ABSTRACT
Cancer stem cells (CSCs) are an important therapeutic target. The therapeutic agents targeting CSCs should lead to improved clinical outcomes. Here we have demonstrated the CSC-suppressing activity of pongol methyl ether (PME), a pure compound from Millettia erythrocalyx. METHODS: CSC-suppressing effects were evaluated by spheroid formation assay and detection of CSC markers. The related CSC cell signals were evaluated by Western blot, immunofluorescence and molecular docking analysis. Proteins affected by PME treatment were subjected to bioinformatic analysis. Protein-protein interaction (PPI) networks were constructed by the Search Tool for Interactions of Chemicals (STITCH). The Kyoto Encyclopedia of Genes and Genomes (KEGG) mapper were used to confirm the underlying pathways. RESULTS: PME (5-25 µM) significantly suppressed the ability of lung cancer cells to form colonies, grow in an anchorage-independent manner and generate tumour spheroids. PME at 25 µM significantly decreased the CSC markers (CD133 and ALDH1A1) and pluripotent transcription factors (Oct4 and Nanog). Akt, the key upstream signal of CSC control, was significantly decreased by the PME treatment. The molecular docking indicated that PME was bound to Akt-1 with a binding affinity of -9.2 kcal/mol greater than the Akt-1 inhibitor (reference compound; CQW). The STITCH network identified a total of 15 proteins interacted in PPI networks, and Akt-1 was identified as a central protein. The KEGG mapper indicated that the selected CSC markers were mostly involved in the 'signalling pathways regulating pluripotency of stem cells' pathway map and Akt, Oct4 and Nanog were the regulatory proteins in the dominant pathway. In addition, PME (10-25 µM) can suppress spheroid formation and reduce CSC-specific marker expression in patient-derived primary lung cancer cells. CONCLUSIONS: Our study revealed a novel pharmacological effect and the underlying mechanism of PME that can attenuate CSC phenotypes in lung cancer cells and may be developed for lung cancer therapy.
ABSTRACT
BACKGROUND/AIM: Integrin-targeting compounds have shown clinically significant benefits in many patients. Here, we examined the activity of millettocalyxin B, extracted from the stem bark of Millettia erythrocalyx, in lung cancer cells. MATERIALS AND METHODS: The viability of human lung cancer cells was investigated by the 3-(4,5-dimethylthiazol-2-yl)-2,5diphenyl tetrazoliumbromide (MTT) assay. Migration and invasion assays were performed. Phalloidin-rhodamine staining was used to determine the formation of filopodia. Western blot analysis and immunofluorescence staining were used to identify the signaling proteins involved in migration regulation. RESULTS: Non-toxic concentrations (0-25 µM) of millettocalyxin B reduced migration and invasion of lung cancer A549 cells. Filopodia were significantly reduced in millettocalyxin B-treated cells. The migration regulatory proteins including integrin α5, active FAK, active Akt, and Cdc42 were significantly decreased in Millettocalyxin B-treated cells. CONCLUSION: Our findings revealed a novel anti-migration and anti-invasion effects and the underlying mechanism of millettocalyxin B, which may be exploited for cancer treatment.
