Native human autoantibodies targeting GIPC1 identify differential expression in malignant tumors of the breast and ovary.
BACKGROUND
We have been studying the native humoral immune response to cancer and have isolated a library of fully human autoantibodies to a variety of malignancies. We previously described the isolation and characterization of two fully human monoclonal antibodies, 27.F7 and 27.B1, from breast cancer patients that target the protein known as GIPC1, an accessory PDZ-domain binding protein involved in regulation of G-protein signaling. Human monoclonal antibodies, 27.F7 and 27.B1, to GIPC1 demonstrate specific binding to malignant breast cancer tissue with no reactivity with normal breast tissue.


METHODS
The current study employs cELISA, flow cytometry, Western blot analysis as well as immunocytochemistry, and immunohistochemistry. Data is analyzed statistically with the Fisher one-tail and two-tail tests for two independent samples.


RESULTS
By screening several other cancer cell lines with 27.F7 and 27.B1 we found consistently strong staining of other human cancer cell lines including SKOV-3 (an ovarian cancer cell line). To further clarify the association of GIPC1 with breast and ovarian cancer we carefully studied 27.F7 and 27.B1 using immunocytochemical and immunohistochemical techniques. An immunohistochemical study of normal ovarian tissue, benign, borderline and malignant ovarian serous tumors, and different types of breast cancer revealed high expression of GIPC1 protein in neoplastic cells. Interestingly, antibodies 27.F7 and 27.B1 demonstrate differential staining of borderline ovarian tumors. Examination of different types of breast cancer demonstrates that the level of GIPC1 expression depends on tumor invasiveness and displays a higher expression than in benign tumors.


CONCLUSIONS
The present pilot study demonstrates that the GIPC1 protein is overexpressed in ovarian and breast cancer, which may provide an important diagnostic and prognostic marker and will constitute the basis for further study of the role that this protein plays in malignant diseases. In addition, this study suggests that human monoclonal antibodies 27.F7 and 27.B1 should be further evaluated as potential diagnostic tools.
Yavelsky
Victoria
V
Department of Virology, Faculty of Health Sciences, Ben Gurion University of Negev, Beer Sheva 84105, Israel. yavelsky@bgu.ac.il
Rohkin
Sarit
S
Shaco-Levy
Ruthy
R
Tzikinovsky
Alina
A
Amir
Tamar
T
Kohn
Hila
H
Delgado
Berta
B
Rabinovich
Alex
A
Piura
Benjamin
B
Chan
Gerald
G
Kalantarov
Gavreel
G
Trakht
Ilya
I
Lobel
Leslie
L
D048868:Adaptor Proteins, Signal Transducing / Q000096:biosynthesis* / Q000737:chemistry / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000737:chemistry; D001323:Autoantibodies / Q000737:chemistry*; D001940:Breast / Q000378:metabolism; D001943:Breast Neoplasms / Q000276:immunology / Q000378:metabolism*; D045744:Cell Line, Tumor; D018450:Disease Progression; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D010051:Ovarian Neoplasms / Q000276:immunology / Q000378:metabolism*; D010865:Pilot Projects
D048868:Adaptor Proteins, Signal Transducing; D000911:Antibodies, Monoclonal; D001323:Autoantibodies; C492009:GIPC1 protein, human