Cell growth and cholesterol metabolism in human glucose-6-phosphate dehydrogenase deficient lymphomononuclear cells

Atherosclerosis is an inflammatory-fibroproliferative response of the arterial wall involving a complex set of interconnected events where cell proliferation (lymphomonocytes, and endothelial and smooth-muscle cells) and substantial perturbations of intracellular cholesterol metabolism are considered to be among the main features. Glucose-6-phosphate dehydrogenase (G6PD), the key enzyme of the hexose-monophosphate shunt pathway, is an essential enzyme involved in both cell growth and cholesterol metabolism, raising the question as to whether G6PD deficiency may have metabolic and growth implications in a deficient population. In the present study, we investigated cell growth and cholesterol metabolism in peripheral blood lymphomononuclear cells (PBMC) from G6PD-normal (n = 5) and -deficient (n = 5) subjects stimulated with lectins (phytohaemoagglutinin and Concanavalin A). G6PD activity, DNA ([3H]-thymidine incorporation) cholesterol synthesis and esterification ([14C]-acetate and [14C]-oleate incorporation), and G6PD, HMGCoA reductase and low density lipoprotein (LDL) receptor mRNA levels (RT-PCR) all increased following lectin stimulation in both normal and G6PD-deficient cells. However, these parameters were significantly lower in G6PD-deficient cells (P < 0.05). It is of interest that G6PD-deficient PBMC, which showed lower expression of G6PD and higher expression of the LDL receptor gene than normal PBMC under basal conditions, exhibited an opposite pattern after stimulation: G6PD and HMGCoA reductase being expressed at significantly higher levels in deficient than in normal cells (P < 0.05). We conclude that the reduced capability of G6PD-deficient cells to respond to mitogenic stimuli and to synthesize cholesterol esters may represent favourable conditions for reducing the risk of cardiovascular diseases.