Human rhabdomyosarcoma cells retain insulin-regulated glucose transport activity through glucose transporter 1

We evaluated the expression of glucose transporter (glut) isoforms and its function in RD cells, human rhabdomyosarcoma, which retain the potential to differentiate into muscle. Gluts 1, 3, and 4 were expressed in RD cells, a s detected by reverse-transcription polymerase chain reaction and immunocyt ochemistry, Supraphysiological concentration (1 mu M) of insulin treatment increased 2-deoxy glucose transport by up to 1.68-fold together with concom itant tyrosine phosphorylation of the insulin receptor beta subunit and of insulin receptor substrate 1. Suppression of glut 1 mRNA by 38% by antisens e oligonucleotide transfection led to a reduction of basal and insulin-stim ulated 3-deoxy glucose transport by 38 and 55%, respectively. Suppression o f gluts 3 and 4 by antisense oligonucleotide transfection did not affect bo th basal and insulin-stimulated 2-deoxy glucose transport. Thus, glut 1 acc ounts for the major part of basal and insulin-stimulated glucose transport in RD cells. Next, we transfected expression vectors carrying human gluts 1 and 4 cDNAs into RD cells to add further support for the role of glut 1 in glucose transport. Overexpression of glut 1 stimulated basal and insulin-s timulated 2-deoxy glucose transport by 1.66- and 1.43-fold, respectively. G lut 4 overexpression did not affect basal and insulin-stimulated 2-deoxy gl ucose transport. Western blot analysis using glut 1 antibody showed that gl ut 1 was redistributed from intracellular membrane to plasma membrane. Thes e observations support the notion that RD cells, with the potential to diff erentiate into muscle, retain insulin responsiveness. As human muscle cell lines are not available at this point, RD cells can serve as a useful alter native to human muscle for studies related to insulin signal transduction a nd glucose transport. (C) 2000 Academic Press.