EFFECT OF ENDOGENOUS METHYLGLYOXAL ON CHINESE-HAMSTER OVARY CELLS GROWN IN CULTURE

Methylglyoxal is a ketoaldehyde that reacts readily under physiologica l conditions with biologically relevant ligands, such as amine and sul fhydryl groups. It is produced in mammalian cells primarily as a by-pr oduct of glycolysis. The level of glucose, L-glutamine and fetal bovin e serum in culture media was found to significantly affect levels of i ntracellular methylglyoxal in Chinese hamster ovary cells. Medium with 25 mM glucose and 5 mM L-glutamine caused an increase in free methylg lyoxal levels of 90 to 100% relative to medium containing 5 mM glucose and 2 mM L-glutamine. Both of these media compositions are representa tive of those found in commercially available media. Pseudomonas putid a glyoxalase I was expressed in Chinese hamster ovary cells to enhance methylglyoxal detoxification. The Chinese hamster ovary cell clones s howed an 80 to 90% decrease in free methylglyoxal levels. The colony-f orming ability of these cells was compared to wild-type Chinese hamste r ovary cells under conditions found to cause elevated methylglyoxal l evels. The wild-type cells showed a 10% decrease in colony-forming abi lity relative to the clones. This decrease was found to be statistical ly significant (P > 0.99) by analysis of variance. The variation in co lony-forming ability amongst the clones was statistically insignifican t. More importantly, the clones showed increased colony-forming abilit y relative to the wild-type cells under conditions of higher methylgly oxal production with fair to good statistical significance (P > 0.75 t o P > 0.95). This result is the first quantifiable evidence that endog enously produced methylglyoxal can negatively affect cell function und er conditions found in animal cell culture.