Exposure of Hela Cells to Serum Results in Increased Cellular Thiol Concentration and Formaldehyde-Induced DNA-Protein Crosslink

How does inhaled formaldehyde transfer the genotoxicity from exposure organ to site distant organs via blood? This is the key question to understand leukemia induced by formaldehyde. To answer this question, we used new born calf serum (NBS) as "blood" and Hela cells as materials to investigate its effects on cellular thiol concentration and DNA-protein crosslink (DPC) induced by formaldehyde. Our results showed that when new born calf serum (NBS) were absent, 250 mumolldrL^-1 formaldehyde induced relatively low amount of DPC, while cellular thiol concentration was also low. In contrast, DPC formation and cellular thiol concentration were significantly elevated in the presence of 1% and 10% NBS (p<0.01, p<0.05). These results indicated that NBS could regenerate cellular thiol concentration and stimulate DPC formation as a consequence in formaldehyde exposed cells. This effect may provide a basis for the understanding of site distant toxicity of formaldehyde and to explain whether inhaled formaldehyde could induce leukemia.