Gambogic Acid Kills Colorectal Cancer Stem Cells By Inhibiting The EGFR/ERK/ZFP36 Signaling Pathway

Aim: Gambogic acid(GA),a new and high-efficiency broad-spectrum antitumor drug,plays a very important role in alleviating the suffering of the vast number of cancer patients and improving the quality of life of the patients.Whether GA inhibits putative cancer stem cells(CSCs),which are considered to be the major cause of cancer treatment failure,remains largely unknown.This study investigated whether GA inhibits the CSCs of colorectal cancer(CRC)and its possible mechanisms.Methods: In this study,cck-8 assay was used to evaluate the inhibitory effect of gamboxanic acid on colorectal cancer tumor cells after treatment with gamboxanic acid.The percentage of side group cells(SP cells)and the percentage of CD133+CD44+ cells were compared and analyzed by tumor globulogenesis experiment and flow cytometry,and the expression of stem cell-related genes was detected to evaluate the killing effect of banguanic acid on colorectal cancer tumor stem cells.An m RNA microarray was performed to identify the downstream gene affected by GA and rescue assays were performed to further clarify whether the downstream gene is involved in the GA induced decrease of the colorectal cancer tumor stem cells.This study in order to cancer stem cells in vivo and in vitro observed visually,built in under the control of Nanog promoter with Green fluorescent protein(Green fluorescent protein,GFP)and Luciferase(Luciferase,Luc)dual p LV-PNanog-GFP report gene-T2A-Luc slow virus vector,and the virus build colorectal cancer cells,using in vivo bioluminescence imaging technology assessment gambogic acid to a tumor-burdened cancer stem cells in mice.Results: GA significantly reduced tumor sphere formation and the percentages of side population and CD133+CD44+ cells,while also decreasing the expression of stemness and EMT-associated markers in CRC cells in vitro.GA killed tumor stem cells by upregulating the expression of ZFP36,which is dependent on the inactivation of the EGFR/ERK signaling pathway.The re-established GFP+ cells transfected with the pnanog-gfp-t2a-luc gene have the "dry" characteristics of tumor stem cells.The in vivo results showed that GA significantly inhibited tumor growth in nude mice,accompanied by a remarkable reduction in the putative CSC number,based on whole-body bioluminescence imaging.Conclusion: These findings suggest that GA significantly inhibits the self-renewal ability of colorectal cancer tumor stem cells in vivo and in vitro by inhibiting the activation of the EGFR/ERK/ZFP36 signaling pathway,and may be an effective anticancer treatment candidate.