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Correlation between the effects of polyamine analogues on DNA conformation and cell growth
H S Basu1, B G Feuerstein, D F Deen
1Brain Tumor Research Center, Department of Neurological Surgery, School of Medicine, University of California, San Francisco 94143.
Abstract:
Effects of a number of synthetic analogues of the natural polyamines on the B-Z transition of poly(dG-me5dC) and on the aggregation of calf thymus DNA in solution were studied using circular dichroic and UV spectroscopy. The efficiency of induction of the B-Z transition decreased with a decrease in the length of the central alkyl chain of the analogues, and the ability of analogues to aggregate DNA was markedly reduced for compounds ethylated at the terminal amines. Both structural variations appear to have important effects on the biological functions of polyamines. Most analogues studied depleted intracellular levels of natural polyamines, but only those that did not readily induce the B-Z transition and/or aggregate DNA were good inhibitors of cell growth. All but one of the analogues studied were able to rescue cells--at least in part--from the growth-inhibitory effects of alpha-difluoromethylornithine. The single analogue that was unable to effect rescue also failed to induce both the B-Z transition and the aggregation of DNA.
Insights
Synthetic polyamine analogues affect DNA structure and cell growth. Structural changes influencing DNA binding and B-Z transition correlate with cell growth inhibition and rescue from drug effects.
Area of Science:
- Biochemistry
- Molecular Biology
- Genetics
Background:
- Polyamines are crucial for DNA structure and cell proliferation.
- Synthetic analogues are explored to understand polyamine function.
- The B-Z transition and DNA aggregation are key polyamine-mediated DNA alterations.
Purpose of the Study:
- To investigate how synthetic polyamine analogues impact the B-Z transition of poly(dG-me5dC) and calf thymus DNA aggregation.
- To correlate structural features of analogues with their biological effects on cell growth.
- To assess the ability of analogues to modulate cellular polyamine levels and rescue cells from growth inhibition.
Main Methods:
- Circular dichroic spectroscopy to monitor DNA conformational changes (B-Z transition).
- UV spectroscopy to study DNA aggregation.
- Cell growth assays to evaluate the biological activity of analogues.
- Measurement of intracellular natural polyamine levels.
Main Results:
- Decreased central alkyl chain length reduced B-Z transition induction efficiency.
- Ethylation of terminal amines significantly impaired DNA aggregation.
- Analogues that failed to induce B-Z transition or aggregate DNA were potent cell growth inhibitors.
- Most analogues depleted natural polyamines, but only specific structural types inhibited growth.
- Analogues that induced B-Z transition and/or DNA aggregation could rescue cells from growth inhibition.
Conclusions:
- Structural modifications of polyamine analogues critically influence their DNA interaction capabilities.
- The ability to induce B-Z transition and DNA aggregation is linked to inhibition of cell growth.
- Specific polyamine analogue structures are effective in modulating DNA structure and cellular processes, offering potential therapeutic avenues.