Abstract
Background: Colorectal cancer (CRC) is a global health burden characterized by significant morbidity and mortality rates. While current therapeutic strategies, including surgical intervention and adjuvant chemotherapy, have shown moderate success, patients with advanced-stage CRC frequently encounter substantial therapeutic obstacles, primarily stemming from acquired drug resistance and tumor immune evasion. Emerging research suggests that phytochemicals are promising therapeutic candidates due to their pleiotropic regulatory capacities, particularly their capability to modulate immune checkpoint inhibitor (ICI) resistance pathways. These bioactive compounds could be used to develop novel therapeutic approaches based on the epigenetic reprogramming of tumor cells and the remodeling of the metabolism-immune crosstalk axis in the tumor microenvironment (TME). This study aimed to investigate the effects and underlying mechanisms of andrographolide in targeting mitochondrial function and remodeling the tumor immune microenvironment in CRC. Methods: This study used Cell Counting Kit-8, live and dead cell staining, immunofluorescence, western blotting, enzyme-linked immunosorbent assay, flow analysis (using CT26 cells), and mouse xenografts to explore the anti-tumor effect and mechanism of andrographolide, a natural product, in CRC. Results: By targeting the voltage-dependent anion channel (VDAC) protein, andrographolide affects the mitochondrial membrane potential of CRC cells, activates the natural immune pathway of cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) during tumor proliferation, and reshapes the TME of CRC by recruiting dendric cells, CD4+ T cells, and CD8+ T cells, and reducing immunosuppressive regulatory T cells. Conclusions: This study revealed the anti-tumor effect of andrographolide in CRC and the mechanism of immune metabolism regulation. Our findings provide a theoretical basis for the application of natural products in CRC immunotherapy.