Expression Of Leptin And Vascular Endothelial Growth Factor In Gastric Cancer And Their Significance

Objective: Leptin, the product of the ob gene, plays a crucial role in the homeostasis of body weight by regulating food intake and energy expenditure. Recently, it was founded that leptin could stimulate the growth, migration and invasion of tumor cells and promote angiogenesis processes. The aim of the present study was to examine the expression of leptin and vascular endothelial growth factor (VEGF) to investigate their roles in gastric cancer. Methods: Specimens of cancer tissues were obtained from 50 patients with gastric cancer (34 men and 16 women, mean age 58.2 years) who underwent gastrectomy from March to December in 2004 in our hospital. From 30 of them normal tissues were also obtained as control, that is ,the cutting edge surgically resected tissues which were at least 5cm distant from the primary tumor and were confirmed pathologically containing no malignant cells. All tissue specimens were routinely fixed in 10% phosphate-buffered formalin and embedded in paraffin. The expression of leptin and VEGF in every tissue specimen were examined by immunohistochemical staining (SP). Nutritional assessments and symptom scores were also obtained in all patients. Results: 1. Leptin protein was measured in both normal tissues and cancer tissues. The expression of leptin in cancer tissues was higher than in normal tissues (72% vs 46.67%,χ2 =5.13,P<0.05). 2. The expression of VEGF in cancer tissues was higher than in normal tissues (60% vs 36.67%,χ2 =4.09,P<0.05). 3. The positive rates of leptin in tumors with serosa invasion and lymph node metastasis and in advanced stage(stageⅢ+Ⅳ) were higher than those without serosa invasion and without lymph node metastasis and in relatively early stage (stage Ⅰ+ Ⅱ)(82.35%, 80.49%, 91.67% vs 50%, 33.33%, 53.85%, respectively, P<0.05). 4. The positive rates of VEGF in tumors with serosa invasion and lymph node metastasis and in advanced stage (stageⅢ+Ⅳ) were higher than those without serosa invasion and without lymph node metastasis and in relatively early stage (stageⅠ+Ⅱ)(73.53%, 68.29%, 79.17% vs 31.25%, 22.22%, 42.31%, respectively, P<0.05). 5. Correlation analysis showed that there was a positive correlation between the expression of leptin and VEGF(r=0.404,P <0.01). 6. In both male and female patients, there was no correlation between BMI and the expression of leptin in cancer tissues and in normal tissues. While, the expression of leptin inboth cancer tissues and normal tissues correlated with weight loss (r=0.893, 0.634,P<0.001, 0.001). 7. Correlation analysis showed that the expression of leptin in both cancer tissues and normal tissues correlated with the symptom scores of losing appetite(r=0.343,0.600,P<0.05,0.001)and early satiety(r=0.341,0.637,P<0.05,0.001). Conclusions 1. The expression of leptin and VEGF in gastric cancer tissues is higher than in normal tissues. Leptin might play a role in the course of tumor invasion and metastasis via up-regulating the expression of VEGF or cooperating with VEGF. 2. In gastric cancer patients, gastric leptin might play a role in the control of food intake and thereby regulate body weight.