Lack of effective T-lymphocyte response to the PAX3/FKHR translocation area in alveolar rhabdomyosarcoma.
OBJECTIVE
Alveolar rhabdomyosarcoma (ARMS) frequently contains the fusion transcription factor PAX3/FKHR. Therefore, clinical studies have been initiated to utilize the PAX3/FKHR translocation point area as a peptide vaccine against ARMS. Our study was directed at identifying antigenic T-lymphocyte epitopes at the PAX3/FKHR translocation point area.


METHODS
The peptide sequence surrounding the PAX3/FKHR translocation point was evaluated by MHC binding algorithms for potential T-lymphocyte antigenic epitopes (class I molecules HLA-A1, -A2 and -A3; class II molecules HLA-DR1, -DR4 and -DR7). Using in vitro techniques, dendritic cells loaded with PAX3/FKHR peptides were used to stimulate naive T-lymphocytes. T-lymphocyte activity was then evaluated by 51Cr release and 3H-thymidine uptake assays.


RESULTS
Only one HLA-A3-restricted epitope was predicted by the algorithms. The peptide was prepared and tested for its ability to stimulate naive cytotoxic T-lymphocytes (CTLs). Unfortunately, the peptide was unsuccessful at stimulating naive CTL. However, induction of naive helper T-lymphocytes (HTL) to recognize and respond to the PAX3/FKHR translocation peptide was successful. Yet, this HTL peptide activity did not translate into recognition of PAX3/FKHR-containing ARMS tumor cells.


CONCLUSIONS
It appears that the fusion area of PAX3/FKHR may not be a good source of antigenic anti-tumor peptide epitopes. These results raise serious concerns about the success and applicability of future peptide-based vaccine immunotherapy directed at the PAX3/FKHR translocation point.
Rodeberg
David A
DA
Department of Surgery, Mayo Clinic, 200 First Street, SW, Rochester, MN, 55905, USA. rodeberg.david@mayo.edu
Nuss
Rebecca A
RA
Heppelmann
Carrie J
CJ
Celis
Esteban
E
D000595:Amino Acid Sequence; D019496:Cancer Vaccines / Q000276:immunology*; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000276:immunology*; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D015791:HLA-A3 Antigen / Q000276:immunology; D006801:Humans; D008969:Molecular Sequence Data; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D011993:Recombinant Fusion Proteins / Q000276:immunology*; D018232:Rhabdomyosarcoma, Alveolar / Q000235:genetics / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology; D014157:Transcription Factors / Q000235:genetics / Q000276:immunology*; D014178:Translocation, Genetic
D019496:Cancer Vaccines; D004268:DNA-Binding Proteins; C085126:FOXO1 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D015791:HLA-A3 Antigen; D000072041:PAX3 Transcription Factor; C489409:PAX3 protein, human; D051761:Paired Box Transcription Factors; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors