Immunohistochemical analysis of pericryptal fibroblast sheath and proliferating epithelial cells in human colorectal adenomas and carcinomas with adenoma components.

In order to examine stromal-epithelial interaction during the oncogenic progression of large bowel tumors, the association between pericryptal fibroblast sheath (PCFS) and expression of Ki-67 antigen was evaluated in 87 cases of colorectal adenoma and 95 cases of carcinoma with an adenoma component (CWA). For the immunohistochemistry, anti-alpha-smooth muscle actin antibody (alpha-SMA) and anti-Ki-67 antigen antibody (MIB-1) were used. In adenomas and adenoma components of CWA, the quantity of neoplastic glands with PCFS was reduced relative to the progression of histological atypia. Pericryptal fibroblast sheath was virtually absent from invasive carcinoma areas of CWA. Increased expression of Ki-67 correlated with the degree of histological atypia of adenomas. A significant reverse correlation was also seen between Ki-67 expression and PCFS-positive glands in adenoma components of CWA. These findings suggest that the prevalence of PCFS and Ki-67 expression are important indicators of colorectal neoplasia progression. The significant reduction of PCFS in colorectal epithelial neoplasms reflects progression in the adenoma-carcinoma sequence.