Association of downregulated glycotumor-markers and in vivo rejection

我们的原始胆管癌细胞系TK具有在培养基中分泌糖基化肿瘤标志物如CA 19 -9、CA 50或唾液酸刘易斯x（sLe^x）的特性。将IL-2和/或B7- 1基因转染TK后，在免疫低下的SCID小鼠皮下移植瘤细胞中观察到强烈的细胞病变效应和体内排斥反应，而在野生型细胞系中没有观察到这些特征性的变化，根据这些宝贵的研究结果，我推测这些特征性的变化可能是由于转染基因的强制表达引起糖基化抗原的异常表达。这些抗原被糖基转移酶，特别是Fuc-T组酶糖基化。目前已在人类中克隆了TIII、TIV、TV、TVI和TVII 5种亚型，并且证实FucTIII和TVII直接负责CA 19 -9和sLe^x以及Le^a或Le^B的合成。在这种情况下，我直接比较了每个转染子中糖基化抗原的糖基转移酶活性和量。此外，我还研究了这些细胞是否在糖基转移酶基因的关键元件上发生了突变。当通过HPLC测定时，尽管CA 19 -9、CA 50和sLex的表达在每个转染子中变化，但这些变化与酶活性不相关。通过RT-PCR证实Fuc-TVII基因转录水平没有发生变化，基因组DNA测序证实Fuc-TIII基因特异区没有发生突变。然而，由于我通过植入研究再次证实了显著的肿瘤排斥反应，因此需要进一步的研究来解释这一现象。

Our original cholangiocarcinoma cell line, TK has a property to secrete some glycosylated tumor markers such as CA19-9, CA50 or sialyl Lewis x (sLe^x) in the culture medium. When IL-2 and/or B7-l gene was transfected into the TK, I observed strong cytopathic effects and in vivo rejections in subcutaneous implantation of the tumor cells in immunocompromised SCID mouse, which did not occur in the wild type cell line.From the precious results of studies, I reasoned that these characteristic changes might originate from aberrant expressions of gylcosylated antigens caused by forced expression of transfected genes. These antigens are glycosylated by glycotransferase, especially by Fuc-T group enzymes. Currently, 5 subtypes, TIII, TIV, TV, TVI, and TVII, has been cloned in human and FucTIII and TVII are proved to be frankly responsible for synthesis of CA19-9 and sLe^x as well as Le^a or Le^b. In this stance, I performed direct comparisons of glycotransferase activity and amounts of gylcosylated antigens in each transfectants. Furthermore, I studied if these cells have mutations in the key elements of glycotransferase gene. When determined by HPLC, although expressions of CA19-9, CA50, and sLex varied in each transfectant these variances were not correlated with enzyme activities. I also confirmed no changes in Fuc-TVII transcription by RT-PCR.In each transfectant, there were no mutations in Fuc-TIII gene specific region by genomic DNA sequences. However, since I reconfirmed significant tumor rejections by implantation study, further studies will be needed to explain the phenomenon.