Figure 3. Senescence promotes tumor metastasis and relapse.

(A–C) fLUC-MMTV-PyMT cells (10⁵) were injected into the mammary fat pad of p16-3MR female mice and treated with PBS or Doxo (10 mg/kg). 7–10 days later, the animals were injected with PBS or 25 mg/kg GCV for 5 days (daily i.p. injections). (A) Mice were followed for survival. N=5. (B) 7, 14 and 21 days after cancer cell injections, Doxo-treated mice were given D-Luciferin and luminescence was measured using the Xenogen Imaging system. Luminescence identified fLUC-MMTV-PyMT cells. At 21 days, the number of mice with metastasis was evaluated based on luminescence of fLUC-MMTV-PyMT cells (C). (D–G) fLUC-MMTV-PyMT cells (10⁵) were injected into the mammary fat pad of p16-3MR mice. 10 days later, primary tumors were surgically removed and mice were treated with Doxo (10 mg/kg), then, 3 days later, with PBS or 25 mg/kg GCV for 5 days (daily i.p. injections). (D) Mice were given D-Luciferin and luminescence of the primary tumors was measured and quantified at the indicated time points using the Xenogen Imaging system. Luminescence identified fLUC-MMTV-PyMT cells. N=8. (E) 4 weeks after Doxo treatment, metastasis was evaluated based on luminescence signals from lungs, as described in D. N=8. (F–G) Lungs were excised and luminescence was measured to quantify the number of metastasis using the Xenogen Imaging system. N=6 for Doxo + PBS, N=3 for Doxo + GCV. Data are means ± SEMs. *p<0.05; **p<0.01; ***p<0.001.