Pseudostellaria heterophylla (Miq.) Pax, a traditional folk medicine, ameliorates colorectal cancer by remodeling the tumor immune microenvironment

Ethnopharmacological relevance: Pseudostellaria heterophylla (Miq.) Pax (PH) is a traditional folk medicine, which is widely used clinically for digestive system tumors such as esophageal, gastric, colorectal, and liver cancers. The anti-tumor effect and mechanism of PH in colorectal Cancer (CRC) deserves further study.

Aim of the study: The objective of this study is to examine the effects and the underlying mechanisms of aqueous extract of Pseudostellaria heterophylla (Miq.) Pax (AEPH) in the CRC.

Materials and methods: The components of AEPH were fully resolved using ultra-high-performance liquid chromatography coupled with quadrupole-orbitrap high-resolution mass spectrometry (UHPLC-Q/Orbitrap HRMS). The effect of AEPH was evaluated in vivo using the MC38 mouse colon Cancer model, and its impact on the tumor microenvironment was analyzed by flow cytometry. Bioinformatics analysis, combined with transcriptome Sequencing, was utilized to further investigate the signaling pathways of AEPH in CRC cells.

Results: A mass spectrometry analysis identified 371 compounds in AEPH, each with a comprehensive score exceeding 60. In vivo experiments demonstrated that AEPH suppressed the growth of MC38 tumors without exhibiting obvious toxicity. Mechanistic studies revealed that AEPH inhibited the JNK signaling pathway, reduced Chemokine C-C Motif Chemokine Ligand 5 (CCL5) secreted by CRC cells, hindered the recruitment of M2-like tumor-associated macrophages (TAMs), promoted the infiltration of IFN-γ⁺ CD8⁺ T cells, and improved the immunosuppressive microenvironment of CRC.

Conclusion: AEPH contributes to the remodeling of the tumor immune microenvironment primarily through the inhibition of CCL5-mediated recruitment of M2-like TAMs. The findings of this study offer a novel perspective on the potential development of AEPH as a therapeutic agent for CRC.

Chemokine C-C Motif chemokine ligand 5; Colorectal cancer; Pseudostellaria heterophylla (Miq.) pax; Tumor immune microenvironment; Tumor-associated macrophages.