Expression of Interleukin-11 and Interleukin-11 receptor α in human colorectal adenocarcinoma; Immunohistochemical analyses and correlation with clinicopathological factors

AIM: There is strong evidence that interleukin-11 (IL-11) is involved in the regulation of tumor progression, cellular growth and differentiation. Recently, interleukin-11 receptor (IL-11R) has been detected on some cancer cells. In this study, we investigated the expression of IL-11 and IL-11R in colorectal adenocarcinoma. METHODS: To elucidate the involvement of IL-11 and IL-11Ra in human intestinal adenocarcinomas, we examined 115 cases of surgically resected human colonic adenocarcinoma and 11 cases of adenoma by immunohistochemistry and Western blotting. RESULTS: Among 115 cases of adenocarcinoma, 100 cases (87.0%) showed positive staining in the cytoplasm of carcinoma cells for the IL-11, and 87 cases (75.6%) were positive for the IL-11Ra. Six cases (54.5%) and four cases (36.4%) of 11 adenomas were positive for IL-11 and IL-11Ra, respectively. The expression of IL-11Ra correlated with the histological differentiation (P = 0.033503), the depth of tumor invasion (P = 0.006395), Dukes'classification (P = 0.015648) and lymphatic invasion (P = 0.003865). However, the expression of IL-11Ra was not correlated with the venous invasion and the presence of lymph node metastasis. The expression of IL-11 was not correlated with any clinicopathological factors. In Western blot analysis, two human colorectal carcinoma cell lines and four tissues of surgically resected human carcinoma expressed both IL-11 and IL-11Ra proteins. CONCLUSION: IL-11 and IL-11Ra are highly expressed in human colorectal adenocarcinoma and the IL-11Ra expression is correlated with clinicopathological factors. These findings suggest that the expression of IL-11Ra is an important factor for the invasion of human colorectal adenocarcinoma.