Effect of LDL and serum from diabetic subjects on DNA synthesis in HIT-cells in culture.

The effect of lipoprotein-deficient serum (LPDS) with and without added low-density lipoprotein (LDL), isolated from diabetic subjects, on the replication of SV40-transformed islet cells (HIT cells) was investigated. Whole serum as well as LPDS preparations stimulated DNA synthesis maximally when added to the culture medium at a final concentration of 0.1%. The addition of LDL at 25 and 175 micrograms protein/ml medium did not cause further stimulation. On the contrary, the higher concentrations resulted in a significant inhibition. These results suggest that previously observed stimulation of DNA synthesis in smooth muscle cells by LDL from diabetic subjects is most likely due to the presence of growth factors in the serum of these patients and not to LDL per se.