|Budget Amount *help
¥1,800,000 (Direct Cost : ¥1,800,000)
Fiscal Year 1995 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1994 : ¥1,400,000 (Direct Cost : ¥1,400,000)
It was found that administration of spermidine to cultured rat hepatoma (HTC) cells depleted of polyamine with ornithine decarboxylase inhibitor, 1-aminooxy-3-aminopropane (AOAP), 1ed to an abnormal accumulation of cellular spermidine followed by the cell death. although, some morphorogical features suggested it was apoptosis, mitocondrial damage was observed in electron micrograph and a clear fragmentation of DNA was not observed in the analysis of cellular DNA by gel electrophoresis.
Mechanism of tha abnormal accumulation of spermidine was examined. It was found that the accumulation was dependent on the exposure period of AOAP to the cells, and that the longer exposure of AOAP inhibited repression of spermidine uptake activity. As protein synthesis rate was decreased to 20% of control by the longer exposue of AOAP,it was suggested that inhibition of synthesis of a protein by the long exposure of AOAP to the cells which was needed in the repression of spermidine uptake activity led to the abnormal accumulation of spermidine.
In order to develope a prodrug which enable us to introduce excess polyamine into cells diacetly derivatives of polyamine were synthesized and examined. It was found that diacetyl pentaamines were good substrates of polyamine uptake system and polyamine oxidase, and then efficiently converted into spermidine or norspermidine in HTC cells. But these compounds were not successfully taken into the cells to an abnormal accumulation level, suggesting that the srtucture which does not utilize polyamine transport system is needed for the compound to be accumulate to excess level in cells.