Clinico-pathological Significance Of RCAS1 Expression In Colorectal Cancer

Background: High expression of RCAS1(receptor-binding cancer antigen expressed on SiSo cells) has been demonstrated immunohistochemically in tumours of the cervix, breast, lung, and stomach; however, there are few reports on the expression of RCAS1 molecules in colorectal cancer. In this study, we explored the relationship between the expression of RCAS1 and clinical pathological factors in colorectal cancer.Methods: We investigated RCAS1 expression in 44 colorectal cancer tissues ,10 colorectal adenoma tissues and 10 normal colorectal tissues by immunohistochemical means. We then analyzed the relationship between RCAS1 expression and clinicopathological variables.Results: The expression of RCAS1 was also detected in all cases of colorectal cancer ,normal colorectal epithelium and adenomatous polyps.The expression pattern of RCAS1 in colorectal cancer cells could be classified as granular staining either enriched in the glandular side of the cytoplasm and membrane with polarity (P pattern) or scattered diffusely in the cytoplasm and on the cell membranes (D pattern). The D pattern of colorectal cancers was more frequently recognized in carcinomas with regional lymph node metastasis (P<0.05) and in those that had invaded beyond the submucosa (P<0.05),compared with the P pattern. In contrast, most RCAS1-positive specimens of colorectal adenoma and normal mucosa were of the P pattern. Staining for the RCAS1 protein was intense in high stages of colorectal cancer(p<0.05), and in carcinomas with regional lymph node metastasis (P<0.05) and in those with poor differentiation (P<0.05). There was no relationship with age, gender and location. All lymph node and liver metastases showed high expression of RCAS1 protein.Conclution :The expression and distribution of RCAS1 may be involved in malignant transformation, tumor progression, differentiation. RCAS1 appears to be upregulated in high stages of colorectal cancer. RCAS1 expression might be a useful additional criterion for staging this cancer.