Cantharidin And Norcantharidin Enhance Drug Sensitivity By Impairing Stemness Of Pancreatic Cancer Cells

Objective:Increasing evidence suggests that tumors are composed of a heterogeneous cell population with a small subset of cancer stem cells(CSCs)that sustain tumor formation and growth,and are hypothesized to account for therapeutic resistance.Based on the expression of the surface markers,CD44,CD24and EPCAM,putative CSCs have also been identifed in pancreatic cancers.It has been well established that aberrant activation of?-catenin signaling pathway may contribute to the maintenance of CSCs.Cantharidin,which targets protein phophatase 2A(PP2A),is an active constituent of mylabris,a traditional Chinese medicine.In our previous studies,we demonstrated that cantharidin treatment induced phosphorylation of?-catenin,leading to repression on?-catenin pathway.Therefore,in the present study,we investigated whether cantharidin and its derivant,norcantharidin,could repress the stemness of pancreatic cancer cells through repression on?-catenin pathway.In the present study,we investigated whether cantharidin and norcantharidin repressed stemness of pancreatic cancer cells in a?-catenin pathway-dependent manner,providing a basis for further development of cantharidin as a promising therapeutic agent for the treatment of pancreatic cancer.Methods:1.Proliferation of PANC-1 and CFPAC-1 cells treatment with PP2A inhibitors(cantharidin and norcantharidin)were investigated by MTT assay.2.The clone formation ability of PANC-1 and CFPAC-1 cells treatment with PP2A inhibitors(cantharidin and norcantharidin)were investigated by plate clone formation assay.3.Microarray analyses were performed to determine the related genes expression of stem cell in mRNA level.4.The protein expression levels of CD24,CD44 and EPCAM in pancreatic cancer cells was measured by using flow cytometry.5.The CD44~+/CD24~+/EPCAM~+proportion in pancreatic cancer cells was measured by using flow cytometry.6.Gene expression at the mRNA of CD24,CD44 and EPCAM in pancreatic cancer cells was measured by using real-time PCR.Results:1.Cantharidin and norcantharidin repressed pancreatic cancer cell growth.2.Cantharidin and norcantharidin inhibited the clone formation abilit3.Cantharidin and norcantharidin repressed CD24,CD44 and EPCAM expression at mRNA levels.4.Cantharidin and norcantharidin repressed CD24,CD44 and EPCAM expression at protein levels.5.Cantharidin and norcantharidin repressed CD44~+/CD24~+/EPCAM~+proportion in pancreatic cancer cells.6.Cantharidin and norcantharidin repressed expression of CD24,CD44 and EPCAM?-catenin pathway-dependently.7.Cantharidin and norcantharidin strengthened cytotoxicity of gemcitabine and erlotinib.Conclusion:Our present results indicated for the first time that PP2A inhibitors(cantharidin and norcantharidin)can repress the stemness of pancreatic cancer cells via?-catenin pathway,and strengthen the cytotoxicity of gemcitabine and erlotinib.Our findings may shed a new treatment of pancreatic cancer.