Effect of Palmatine Binding to MYC G-quadruplex on Proliferation and Apoptosis of Colon Cancer Cells and Molecular Mechanism / 中国实验方剂学杂志

ABSTRACT

Objective:To explore whether palmatine interferes with the proliferation and apoptosis of colon cancer HCT116 cells by binding to G-quadruplex in the promoter region of MYC proto-oncogene and its possible molecular mechanism. Method:Fluorescence spectrum was used to analyze the binding ability of palmatine to MYC G-quadruplex. Circular dichroism analysis was conducted to confirm the effect of palmatine on the configuration of MYC G-quadruplex， followed by the prediction of their binding mode based on molecular docking and the localization analysis of palmatine in HCT116 cells under a fluorescence microscope. The effects of palmatine on MYC gene transcription and MYC protein expression were determined by real-time fluorescence quantitative polymerase chain reaction and Western blot， respectively. The effects of palmatine on the viability and apoptosis of HCT116 cells were further assayed by thiazolyl blue tetrazolium bromide （MTT） assay and flow cytometry. Result:As revealed by fluorescence spectrum and molecular docking analysis， palmatine might bind to G-quadruplex of MYC gene through stacking. Circular dichroism analysis showed that palmatine could maintain the parallel configuration of MYC<italic> </italic>G-quadruplex. It was discovered in fluorescence imaging that palmatine was distributed in the nucleus and bond to G-quadruplex of MYC gene. In addition， palmatine inhibited MYC gene transcription， MYC protein expression， as well as the viability of HCT116 cells， and promoted the apoptosis of HCT116 cells. Conclusion:Palmatine is able to bind to MYC G-quadruplex to further inhibit the expression of MYC gene and protein expression， which may be one of the molecular mechanisms of palmatine in suppressing the proliferation of colon cancer HCT116 cells and facilitating their apoptosis.