Leelawat K, Watanabe T, Nakajima M, Tujinda S, Suthipintawong C, Leardkamolkarn V
Department of Anatomy, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
J Clin Pathol. 2003 Oct;56(10):764-8. doi: 10.1136/jcp.56.10.764.
RCAS1 (receptor binding cancer antigen expressed on SiSo cells) is a tumour associated antigen. It is involved in immune evasion by tumour cells, by binding to receptors on cells involved in the immune response, such as T cells and natural killer cells, and inducing apoptosis. High expression of RCAS1 has been demonstrated immunohistochemically in tumours of the cervix, breast, lung, and stomach; however, the expression of RCAS1 has never been investigated in colorectal cancer.
To investigate the expression of RCAS1 in colorectal cancer and identify at which stages of colorectal carcinogenesis it is expressed.
Sixty surgically resected colorectal cancer specimens obtained from Rajavithi Hospital, Bangkok, Thailand were studied. RCAS1 expression was detected immunohistochemically using monoclonal anti-RCAS1 antibody. RCAS1 mRNA expression was also investigated by reverse transcription polymerase chain reaction in the freshly isolated tissues, and serum RCAS1 was measured by enzyme linked immunosorbent assay.
Staining for the RCAS1 protein was intense in high stages of colorectal cancer, but weak in normal tissues. The RCAS1 mRNA results correlated with the immunohistochemistry results. Positive serum RCAS1 concentrations were found in 10 of 18 patients with stage II disease and 12 of 32 with stage III and IV, but not in patients with stage I disease. All lymph node and liver metastases showed high expression of RCAS1 protein.
RCAS1 appears to be upregulated in high stages of colorectal cancer, both in the serum and the tissue. RCAS1 expression might be a useful additional criterion for staging this cancer.
RCAS1（SiSo细胞上表达的受体结合癌抗原）是一种肿瘤相关抗原。它通过与免疫反应相关细胞（如T细胞和自然杀伤细胞）上的受体结合并诱导细胞凋亡，参与肿瘤细胞的免疫逃逸。免疫组织化学已证实在子宫颈癌、乳腺癌、肺癌和胃癌中RCAS1高表达；然而，从未在结直肠癌中研究过RCAS1的表达。
研究RCAS1在结直肠癌中的表达，并确定其在结直肠癌发生的哪些阶段表达。
研究了从泰国曼谷拉贾维蒂医院获得的60例手术切除的结直肠癌标本。使用单克隆抗RCAS1抗体通过免疫组织化学检测RCAS1表达。还通过逆转录聚合酶链反应在新鲜分离的组织中研究RCAS1 mRNA表达，并通过酶联免疫吸附测定法测量血清RCAS1。
RCAS1蛋白染色在结直肠癌的晚期强烈，但在正常组织中较弱。RCAS1 mRNA结果与免疫组织化学结果相关。在18例II期疾病患者中有10例、32例III期和IV期患者中有12例血清RCAS1浓度呈阳性，但I期疾病患者中未发现。所有淋巴结和肝转移灶均显示RCAS1蛋白高表达。
RCAS1似乎在结直肠癌的晚期在血清和组织中均上调。RCAS1表达可能是该癌症分期的一个有用的附加标准。
