axis

目的探讨lncRNA SNHG4在乳腺癌中的表达以及调控乳腺癌细胞铁死亡的作用机制。方法收集2017年1月—2018年12月于我院乳腺外科进行手术治疗的100例乳腺癌患者癌组织及距肿瘤边缘3~5 cm的癌旁组织,应用RT-PCR技术分析SNHG4在乳腺癌组织及配对癌旁组织中的表达。构建SNHG4敲降的乳腺癌MDA-MB-468细胞系及过表达SNHG4的乳腺癌Hs578T细胞系,CCK-8法测定SNHG4对乳腺癌细胞增殖能力的影响,应用铁含量测定试剂盒及MDA测定试剂盒检测铁及ROS改变,Western blot实验检测GPX4及EP300蛋白表达,分析EP300与SNHG4及SNHG4与GPX4表达的相关性。结果SNHG4在乳腺癌组织中表达高于癌旁组织(P<0.01),且在侵袭转移能力强的Basal-Like型及ER(-)乳腺癌中高表达(P<0.01),SNHG4高表达与乳腺癌患者的总生存期(OS)及无病生存期(DFS)短相关(P<0.01)。敲降SNHG4导致细胞活力降低(P<0.01),且该作用可被铁死亡抑制剂逆转。机制方面,SNHG4通过上调GPX4表达抑制铁死亡,SNHG4上游可受到组蛋白乙酰基转移酶EP300的正向调控,EP300与SNHG4的表达正相关(P<0.01)。结论SNHG4在乳腺癌中高表达且可通过EP300-SNHG4-GPX4轴抑制乳腺癌细胞铁死亡。

Objective This study aimed to investigate the expression of lncRNA SNHG4 in breast cancer and the mechanism of regulating ferroptosis in breast cancer cells.Methods The tumor tissues of 100 breast cancer patients who underwent surgery in our hospital from January 2017 to December 2018 and the adjacent tissues 3-5 cm away from the tumor edge were collected,and the expression of SNHG4 in breast cancer tissues and paired adjacent tissues was analyzed by RT-PCR.The MDA-MB-468 cell line of breast cancer with SNHG4 knockdown and Hs578T cell line of breast cancer with SNHG4 overexpression were constructed.The CCK-8 assay was used to measure the effect of SNHG4 on the proliferation of breast cancer cells.The changes of iron and ROS were detected by iron content assay kit and MDA assay kit.Western blot was used to detect the expression of GPX4 and EP300 proteins.The correlation between the expression of SNHG4 and EP300,and SNHG4 and GPX4 was analyzed.Results The expression of SNHG4 in breast cancer tissues was higher than that in adjacent tissues(P<0.01),and it was highly expressed in Basal-Like type and ER(-)breast cancer with strong invasion and migration(P<0.01).The high expression of SNHG4 was correlated with the short overall survival(OS)and disease-free survival(DFS)of breast cancer patients(P<0.01).Knockdown of SNHG4 resulted in decreased cell viability(P<0.01),and this effect could be reversed by inhibitor of ferroptosis.In terms of mechanism,SNHG4 inhibited ferroptosis by up-regulating the expression of GPX4.The upstream of SNHG4 could be positively regulated by histone acetyltransferase,EP300,and EP300 was positively correlated with the expression of SNHG4(P<0.01).Conclusion SNHG4 is highly expressed in breast cancer and can inhibit ferroptosis of breast cancer cells through EP300-SNHG4-GPX4 axis.