[Nicotinamide decreases DNA destabilization in K562 cells treated with AlF(-4)]

Area of Science:

• Cell biology
• Molecular toxicology

Background:

• The human erythromyeloleukosis cell line K562 is a model for studying cellular responses to toxic agents.
• Poly(ADP-ribose)polymerase (PARP) is a key enzyme involved in DNA repair and cellular stress responses.

Purpose of the Study:

• To investigate the effects of tetrafluoroaluminate (AlF4-) on K562 cell proliferation, survival, and DNA integrity.
• To explore the role of nicotinamide, a PARP inhibitor, in modulating AlF4--induced cellular damage and susceptibility to immune cell-mediated lysis.

Main Methods:

• Trypan blue exclusion assay to assess cell viability and proliferation.
• Quantification of DNA fragmentation using 3H-thymidine labeling.
• Assessment of cell susceptibility to non-MHC-restricted lysis by rat spleen cells.
• Measurement of intracellular NAD+ and NADH levels.

Main Results:

• AlF4- significantly reduced K562 cell proliferation and survival after 18-hour incubation, with increased DNA fragmentation.
• Nicotinamide suppressed AlF4--induced DNA fragmentation and reduced K562 and YAC-1 cell susceptibility to lysis.
• Nicotinamide treatment increased intracellular NAD+ and NADH levels by three-fold without affecting K562 cell survival.

Conclusions:

• AlF4- induces DNA damage and impairs K562 cell viability, potentially through mechanisms involving PARP.
• Nicotinamide mitigates AlF4--induced DNA damage and reduces immune cell-mediated lysis by inhibiting PARP activity and DNA repair.
• The findings suggest that AlF4--induced suppression of K562 proliferation leads to the accumulation of unrepaired DNA damage.