Tumor-associated antigen profiling in breast and ovarian cancer: mRNA, protein or T cell recognition?
OBJECTIVE
The absence of tumor-associated antigens (TAA) which might elicit an immune response is one reason for the disappointing results of therapeutical vaccines in cancer patients. Moreover, impaired expression of MHC class-I and components involved in antigen processing, such as TAP-1, -2, LMP-2, -7, and MECL-1, may lead to tumor escape from immune recognition. Expression profiling of TAA is one approach towards the design of well-defined and individualized anti-tumor vaccines.


METHODS
Quantitative polymerase chain reaction (qRT-PCR) is the method of choice to characterize immunologically relevant properties of individual tumors. However, the application of qRT-PCR as a surrogate parameter for the expression of TAAs depends upon the assumption that the level of an mRNA species correlates with the cellular level of the protein it encodes. Therefore, we additionally analyzed TAA expression by immunofluorescence and T cell recognition.


RESULTS
In the present study we were unable to confirm that impaired TAP-1 or -2 (transporter associated with antigen processing) expression characterized at the mRNA level is an appropriate surrogate parameter for down-regulated MHC class-I expression in breast cancer. In addition, we analyzed the expression pattern of TAAs in breast and ovarian cancer cell lines. Besides the well-known over-expression of HER-2/neu, CEA, and MUC-1, multiple antigens of the MAGE-family were frequently co-expressed. We investigated whether detection of TAAs by qRT-PCR correlates with monoclonal antibody staining, and which method could predict T cell recognition. We demonstrated a correlation between tumor cell lysis by HLA-A*0201-restricted, MUC-1-specific CTL and threshold levels of MUC-1-specific mRNA.


CONCLUSIONS
MUC-1 is an example that TAA profiling by RT-PCR and flow cytometry can fail to correlate with each other and are of limited value in the prediction of T cell recognition.
Kayser
Simone
S
Department of Gynecology and Obstetrics, University of Tübingen, Calwerstrasse 7, 72076, Tübingen, Germany.
Watermann
Iris
I
Rentzsch
Christine
C
Weinschenk
Toni
T
Wallwiener
Diethelm
D
Gückel
Brigitte
B
D018528:ATP-Binding Cassette Transporters; D000951:Antigens, Neoplasm / Q000032:analysis*; D001483:Base Sequence; D001943:Breast Neoplasms / Q000276:immunology*; D002277:Carcinoma / Q000276:immunology* / Q000378:metabolism; D045744:Cell Line, Tumor; D005260:Female; D015395:Histocompatibility Antigens Class I / Q000032:analysis; D000949:Histocompatibility Antigens Class II / Q000032:analysis; D006801:Humans; D016130:Immunophenotyping; D009363:Neoplasm Proteins / Q000032:analysis*; D010051:Ovarian Neoplasms / Q000276:immunology* / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis*; D013601:T-Lymphocytes / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
D018528:ATP-Binding Cassette Transporters; D000951:Antigens, Neoplasm; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II; D009363:Neoplasm Proteins; D012333:RNA, Messenger; C477327:transporter associated with antigen processing (TAP)