Expression of the SART1 tumor-rejection antigens in colorectal cancers.
OBJECTIVE
Colorectal cancer is one of the major causes of cancer death in the world, including in the United States and Japan. We recently identified the tumor-rejection antigen gene SART1, which encodes both the SART1(259) antigen expressed in the cytosol of epithelial cancers and the SART1(800) antigen expressed in the nucleus of the majority of proliferating cells. This study investigated the expression of these tumor antigens to explore a potential molecule for specific immunotherapy of colorectal cancer patients.


METHODS
SART1 antigens were investigated by Western blotting in six colorectal cancer cell lines and in 33 colorectal cancer tissues. The cancer cell lines were tested for their ability to stimulate interferon-gamma production by the human-leukocyte-antigen-A24-restricted and SART1-specific cytotoxic T lymphocytes and were also tested for their susceptibility to the lysis by the cytotoxic T lymphocytes.


RESULTS
The SART1(259) antigen was detected in the cytosol of four of six cancer cell lines, 13 of 33 (39 percent) cancer tissues, and 0 of 20 nontumorous colorectal tissues. The SART1(800) antigen was expressed in the nucleus of all the colorectal cancer cell lines, 18 of 33 (55 percent) cancer tissues, and 0 of 20 nontumorous tissues. The human-lymphocyte-antigen-A24-restricted and SART1-specific cytotoxic T lymphocytes killed the human-lymphocyte-antigen-A24+ SART1(259+) cancer cells.


CONCLUSIONS
The SART1(259) antigen could be an appropriate target molecule for specific immunotherapy of approximately 40 percent of the human-lymphocyte-antigen-A24+ patients with colorectal cancer.
Sasatomi
T
T
Department of Immunology, Kurume University School of Medicine, Fukuoka, Japan.
Yamana
H
H
Shichijo
S
S
Tanaka
S
S
Okamura
T
T
Ogata
Y
Y
Itoh
K
K
Shirouzu
K
K
D000230:Adenocarcinoma / Q000276:immunology* / Q000473:pathology; D000951:Antigens, Neoplasm / Q000032:analysis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D001707:Biopsy, Needle; D015179:Colorectal Neoplasms / Q000276:immunology* / Q000473:pathology; D046508:Culture Techniques; D006801:Humans; D009363:Neoplasm Proteins / Q000032:analysis*; D017411:Ribonucleoproteins, Small Nuclear; D012680:Sensitivity and Specificity
D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins; D017411:Ribonucleoproteins, Small Nuclear; C431323:SART1 protein, human