Résumé
AIM:To investigate the stemness of mouse triple-negative breast cancer (TNBC) 4T1 cells induced by doxorubicin (DOX) and the underlying mechanism.METHODS:The 4T1 cells and MDA-MB-468 cells were treated with DOX at different concentrations (0, 0.05, 0.1 and 0.5μmol/L) for 24 h, and the shape and viability of the cells were observed.The concentration of DOX at 0.1μmol/L was chosen as the optimal concentration for the following experiments.The 4T1 cells and MDA-MB-468 cells resistant to DOX were established by continuous stimulation with DOX for 4 weeks, and named as 4T1-DOX and MDA-MB-468-DOX.Sphere formation assay was used to detect the stemness of 4T1cells and MDA-MB-468 cells.The expression of CD133 was observed by immunofluorescence staining.The expression of CD44 was analyzed by flow cytometry.The protein levels of Stat3, phosphorylated Stat3 (p-Stat3) and Oct-4 were determined by Western blot.RESULTS:The sphere formation ability of the 4T1-DOX cells was stronger than that of the 4T1control cells.The 4T1-DOX cells expressed high levels of the stemness markers CD133 and CD44 as compared with the 4 T1 cells (P<0.05).Furthermore, the 4T1-DOX cells exhibited enhanced activation of Stat3 (p-Stat3) and increased expression of Oct-4 (P<0.05) , while the expression of total Stat3 had no obvious variation.In addition, when activation of Stat3 was inhibited by WP1066, the protein levels of p-Stat3, Oct-4 and CD44 were down-regulated (P<0.05).Furthermore, inhibition of Stat3 phosphorylation reduced the sphere formation ability of the 4T1-DOX cells (P<0.05).CONCLUSION:DOX induces the stemness of mouse TNBC 4T1 cells through Stat3-Oct-4 signaling pathway.