Differential expression of mucins in Middle Eastern patients with colorectal cancer

Mucin overexpression has been implicated in the tumorigenesis and progression of colorectal carcinoma (CRC). However, data obtained on the prognostic importance of mucin expression in CRC is inconsistent. Due to lack of data on mucin expression and the increase in CRC incidence in Saudi Arabia, the aim of the present study was to analyze the mucin expression profile in patients with CRC in this ethnic group. The present study consisted of 22 patients that underwent surgery for CRC. Histopathological and immunohistochemical staining was performed on CRC tumor and adjacent normal tissues. A tissue microarray was prepared from the tumor and normal adjacent samples to investigate the mucin expression profile using immunohistochemistry. Formalin-fixed paraffin-embedded human colorectal cancer tissues were immunostained with mucin 1 (MUC1), mucin 2 (MUC2) and mucin 5AC (MUC5AC) antibodies. Associations between mucin expression and histopathological variables were evaluated. The present study indicated that MUC1 was highly expressed in early (stage I and II; P=0.0016) and late (stage III and IV; P<0.0001) stage CRC tissues compared to normal adjacent tissues. However, MUC2 expression was observed to be downregulated in early and late stage CRC tissues compared to normal and adjacent tissues. Furthermore, serum MUC1 levels were observed to be increased in early and late stage CRC. The present findings indicate that MUC1 expression was significantly higher in early and late stage CRC tissues and MUC2 was downregulated in CRC tissues compared with normal adjacent tissues, and serum MUC1 protein was significantly higher in CRC patients compared to control serum. In conclusion, during colorectal tumorigenesis the pattern of MUC1 and MUC2 expression is altered in Saudi Arabian patients with CRC compared with normal. A higher expression of MUC1 may be used as an independent biomarker in various stages of CRC tumors, which would aid in the early detection of CRC.