Hypoxia upregulates amino acid transport in a human neuroblastoma cell line.
OBJECTIVE
Some tumor cells survive and even grow in hypoxic conditions. We examined the effect of hypoxia on amino acid transport in a human neuroblastoma cell line SK-N-SH.


METHODS
Cells were incubated under hypoxic conditions (1% O2-5% CO2-94% N2). After 0, 8, 16, and 24 hours, the transport of 3H-glutamine, 3H-glutamate, and 3H-leucine was assayed. 3H-Thymidine and 3H-leucine incorporation was measured for the determination of DNA and protein synthesis, respectively.


RESULTS
Hypoxia increased Na+-dependent glutamine and Na+-independent leucine transport significantly at 16 and 24 hours compared with control (P < .01) by a mechanism that increased Vmax without affecting Km. These increases were completely blocked by actinomycin D and cycloheximide. There was no significant difference in Na+-dependent glutamate transport between control and hypoxic groups. DNA and protein synthesis significantly decreased in the hypoxic condition compared with control (P < .01).


CONCLUSIONS
This study demonstrated that hypoxia upregulates amino acid transport in a human neuroblastoma cell line. This mechanism may allow cells to survive and even grow under hypoxic conditions.
Soh
Hideki
H
Department of Pediatric Surgery, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan.
Wasa
Masafumi
M
Fukuzawa
Masahiro
M
D000596:Amino Acids / Q000378:metabolism*; D001692:Biological Transport; D015687:Cell Hypoxia; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D006801:Humans; D000860:Hypoxia / Q000378:metabolism*; D007930:Leucine / Q000378:metabolism; D009447:Neuroblastoma / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
D000596:Amino Acids; D011500:Protein Synthesis Inhibitors; D005973:Glutamine; D003609:Dactinomycin; D018698:Glutamic Acid; D003513:Cycloheximide; D007930:Leucine