Aucubin enhances the antitumor activity of cisplatin through the inhibition of PD-L1 expression in hepatocellular carcinoma.

BACKGROUND: 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. PURPOSE: 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. STUDY DESIGN AND METHODS: 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-ß-catenin, and ß-catenin in vitro. Immunofluorescence was carried out to examine ß-catenin nuclear accumulation in HCC cells. Immunohistochemistry was used to detect tumoral PD-L1 and CD8α expression in xenograft mouse model. RESULTS: 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/ß-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/ß-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. CONCLUSION: Aucubin exerts antitumor activity against HCC and also enhances the antitumor activity of cisplatin by suppressing the Akt/ß-catenin/PD-L1 axis.

Antihypertensive Activity of Eucommia Ulmoides Oliv: Male Flower Extract in Spontaneously Hypertensive Rats.

Eucommia ulmoides Oliv. is a traditional medical plant in Asia; however, it is still unknown whether Eucommia male flowers have an antihypertensive activity. In this study, we found that the aqueous extract of Eucommia ulmoides Oliv. male flowers can lower the blood pressure of SHR in a dose-dependent manner. Mechanistic studies suggested that the aqueous extract of male flowers can promote the mRNA and protein expressions of ACE2 in the kidney of SHR. ELISA assay showed that the plasma levels of ANG II was decreased, while ANG-(1-7) was increased in SHR treated with the aqueous extract of male flowers. ACE2 inhibitor DX600 can reverse the aqueous extract of Eucommia ulmoides Oliv. male flower-induced downregulation of Ang II and upregulation of Ang-(1-7), as well as the reduction of blood pressure in SHR. Moreover, Ang-(1-7)-Mas receptor antagonist A-779 abolished the antihypertensive effects of the aqueous extract of Eucommia ulmoides Oliv. male flower in SHR. The aqueous extract of Eucommia ulmoides Oliv. male flowers exhibited an antihypertensive action through the activation of ACE2-Ang-(1-7)-Mas signaling pathways in spontaneously hypertensive rats.