Antiproliferative effects of galectin-1 from Rana catesbeiana eggs on human leukemia cells and its binding proteins in human cells

Abstract

Galectin-1 from American bullfrog, RCG1, was isolated to high purity, and its growth inhibitory properties against human cells were examined. The results demonstrated that highly purified RCG1 induced large cell aggregates and revealed cell-type-specific growth inhibition. It significantly inhibited all human leukemia cell lines tested such as HL-60, U937, and K562 cells but did not inhibit human colon cancer cell line, Colo 201, or mouse mammary tumor cell line FM3A cells. Although most of the galectin-induced growth inhibitions are known to be apoptic, RCG1 induced growth arrest and neither apoptosis nor necrosis. RCG1-mediated growth inhibition was specifically suppressed by the corresponding sugar, lactose, but not by sucrose or even the structurally similar sugar, melibiose. Several studies have reported that galectin-mediated biological functions were modulated by charge modification. Since the high purity of RCG1 was demonstrated but a moderate degree of growth inhibition occurred, it is possible protein charge modification was examined by isoelectric focusing, and it was found to be highly heterogeneous in charge. RCG1 binding proteins in human cells were analyzed by lectin blotting using biotinylated RCG1, and lectin blotting revealed that in human cell extracts the specific proteins at molecular weight 37 and 50 kDa possessed the responsive features of RCG1 binding and lactose competition.

Different aspects and potential applications of Amphibian Lectins in modern biology: Functional Tableau

“…Galectins (G or S) are a well-defined family ofbeta-galactoside animal lectins characterized by a high sequence homology in the carbohydrate-binding domain. Galectin-1 from American bullfrog(Rana catesbeiana), RCG1 significantly inhibited all human leukemia cell lines tested such as HL-60, U937, and K562 cells but did not inhibit human colon cancer cell line, Colo 201, or mouse mammary tumor cell line FM3A cells [24]. .…”

“…. RCG1-mediated growth inhibition was specifically suppressed by the corresponding sugar, lactose, but not by sucrose or even the structurally similar sugar, melibiose.RCG1 binding proteins in human cells were analyzed by lectin blotting using biotinylated RCG1, and lectin blotting revealed that in human cell extracts the specific proteins at molecular weight 37 and 50 kDa possessed the responsive features of RCG1 binding and lactose competition [24]. Antibody cross-reactivities between purified S-type lectins from Bufoarenarum ovary and human spleen and some other Stype lectins showed that they share epitopes [26].…”