The rearrangement of polyamine biosynthesis regulation in tumor cells: Stabilization of the proliferative regimen and induction of autonomos fluctuations

An analysis was performed of the influence of correlation of the activity b etween two regulatory enzymes (sperminsynthase and decarboxylase S-adenosil -L-methionin) on the general autoregulation in the process and the nature o f polyamine metabolism. It was shown that the reduction of S-AMDC activity: (or, activation of spermidinsynthase) results in-the fixed relaxation regim en of metabolism and a loss of ability to switch over to the proliferative biosynthesis mode in response to an extremal stimulus. The increased activi ty in S-AMDC (or reduced activity of spermidinsynthase) results in the abol ition of the trigger nature in polyamine metabolic regulation and fixation of metabolism in the proliferative mode. It is these changes that take plac e in polyamine metabolism during tumor transformation and progression. It w as shown that during concurrent activation of ODC and S-AMDC, usually seen in tumors, polyamine metabolism must unavoidably change over from a station ary one with fixed dynamic concentrations of all polyamines to the autofluc tuating one with permanently altering concentrations. On the basis of compa rison between theoretic conclusions and literature data we inferred that th e conversions from proliferative quiescence to proliferation is always acco mpanied by a switch-over to the autofluctuating functional mode in the syst em of proliferation control.