It is suggested that recombinant galectin 9 (rGal 9),produced in host Escherichia coli, exhibits an immunesystem-mediated action and a direct action on tumor cells(i.e., activity of inducing the intercellular adhesion andapoptosis of the tumor cells), thereby potent in inducingthe inhibition of cancer metastasis and reduction.Moreover, the rGal 9 exerts no efficacy on non-activatedlymphocytes but can induce apoptosis in activated T cells,in particular, CD4-positive T cells causing an excessiveimmune response. The rGal 9 has a further potentapoptosis-inducing property on synovial cells participatingin joint deformation in rheumatism, etc. In the rGal 9,however, a link domain linking two CRDs is highlysusceptible to protease and, therefore, is very easilydigestible with the enzyme, thereby losing the aboveactivities. Thus, there is a need for a more stabilizedmolecule in view of further studies. Modification of thelink domain linking two CRDs in galectin 9 provides amodified molecule having an elevated activity without anyundesirable effects on the above activities.
