Extracts of Zuo Jin Wan, a traditional Chinese medicine, phenocopies 5-HTR1D antagonist in attenuating Wnt/β-catenin signaling in colorectal cancer cells

BACKGROUND: In vitro and in vivo studies have shown that Zuo Jin Wan (ZJW), a herbal formula of traditional Chinese medicine (TCM), possessed anticancer properties. However, the underlying mechanism for the action of ZJW remains unclear. Various subtypes of 5-Hydroxytryptamine receptor (5-HTR) have been shown to play a role in carcinogenesis and cancer metastasis. 5-HTR1D, among the subtypes, is highly expressed in colorectal cancer (CRC) cell lines and tissues. The present study aimed at investigating effect of ZJW extracts on the biological function of CRC cells, the expression of 5-HTR1D, and molecules of Wnt/β-catenin signaling pathway. METHODS: In this study, the effect of ZJW extracts on 5-HTR1D expression and Wnt/β-catenin signaling pathway were investigated and contrasted with GR127935 (GR), a known 5-HTR1D antagonist, using the CRC cell line SW403. The cells were respectively treated with GR127935 and different doses of ZJW extracts. Proliferation, apoptosis, migration, and invasion of SW403 cells were compared between ZJW and GR127935 treatments. The expression of 5-HTR1D and signaling molecules involved in the canonic Wnt/β-catenin pathway were determined by Western blot analysis. RESULTS: After ZJW extracts treatment and GR127935 treatment, G1 arrest in cell cycle of SW403 was increased. Cell apoptosis was pronounced, and cell migration and invasion were suppressed. SW403 cells showed a dose-dependently decreased expression of 5-HTR1D, meanwhile, β-catenin level was significantly decreased in nucleus of cells cultured with GR127935. Treatment of ZJW extracts dose-dependently resulted in decreased 5-HTR1D and a concomitant reduction in the Wnt/β-catenin signal transduction, an effect indistinguishable from GR127935 treatment. CONCLUSION: The anticancer activity of ZJW extracts may be partially achieved through attenuation of the 5-HTR1D-Wnt/β-catenin signaling pathway.