AJP - Endocrinology and Metabolism, Vol 241, Issue 2 129-E135, Copyright © 1981 by American Physiological Society
Chondrosarcoma growth: influence of diabetes, caloric restriction, and insulin treatment
W. D. McCumbee and H. E. Lebovitz
Diabetes and malnutrition result in decreased somatomedin production and
cartilage growth in rats. The growth and metabolism of the Swarm rat
chondrosarcoma are dramatically affected by somatomedins. Data presented
here show that streptozotocin diabetes and diet restriction inhibit in vivo
chondrosarcoma growth. Tumors grown in diabetic rats were significantly
smaller than tumors grown in diet-restricted rats showing the same changes
in body weight. Insulin treatment increased the rate of tumor growth in
diabetic rats. Tumors grown in rigidly controlled diabetic rats were as
large as tumors grown in nondiabetic controls. Diet restriction and
diabetes reduced the capacity of the serum of the rat to stimulate
alpha-amino[14C]isobutyrate uptake and [3H]uridine incorporation into RNA
in chondrosarcoma pieces grown in nondiabetic rats. This somatomedin
activity of the serum was restored by treating diabetic rats with insulin.
There was a significant correlation between the in vitro stimulatory effect
of a particular serum pool on chondrosarcoma metabolism and in vivo
chondrosarcoma growth in the animals from whom the serum was obtained.
These studies demonstrate that the in vivo growth of malignant chondrocytes
is similar to that of normal chondrocytes with respect to the role of
nutrition and insulin.
