Preparation of recombinant MK-1/Ep-CAM and establishment of an ELISA system for determining soluble MK-1/Ep-CAM levels in sera of cancer patients.
The MK-1 antigen, also termed as Ep-CAM, is a membrane glycoprotein that is overexpressed on the majority of tumor cells of epithelial origin and thereby can be used as a target of immunodetection and immunotherapy of cancer. It has previously been shown that several type-I transmembrane proteins, including E-cadherin, ErbB-2 and intercellular adhesion molecule-1 (ICAM-1), may be useful as tumor markers because they are released into the circulation of many cancer patients. To address the question of whether MK-1, the same type-I membrane protein, is also released into the sera, we developed a sandwich-type enzyme-linked immunosorbent assay (ELISA) system by preparing a recombinant MK-1 protein and two anti-MK-1 monoclonal antibodies with different epitope specificities. Using this ELISA, we found that the MK-1 levels in serum samples from healthy volunteers were all less than 2 ng/ml, whereas the Mk-1 levels in sera of about 10% of patients with malignant tumors of various tissue origins were increased to 2-78 ng/ml, indicating that MK-1 is released from tumor cells into the circulation under certain conditions. These findings should be borne in mind when trying to perform passive antibody therapy for cancer using anti-MK-1 antibody.
Abe
Hironori
H
Department of Biochemistry, Fukuoka University School of Medicine, Fukuoka 814-0180, Japan.
Kuroki
Motomu
M
Imakiire
Takayuki
T
Yamauchi
Yasushi
Y
Yamada
Hiromi
H
Arakawa
Fumiko
F
Kuroki
Masahide
M
D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis; D000951:Antigens, Neoplasm / Q000097:blood* / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D014408:Biomarkers, Tumor / Q000097:blood* / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D012831:Bombyx; D015815:Cell Adhesion Molecules / Q000097:blood* / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D000071858:Epithelial Cell Adhesion Molecule; D006801:Humans; D008562:Membrane Glycoproteins / Q000097:blood* / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D051379:Mice; D008807:Mice, Inbred BALB C; D009369:Neoplasms / Q000097:blood; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D012995:Solubility
D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D015815:Cell Adhesion Molecules; D000071858:Epithelial Cell Adhesion Molecule; D008562:Membrane Glycoproteins; D011993:Recombinant Fusion Proteins