Bacillus intermedius ribonuclease as inhibitor of cell proliferation and membrane current

The antiproliferative action of the guanine-specific ribonuclease secreted by Bacillus intermedius (binase) was studied in different chicken and mouse cell lines. The proliferation rate of chicken embryo fibroblasts, either n ormal or Rous sarcoma virus-transformed, was significantly reduced by binas e treatment. Among mouse fibroblasts, v-ras-transformed NIH3T3 cells were s ensitive to binase, whereas the growth of non-transformed, v-src-transforme d or v-fms-transformed NIH3T3 cells was not affected. A 48 h treatment with binase inhibited the Ca2+-dependent K+ current of v-ras-transformed NIH3T3 cells but had no effect on this membrane current in non-transformed and in v-src- or v-fms-transformed NIH3T3 cells. Our results suggest that mammali an cells expressing the ras-oncogene are a potential target for the antipro liferative action of binase. (C) 2001 Elsevier Science Ireland Ltd. All rig hts reserved.