ABSTRACT
Objective To investigate midkine (MK) level in serum of patients with esophageal squamous cell carcinoma (ESCC) before and after operation,detect the expression of MK protein in tissues and analyze its relationship with the malignant biological behavior of ESCC.Methods The MK levels in serum were detected by enzyme-linked immunosorbent assay in 30 healthy cases and 55 patients with ESCC when the day before operation and the tenth-day after operation.Then the expression of MK protein in 55 patients surgically removed ESCC were detected by immunohistochemistry using monoclonal antibodies against human MK.Results The average optical density of MK in serum of ESCC patients before operation was 0.1006±0.0624,0.0455±0.0155 in normal control group,0.0752±0.0267 in postoperative control group (t =6.203,P ＜ 0.001).The MK levels in serum of ESCC patients before operation were significantly higher than those after operation (t =4.357,P ＜ 0.001) and those in healthy controls (P ＜ 0.05).The expression of MK protein was no statistically significant correlation with tumor size (x2 =0.131),TNM stage (x2 =0.315) and lymph node metastasis (x2 =0.282) in ESCC (all P ＞ 0.05).But significant correlation was noted between the expression of MK protein and the vasculature involving of the cutting edge (x2 =4.223),degree of cellular differentiation (x2 =10.326),invasive extent of the carcinoma (x2 =20.556) (all P ＜ 0.05).Conclusion MK is overexpressed in ESCC patient' s serum and tissue.The high level of preoperative serum MK is caused by the tumor.