Mucin expression patterns in Thai colorectal cancer

Abstract

Colorectal cancer (CRC) is the third cause of death in cancer in the world etc. CRC is divided into 2 types; non-mucinous and mucinous types. The mucinous type of CRC is named by predominantly mucin feature secreted by goblet cells. Mucinous type was more frequently present in the proximal colon than in the distal colon and was mostly found in female and younger patients. Moreover, mucinous type was associated with poor prognosis and response to chemical therapies. In this study, we firstly aimed to investigate acid and neutral mucins expression patterns in the normal large intestine. Secondly, we were to compare the acid and neutral mucins, and MUC2 protein expression in mucinous and non-mucinous types of CRC early stage. All sample blocks were fixed and sectioned in 3 µm thickness. The sectioned was stained by Alcian blue (AB) pH2.5, Periodic acid Schiff (PAS), and Alcian blue combined with Periodic acid Schiff (AB-PAS) for examined acid and neutral mucins expression in normal large intestine and CRC tissues. The MUC2 protein expression in mucinous and non-mucinous CRC tissues was investigated by immunohistochemistry (IHC). In normal large intestine, we found the acid mucin showed significantly gradually increasing whereas the neutral mucin significantly gradually decreased from cecum to rectal parts of large intestine (p<0.001). In the non-mucinous type of CRC, the acid and neutral mucins, and MUC2 protein expression were significantly decreased in the cancer area compared to the normal area (p<0.001). The acid mucin and MUC2 protein expression were significantly increased but neutral mucin was significantly decreased in cancer area compared to the normal area of the mucinous type of CRC (p<0.001). Moreover, both mucinous and non-mucinous types of CRC showed the positive association between acid and MUC2 protein (p<0.001). In conclusion, increased acid mucin and MUC2 protein are correlated to mucinous type of CRC and thus may first step in the prognostic study of mucinous CRC subtype.

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