Alteration in immunoexpression of glucose transporter 2 in liver of tumour-bearing rats.
To elucidate interactions between the glucose transport system and hepatic glucose production in the tumour-bearing state, glycogen storage, expression of glucose transporter isoform 2 (Glut 2) and activities of glucose-6-phosphatase (G-6-Pase) and hexokinase were histochemically examined in hepatocytes of tumour-bearing rats. Five male F344 rats, subcutaneously inoculated with methylcholanthrene (MCA)-induced sarcoma cells were compared with five pair-fed animals and four ad libitum fed controls. Glycogen storage was markedly decreased in liver cells of tumour-bearing rats compared to in those of control animals. Glut 2 immunoreactivity was uniformly seen in the cellular membrane of hepatocytes from control animals. In rats bearing sarcoma, the staining intensity was significantly decreased, suggesting that Glut 2 with its bi-directional transport capacity was down-regulated in the tumour-bearing state. Positive staining for hexokinase activity was located in the perivenous area in livers from control animals and was more diffusely located and more intense in livers from tumour-bearing animals. G-6-Pase activity, limited to the peripheral area in livers from controls, extended to the intermediate area and had stronger reactivity in livers from tumour-bearing animals. In the tumour-bearing cachectic condition, glucose may be partially consumed by a futile cycle, hepatic metabolic zonation was disturbed, and the release of glucose from the liver may not be mediated by a facilitative glucose transporter-2.
Doi
C
C
First Department of Surgery, Yokohama City University School of Medicine, Japan.
Noguchi
Y
Y
Ito
T
T
Yoshikawa
T
T
Makino
T
T
Matsumoto
A
A
D000818:Animals; D002100:Cachexia / Q000378:metabolism; D005952:Glucose-6-Phosphatase / Q000378:metabolism; D006593:Hexokinase / Q000378:metabolism; D007124:Immunoenzyme Techniques; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D008748:Methylcholanthrene; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism*; D009368:Neoplasm Transplantation; D051381:Rats; D011916:Rats, Inbred F344; D012513:Sarcoma, Experimental / Q000139:chemically induced / Q000201:enzymology / Q000378:metabolism*
D009004:Monosaccharide Transport Proteins; D009363:Neoplasm Proteins; D008748:Methylcholanthrene; D006593:Hexokinase; D005952:Glucose-6-Phosphatase