EFFECTS OF 4-HYDROXYNONENAL AND N-ACETYL-L-CYSTEINE ON MYC-INDUCED APOPTOSIS

Apoptosis has been described as programmed active cell death. Overexpr ession of the c-Myc gene has been shown to induce apoptosis in Rat1A/M yc-ER cells when combined with a growth blocking agent. In the present study, we tested whether 4-Hydroxynonenal (HNE) or N-acetyl-L-cystein e (LNAC) affect apoptotic death in serum deprived Rat1A/Myc-ER cells c aused by the c-Myc protein. The incidence of apoptosis in growth arres ted cells was confirmed photographically and by ladder pattern formati on 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 o f 2 mu M beta-estradiol. Two separate parameters were used to determin e the rate of cell death. In the first, the amount of DNA isolated fro m dying cells was compared by UV absorption. As the second parameter, the cell numbers were determined by counting. Our results showed that 1 mu M of HNE has no effect on apoptotic cell death. However, 10 mu M HNE decreased the amount of DNA isolated while increasing the cell cou nt 14% relative to cells treated only with beta-estradiol. In addition , we found that various concentrations of the antioxidant LNAC does no t protect cells from c-Myc induced death. However, it supports cell su rvival in 0.5% serum and causes an increase in cell number.