Figure 6

R2 significantly decreased tumor growth and activated p21 in HCT116 p53 ⁺ / ⁺ but not in HCT116 53 ^- / ^- tumor xenografts in vivo. A. Upper panel: HCT116 p53⁺/⁺ and HCT116 p53^-/^- cells were injected subcutaneously into the right and left leg flanks respectively. The control untreated mice were injected subcutaneously with 1xPBS. The treated group of mice was injected subcutaneously with 60 mg/kg of R2. In the case of R2-treated HCT116p53⁺/⁺ xenografts tumor volume decreased significantly (Student’s t-test, p<0.05, marked by asterisk), while HCT116p53^-/^- xenograft tumor volume was not decreased in p53^-/^- xenografts. Lower panel: R2 caused activation of p21 in HCT116p53⁺/⁺ tumors, but not in HCT116p53^-/^- xenograft tumors. R2 increased p21 expression and activated caspase-3 in HCT116 p53⁺/⁺ xenografts but not in HCT116 p53^-/^- xenografts. B. R2 disrupted FAK and p53 complex in HCT116p53⁺/⁺ xenografts. R2 disrupted FAK and p53 complex in HCT116 p53⁺/⁺ xenografts. We immunoprecipitated p53 in tumor xenograft samples and performed Western blotting with FAK antibody in untreated and R2-treated tumor xenografts. The complex of FAK and p53 was present in untreated xenografts, while the complex was not detected in R2-treated xenografts. Two representative tumors are shown for each group.