Effect of 6,6′-Dithiodinicotinic Acid on the Dissemination of Ehrlich Ascites Tumour

Abstract

PREVIOUS studies have shown that 6,6′-dithiodinicotinic acid (carboxypyridine disulphide, CPDS), while reacting with —SH groups of Ehrlich ascites tumour cells, does not enter these cells to any appreciable extent^1,2. The reaction of CPDS with cell —SH groups leads to the formation of stable mixed disulphides^3,4. as in the case with other disulphides of analogous structure². Other types of cells, such as human lymphocytes and blood platelets⁴, or mouse kidney (unpublished observations), are similarly affected by CPDS. The effect of CPDS treatment on the mammalian cells studied is two-fold: (a) the external —SH groups are blocked, and (b) this blocking introduces one carboxyl group on the cell surface for each —SH blocked. This interaction is described in more detail elsewhere³. Because —SH groups are not ionized at physiological pH, but carboxyl groups are, the net charge of the cell is made more negative by this treatment. It is known³ that this modification does not effect respiration and glycolysis of Ehrlich ascites cells.