Figure 1: p53 regulates the fraction of mucoepidermoid carcinoma cancer stem cells in vitro.

A, Western blot showing baseline protein levels for MDM2, p53, p21 and Bmi-1 in human mucoepidermoid carcinoma (MEC) cell lines (UM-HMC-1, UM-HMC-3A, UM-HMC-3B). B, Western blots of MEC cells treated for 24 and 48 hours with MI-773, a 1^st generation small molecule inhibitor of the MDM2-p53 interaction. C, Graph depicting the fraction of cancer stem cells (ALDH^highCD44^high) measured by flow cytometry of MEC cell lines treated with MI-773 for 72 hours. D, Western blots verifying the impact on p53 protein expression in cells transduced with shRNA-p53 sequences. E, Graphs depicting cell density measurements of p53-silenced or vector control cells treated with MI-773 for 48 hours. Data was normalized against vehicle control. Graph inserts: half-maximal inhibitory concentrations (IC₅₀) for MI-773. F, Western blots for MDM2, p53 and p21 of p53-silenced and control cells treated with MI-773 for 48 hours. G, Graph summarizing flow cytometry analysis of the ALDH^highCD44^high cell fraction in vector control and p53-silenced cells treated with MI-773 for 72 hours. All results are representative of at least two independent experiments. Data was analyzed by two-tailed student’s t-test (α=0.05) in two group comparisons or one-way ANOVA followed by post-hoc Tukey (α=0.05) for multiple group comparisons. * P<0.05, ** P<0.001, *** P<0.0001, ns=not significant.