Flow cytometric evaluation of the DNA profile and cell cycle of zinc supplemented human Chang liver cells.

Zinc, an essential trace element, is important for normal cell growth. Growing children, especially at puberty, require increased zinc (2.8 mg/day for males and 2.65 mg/day for females). The DNA profile and cell cycle of human Chang liver cells grown in 0-900 mumol/L zinc chloride supplemented serum-free media for 24 h were analyzed using a Coulter flow cytometer. There was no significant difference in the G1, S and G2/M phases between zinc treated cells and control cultures except at 90 and 900 mumol/L zinc chloride. At these two higher dosages, fragmentation of genomic DNA into sub-2N DNA (sub-G1 DNA), generally considered a hallmark of programmed cell death (PCD), was noted. Results of the present study seem to suggest that growth regulation by zinc during growth spurts such as at puberty, could also be influenced by other factors besides its direct effect on DNA synthesis. In addition, high dosages of zinc could be cytotoxic.