Expression of tumor-associated antigen RCAS1 and its possible involvement in immune evasion in oral squamous cell carcinoma.
BACKGROUND
RCAS1 (receptor-binding cancer antigen expressed on SiSo cells) is known to induce apoptosis in its receptor-positive cells. The authors investigated RCAS1 expression in oral squamous cell carcinoma (SCC) and its association with the apoptosis of tumor-infiltrating lymphocytes (TILs).


METHODS
In 130 patients with oral SCC, the expression of RCAS1 in tumor cells was immunohistochemically examined and the apoptosis of TILs was examined by Terminal Deoxynucleotidyltransferase-mediated dUTP Nick End Labeling (TUNEL) staining.


RESULTS
RCAS1 was detected both on the cytoplasm and the membrane of tumor cells in 41 of 130 cases (31.5%). Focusing on the expression at the invasive front interacting with host immune cells, RCAS1 was detected in 22 of 130 cases (16.9%). The percentage of TUNEL-positive TILs in cases with RCAS1-positive SCCs was significantly higher than in cases with RCAS1-negative SCCs (P < 0.0001).


CONCLUSIONS
RCAS1 can be expressed on oral SCC cells and may be involved in the tumor escape from the host immune system by inducing the apoptosis of TILs.
Toyoshima
T
T
Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Nakamura
S
S
Kumamaru
W
W
Kawamura
E
E
Ishibashi
H
H
Hayashida
J-N
JN
Moriyama
M
M
Ohyama
Y
Y
Sasaki
M
M
Shirasuna
K
K
D000368:Aged; D000951:Antigens, Neoplasm / Q000096:biosynthesis* / Q000502:physiology*; D017209:Apoptosis; D002294:Carcinoma, Squamous Cell / Q000276:immunology*; D016009:Chi-Square Distribution; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007157:Immunologic Surveillance; D020287:In Situ Nick-End Labeling; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000276:immunology*; D011379:Prognosis; D018709:Statistics, Nonparametric; D019139:Tumor Escape / Q000276:immunology*
D000951:Antigens, Neoplasm; C120762:EBAG9 protein, human