Detection of colorectal dysplasia using fluorescently labelled lectins.

Joe Chin-Hun Kuo,Sarah Dawson,Nicola S Fearnhead,Kevin M Brindle,André A Neves,Richard Miller,Kiran Guttula,Douglas J Winton,William J Howat,Deepak Parashar,Ashraf E K Ibrahim

doi:10.1038/srep24231

Abstract

Colorectal cancer screening using conventional colonoscopy lacks molecular information and can miss dysplastic lesions. We tested here the ability of fluorescently labelled lectins to distinguish dysplasia from normal tissue when sprayed on to the luminal surface epithelium of freshly resected colon tissue from the Apcmin mouse and when applied to fixed human colorectal tissue sections. Wheat germ agglutinin (WGA) showed significantly decreased binding to adenomas in the mouse tissue and in sections of human colon from 47 patients. Changes in WGA binding to the human surface epithelium allowed regions containing normal epithelium (NE) or hyperplastic polyps (HP) to be distinguished from regions containing low-grade dysplasia (LGD), high-grade dysplasia (HGD) or carcinoma (C), with 81% sensitivity, 87% specificity and 93% positive predictive value (PPV). Helix pomatia agglutinin (HGA) distinguished epithelial regions containing NE from regions containing HP, LGD, HGD or C, with 89% sensitivity, 87% specificity and 97% PPV. The decreased binding of WGA and HPA to the luminal surface epithelium in human dysplasia suggests that these lectins may enable more sensitive detection of disease in the clinic using fluorescence colonoscopy.

Highlights

Progression of colorectal cancer (CRC) from low- to high-grade dysplasia[1] provides an opportunity for prophylactic removal[2,3] of low-risk adenomas, which has been shown to reduce mortality[4]
We have investigated here the potential of fluorescently labelled lectins to detect dysplasia elsewhere in the gastrointestinal tract, in this case the colon, using lectins that have been reported previously to show changes in binding to colorectal neoplasia, including Helix pomatia agglutinin (HPA)[30], Artocarpus integrifolia or jackfruit lectin (JFL)[31], Arachis hypogaea or peanut agglutinin (PNA)[32], Glycine max or soybean agglutinin (SBA)[33], and Triticum vulgaris or wheat germ agglutinin (WGA)[31]
Binding of WGA was quantified and expressed as the mean fluorescence intensity (MFI) ratio of lectin-to-background (Fig. 1c). This paired analysis showed a reduction in WGA binding to adenomas in the colon (Fig. 1c(i)), and in the small intestine (Fig. 1c(ii))

Summary

Introduction

Progression of colorectal cancer (CRC) from low- to high-grade dysplasia[1] provides an opportunity for prophylactic removal[2,3] of low-risk adenomas, which has been shown to reduce mortality[4]. Using freshly resected colon tissue from the Apcmin mouse and formalin fixed paraffin embedded (FFPE) human tissue sections, we show that some of these lectins, when fluorescently labelled, can distinguish between normal and dysplastic tissue from their differential binding to colorectal luminal surface epithelium. Since this surface is accessible to endoscopic examination, these lectins have the potential to be translated to the clinic for detecting colorectal dysplasia using fluorescence colonoscopy

Methods

Results

Conclusion