Anti-60S ribosomal protein L29 antibody: New anticancer agent discovered from human sera.

3071 Background: Incidence of hepatocellular carcinoma (HCC) is lower in autoimmune hepatitis (AIH) than chronic viral hepatitis. In AIH, serum immunoglobulin G (IgG) levels are associated with the clinical features. In this study, we searched IgG showing anti-tumor effect in sera of AIH patients. Methods: Total IgG was extracted from sera of AIH patients by using protein G. Anti-tumor effects of the total IgG were evaluated by MTT assay using human HCC Huh7 cells and PLC/PRF/5 cells. Autoantigens in membrane proteins of Huh7 cells were screened by immunoprecipitation followed by liquid chromatography-mass spectrometry (LC-MS) shotgun analysis. Results: In one AIH patient without any cancers, addition of total IgG extracted from her serum to the culture inhibited the proliferation of Huh7 cells and PLC/PRF/5 cells, and decreased intracellular levels of β-Catenin and Cyclin-D1. In this patient, autoantigens in membrane proteins were screened, and 60S ribosomal protein L29 (RPL29) was identified from the MS...