Acquired drug resistance is a main reason for limiting the application of sorafenib in HCC treatment. This study aimed to explore the role and mechanisms of a novel long non-coding RNA (lncRNA), lnc-TSI, in sorafenib resistance of HCC. The interaction between lnc-TSI and miR-4726-5p, and miR-4726-5p and KCNMA1 were predicted using bioinformatic tools. Expression of the molecules in the lnc-TSI/miR-4726-5p/KCNMA1 axis in clinical samples and cell lines, as well as the sorafenib resistant HCC cell lines, was determined using qRT-PCR or western blotting. Expressions of lnc-TSI, miR-4726-5p, and KCNMA1 were manipulated in HepG2 and Huh7 cells through plasmid transfection or lentivirus infection. The CCK-8, flow cytometry, and Tunel assays were employed to determine the role of this axis on sorafenib resistance of HCC. A xenograft model was established using sorafenib-resistant HepG2 and Huh7 cells followed by in vivo sorafenib treatments to confirm the in vitro findings. Lnc-TSI and KCNMA1 expressions were significantly downregulated in HCC clinical samples and cell lines, especially in sorafenib resistance ones, while mi-4726-5p presented a reversed expression pattern. Lnc-TSI interacted with miR-4726-5p, and Lnc-TSI acts as a ceRNA via sponging miR-4726-5p in HCC cells. Overexpression of lnc-TSI and KCNMA1 promoted apoptosis and decreased cell viability of sorafenib-treated HCC cells, thus alleviated sorafenib resistance. miR-4726-5p mimic reversed the KCNMA1-mediated sorafenib sensitivity-promoting effect, while additional overexpression of lnc-TSI reversed the effect of miR-4726-5p. In vivo analysis also showed that overexpression of ln-TSI diminished sorafenib resistance in mice inoculated with sorafenib-resistant HCC cells via increasing KCNMA1 expression and decreasing miR-4726-5p expression. The lnc-TSI/miR-4726-5p/KCNMA1 axis plays a critical role in regulating the resistance of HCC to sorafenib, and might serve as a therapeutic target to manage sorafenib resistance of HCC in clinic.

获得性耐药是限制索拉非尼在HCC治疗中应用的主要原因。本研究旨在探讨新型长链非编码RNA（lncRNA）lnc-TSI在HCC索拉非尼耐药中的作用和机制。使用生物信息学工具预测lnc-TSI和miR-4726-5p以及miR-4726-5p和KCNMA1之间的相互作用。使用 qRT-PCR 或蛋白质印迹法测定临床样本和细胞系以及索拉非尼耐药 HCC 细胞系中 lnc-TSI/miR-4726-5p/KCNMA1 轴中分子的表达。通过质粒转染或慢病毒感染，在 HepG2 和 Huh7 细胞中操纵 lnc-TSI、miR-4726-5p 和 KCNMA1 的表达。采用 CCK-8、流式细胞术和 Tunel 测定来确定该轴对 HCC 索拉非尼耐药的作用。使用索拉非尼耐药的 HepG2 和 Huh7 细胞建立异种移植模型，然后进行体内索拉非尼治疗以证实体外研究结果。Lnc-TSI 和 KCNMA1 表达在 HCC 临床样本和细胞系中显着下调，尤其是在索拉非尼耐药细胞中，而 mi-4726-5p 则呈现相反的表达模式。Lnc-TSI 与 miR-4726-5p 相互作用，并且 Lnc-TSI 通过在 HCC 细胞中海绵 miR-4726-5p 充当 ceRNA。lnc-TSI和KCNMA1的过表达促进索拉非尼处理的HCC细胞凋亡并降低细胞活力，从而减轻索拉非尼耐药。miR-4726-5p 模拟物逆转了 KCNMA1 介导的索拉非尼敏感性促进作用，而 lnc-TSI 的额外过表达则逆转了 miR-4726-5p 的作用。体内分析还表明，ln-TSI 的过表达通过增加 KCNMA1 表达和减少 miR-4726-5p 表达，减少了接种索拉非尼耐药 HCC 细胞的小鼠的索拉非尼耐药性。lnc-TSI/miR-4726-5p/KCNMA1轴在调节HCC对索拉非尼耐药中发挥着关键作用，可能作为临床控制HCC索拉非尼耐药的治疗靶点。