目的：探讨circ_0005075 对肝癌细胞增殖和侵袭的影响及其作用机制。方法：收集唐山市工人医院2015 年3 月至2018 年3 月收治的35 例肝癌患者手术切除的肝癌及其相应癌旁组织，采用qPCR 检测肝癌、癌旁组织及细胞系（HCCC9810、HepG2、HLE 肝癌细胞和THLE-3 肝上皮细胞）中circ_0005075 和miR-335 的表达水平。双荧光素酶报告基因实验验证circ_0005075、miR-335 及CCND1 三者间的靶向关系。采用脂质体介导方法将sh-circ_0005075、miR-335 mimics、miR-335 mimics+pcDNA-CCND1、sh-circ_0005075+pcDNA-CCND1、pcDNA-circ_0005075+miR-335 mimics、sh-CCND1+pcDNA-circ_0005075 转染肝癌细胞HCCC9810，应用MTT和Transwell 法检测circ_0005075/miR-335/CCND1 分子轴正向和回复作用对HCCC9810 细胞增殖和侵袭的影响。结果：circ_0005075 在肝癌组织及细胞系中高表达（均P<0.01），且在HCCC9810 细胞中表达水平最高（P<0.05）。双荧光素酶报告基因实验结果显示，circ_0005075 靶向负调控miR-335 的表达水平（P<0.05），且CCND1 是miR-335 的靶基因（P<0.05）。正向和回复实验证明，敲降circ_0005075 或过表达miR-335 都通过调控CCND1 抑制HCCC9810 细胞增殖和侵袭（P<0.05 或P<0.01）。结论：circ_0005075 通过海绵吸附miR-335 上调CCND1 的表达水平，进而促进HCCC9810 细胞的增殖和侵袭。

Objective: To explore the effect of circ_0005075 on the proliferation and invasion of liver cancer cells and its underlying mechanism. Methods: A total of 35 cases of cancer tissues and corresponding para-cancerous tissues from liver cancer patients, who underwent surgical resection in Tangshan Workers’Hospital from March 2015 to March 2018, were collected for this study. qPCR was used to detect the expression levels of circ_0005075 and miR-335 in liver cancer tissues, para-cancerous tissues, liver cancer cell lines (HCCC9810, HepG2, HLE and hepatic epithelial THLE-3 cells). Dual luciferase reporter gene assay was used to verify the targeting relationship among circ 0005075, mir-335 and CCND1. By using liposome-mediated method, Sh-circ_0005075, miR-335 mimics, miR-335 mimics+pcDNA-CCND1, sh-circ_0005075+pcDNA-CCND1, pcDNA-circ_0005075+miR-335 mimics, sh-CCND1+pcDNA-circ_0005075 were transfected into HCCC9810 cells, respectively. The effects of circ_0005075/miR-335/CCND1 molecular axis on the proliferation and invasion of HCCC9810 cells were detected by MTT and Transwell methods. Results: circ_0005075 was highly expressed in liver cancer tissues and cell lines (P<0.01) ,and the highest expression in HCCC9810 cells (P<0.05). Dual luciferase reporter gene results showed that circ_0005075 negatively regulated miR-335 (P<0.05), and CCND1 was a target gene of miR-335 (P<0.05). Further experiments proved that knockdown of circ_0005075 or overexpression of miR-335 could inhibit the proliferation and invasion of HCCC9810 cells by regulating CCND1（P<0.05 or P<0.01）. Conclusion: Circ_0005075 upregulates the expression level of CCND1 by sponging miR-335, thereby promoting the proliferation and invasion of HCCC9810 cells.