Tumor hypoglycemia induced in nude mice by a heterotransplantable human ovarian carcinoma line (OCL-1).

Tumor hypoglycemia induced by a heterotransplantable human ovarian carcinoma line (OCL-1) was described. Plasma glucose decreased to 36 +/- 9 mg/dl (S.D.) at 8 to 12 weeks after the transplantation. Significant amounts of immunoreactive insulin and insulin-like active substance could not be detected in tumor tissues. Plasma immunoreactive insulin levels were low, and glucagon levels were high in OCL-1-bearing nude mice, compared with the control. Light- and electron-microscopically, tumor cells possessed large amounts of glycogen, and this finding was also biochemically confirmed. OCL-1 tumor showed high glycogen synthetase activity compared with other control tumors, while glycogen phosphorylase activity was the same level as other tumors. The high glycogen synthetase activity was considered to be the cause of glycogen accumulation in tumor cells. Hypoglycemia in OCL-1-bearing nude mice was considered to be caused by abnormal redistribution of glycogen, i.e., marked accumulation of glycogen in tumor tissues and depletion of glycogen in the host liver. This OCL-1 tumor-nude mice system was thought to be a good model for research on the mechanisms of tumor hypoglycemia occurring in cancer patients with nonpancreatic islet cell tumors.