Prostate cancer is the most frequently diagnosed cancer in men. Whereas chronic calorie restriction (CCR) delays prostate tumorigenesis in some rodent models, the impact of intermittent caloric restriction (ICR) has not been determined. Here, transgenic adenocarcinoma of the mouse prostate (TRAMP) mice were used to compare how ICR and CCR affected prostate cancer development. TRAMP mice were assigned to ad libitum (AL), ICR (2 wk 50% AL consumption followed by 2 wk pair feeding to AL consumption), and CCR (25% AL consumption) groups at 7 wk of age and followed until disease burden necessitated euthanasia or mice reached terminal endpoints (48 or 50 wk of age). Body weights fluctuated in response to calorie intake (P < 0.0001). ICR mice were older at tumor detection than AL (P = 0.0066) and CCR (P = 0.0416) mice. There was no difference for age of tumor detection between AL and CCR mice (P = 0.3960). Similar results were found for survival. Serum leptin, adiponectin, insulin, and IGF-I were all significantly different among the groups. These results indicate that the way in which calories are restricted impacts both time to tumor detection and survival in TRAMP mice, with ICR providing greater protective effect compared to CCR.
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We thank the staff of the Hormel Institute Animal Facility for their dedication to this project. We are also grateful to Adele Marrangoni for carrying out the serum analysis (Grant P30 CA47904-19) and Nicole Smith for performing the PIXImus body scans. This work was supported in part by The Hormel Foundation and United States Army Department of Defense grant DAMD17-03-1-0258.