Molecular and functional analysis of glutamine uptake in human hepatoma and liver-derived cells.
Human hepatoma cells take up glutamine at rates severalfold faster than the system N-mediated transport rates observed in normal human hepatocytes. Amino acid inhibition, kinetic, Northern blotting, RT-PCR, and restriction enzyme analyses collectively identified the transporter responsible in six human hepatoma cell lines as amino acid transporter B(0) (ATB(0)), the human ortholog of rodent ASCT2. The majority of glutamine uptake in liver fibroblasts and an immortalized human liver epithelial cell line (THLE-5B) was also mediated by ATB(0). The 2.9-kb ATB(0) mRNA was equally expressed in all cell lines, whereas expression of the system A transporters ATA2 and ATA3 was variable. In contrast, the system N isoforms (SN1 and SN2) were expressed only in well-differentiated hepatomas. ATB(0) mRNA was also expressed in cirrhotic liver and adult and pediatric liver cancer biopsies but was not detectable in isolated human hepatocytes or fetal liver. Although the growth of all hepatomas was glutamine dependent, competitive inhibition of ATB(0)-mediated glutamine uptake blocked proliferation only in poorly differentiated cells lacking SN1 or SN2 expression and exhibiting low glutamine synthetase mRNA levels.
Bode
Barrie P
BP
Surgical Oncology Research Laboratories, Department of Surgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA. bodebp@slu.edu
Fuchs
Bryan C
BC
Hurley
Bryan P
BP
Conroy
Jennifer L
JL
Suetterlin
Julie E
JE
Tanabe
Kenneth K
KK
Rhoads
David B
DB
Abcouwer
Steve F
SF
Souba
Wiley W
WW
D026962:Amino Acid Transport System ASC / Q000502:physiology; D001692:Biological Transport; D015152:Blotting, Northern; D006528:Carcinoma, Hepatocellular / Q000378:metabolism* / Q000473:pathology; D002352:Carrier Proteins / Q000378:metabolism; D002455:Cell Division / Q000502:physiology; D002478:Cells, Cultured; D005347:Fibroblasts / Q000378:metabolism; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism / Q000493:pharmacokinetics*; D006801:Humans; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D008103:Liver Cirrhosis / Q000378:metabolism / Q000473:pathology; D008113:Liver Neoplasms / Q000378:metabolism* / Q000473:pathology; D015778:Minor Histocompatibility Antigens; D012016:Reference Values; D020133:Reverse Transcriptase Polymerase Chain Reaction
D026962:Amino Acid Transport System ASC; D002352:Carrier Proteins; D015778:Minor Histocompatibility Antigens; C420506:SLC1A5 protein, human; D005973:Glutamine; D005974:Glutamate-Ammonia Ligase