Chaihu Shugan San formula alleviates psychological stress-induced ovarian cancer susceptibility by inhibiting ubiquitin degradation of TLR2 in macrophages

Background

Psychological stress is increasingly recognized for its potential to expedite tumor growth and enhance cancer susceptibility, yet the specific mechanisms at play remain largely unclear. Traditional Chinese Medicine (TCM) formulation, Chaihu Shugan San formula (CHSGS), known for its efficacy in alleviating liver Qi stagnation syndrome, has exhibited therapeutic benefits in cancer management. Macrophages are key immune cells in the tumor microenvironment, and their phagocytic and clearance functions for tumor cells play a crucial role in the occurrence and progression of tumors. In previous studies, we have found that macrophage phagocytosis is closely related to psychological stress-induced tumor susceptibility. However, the detailed comprehension of CHSGS’s pharmacological mechanism and bioactive ingredients that are pertinent to its clinical use in treating ovarian cancer exacerbated by stress remains an open question in the field.

Purpose

This study aimed to elucidate the impact and mechanism of CHSGS in modulating psychosocial stress-associated ovarian cancer susceptibility, while also pinpointing its primary bioactive constituents responsible for mediating antitumor effects in ovarian cancer.

Methods

Initially, the relationship between the macrophage phagocytosis impaired by psychological stress and the ubiquitin degradation of Toll-like receptor 2 (TLR2) using flow cytometry and co-immunoprecipitation (CO-IP). The therapeutic efficacy and mechanism of CHSGS on ovarian cancer were evaluated by the tumor volume, tumor weight, macrophage phagocytosis and CO-IP analysis. Then, the impact of the key active ingredients in CHSGS on the of TLR2/MARCH6 interaction was further elucidated through molecular docking analysis, assessment of cell viability, phagocytosis of macrophage, CO-IP analysis and microscale thermophoresis (MST) assays. Finally, the therapeutic efficacy and mechanisms of baicalin in ovarian cancer were evaluated based on the results of tumor volume, tumor weight, and macrophage phagocytosis in vivo.

Results

Our findings indicate that psychosocial stress promotes lipid peroxidation in macrophages, which in turn recruits the E3 ubiquitin ligase MARCH6 and triggers the proteasome-dependent degradation of TLR2, thereby impairing macrophage phagocytic function and increasing ovarian cancer susceptibility. CHSGS intervention effectively disrupted the binding relationship between TLR2 and MARCH6, markedly diminishing TLR2 degradation and consequently restoring the macrophage's phagocytic capability. Baicalin is a promising active ingredient of CHSGS that can alleviate stress-induced impairment of macrophage phagocytosis by inhibiting the binding of TLR2/MARCH6.

Conclusion

Our results reveal that stress enhances susceptibility to ovarian cancer via ubiquitin degradation of TLR2 in macrophages, and indicate that the TLR2/MARCH6 complex could serve as a promising therapeutic target for CHSGS in the treating ovarian cancer.