A human monoclonal autoantibody to breast cancer identifies the PDZ domain containing protein GIPC1 as a novel breast cancer-associated antigen.
BACKGROUND
We have been studying the native autoimmune response to cancer through the isolation of human monoclonal antibodies that are cancer specific from cancer patients. To facilitate this work we previously developed a fusion partner cell line for human lymphocytes, MFP-2, that fuses efficiently with both human lymph node lymphocytes and peripheral blood lymphocytes. Using this unique trioma fusion partner cell line we isolated a panel of autologous human monoclonal antibodies, from both peripheral blood and lymph node lymphocytes, which are representative of the native repertoire of anti-cancer specific antibodies from breast cancer patients.


METHODS
The current study employs immunocytochemistry, immunohistochemistry, Western blot analysis as well as Northern blots, Scatchard binding studies and finally SEREX analysis for target antigen identification.


RESULTS
By application of an expression cloning technique known as SEREX, we determined that the target antigen for two monoclonal antibodies, 27.B1 and 27.F7, derived from lymph node B-cells of a breast cancer patient, is the PDZ domain-containing protein known as GIPC1. This protein is highly expressed not only in cultured human breast cancer cells, but also in primary and metastatic tumor tissues and its overexpression appears to be cancer cell specific. Confocal microscopy revealed cell membrane and cytoplasmic localization of the target protein, which is consistent with previous studies of this protein.


CONCLUSIONS
We have determined that GIPC1 is a novel breast cancer-associated immunogenic antigen that is overexpressed in breast cancer. Its role, however, in the initiation and/or progression of breast cancer remains unclear and needs further clarification.
Rudchenko
Sergei
S
College of Physicians and Surgeons, Columbia University, 630 W, 168 St,, New York, NY 10032, USA. RudchenkoS@HSS.EDU
Scanlan
Matthew
M
Kalantarov
Gavreel
G
Yavelsky
Victoria
V
Levy
Chen
C
Estabrook
Alison
A
Old
Lloyd
L
Chan
Gerald L
GL
Lobel
Leslie
L
Trakht
Ilya
I
D048868:Adaptor Proteins, Signal Transducing / Q000096:biosynthesis* / Q000737:chemistry*; D000911:Antibodies, Monoclonal / Q000737:chemistry*; D000951:Antigens, Neoplasm / Q000737:chemistry*; D001323:Autoantibodies / Q000737:chemistry*; D015551:Autoimmunity; D001943:Breast Neoplasms; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D007700:Kinetics; D017434:Protein Structure, Tertiary
D048868:Adaptor Proteins, Signal Transducing; D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D001323:Autoantibodies; C492009:GIPC1 protein, human