【摘要】 目的　探讨人胃低分化腺癌SGC 790 1细胞与1 2 5I 叶酸体外结合特性及其细胞表面存在高密度、高亲和力叶酸受体的可能性。方法　采用放射配基受体结合分析法 ,观察SGC 790 1细胞和1 2 5I 叶酸结合与时间的关系、特异结合位点及亲和程度、不同竞争剂对SGC 790 1细胞结合1 2 5I 叶酸的影响及SGC 790 1细胞内化1 2 5I 叶酸的程度。结果　SGC 790 1细胞与1 2 5I 叶酸结合具有特异性、高亲和性、饱和性、竞争性及温度依赖性 ,其最大叶酸特异结合位点Bmax为 14 3 2 6fmol 10 6 细胞 ,平衡解离常数Kd 为 2 86× 10 - 1 0 mol L ,1 2 5I 叶酸可通过叶酸受体途径内化入SGC 790 1细胞。结论　SGC 790 1细胞表面具有高密度和高亲和力的叶酸受体及可供介导叶酸靶向诊断和治疗的靶点。更多还原

【Abstract】 Objective To investigate binding characteristics of 125I-folate to cultured human gastric cancer SGC-7901 cell line, and to evaluate the possibilities of the existence of high density, high affinity folate receptors in SGC-7901 cell line, and whether SGC-7901 can be used as a new target for folate receptor mediated, non-destructive diagnosis and tumor-targeting drug and gene delivery. Methods Binding kinetics of 125I-folate to SGC-7901 cells , effect of SGC-7901 cell concentrations on binding, radioligand saturation binding experiment, competition assay, and internalization of 125I-folate into SGC-7901 cells were investigated by classic radioligand binding techniques. Results Specific binding of 125I-folate to its receptors in SGC-7901 was time, temperature, and concentration dependent, and showed to be of high affinity, satuarable, competitable. The best fit to the data was of a single-binding-site model with a equilibrium dissociation constant (K d) of 2.86×10 -10 mol/L, and a maximum binding density (B max) 143.26 fmol/106cells. SGC-7901 cell bound 125I-folate was internalized at 37 ℃. These characteristics were in agreement with earlier studies on other kinds of cancer cells that overexpress folate receptors. Conclusion Gastric cancer SGC-7901 cell line is of the characteristics of high density, high affinity folate receptors and has the possibilities of serving as a new target for folate receptor mediated tumor specific diagnosis and therapeutics, but that conception needs further identification.更多还原