Inhibition of tumor growth by a truncated and soluble form of melanotransferrin.

Melanotransferrin is a glycoprotein expressed at the cell membrane and secreted in the extracellular environment. Recombinant truncated form of membrane-bound melanotransferrin (sMTf) was reported to exert in vitro anti-angiogenic properties. Here we show that sMTf treatment leads to a 50% inhibition of neovascularization in Matrigel implants when stimulated by growth factors. Using a glioblastoma xenograft model, we demonstrate that sMTf delivery at 2.5 and 10 mg/kg/day by micro-osmotic pump inhibits tumor growth by 73% and 91%, respectively. In a lung carcinoma xenograft model, sMTf treatment at 2.5 and 10 mg/kg/day impeded tumor growth by 87% and 97%. Furthermore, subcutaneous glioblastoma and lung carcinoma tumors from mice treated with 10 mg/kg/day of sMTf present insignificant growth toward the study. In association with a reduction in endoglin mRNA expression, the hemoglobin content decreased by half in sMTf-treated glioblastoma tumors. In vitro experiments revealed that NCI-H460 cells treated with sMTf display an inhibition in their invasive capabilities with a concomitant reduction in the expression of the low-density lipoprotein receptor protein and urokinase plasminogen activator receptor. Altogether, our results demonstrate that sMTf exerts anti-cancer and anti-angiogenic activities, suggesting that its administration may provide novel therapeutic strategies for the treatment of cancer.