Indole-3-Acetic Acid-Derived Carbon Dots Inhibit the Malignant Progression of Colorectal Cancer via Negative Regulation of the MAPK/ERK Pathway

Abstract

Objective: Colorectal cancer treatment faces challenges such as drug resistance and toxicity, highlighting the need for novel and safer therapeutic strategies. This study utilized indole-3-acetic acid (IAA), a gut microbial metabolite, as a precursor to synthesize IAA-derived carbon dots (IAA-CDs) via hydrothermal method, and evaluated their anti-colorectal cancer activity and underlying mechanisms. Methods: IAA-CDs were prepared via a one-pot hydrothermal method (200 ℃, 9 h). Physicochemical properties were characterized by transmission electron microscopy and UV-Vis spectroscopy. Human colorectal cancer HCT116 cells were used as a model. CCK-8 and wound healing assays were employed to assess the effects of IAA-CDs on proliferation and migration. Transcriptome sequencing (RNA-seq) was performed to analyze differentially expressed genes and enriched pathways. A HCT116 tumor-bearing nude mouse model was established, and IAA-CDs were administered orally (10 mg/kg, every other day for 14 days) to evaluate in vivo anti-tumor efficacy, as well as liver and kidney function and histological safety of major organs. Results: IAA-CDs exhibited uniform spherical morphology (particle size 1.88±0.37 nm) with typical optical characteristics of carbon dots. In vitro experiments demonstrated that IAA-CDs inhibited human colorectal cancer HCT116 cell proliferation in a dose-dependent manner and significantly suppressed wound closure in the scratch assay (P < 0.05). RNA-seq revealed 55 upregulated and 28 downregulated genes, enriched in negative regulation of MAPK cascade, negative regulation of ERK cascade, retinol/retinoic acid metabolism, tryptophan metabolism, IL-17 signaling, and cAMP signaling pathways. In vivo, IAA-CDs treatment significantly attenuated tumor volume growth and reduced tumor weight compared with the control group (P < 0.05). Serum liver and kidney function markers (ALT, AST, CREA, UREA) and HE staining of major organs showed no significant abnormalities (P > 0.05). Conclusion: IAA-CDs suppress the growth and migration of HCT116 cells both in vitro and in vivo, while exhibiting a favorable biosafety profile. The mechanism may involve negative regulation of MAPK/ERK proliferation signaling and reprogramming of retinol/retinoic acid and tryptophan metabolism. This study provides a new strategy for utilizing gut metabolites via nanotransformation for colorectal cancer therapy.