Induction of Cytolysis of Cultured Lymphoma Cells by Adenosine 3′:5′-Cyclic Monophosphate and the Isolation of Resistant Variants

Abstract

Cultured mouse lymphosarcoma cells are killed on exposure to 0.1 mM N(6),O(2')-dibutyryl-adenosine 3':5'-cyclic monophosphate. A population of cells resistant to the killing effect of dibutyryl cyclic AMP at concentrations as high as 1 mM was selected. The growth characteristics of the resistant cells were similar to those of the sensitive parental line. However, the resistant cells contain less cytoplasmic cyclic AMP-binding proteins and decreased cyclic AMP-stimulated protein kinase activity. It is proposed that transition from sensitivity to resistance to dibutyryl cyclic AMP in lymphoma cells is connected with a modification of the cyclic AMP-binding protein, which appears to be the regulatory subunit of the cyclic AMP-activated protein kinase.