Figure 7.

p53-dependent expression of CCL2 in senescent MEFs induces NK cell migration in vitro. (A) MEFs from WT or Trp53^−/− C57BL/6 mice were transduced with an expression vector encoding H-RasV12 or empty vector and selected with puromycin for 8 d. After 8 d, cells were harvested for RNA preparation, and culture supernatants prepared. (B) Ccl2 gene expression is induced by transduction of H-RasV12 in WT MEFs, but not in p53 KO MEFs, as determined by quantification by Q-RT-PCR. mRNA amounts were normalized to the 18S rRNA reference. Student’s t tests were performed comparing p53-off versus p53-on groups. Histograms represent means and standard errors of three independent experiments. (C) CCL2 amounts were measured in cell culture supernatants by ELISA. The values represent the amount of CCL2 in nanograms per 10⁶ cells. Student’s t tests were performed comparing p53-off versus p53-on groups. Histograms represent means and standard errors of three independent experiments. (D) Migration of IL-2–activated NK cells induced by H-RasV12–expressing WT or p53 KO MEF, with or without the addition of CCL2 antibodies or control rabbit IgG. One-way ANOVA and Tukey’s comparison tests were performed on groups. Histograms represent means and standard errors of three independent experiments. *, P < 0.05; **, P < 0.01; ***, P < 0.001.