Figure 2. Enriched environment reduced tumor growth in syngeneic mouse models of pancreatic cancer.

Mice were housed in the enriched environment (EE) or the standard environment (SE) for 3 weeks and then subcutaneously injected with Panc02 cells (6 × 10⁵ cells per mouse). (A) Growth curve based on the tumor volumes monitored once a week after implantation. (B) Subcutaneous Panc02 tumors dissected at the time of sacrifice. (C) Comparison of tumor weights between the SE and EE mice. EE housing significantly inhibited the growth of the subcutaneous Panc02 tumors. Reduced tumor sizes in EE were associated with the decreased proliferating cell nuclear antigen (PCNA) staining of the Panc02 tumors. (D) Representative immunohistochemical staining of PCNA in the Panc02 tumors from the SE and EE mice. Scale bars: 50 μm. (E) Quantitative analysis of PCNA⁺ tumor cells. EE- and SE-housed mice were also orthotopically injected with Panc02 cells (1 × 10⁵ cells per mouse). (F) Orthotopic Panc02 tumors dissected at the time of sacrifice. (G) Comparison of orthotopic tumor weights between the SE and EE mice. There were significantly reductions in the tumor weights in the EE-housed mice. (A, C, E, G) Data are presented as the mean ± SEM; n = 12 per group. * P < 0.05, ** P < 0.01 versus SE mice.