“Top-down and Bottom-up” cholesterol-depleting biomimetic nanoparticle for enhancing sonodynamic therapy against hepatocellular carcinoma

Cholesterol depletion in tumor cells has been demonstrated as an effective strategy for cancer therapy. Previous studies have shown that cholesterol oxidase (COD) could promote cholesterol consumption. However, these tumor cells typically upregulate cholesterol synthesis as a compensatory mechanism to meet the rapid proliferation demands. To address this issue, we synthesized HM/ZIF-8@COD/IR820 nanoparticle, which simultaneously facilitates cholesterol depletion and inhibits cholesterol synthesis to enhance sonodynamic therapy against hepatocellular carcinoma (HCC). This HM/ZIF-8@COD/IR820 biomimetic nanoparticle was constructed by encapsulating cholesterol oxidase (COD) and the sonosensitizer indocyanine green (IR820) into ZIF-8 nanoparticle, followed by coating with a hybrid cell membrane from tumor cells and erythrocyte membrane. The hybrid membrane provides tumor-targeting capability, enabling HM/ZIF-8@COD/IR820 nanoparticle homes to Hepa1-6 tumor and disassembles in response to the acidic microenvironment and ultrasound stimulation. In vitro and in vivo studies confirmed significant cholesterol depletion and alleviation of hypoxia in Hepa1-6 cells. Upon ultrasound activation, a significant amount of reactive oxygen species (ROS) was generated, thereby enhancing the therapeutic effect on the inoculated tumors. Non-targeted metabolomics analysis further validated the downregulation of cholesterol metabolism-related pathways, which was consistent with the Filipin staining results observed in cellular experiments. Importantly, Hepa1-6 tumor growth was significantly suppressed and the inhibition rate reached 90%. These findings highlight HM/ZIF-8@COD/IR820 as a promising biomimetic nanoparticle orchestrates a two-pronged attack on hepatocellular carcinoma cholesterol metabolism: top-down suppression of cholesterol biosynthetic pathways, and bottom-up elimination of existing cholesterol stores, yielding outstanding therapeutic effects against HCC. • “Top-down and Bottom-up” Cholesterol-depleting Biomimetic Nanoparticle HM/ZIF-8@COD/IR820 was developed for enhancing sonodynamic therapy against hepatocellular carcinoma. • HM/ZIF-8@COD/IR820 nanoparticle was able to target to tumor tissues and degradate under the acid surroundings of the tumor, which facilitated the release of Zn 2+ and COD. • The accumulation of Zn 2+ and the release of COD can inhibit cholesterol from “Top-down” synthesis and promote cholesterol depletion from “Bottom-up”, that co-down regulated cholesterol related metabolism. • The depletion of cholesterol increased the expression of the pro-apoptotic protein Bax and decreased the anti-apoptotic protein Bcl-2 to promote Hepa1-6 tumor cell apoptosis. • H 2 O 2 generated by COD could be further catalyzed by HM/ZIF-8@COD/IR820 to produce O 2 , which alleviated cellular hypoxia and enhanced the sonodynamic therapy.