ABSTRACT
BACKGROUND: Though leptin, the adipocytes-derived hormone, plays an important role in obesity, it can act as a growth factor for several cancers including gastrointestinal malignancies. Based on this background, we investigated whether leptin expression correlated with the clinicopathological characteristics or disease outcome in patients with colon cancer. We immunohistochemically analyzed the expression of leptin in a "colon adenoma-carcinoma sequence" in the normal colon mucosa, an adenomatous polyp and adenocarcinoma tissue, from a surgical resection for each patient. METHODS: We collected samples from 24 patients with a colorectal adenocarcinoma that was removed in either a total colectomy or hemicolectomy, and who presented with an adenomoatous polyp and an adenocarcinoma in the same surgical specimen. Leptin expression was assessed using immunohistochemical methods and was evaluated by grading the staining intensity as 0, +1, +2, +3. RESULTS: Whereas leptin expression was observed in 4.2% (1/24) of the normal colon mucosa, adenomatous polyps and adenocarcinomas showed 33.3% (8/24) and 50.0% (12/24) expression of leptin, respectively (p<0.05), suggesting that leptin expression in the adenomatous polyps and adenocarcinomas was higher than in the normal colon mucosa (p<0.05). There was no significant difference in leptin expression between the adenomatous polyps and adenocarcinomas, statistically. There was no relationship between leptin expression and patients age, sex, BMI (body mass index), cancer stage, and lymph node metastasis. However, the tumor size in the positive leptin expression group was larger than in the negative leptin expression group (5.6+/-2.2 cm vs 3.9+/-1.4 cm; p<0.05) CONCLUSIONS: Since leptin expression in adenomatous polyps and adenocarcinomas was higher than in the normal colon mucosa and leptin expression significantly correlated with the tumor size, leptin might play a role in the development of an adenomatous polyp and an adenocarcinoma in the colon. However, leptin does not contribute to the progression of colon adenoma, and further evaluation studies will be required.