Fragments of human oncoprotein MDM2 reveal variable distribution within and on cultivated human hepatoma cells.
Human oncoprotein MDM2 reveals a MHC class I binding motif HMDM441 characterizing MDM2 as a potential tumor antigen. To analyze the distribution of MDM2 proteins containing this motif in liver cancer cells we produced rabbit anti-HMDM441 serum. The novel antibodies bound to an MDM2 fragment of approximately 55 kDa which lacked the N-terminal region and was present in lysate and supernatant of a human hepatoma cell line overexpressing normal 90-kDa MDM2. The 55-kDa fragment was detected in the cytoplasm and nucleoli and at the nuclear envelope of hepatoma cells, whereas normal hepatocytes were negative. Double-fluorescence labeling indicated that the MDM2 fragments and MHC class I molecules were coexpressed on the surface of the hepatoma cells. Further studies must clarify whether MDM2 fragments containing motif HMDM441 are novel targets of immunotherapy and immunochemical tumor diagnosis.
Schlott
T
T
Department of Cytopathology, Georg-August-University, Goettingen, Germany. tschlott@med.uni-goettingen.de
Scharf
J G
JG
Soruri
A
A
Fayyazi
A
A
Griesinger
C
C
Albrecht
C
C
Eiffert
H
H
Droese
M
M
D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000378:metabolism* / Q000473:pathology; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000378:metabolism*; D051736:Proto-Oncogene Proteins c-mdm2; D014407:Tumor Cells, Cultured
D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2