Platinum-Metformin Conjugates Acting as Promising PD-L1 Inhibitors through the AMP-Activated Protein Kinase Mediated Lysosomal Degradation Pathway.

With the development of metalloimmunology, the potential of platinum drugs in cancer immunotherapy has attracted extensive attention. Although immunochemotherapy combining PD-1/PD-L1 antibodies with platinum drugs has achieved great success in the clinic, combination therapy commonly brings new problems. Herein, we have developed a platinum-metformin conjugate as a promising alternative to antibody-based PD-L1 inhibitors, not only disrupting PD-1/PD-L1 axis on cell surface but also down-regulating the total PD-L1 levels in non-small cell lung cancer (NSCLC) cells comprehensively, thus achieving highly efficient immunochemotherapy by a single small molecule. Mechanism studies demonstrate that Pt-metformin conjugate can selectively accumulate in lysosomes, promote lysosomal-dependent PD-L1 degradation via the AMPK-TFEB pathway, and modulate the upstream regulatory proteins related to PD-L1 expression (e.g. HIF-1α and NF-κB), eventually decreasing the total abundance of PD-L1 in NSCLC, overcoming tumor hypoxia, and activating anti-tumor immunity in vivo. This work suggests an AMPK-mediated lysosomal degradation pathway of PD-L1 for the first time and provides a unique design perspective for the development of novel platinum drugs for immunochemotherapy.

A Golgi-Targeted Platinum Complex Plays a Dual Role in Autophagy Regulation for Highly Efficient Cancer Therapy.

Regulating autophagy to control the homeostatic recycling process of cancer cells is a promising anticancer strategy. Golgi apparatus is a substrate of autophagy but the Golgi-autophagy (Golgiphagy) mediated antitumor pathway is rarely reported. Herein, we have developed a novel Golgi-targeted platinum (II) complex Pt3, which is ca. 20 times more cytotoxic to lung carcinoma than cisplatin and can completely eliminate tumors after intratumoral administration in vivo. Its nano-encapsulated system for tail vein administration also features a good anti-tumor effect. Mechanism studies indicate that Pt3 induces substantial Golgi stress, indicated by the fragmentation of Golgi structure, down-regulation of Golgi proteins (GM130, GRASP65/55), loss of Golgi-dependent transport and glycosylation. This triggers Golgiphagy but blocks the subsequent fusion of autophagosomes with lysosomes, that is a dual role in autophagy regulation, resulting in loss of proteostasis and apoptotic cell death. As far as we know, Pt3 is the first Golgi-targeted Pt complex that can trigger Golgi stress-mediated dual-regulation of autophagic flux and autophagy-apoptosis crosstalk for highly efficient cancer therapy.

A platinum-ruthenium hybrid prodrug with multi-enzymatic activities for chemo-catalytic therapy of hypoxic tumors.

Regulation of tumor hypoxia and redox homeostasis is a promising strategy for cancer therapy. Nanocatalytic medicine has played more and more important roles in this field because it can cleverly convert the efficiency and selectivity of catalysis into high therapeutic efficiency. Herein, we developed a platinum(iv)-ruthenium hybrid prodrug, named as Pt-Ru, for efficient chemo-catalytic synergistic therapy of hypoxic tumors. The ruthenium hybridization endowed the Pt(iv) prodrug with multi-enzyme catalytic activity, that is, mimicking catalase (CAT) to generate O2 in situ, mimicking peroxidase (POD) to produce reactive oxygen species, and mimicking glutathione peroxidase (GPx) to deplete GSH, thus effectively overcoming tumor hypoxia and cisplatin resistance. As a result, Pt-Ru treatment led to a superior anticancer efficacy to cisplatin both in vitro and in vivo. This work suggested redox homeostasis regulation as a tantalizing angle for developing the next generation of platinum drugs.