Novel TLR2 agonist Amuc_C derived from exhibits potent anti-tumor activity in colorectal cancers.

Colorectal cancer (CRC) is a challenging disease. Recent studies have gradually emphasized the development of novel immunotherapies rather than traditional treatments. Toll-like receptor (TLR) agonists are critical in innate immune responses to orchestrate anti-tumor efficacies, which are attributed to their aptitude to stimulate antigen-presenting cells (APCs) and thus activate tumor-specific T cells. Although several TLR agonists have been proposed for treating tumors, their therapeutic efficacy remains controversial. Therefore, the current study aimed to develop a novel TLR2 agonist, Amuc_1100 C-terminal (Amuc_C), a purified membrane protein from (), and evaluate its anti-tumor properties. Herein, a murine CRC model, CT26, was employed. Tumor-bearing mice received intertumoral treatment with Amuc_C. The anti-tumor effects were determined by flow cytometry, cytokine enzyme-linked immunosorbent assay (ELISA), and immunofluorescence assays. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was then employed to uncover the potent mechanisms. Amuc_C significantly increased the amounts of tumor-infiltrating lymphocytes and systemic immune cells, especially cytotoxic T cells, M1 macrophages, and type 1 dendritic cells. Furthermore, Amuc_C triggered IL-1β, TNF-α, and IFN-γ productions, significantly decreasing tumor growth, and prolonged overall survival. The immunotherapeutic mechanisms revealed by proteomics data were related to the activation of immune responses, the induction of cell cycle arrest, and the inhibition of cell proliferative signaling pathways. In summary, the current study has demonstrated that administration of Amuc_C improves the APCs and escalates adaptive anti-tumor immunity. With the demand for effective anti-tumor treatments, our results provide a compelling proof-of-concept of a TLR2 agonist for cancer immunotherapy.