Medical College of Soochow University, Suzhou, jiangsu, PR China.
Department of General Surgery, The First Affiliated Hospital of Gannan Medical University, Ganzhou, Jiangxi, PR China.
Cell Biol Int. 2022 Feb;46(2):213-221. doi: 10.1002/cbin.11719. Epub 2021 Dec 2.
Sorafenib is the important first-standard drug for patients with advanced hepatocellular carcinoma (HCC). A major obstacle to successful treatment is sorafenib resistance. However, the mechanism of sorafenib resistance is unclear. The present study aimed to determine the involvement of dipeptidyl peptidase-8 (DPP8) in sorafenib resistance. DPP8 expression was detected using quantitative real-time PCR (qPCR) and western blot analysis. The effect of DPP8 on sorafenib resistance was examined using terminal deoxynulceotidyl transferase nick-end-labeling (TUNEL), colony formation, flow cytometry, luciferase reporter, immunofluorescence, and immunoprecipitation (IP) assays. We found that DPP8 mRNA and protein levels were dramatically upregulated in HCC. Gene set enrichment analysis (GSEA) illustrated that DPP8 might be involved in apoptosis regulation. Downregulation of DPP8 substantially promoted the sensitivity of HCC cells to sorafenib. Further analysis showed that DPP8 might regulate nuclear factor kappa B (NF-κB) signaling, which was confirmed using a luciferase reporter assay. Downregulation of DPP8 decreased the expression levels of downstream genes of the NF-κB pathway. IP showed that DPP8 can interact with NF-κB subunit c-Rel, an important protein of NF-κB signaling. Finally, a drug combination of sorafenib and Val-boroPro induced higher mortality of HCC cells than sorafenib alone in DPP8-upregulated cells. Our findings indicated that using the inhibitor Val-boroPro might be a promising method to enhance sorafenib sensitivity in advanced HCC.
索拉非尼是晚期肝细胞癌（HCC）患者的重要一线标准药物。成功治疗的主要障碍是索拉非尼耐药。然而，索拉非尼耐药的机制尚不清楚。本研究旨在确定二肽基肽酶-8（DPP8）是否参与索拉非尼耐药。采用实时定量 PCR（qPCR）和Western blot 分析检测 DPP8 的表达。采用末端脱氧核苷酸转移酶缺口末端标记（TUNEL）、集落形成、流式细胞术、荧光素酶报告基因、免疫荧光和免疫沉淀（IP）检测 DPP8 对索拉非尼耐药的影响。结果发现，DPP8mRNA 和蛋白水平在 HCC 中显著上调。基因集富集分析（GSEA）表明 DPP8 可能参与细胞凋亡调控。下调 DPP8 可显著提高 HCC 细胞对索拉非尼的敏感性。进一步分析表明，DPP8 可能通过核因子 kappa B（NF-κB）信号通路进行调节，这一结果通过荧光素酶报告基因检测得到了证实。下调 DPP8 可降低 NF-κB 通路下游基因的表达水平。IP 显示 DPP8 可与 NF-κB 亚基 c-Rel 相互作用，c-Rel 是 NF-κB 信号的重要蛋白。最后，在 DPP8 上调的细胞中，索拉非尼与 Val-boroPro 的药物组合诱导 HCC 细胞死亡率高于单独使用索拉非尼。本研究结果表明，使用抑制剂 Val-boroPro 可能是提高晚期 HCC 中索拉非尼敏感性的一种有前途的方法。
