Modulation of glucose-6-phosphate dehydrogenase expression in a stable mammalian model
DeLuca, C.; Mason, J.A.
Cellular and Molecular Biology 29(6): 509-516
1983
ISSN/ISBN: 0145-5680 PMID: 6652647 Document Number: 217849
A cytochemical technique was used to demonstrate glucose-6-phosphate-D (G6PD) activity in parenchymal cells of tumors formed by inoculation of cultured rat hepatoma cells which lack detectable G6PD in vitro. A subline of the H4-II-E-C3 cell line, U/BRH, is described which lacks G6PD activity in vitro but has maintained a capacity for the expression of G6PD when proliferating as a tumor in vivo. Electrophoretic examinations of preparations from tumors demonstrate G6PD activity that is distinct from that of blood cells and resembles that found in liver tissue. Primary cultures of cells from newly formed tumors again fail to exhibit detectable G6PD activity within 3-4 days after explantation. These persist in vitro as G6PD-negative cell lines and also form tumors whose parenchmal cells contain G6PD activity. The capability for continued re-expression of the active enzyme in vivo after it can no longer be detected in vitro has remained a stable characteristic of the U/BRH subline throughout 8 yr of culture. The use of this experimental system is proposed for studies on the modulation of mammalian gene expression.