FLI-1 mediates tumor suppressor function via Klotho signaling in regulating CRC
FLI-1 mediates tumor suppressor function via Klotho signaling in regulating CRC
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FLI-1 通过 Klotho 信号传导调节 CRC 介导肿瘤抑制功能
DOI：
10.1002/cbin.11347
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发表时间：
2020
影响因子：
3.9
通讯作者：
He Yongheng
中科院分区：
文献类型：
--
作者：
Xie Biao;Hu Fan;Li Mei;Mo Li;Xu Chongsi;Xiao You;Wang Xiaoyan;Nie Jing;Yang Lixia;He Yongheng
结直肠癌（Colorectal cancer，CRC）是一种发病率和死亡率都很高的侵袭性恶性肿瘤。尽管已经开发出靶向治疗，但伴有远处转移的CRC患者的5年生存率仍然很低。因此，新靶点的鉴定对于改善CRC治疗仍然是重要的。Klotho是一种抑癌基因，在大肠癌中表达异常。在这项研究中，研究了FLI-1基因在调节Klothogene表达和Klotho相关信号传导中的作用，以及FLI-1对CRC细胞系中集落形成、侵袭和凋亡的影响。使用商业甲基化试剂盒分析FLI-1基因的甲基化。结果显示，与正常结肠黏膜上皮细胞相比，6株大肠癌细胞系中FLI-1 mRNA和蛋白表达均下调，且与DNA甲基化水平呈负相关。在HT 29细胞中，FLI-1基因表达沉默降低Klotho蛋白表达和β-catenin蛋白在Thr 41/Ser 45的磷酸化，但增加Wnt 3a和β-catenin蛋白表达和IGF-1 R磷酸化。与沉默FLI-1相反，过表达FLI-1显著增加Klotho蛋白表达和β-catenin蛋白在Thr 41/Ser 45的磷酸化，但降低Caco-2细胞中Wnt 3a和β-catenin蛋白表达和IGF-1 R磷酸化。FLI-1基因表达的沉默显著增加了HT 29细胞的集落形成和侵袭，但减少了细胞凋亡。相反，过表达FLI-1基因显著降低Caco-2细胞的集落形成和侵袭，但增加细胞凋亡。这些发现表明FLI-1在CRC细胞中作为肿瘤抑制因子发挥作用，并积极调节Klotho信号传导。FLI-1基因的高甲基化可能是大肠癌细胞FLI-1基因表达缺失的原因之一。
Colorectal cancer (CRC) is an aggressive malignancy with a high incidence and mortality rate. Although a targeting therapy has been developed, the 5‐year survival rate is still very low in CRC patients with distant metastasis. Thus, the identification of new targets is still significant for improving CRC treatment. Klotho is a tumor suppressor, and its expression is aberrant in CRC. In this study, the roles of theFLI‐1gene in regulatingKlothogene expression and Klotho‐associated signaling, as well as the effects of FLI‐1 on colony formation, invasion, and apoptosis were investigated in CRC cell lines. The methylation of the FLI‐1 gene was analyzed using a commercial methylation kit. Results showed thatFLI‐1messenger RNA and protein expression were downregulated in six CRC cell lines when compared with the normal colon mucosal epithelial cell line, which negatively correlated with the level of DNA methylation. Silencing ofFLI‐1gene expression decreased Klotho protein expression and phosphorylation ofβ‐catenin protein at Thr41/Ser45, but increased Wnt3a and β‐catenin protein expression and IGF‐1R phosphorylation in HT29 cells. In contrast to silencingFLI‐1, overexpressingFLI‐1significantly increased Klotho protein expression and phosphorylation of β‐catenin protein at Thr41/Ser45, but decreased Wnt3a andβ‐catenin protein expression and IGF‐1R phosphorylation in Caco‐2 cells. Silencing ofFLI‐1gene expression significantly increased colony formation and invasion, but decreased apoptosis in HT29 cells. In contrast, overexpressing theFLI‐1gene significantly decreased colony formation and invasion, but increased apoptosis in Caco‐2 cells. These findings suggest that FLI‐1 functions as a tumor suppressor in CRC cells and positively regulates Klotho signaling. Hypermethylation may be one of the causes of the loss ofFLI‐1gene expression in CRC cells.