Rat C6 and human astrocytic tumor cells express a neuronal type of glutamate transporter.

C6 glioma cells take up aspartate and glutamate by a Na(+)-dependent transporter. Using the polymerase chain reaction and degenerate oligonucleotide primers corresponding to conserved regions of previously cloned glutamate transporters, we isolated from these cells a partial cDNA clone with a sequence of the neuronal type EAAC1 glutamate transporter. The cells express a 4.4 kb message that hybridizes to this cDNA, and they do not express either of the previously described glial type glutamate transporters, GLT-1 or GLAST. The cells were sensitive to the toxic aspartate analog alanosine, which enters the cells by a glutamate transporter. Several human brain tumors examined, including some astrocytic tumors, expressed the EAAT3 glutamate transporter, which is the human homolog of the rodent EAAC1 transporter. Some of the tumors also expressed the other types of glutamate transporter.