Influence of suramin on some DNA-directed enzymes and primary cultures of chicken embryo and rat cells.

The influence of suramin on O6-alkylguanine-DNA alkyltransferase (AT), DNase I and poly(adenosine diphosphate ribose)polymerase (PADPR) as well as on primary cultures of rat and chick embryo cells was examined by using some short-term tests. AT and DNase I were inhibited by suramin in a dose-dependent manner (DE50 = 65 and 100 micrograms/ml, respectively). PADPR activity was increased over a concentration range of 40-320 micrograms/ml. At concentrations above 40 micrograms/ml suramin decreased scheduled and unscheduled DNA synthesis. At doses of below 20 micrograms/ml the substance slightly stimulated unscheduled DNA synthesis in embryonic cells. Suramin enhanced nucleoid sedimentation and diminished the viscosity of alkaline cell lysates. From the present results it is concluded that suramin, at clinically relevant concentrations, is able to interact with enzyme systems which are critical to important nuclear functions and to interfere--in a cell specific manner--with histones and/or matrix proteins, resulting in greater chromatin compactness.