Figure 6. Cav1-deficient stromal fibroblasts mediated radiation resistance.

(A) Co-implantations of PC3 tumor cells (0.5*10⁶ cells each) after Cav1 silencing [shCav1, PC3(−)] in combination HS5 Cav1-silenced fibroblasts [shCav1, HS5(−)] (0.5*10⁶ cells each) or control fibroblasts [shCtrl, HS5(+)] were performed by subcutaneously transplanted onto the hind limb of NMRI nude mice. One set of animals from each group received a single radiation dose of 10 Gy to the tumor after manifestation of the tumor at day 3. Tumor volume was determined at indicated time points using a sliding caliper (left diagram). Data are presented as mean ± SEM from 3 independent experiments (37 mice in total: PC3(−)HS5(+) 0 Gy n = 10; PC3(−)HS5(+) 10 Gy n = 8; PC3(−)HS5(−) 0 Gy n = 9; PC3(−)HS5(−) 10 Gy n = 10). Tumor growth and respective computed median growth delay was determined as time (days) until a four-fold tumor volume was reached (right diagram). *p < 0.05, ***p < 0.005 by one-way ANOVA followed by post-hoc Tukey’s test. (B–D) Expression levels of indicated proteins were analyzed in whole protein lysates using Western blot analysis. Representative blots are shown. For quantification blots were analyzed by densitometry and the respective signal was related to beta-actin (at least n = 4 for each group). When the Cav1 phosphorylation status was determined the obtained phospho-specific signal was related to the signal of the total Cav1 protein [phCav1/Cav1]. P-values were indicated: *p < 0.05, **p ≤ 0.01, ***p ≤ 0.005, ****P ≤ 0.001 by one-way ANOVA followed by post-hoc Tukey test.