Monochloramine induced DNA fragmentation in gastric cell line MKN45.

Monochloramine (NH2Cl) is known to be one of the virulence factors in Helicobacter pylori-associated gastric mucosal injury. The present study was designed to examine NH2Cl-evoked DNA fragmentation in the gastric epithelial cell line MKN45. NH2Cl was produced by mixing NH3 with sodium hypochlorite (NaClO). MKN45 cells were exposed to NH2Cl, NH3, or NaClO in Hanks' balanced salt solution. DNA cleavage was evaluated quantitatively by photometeric enzyme immunoassay for the in vitro determination of cytoplasmic mono- and oligonucleosomes. Damage to the plasma membrane was assessed by measuring the activity of lactate dehydrogenase in the supernatants. Separately, DNA ladder formation was performed to confirm the incidence of DNA fragmentation. NH2Cl (0.001-0.01 mM) significantly increased the cytoplasmic mono- and oligonucleosomes, suggesting the incidence of DNA cleavage. The DNA ladder was clearly evoked by NH2Cl. NH2Cl induced a DNA fragmentation, one of the important aspects in apoptosis, in the gastric cell line MKN45.