Alterations in lectin binding in the proximal and distal colon of Sprague-Dawley rats with 1,2 dimethylhydrazine administration

Sequential changes in rhodamine or fluorescein isothiocyanate-conjugated lectin binding of proximal and distal colonic crypts were studied during and after the administration of the 1,2 dimethylhydrazine (DMH). Five adult its unexposed to DMH or vehicle served as baseline controls. Tissue from normal appearing colon and tumor tissue was incubated with Ulex europaeus agglutinin 1 (UEA), Arachis hypogaea (PNA), Dolichos biflorus (DBA) and Griffonia simplicafolia 1 (GSA1). Distinct regional differences were noted in the baseline controls. UEA, PNA and DBA binding were absent in the distal colonic crypt cells. In the proximal colon minimal UEA and PNA binding was noted in the lower crypt whereas DBA binding was intense. GSA1 binding was diffuse in the upper and lower crypt of both regions. During carcinogenesis a progressive increase in PNA binding was noted in normal appearing colonic crypts from both regions. A progressive increase in PNA binding in proximal and distal colonic tumors was noted over time. Similar to normal tissue, DBA bound markedly to proximal colon tumors but was absent in most distal colonic tumors. UEA stained all proximal tumors intensely at all time points. In distal colonic tumors, UEA staining was diminished at 30 weeks compared to tumors analyzed at 16, 22 and 26 weeks. Mucin depletion was also a feature of tumor tissue compared to adjacent normal and hyperplastic glands. This study documents the region specific changes in lectin binding in normal and neoplastic colonic crypts induced by DMH.