Diet-induced obesity and mammary tumor development in MMTV-neu female mice.
Obesity is a risk factor for postmenopausal breast cancer and is associated with shortened latency and/or increased mammary tumor (MT) incidence in animals. Elevated body weight is usually associated with hormone-responsive tumors. In agreement with these data we previously showed that latency of hormone-responsive MTs in MMTV-TGF-alpha mice with diet-induced obesity was significantly shortened. Here, we used the same protocol to determine the impact of diet-induced obesity on estrogen receptor-negative MT development in MMTV-neu (strain 202) mice. Mice were fed a low-fat diet (n=20) or a high-fat diet (n=54) from 10 wk of age. Body weight at 19 wk of age was used to assign high-fat mice to obesity-prone, overweight, and obesity-resistant groups. Mice were euthanized due to MT size or at 85 wk of age. Final body weights of obesity-prone mice were heaviest, and those of obesity-resistant and low-fat groups were similar. Fat pad weights were heaviest in obesity-prone mice followed by overweight and obesity-resistant groups, and lightest in low-fat mice. Serum IGF-I levels were similar for low-fat and high-fat mice, whereas leptin was higher in high-fat mice (P <0.0001). MT latency, incidence, metastasis, and burden were similar for all groups. These findings support that obesity is not a risk factor for development of estrogen-negative breast cancer.
Cleary
Margot P
MP
Hormel Institute, University of Minnesota, Austin, MN 55912, USA. mpcleary@hi.umn.edu
Grande
Joseph P
JP
Juneja
Subhash C
SC
Maihle
Nita J
NJ
D000273:Adipose Tissue / Q000473:pathology; D000818:Animals; D004032:Diet; D002149:Energy Intake; D005260:Female; D018734:Genes, erbB-2; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D020738:Leptin / Q000097:blood; D008325:Mammary Neoplasms, Experimental / Q000097:blood / Q000209:etiology* / Q000473:pathology; D008324:Mammary Tumor Virus, Mouse; D051379:Mice; D009765:Obesity / Q000150:complications*; D016211:Transforming Growth Factor alpha / Q000502:physiology
D020738:Leptin; D016211:Transforming Growth Factor alpha; D007334:Insulin-Like Growth Factor I