Effects of 4-hydroxynonenal and N-acetyl-L-cysteine on Myc-induced apoptosis

Apoptosis has been described as programmed active cell death. Overexpression of the c-Myc gene has been shown to induce apoptosis in Rat1A/Myc-ER cells when combined with a growth blocking agent. In the present study, we tested whether 4-Hydroxynonenal (HNE) or N-acetyl-L-cysteine (LNAC) affect apoptotic death in serum deprived Rat1A/Myc-ER cells caused by the c-Myc protein. The incidence of apoptosis in growth arrested cells was confirmed photographically and by ladder pattern formation seen on agarose gel electrophoresis. To study the effect of HNE and LNAC, the cells were cultured in 0.5% serum and treated with various concentrations of HNE and LNAC, c-Myc was then activated by addition of 2 microM beta-estradiol. Two separate parameters were used to determine the rate of cell death. In the first, the amount of DNA isolated from dying cells was compared by UV absorption. As the second parameter, the cell numbers were determined by counting. Our results showed that 1 microM of HNE has no effect on apoptotic cell death. However, 10 microM HNE decreased the amount of DNA isolated while increasing the cell count 14% relative to cells treated only with beta-estradiol. In addition, we found that various concentrations of the antioxidant LNAC does not protect cells from c-Myc induced death. However, it supports cell survival in 0.5% serum and causes an increase in cell number.