Cationic control of gene transcription in tumour cells.

Using ascites tumour cells (Ehrlich carcinoma, plasmacytoma MOPS-21, leukaemia P-388, lympholeukaemia NK/Ly) and bone marrow cells from normal rats, we have demonstrated that transcription of a gene coding for the 35S RNA can be regulated via alteration of the Na+/K+ ratio in the cells. The 35S RNA was transcriptionally active within the range 1 less than or equal to Na+/K+ less than 3 but was switched off at Na+/K+ less than 1. In synchronized Ehrlich carcinoma cells this gene was activated in the early phases of the cell cycle, when the Na+/K+ ratio in the cells exceeded 1. It was concluded that so-called cationic mechanism of regulation of transcription determines the time and sequence of stimulation of certain genes during the course of the cell cycle and that it accounts for transcription of normally repressed genes as a result of malignant transformation.