A monoclonal antibody against the human SUMO-1 protein obtained by immunization with recombinant protein and CpG-DNA-liposome complex.

Post-translational modification regulated by conjugation of a small ubiquitin-like modifier (SUMO) is involved in various cellular processes. In this study, we expressed and purified recombinant human SUMO-1 (hSUMO-1). BALB/c mice were immunized with a complex of hSUMO-1 protein and Lipoplex(O) to produce hSUMO-1-specific antibodies. Using conventional hybridoma technology, we obtained four hybridoma clones derived from the mouse with the highest antibody titer against hSUMO-1. Based on Western blot analysis, our hSUMO-1 monoclonal antibody specifically recognizes hSUMO-1, but not other SUMO proteins. These results support that the anti-hSUMO-1 monoclonal antibody produced with the aid of Lipoplex(O) adjuvant is specific and that Lipoplex(O) is useful for development of monoclonal antibodies against recombinant protein. In addition, we analyzed human tissues to examine the distribution of hSUMO-1. Higher expression of hSUMO-1 was detected in normal adrenal gland, esophagus, pancreas, liver, stomach, kidney, and uterus than in corresponding cancer tissues, suggesting a tumor suppressive function of hSUMO-1.