title: Expression of tumor-associated membrane antigen, RCAS1, in human colorectal carcinomas and possible role in apoptosis of tumor-infiltrating lymphocytes.
abstract: RCAS1, a novel tumor-associated antigen, is expressed in advanced human neoplasias including uterine and ovarian carcinomas. RCAS1 protein was indicated to induce cell cycle arrest and apoptosis of cultured human lymphoid and myeloid cell lines and normal lymphocytes. In the present study, we investigated the expression and prognostic value of RCAS1 in 58 patients with colorectal carcinomas. RCAS1 protein was detected by immunoperoxidase staining using a mouse monoclonal anti-RCAS1 antibody (22-1-1 antibody). Immunohistochemical examination showed expression of RCAS1 in 75% of colorectal carcinomas with lymph node metastases (n = 24), whereas it was present in only 41% of tumors without metastases (n = 34, P <.05). Patients with RCAS1-positive tumors showed a significantly poorer prognosis than those negative for RCAS1 (P <.05). Multivariate analysis using the Cox regression model indicated that RCAS1 positivity was an independent negative predictor for survival (P =.0300; risk ratio, 0.496). In addition, apoptotic cells of tumor-infiltrating lymphocytes were examined using nonradioactive in situ nick translation in paraffin-embedded sections. The proportion of apoptotic tumor-infiltrating lymphocytes was significantly higher in RCAS1-positive colorectal carcinomas (11.2 +/- 1.0) than in RCAS1-negative tumors (7.9 +/- 1.0, P <.05). Our results suggest that overexpression of RCAS1 may negatively affect the prognosis of human colorectal carcinomas and that RCAS1 may play a role in tumor immune privilege in vivo.
authors.affiliation: Department of Surgery II, Nagasaki University School of Medicine, Nagasaki, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Okada
authors.forename: Manabu
authors.initials: M
authors.lastname: Nakashima
authors.forename: Ko
authors.initials: K
authors.lastname: Komuta
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hashimoto
authors.forename: Sadayuki
authors.initials: S
authors.lastname: Okudaira
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Baba
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Hishikawa
authors.forename: Takehiko
authors.initials: T
authors.lastname: Koji
authors.forename: Takashi
authors.initials: T
authors.lastname: Kanematsu
authors.forename: Takeshi
authors.initials: T
authors.lastname: Watanabe
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism* / Q000401:mortality / Q000556:secondary; D000368:Aged; D000951:Antigens, Neoplasm / Q000378:metabolism*; D017209:Apoptosis; D002452:Cell Count; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D020287:In Situ Nick-End Labeling; D016246:Lymphocytes, Tumor-Infiltrating / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015996:Survival Rate
chemical_list: D000951:Antigens, Neoplasm; C120762:EBAG9 protein, human