Aim To study the effect of melatonin on expression and activity of myosin light chain kinase in the artery wall of atherosclerotic rabbits.Methods The rabbit model of atherosclerosis was induced by a high-cholesterol diet.The blood lipid levels were assayed in the serum of each group.MLCK expression was detected by Western blot and immunohistochemical method.MLCK activity was measured by ?-32P-ATP incorporation into myosin light chain.Results The atherosclerosis model was established successfully.The levels of lipids decreased after MLT treatment.After fed with cholesterol for twelve weeks,the expression and activity of MLCK in the artery of atherosclerotic rabbits increased markedly,whereas there was no obvious difference in expression of MLCK in the artery of atherosclerotic rabbits fed with cholesterol and melatonin for twelve weeks compared with that of control.Conclusions It was suggest that high expression and activity of MLCK in the artery might be closely correlated with the development of atherosclerosis.Melatonin played an important role in inhibiting the development of atherosclerosis by decreasing the expression and activity of MLCK.

BACKGROUND/AIMS: Kruppel-like factor 4 (KLF4) is an epithelial-specific transcription factor primarily expressed in the gastrointestinal tract that mediates growth arrest in the colonic epithelium. We tried to find whether KLF4 expression is associated with the progression and differentiation of colorectal cancer. METHODS: We detected KLF4 expression in 109 colorectal specimens (40 normal appearing mucosa, 7 adenomas, and 62 carcinomas) by immunohistochemistry using a tissue microarray. Western blot and RT-PCR analyses were also performed. RESULTS: The upregulation of KLF4 expression in carcinoma tissue was statistically significant (p<0.05) when compared to normal appearing mucosa. The negative and weak positive staining rates in normal appearing mucosa, adenoma, and carcinoma were 42.5%, 71.4%, and 82.3%, respectively, indicating a decreased degree of KLF4 expression over the course of progressive transformation of normal cells into malignant derivatives. KLF4 protein levels showed no correlation with sex, age, or metastatic state (p>0.05), while KLF4 protein expression correlated with the diagnostic stage (p<0.05). Furthermore, strong KLF4 staining was detected in 22.9% (11/48) and 0% (0/14) of well/moderately and poorly differentiated colorectal cancers, respectively. Our results clearly indicate that KLF4 protein expression significantly correlates with the degree of differentiation in colorectal cancers (p<0.05). KLF4 expression in RKO cells is also upregulated by butyrate, an inducer of differentiation. CONCLUSIONS: Downregulation of KLF4 expression may lead to more poorly differentiated tumors.
Adenoma ; Blotting, Western ; Butyrates ; Colon ; Colorectal Neoplasms ; Down-Regulation ; Epithelium ; Gastrointestinal Tract ; Immunohistochemistry ; Kruppel-Like Transcription Factors ; Mucous Membrane ; Transcription Factors ; Up-Regulation