9166

EBAG9

estrogen receptor binding site associated, antigen, 9;EBAG9;estrogen receptor binding site associated, antigen, 9

cancer-associated surface antigen RCAS1|estrogen receptor-binding fragment-associated gene 9 protein|receptor-binding cancer antigen expressed on SiSo cells

8q23

protein-coding

The expression of protein RCAS1 (receptor-binding cancer antigen expressed on SiSo cells), possibly involved in the mechanisms of evasion of immune surveillance by tumours, has been studied in brain astrocytomas grade III and IV and in metastatic carcinomas to the brain by means of double immunofluorescence with antibodies against RCAS1 and respectively anti-GFAP (astroglia) or CD68 or CD74 (macrophages/microglia). expression of RCAS1 has been reported in many types of carcinomas and in some normal cells, including bone marrow macrophages. Nakabayashi and coworkers recently reported expression of RCAS1 in gliomas. So far no attention has been paid to expression of RCAS1 in non-neoplastic cellular elements of tumours such as macrophages and to the expression of RCAS1 in metastatic carcinomas. We found expression of RCAS1 co-localizing with GFAP+ cells of gliomas and with CD68 and CD74 in large macrophages infiltrating metastatic and primary tumours and sometimes in cells which had morphological characteristics of microglia. Moreover, sometimes strong RCAS1 positivity has been found in metastatic carcinomas. Whether expression of RCAS1 in macrophages accompanying brain tumours is of any importance it is not possible to ascertain at present. However, when elucidating the possible role of RCAS1 in tumour biology, it seems to be necessary to include its presence not only in neoplastic cells.

OBJECTIVES: RCAS1 expression is significantly associated with clinical prognosis in various human cancers, which suggests that RCAS1 may be involved in acquisition of malignant phenotypes. To investigate the relationship between RCAS1 and one such characteristic, tumor invasiveness, we examined RCAS1 expression in cervical neoplasms ranging from the precancerous state to invasive cancer. METHODS: RCAS1 expression was studied retrospectively via immunohistochemical methods. Samples consisted of biopsy tissue from 90 patients with intraepithelial neoplasia and resected tumor tissue from 154 patients with invasive cancer. Statistical analysis was done to correlate RCAS1 expression and clinicopathologic variables in patients with a depth of cancer cell invasion into stromal tissue of >5 mm. RESULTS: RCAS1 expression was detected in patients with intraepithelial cancer and invasive cancer but not in patients with dysplasia. The occurrence and degree of RCAS1 expression increased with the depth of invasion. In patients with invasive cancer, RCAS1 overexpression was significantly correlated with invasion of the lymph-vascular space, lymph node metastasis in two or more sites, and tumor volume; RCAS1 expression was not associated with histologic subtype. Overall survival rates for patients with RCAS1 overexpression were significantly shorter than those for patients without RCAS1 overexpression. In connective tissue surrounding tumor cells, the number of cells expressing vimentin significantly decreased in relation to RCAS1 expression level. Moreover, significant associations between expression levels of RCAS1 and those of MMP-1 and laminin-5 were found. CONCLUSION: RCAS1 may contribute to acquisition of malignant uterine cervical phenotypic characteristics including invasion, metastasis, and tumor growth via connective tissue remodeling.

The objectives were to study the expression of receptor-binding cancer antigen expressed on SiSo cells (RCAS1) and estrogen receptor (ER) subtypes in the normal, hyperplastic, and carcinomatous endometrium and to explore their possible role in carcinogenesis and progression of endometrial carcinoma. Immunohistochemistry and semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) were applied to detect protein and messenger RNA expression of RCAS1, ER-alpha, and ER-beta in normal, hyperplastic, and carcinomatous endometrium. Western blotting was also used to detect the RCAS1 protein expression. Immunohistochemistry showed that the high expressions of RCAS1 protein were 0% (0/20), 9.1% (2/22), 40% (8/20), and 68.0% (34/50) in normal, simple, and complex hyperplasia, atypical hyperplasia, and endometrial carcinoma, respectively. There was a significant difference between each group (P < 0.05). The high-level expression of RCAS1 was detected more frequently in endometrial cancer with deep myometrial invasion, vascular invasion, and positive ER-alpha (P < 0.05). Two staining patterns of RCAS1 were observed. All normal, simple, and complex hyperplastic endometrium showed P pattern, while all malignant endometrium were of the D pattern. In atypical endometrium, 25% (5/20) cases showed D pattern. The Western blotting and RT-PCR results correlated with the immunohistochemistry results. The expression and distribution of RCAS1 may be involved in the malignant transformation of endometrium, and RCAS1 coexpression with ER-alpha may be associated with development and metastasis of endometrial carcinoma.

AIM: To investigate the expression of receptor-binding cancer antigen expressed on SiSo cells (RCAS1) in metastatic lymph nodes from gastrointestinal cancer. METHODS: metastatic lymph nodes from gastrointestinal cancer were detected for RCAS1 by immunohistochemical staining and mRNA in situ hybridization. RESULTS: A total of 102 metastatic lymph nodes from bile duct, gastric, colon and pancreatic cancer were investigated for RCAS1 expression. The immunoreactivity of RCAS1 was identified in 100% of metastatic lymph nodes. Both local and distant metastatic lymph nodes showed RCAS1 expression. On the contrary, specimens of non-cancerous lymph nodes were negative for RCAS1. The result of mRNA in situ hybridization was also confirmed by the finding of immunohistochemical staining. RCAS1 mRNA was detected in all tumor cells that metastasized to lymph nodes. CONCLUSION: All metastatic lymph nodes express RCAS1 in tumor cells at both mRNA levels, and RCAS1 that should be used as a complementary factor for identification of metastatic lymph nodes from gastrointestinal cancers.