Figure 1.

Adipocytes secrete levels of IGF-2 that contribute to adipo-CM stimulated breast cancer cell proliferation. (a, b) The total number of live MCF-7 (a) and T-47D (b) cells grown in unconditioned (uncond-M), fibroblast (fibro-CM), or adipocyte (adipo-CM) conditioned medium for three days in culture was determined and is shown relative to the number of live cells in the uncond-M group, which was arbitrarily assigned a value of 1. Data shown are the means ± S.E. for three replicate experiments, and significant (P < 0.05) induction of cell number by fibro-CM (*) compared to the uncond-M group or by adipo-CM (**) compared to the uncond-M and fibro-CM groups is shown. (c, d) Adipokine protein arrays were used to determine the relative levels of adipokines in adipo-CM and fibro-CM. (d) Data shown are the means ± SE for three experiments, and significantly (P < 0.05) higher levels of an adipokine in adipo-CM (*) compared to fibro-CM are shown. Normalized adipokine levels were calculated as the densitometry of an adipokine normalized to the densitometry of an internal loading control. (e, f) The total number of live MCF-7 (e) and T-47D (f) cells treated with nonspecific IgG (5 μg/mL) or a specific IGF-2 blocking antibody (5 μg/mL) in adipo-CM for three days in culture was determined and is displayed relative to the number of live cells in the fibro-CM nonspecific IgG group, which was arbitrarily assigned a value of 1. Data shown are the means ± S.E. for three replicate experiments. A significant (P < 0.05) decrease in cell number by IGF-2 antibody (*) is shown.