Table_1_CircKIF5B Promotes Hepatocellular Carcinoma Progression by Regulating the miR-192 Family/XIAP Axis.docx

BackgroundThe long-term prognosis of HCC (hepatocellular carcinoma) with metastasis remains extremely poor. CircRNAs are promising as critical biological markers in identifying disease mechanisms and developing new effective treatments. However, the role of the aberrant expression of circRNAs in HCC progression remains largely unknown.
MethodsCircKIF5B location was investigated by RNA fluorescence in situ hybridization (RNA-FISH). For circRNA determination, RNase R treatment and Real-Time Quantitative RT-PCR (qRT-PCR) were performed. Transwell chamber assays examined the chemotactic migration and invasion of liver cancer cells.
ResultsThis study identified the circRNA circKIF5B originating from exons 1, 2, and 3 of the KIF5B gene. Importantly, we found that circKIF5B circRNA, rather than KIF5B linear mRNA, was notably upregulated in liver cancer cell lines and tissues. Moreover, we found that silencing circKIF5B markedly reduced the proliferation, invasion, and metastasis of liver cancer cells by sponging the miR-192 family, thus decreasing the expression of X-linked inhibitor of apoptosis (XIAP).
ConclusionOur data demonstrate that circKIF5B can regulate XIAP expression by sponging miR-192 and miR-215 competing for the ceRNA mechanism, indicating that circKIF5B may act as an essential upstream regulator and providing mechanistic evidence to support the view that circKIF5B/miR-192s/XIAP is a promising therapeutic target for treating liver cancer.

背景：伴转移的肝细胞癌（hepatocellular carcinoma, HCC）长期预后极差。环状RNA（circRNAs）是极具潜力的关键生物标志物，可为阐明疾病发病机制、开发新型有效治疗策略提供重要支撑。然而，环状RNA异常表达在肝细胞癌进展中的具体作用仍未得到充分阐明。
方法：本研究通过RNA荧光原位杂交（RNA fluorescence in situ hybridization, RNA-FISH）探究circKIF5B的细胞定位。为检测环状RNA的表达情况，采用RNase R酶处理与实时定量逆转录聚合酶链反应（Real-Time Quantitative RT-PCR, qRT-PCR）技术开展实验。通过Transwell小室实验检测肝癌细胞的趋化迁移与侵袭能力。
结果：本研究鉴定出源自KIF5B基因第1、2、3外显子的环状RNA circKIF5B。值得注意的是，相较于KIF5B线性mRNA，circKIF5B在肝癌细胞系及组织中显著上调。此外，研究发现通过充当miR-192家族的分子海绵，沉默circKIF5B可显著抑制肝癌细胞的增殖、侵袭与转移，进而降低X连锁凋亡抑制蛋白（X-linked inhibitor of apoptosis, XIAP）的表达。
结论：本研究数据证实，circKIF5B可通过竞争性内源RNA（competing endogenous RNA, ceRNA）机制，海绵吸附miR-192与miR-215，从而调控XIAP的表达。这一发现表明circKIF5B可作为关键的上游调控因子，同时为“circKIF5B/miR-192家族/XIAP轴可作为治疗肝癌的潜在治疗靶点”这一观点提供了机制层面的实验证据。