Stimulation of expression of the intestinal glutamine transporter ATB0 in tumor-bearing rats.
BACKGROUND
Glutamine supplementation ameliorates host catabolic response in tumor bearing states. The purpose of this in vivo study was to investigate intestinal glutamine transport and expression of glutamine transporter ATB(0) in methyl-cholanthrene (MCA)-sarcoma bearing rats.


METHODS
Fisher-344 rats underwent subcutaneous flank implantation of MCA-sarcoma cells (saline as control) and were pair-fed an equal quantity of chow as controls, to account for tumor-induced anorexia, until tumors reached 10 or 20% body weight. Intestinal mucosal brush border membrane [3H]-Glutamine transport was measured. Glutamine transporter ATB(0) mRNA and protein levels were measured by real-time PCR and western blot techniques, respectively.


RESULTS
Glutamine transport activity across the intestinal brush border membrane (BBM) was 3.7-fold higher in tumor-bearing rats (TBR) than in controls (TBR 153 +/- 22.6 vs. Control 41.9 +/- 9.7 pmol/mg protein/10s, P < .01). Transporter ATB(0) mRNA levels were 1.4-fold higher in tumor-bearing rats (Relative value TBR .61 +/- .12 vs. Control .43 +/- .1, P < .05). A 1.4-fold increase in transporter ATB(0) protein levels was observed in the tumor-bearing rats (Relative value TBR .52 +/- .07 vs. Control .37 +/- .04, P < .05). Circulating aortic plasma glutamine levels were 1.3-fold higher in tumor bearing rats ([Glutamine] = .63 +/- .02 Control vs. [Glutamine] = .74 +/- .01 mmol/l TBR, P < .0001). Portal venous plasma glutamine levels were also higher in tumor bearing rats ([Glutamine] = .47 +/- .01 Control vs. [Glutamine] = .60 +/- .02 mmol/l TBR, P < .0001).


CONCLUSIONS
Intestinal brush border membrane glutamine transport activity, transporter ATB(0) mRNA and protein levels are up-regulate in tumor-bearing rats.
Choudry
Haroon A
HA
Department of Surgery, The Milton S. Hershey Medical Center, The Pennsylvania State University, College of Medicine, 500 University Drive, P.O. Box MC 850, Hershey, PA 17033, USA.
Souba
Wiley W
WW
Lin
Chengmao
C
Meng
Qinghe
Q
Karinch
Anne M
AM
Huang
Jingli
J
Pan
Ming
M
D000818:Animals; D001692:Biological Transport; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism; D007408:Intestinal Absorption / Q000502:physiology; D007413:Intestinal Mucosa / Q000378:metabolism; D007583:Jejunum / Q000378:metabolism; D008297:Male; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012513:Sarcoma, Experimental / Q000378:metabolism* / Q000473:pathology
D002352:Carrier Proteins; D012333:RNA, Messenger; C037853:glutamine transport proteins; D005973:Glutamine