ANTIMITOCHONDRIAL EFFECTS OF BISETHYL POLYAMINES IN MAMMALIAN-CELLS

The effects of three bisethyl polyamine analogs on mitochondrial struc ture and function were examined in human HeLa and L1210 murine leukemi a cells. N, N' Bis-[3(ethylamino)-propyl]1-7-heptane diamine (BEPH), a nd its octane (BEPO), and butane (BESPM) derivative, were shown by ele ctron microscopy and/or Rhodamine 123 uptake studies to alter the stru ctural integrity of mitochondria when both cell lines were treated at the approximate Ic(50) dose of each drug. At this dose, BEPH had no ma rked effects on levers of the naturally occurring polyamines, putresci ne, spermidine or spermine, in either cell line whereas BEPO and BESPM treatment did result in pool depletion. Southern blot analysis demons trated a rime and dose-dependent loss of mitochondrial DNA from BEPH-t reated L1210 cultures suggesting that loss of mitochondrial integrity extended to the DNA level. Treatment of L1210 cells M with all three a nalogs revealed marked reductions in the activity of two mitochondrial enzymes citrate synthase and cytochrome C oxidase. HeLa cells treated with all three analogs exhibited markedly reduced levels of ATP, comp lete loss of cytidine triphosphate (CTP) and near total depletion of u ridine triphosphate (UTP). There was also a loss of colony forming abi lity in HeLa cells which could be nearly completely reversed by the ad dition of either uridine or cytidine suggesting that NTP reduction may be the primary antiproliferative determinant in these cells. Growth i nhibition by BEPH In L1210 cells was markedly potentiated by the glyco lysis inhibitor, 2-deoxyglucose, which had no such effect in otherwise untreated cells. This suggests that BEPH treatment of L1210 cells res ults in impairment of mitochondrial ATP synthesis and activation of th e glycolytic pathway for energy production. 2-deoxyglucose treatment a lso completely prevented the increase of ATP by EPH treatment of L1210 cells. It is concluded that all three bisethyl polyamines alter HeLa and L1210 mitochondria in both structurally and functionally and that these alterations may play a primary role in the antiproliferative act ivity of these agents in HeLa cells. In L1210, the different spectra o f cellular biochemical changes following bisethyl polyamine treatment suggests that additional mechanisms may be in effect.