Cascade nanozymes based on the “butterfly effect” for enhanced starvation therapy through the regulation of autophagy

Although tumor starvation therapy has been proven to be an excellent method for tumor therapy, its efficiency may be weakened by autophagy, a self-protection mechanism exerted by tumors under starvation stress. Interestingly, over-activated autophagy not only improves the efficacy of starvation therapy, but also induces autophagic death. Herein, we report cascade nanozymes for enhanced starvation therapy by inducing over-activated autophagy. First, glucose oxidase (GOx) modified metal-organic frameworks (NH2-MIL88, MOF) were constructed (MOF-GOx). After loading with curcumin (Cur), Cur@MOF-GOx was further decorated with tumor-targeting hyaluronic acid (HA) to obtain Cur@MOF-GOx/HA nanozymes. GOx can catalyze glucose into H2O2 and gluconic acid, which not only leads to tumor starvation, but also provides reactants for the Fenton reaction mediated by the MOF to generate hydroxyl radicals (˙OH) for chemo-dynamic therapy. Most importantly, protective autophagy caused by tumor starvation can be over-activated by Cur to convert autophagy from pro-survival to pro-death, realizing augmented anticancer therapy efficacy. With these cascade reactions, the synergistic action of starvation, autophagy and chemo-dynamic therapy was realized. Generally, the introduction of Cur@MOF-GOx/HA into tumor cells leads to a "butterfly effect", which induces enhanced starvation therapy through subsequent autophagic cell death to completely break the self-protective mechanism of cancer cells, and generate ˙OH for chemo-dynamic therapy. Precise design allows for the use of cascade nanozymes to realize efficient cancer treatment and restrain metastasis.