Imanishi H, Hada T, Muratani K, Hirano K, Higashino K
Third Department of Internal Medicine, Hyogo College of Medicine, Japan.
Cancer Res. 1990 Jun 1;50(11):3408-12.
An unusual alkaline phosphatase (AP), named HuG-AP, was found in a newly established cell line (HuG-1) derived from a patient with stomach cancer. The enzyme was purified about 300-fold by affinity chromatography. On polyacrylamide gradient (4-30%) gel electrophoresis, the one band with the enzyme activity was observed. The enzymic properties of HuG-AP did not conform to those of liver, intestinal, placental, and germ cell AP isoenzymes which were recognized as homodimeric structure. Thermostability of the HuG-AP showed an intermediate value between intestinal and placental APs. Immunologically, the HuG-AP reacted with both anti-intestinal and anti-placental AP monoclonal antibodies. Dot blot analysis showed that both intestinal and placental AP mRNAs were expressed in HuG-1 cells concurrently. Therefore, we concluded that this novel AP had a hybrid form, namely heterodimeric structure, consisting of one subunit each of intestinal and placental APs. However, all of the properties of this hybrid AP did not conform to the intermediate enzymic properties between intestinal and placental APs which would be shown when they both coexist. Because an AP identical to HuG-AP had already been found in the metastatic lesion of the liver of the same patient, the expression of this novel AP seemed to occur in the patient's original cancer cells but did not result from spontaneous transformation of cultured cells.
在一个新建立的源自胃癌患者的细胞系（HuG-1）中发现了一种异常的碱性磷酸酶（AP），命名为HuG-AP。该酶通过亲和层析纯化了约300倍。在聚丙烯酰胺梯度（4 - 30%）凝胶电泳中，观察到一条具有酶活性的条带。HuG-AP的酶学性质不符合被认为是同二聚体结构的肝、肠、胎盘和生殖细胞AP同工酶的性质。HuG-AP的热稳定性在肠型和胎盘型AP之间呈现中间值。在免疫方面，HuG-AP与抗肠型和抗胎盘型AP单克隆抗体均发生反应。斑点印迹分析表明，肠型和胎盘型AP的mRNA在HuG-1细胞中同时表达。因此，我们得出结论，这种新型AP具有一种杂交形式，即异二聚体结构，由肠型和胎盘型AP各一个亚基组成。然而，这种杂交AP的所有性质并不符合肠型和胎盘型AP同时存在时所呈现的中间酶学性质。因为在同一患者肝脏的转移病灶中已经发现了与HuG-AP相同的AP，所以这种新型AP的表达似乎发生在患者的原始癌细胞中，而不是由培养细胞的自发转化导致的。
