D-glucose metabolism in tumoral pancreatic islet cells with rapid or decreased mitotic activity.

The metabolism of D-glucose was investigated in tumoral islet cells of the RINm5F line with either unaltered or decreased mitotic activity, resulting from the incorporation of D, L-alpha-difluoromethylornithine (DFMO) in the culture medium. In DFMO-treated cells, the oxidation of D-[3,4-14C]glucose was less severely affected than the utilization of D-[5-3H] glucose, at least at hexose concentrations in the 1.0 to 16.7 mM range. This coincided with restoration of the process of glucose-induced stimulation of 3HOH generation from [2-3H]glycerol. Pretreatment with DFMO also resulted in a decreased circulation in the pentose phosphate pathway and the restoration of a preferential stimulation of D-[2-14C]glucose or D-[6-14C]glucose oxidation relative to D-[5-3H]glucose utilization when raising the hexose concentration from 0.2 to 1.0 mM. It is proposed that the interference of cell growth with the metabolic and functional responses of RINm5F cells to D-glucose is relevant to the difference between such responses otherwise found when comparing the behaviour of foetal or neonatal to adult normal islets.