An 18-month-old male Alaskan malamute was euthanized due to slowly growing mass around the left femur after history of left posterior limb lameness. At necropsy, a firm confluent mass approximately 15cm in diameter was noted surrounding the femur and proximal portion of the tibia/ulna with traumatic ulceration of the overlying skin. On cross sections of the mass, many unencapsulated firm tan coalescing lobules were noted. The neoplasm consisted of closely packed spindle cells with homogenous eosinophilic material (osteoids) between the neoplastic cells. The pulmonary metastasis was confirmed. Based on the gross and histopathologic examinations, the case was diagnosed as juvenile osteosarcoma.

Galectin-3 plays an important role in cell development, differentiation and cancer metastasis, including cell-cell/extracellular matrix (ECM) interactions and is supposed to have an effect of apoptosis on T-cells in thymic clonal selection. In this study, to know the effect of galectin-3 on thymocyte development, we used recombinant human galectin-3 (rHgal-3) from Escherichia coli, JM105, which was inserted with human gal-3 gene-transformed plasmid vector (prGal-3) to express human galectin-3. Expressed rHgal-3 was confirmed by western blot using the culture supernant of hybridoma (M3/38) producing monoclonal antibody to human galectin-3. Sepharose gel affinity chromatography was used to purify the expressed rHgal-3. Thymocytes and hepatocytes from 6-week-old male BALB/c mice were incubated with rHgal-3 and showed marked increase of apoptotic population on analysis using flow cytometry with 7-AAD in a dosedependent manner. However, rHgal-3 failed to induce apoptosis on hepatocytes. Interestingly, this apoptotic effect was not inhibited by lactose, a specific lectin domain inhibitor. From these results, we concluded that extrinsic galectin-3 induces apoptosis on mouse thymocytes, and galectin-3 may have an apoptotic effect on T-cells in thymic clonal selection.

The change of plasma prostaglandin E2 level, natural killer cell activity and tumor cell growth were assayed after transplantation of EL-4 leukemia cells in C57BL/6 mice. Plasma prostaglandin E2 level was increased in EL-4 bearing mice, but indomethacin treated mice group showed low level. The tumor-derived prostaglandin E2 inhibited the post-target binding cytolytic process of natural killer activity. Indomethacin inhibited the growth of prostaglandin secreting EL-4 solid tumor