Xianlian Jiedu Decoction induces apoptosis in colorectal cancer via modulation of sphingosine-1-phosphate-dependent JNK/p38 MAPK signaling.

The Xianlian Jiedu Decoction (XLJDD) is a traditional Chinese medicinal formulation commonly used in the clinical treatment of colorectal cancer (CRC).

However, the underlying mechanisms of its therapeutic effects remain to be fully elucidated.

This study aimed to investigate the molecular targets and signaling pathways by which the traditional Chinese medicine compound XLJDD exerted therapeutic effects on CRC. XLJDD drug-containing serum was prepared and applied to CRC cell lines (HCT116 and HT29), and the optimal concentration was determined using the CCK-8 assay. Apoptosis was evaluated using Hoechst 33342 staining, TUNEL assay, JC-1 assay, and Annexin V-FITC/PI flow cytometry respectively. S1P secretion levels in cell culture supernatants were measured by ELISA.

Subcutaneous CT26 mouse tumor models were established and intragastrically administered with the prepared XLJDD decoction. Tumor growth curves were monitored, and final tumor weights were assessed. The tumor tissues were stained with hematoxylin and eosin (H&E) to observe the histopathological changes, while protein expression of Ki-67, Bcl-2, and Caspase-3 was evaluated by immunohistochemistry (IHC). Bulk RNA-seq coupled with transcriptome and GO/KEGG enrichment analyses revealed alterations in key signaling pathways, which were further validated at the protein level by Western blotting.

Collectively, these experiments elucidated that XLJDD exerted anti-colorectal cancer effects by regulating MAPK and related apoptotic signaling pathways. XLJDD drug-containing serum significantly suppressed CRC cell viability and promoted apoptosis in a dose-dependent manner. ELISA results showed that XLJDD drug-containing serum reduced sphingosine-1-phosphate (S1P) levels in CRC cell culture supernatants. In vivo experiments demonstrated that XLJDD-treated tumor-bearing mice exhibited delayed tumor growth, reduced tumor weight, and improved tumor tissue morphology.

Moreover, XLJDD suppressed pro-tumorigenic activity of S1P in a dose-dependent manner. Immunohistochemistry and western blot analysis indicated that XLJDD downregulated Ki-67 and Bcl-2 expression, promoted Caspase-3 activation, and inhibited the JNK/p38 MAPK signaling pathway. Bulk RNA-seq transcriptome and pathway enrichment analyses further confirmed that XLJDD suppressed tumor progression by regulating the S1P-mediated JNK/p38 MAPK pathway, providing experimental evidence to support its clinical application. The XLJDD suppresses the development and progression of CRC by downregulating S1P levels, modulating the JNK/p38 MAPK signaling pathway, enhancing tumor cell apoptosis.