肝细胞癌（HCC）是全球癌症相关死亡的主要原因。然而，aucubin对HCC的抗癌效应尚未报道。顺铂常通过增加程序性死亡配体1（PD-L1）的表达减少肿瘤微环境中的CD8+肿瘤浸润淋巴细胞，这严重影响顺铂治疗HCC患者的预后效果。因此，有必要寻找一种新的治疗途径，增强顺铂对HCC的敏感性。本研究旨在评估aucubin对HCC的抗肿瘤作用，并揭示aucubin和顺铂对HCC的协同作用和机制。采用H22异种移植小鼠模型进行体内实验。通过MTT实验检测肿瘤细胞增殖，通过RT-qPCR分析CD274 mRNA在体内的表达。采用Western blotting测定体内PD-L1、p-Akt、Akt、p-β-catenin和β-catenin的表达水平，采用免疫荧光检测HCC细胞中β-catenin的核累积，采用免疫组织化学检测鼠异种移植模型中的肿瘤PD-L1和CD8α的表达。结果显示，aucubin能够抑制异种移植HCC小鼠模型的肿瘤生长，但并不影响HCC细胞体外的细胞生存。aucubin通过钝化Akt/β-catenin信号通路显著抑制PD-L1表达，逆转了aucubin介导的肿瘤CD8+T细胞浸润，减轻了aucubin对异种移植小鼠模型的抗肿瘤活性。此外，顺铂能够通过激活Akt/β-catenin信号通路诱导PD-L1表达，但在体外可被aucubin阻断。在异种移植小鼠模型中，顺铂能够诱导PD-L1表达，并减轻肿瘤微环境中CD8+T淋巴细胞的浸润。aucubin不仅消除了顺铂诱导的PD-L1表达，还增强了在HCC小鼠异种移植模型中顺铂的抗肿瘤功效。这表明，aucubin对HCC具有抗肿瘤活性，并通过抑制Akt/β-catenin/PD-L1轴增强顺铂的抗肿瘤活性。Copyright © 2023 Elsevier GmbH. All rights reserved.

Hepatocellular carcinoma (HCC) is a leading cause of cancer-associated mortality in the world. However, the anticancer effects of aucubin against HCC have yet to be reported. Cisplatin often decreased CD8+ tumor-infiltrating lymphocytes in the tumor microenvironment through increasing programmed death-ligand 1 (PD-L1) expression, which seriously affected the prognostic effect of cisplatin in the treatment of patients with HCC. Therefore, it is necessary to identify a novel therapeutic avenue to increase the sensitivity of cisplatin against HCC.This study aims to evaluate the anti-tumor effect of aucubin on HCC, and also to reveal the synergistic effects and mechanism of aucubin and cisplatin against HCC.An H22 xenograft mouse model was established for the in vivo experiments. Cancer cell proliferation was detected by MTT assay. RT-qPCR was performed to analyze CD274 mRNA expression in vitro. Western blotting was employed to determine the expression levels of the PD-L1, p-Akt, Akt, p-β-catenin, and β-catenin in vitro. Immunofluorescence was carried out to examine β-catenin nuclear accumulation in HCC cells. Immunohistochemistry was used to detect tumoral PD-L1 and CD8α expression in xenograft mouse model.Aucubin inhibits tumor growth in a xenograft HCC mouse model, but did not affect HCC cell viability in vitro. Aucubin treatment significantly inhibited PD-L1 expression through inactivating Akt/β-catenin signaling pathway in HCC cells. Overexpression of PD-L1 dramatically reversed aucubin-mediated tumoral CD8+ T cell infiltration and alleviated the antitumor activity of aucubin in xenograft mouse model. Moreover, Cisplatin could induce the expression of PD-L1 through the activation of the Akt/β-catenin signaling pathway in HCC cells, which can be blocked by aucubin in vitro. In xenograft mouse model, cisplatin treatment induced PD-L1 expression and alleviated the infiltration of CD8+ T lymphocytes in the tumor microenvironment. Aucubin not only abrogated cisplatin-induced PD-L1 expression but also enhanced the antitumor efficacy of cisplatin in a mouse xenograft model of HCC.Aucubin exerts antitumor activity against HCC and also enhances the antitumor activity of cisplatin by suppressing the Akt/β-catenin/PD-L1 axis.Copyright © 2023 Elsevier GmbH. All rights reserved.