Engineering a Self-Lysing Attenuated Salmonella Typhimurium with Flagellar Display of RGD4C for Targeted Tumor...

Conventional cancer therapies, such as radiotherapy, chemotherapy, and surgery, exhibit notable limitations in the treatment of solid tumors. Bacteria-mediated tumor therapy has been proven to be effective in clinical studies and is regarded as a promising strategy for tumor treatment. Salmonella, as a facultative anaerobic bacterium, can preferentially colonize tumors and remodel the tumor microenvironment to activate the antitumor immune response of the host. Genetically engineered Salmonella possess excellent tumor-targeting capacity, controllability, and adaptability to diverse therapeutic demands, making them ideal carriers for drug delivery. In this study, RGD4C short peptide was displayed on the constitutively expressed flagella of attenuated Salmonella enterica serovar Typhimurium to develop a vector with enhanced motility, tumor-targeting ability, and capacity for deep colonization in hypoxic tumor regions. Meanwhile, to enable Salmonella to exert antitumor activity safely and effectively, a regulated lysis system based on the novel lysing protein M4lys encoded by phage was applied to lyse Salmonella peptidoglycan to release endogenous and exogenous antitumor molecules, and a balanced lethal vector-host system was used to deliver exogenous antitumor molecules (e.g., l-asparaginase, L-ASNase). Collectively, a novel genetically engineered live Salmonella was successfully constructed, which could deliver exogenous antitumor molecules to exert antitumor effects for tumor therapy.