A Comparative Study of the Interaction between Concanavalin A and Mitochondria from Normal and Malignant Cells¹ Free

The concanavalin A (con A)-binding capacity of mitochondria isolated by sucrose density gradient methods from host livers, from Morris hepatomas 7800 and 7777, and from mouse myeloma MOPC-46 were compared. con A binding to the various mitochondrial preparations was quantitated using an isotopic assay procedure in which con A-acetyl-³H is used and by a spectrophotometric agglutination method using native con A. Readily accessible con A-binding sites were determined using washed, intact mitochondria, and total binding sites were evaluated by carrying out incubations in the presence of Triton X-100 (1%). Detergent treatment caused extensive disruption of mitochondrial membranes and increased 2.5- to 3.0-fold the amount of con A-acetyl-³H bound by control liver mitochondria. Tumor-derived mitochondria bound significantly less con A than did the corresponding host liver preparations, indicating an alteration in the glycoproteins of tumor mitochondria. Triton X-100-treated hepatoma 7800 and 7777 mitochondria were capable of binding only 50 and 70% as much con A-acetyl-³H, respectively, when compared with mitochondria isolated from the host liver controls.

The data suggest either that there is a decrease in the concentration of glycoproteins in tumor mitochondria or that there are qualitative changes in the structure of their oligosaccharide side chains. The altered reactivity of tumor mitochondria to con A cannot be accounted for on the basis of differential growth rates of tumor and host liver tissue since mitochondria isolated from regenerating rat liver do not differ from normal rat liver mitochondria in their con A-binding properties.