Progressive cellular response in the lamina propria of the colorectal adenoma-carcinoma sequence.

ABSTRACT

AIMS: The lamina propria is inevitably involved in epithelial transformation. The aim was to evaluate the dynamic cellular changes in the tumour lamina propria throughout the colorectal adenoma-carcinoma sequence. METHODS AND RESULTS: Using immunohistochemistry and double immunohistochemistry, we examined lamina propria cellular changes in 41 colorectal adenomas, 25 colorectal cancers and 15 control tissues. The results showed that the proliferation labelling index in lamina propria cells began to increase in the precancerous lesions (adenomas) and became even higher in the colorectal cancers; these proliferative cells were primarily identified as myofibroblasts and lymphocytes. Phenotypic analysis revealed gradually increasing lymphocytic infiltration in both the lamina propria and adenomatous epithelium, as well as myofibroblasts in the lamina propria. However, the intraepithelial macrophage density also showed a tendency to increase gradually. Furthermore, cyclooxygenase-2-expressing cell density and microvessel density gradually increased in the tumour lamina propria throughout the adenoma-carcinoma sequence. CONCLUSIONS: Progressive cellular responses in the lamina propria could be involved in the adenoma-carcinoma transition.