Orntoft T F, Meldgaard P, Pedersen B, Wolf H
Department of Clinical Biochemistry, Aarhus University Hospital, Skejby, Denmark.
Cancer Res. 1996 Mar 1;56(5):1031-36.
The molecular mechanism that in human bladder tumors leads to the loss of blood group ABO glycosyltransferase activity and, thereby, the loss of ABO antigens was investigated. In 15 tumors and 3 normal biopsies from blood group AB individuals and 7 tumors and 3 normal biopsies from blood group O individuals, mRNA was detected by a reverse transcription PCR (RT-PCR) assay, and the ABO blood group structure was determined by immunohistology. The RT-PCR spanned several introns in the ABO gene to exclude DNA contamination, and the RT-PCR product was shown to reflect the ABO gene message by dideoxy sequencing. The ABO mRNA was present in normal urothelium and low-grade tumors but disappeared from high grade tumors. This correlation to tumor grade was significant (P<0.04). Immunohistochemistry with monoclonal anti-blood group antibodies showed a complete correlation between the presence of mRNA and the presence of AB carbohydrate structures on cell surfaces. In two urothelial cell lines, genotyped as A/- and A/A, growth stimulation with the cholera toxin B subunit led to a total loss of ABO mRNA, and epidermal growth factor stimulation had an identical effect on one of the cell lines. We conclude that the ABO glycosylation in normal and malignant urothelium is regulated at the mRNA level, and that a mechanism associated with cell proliferation may trigger down-regulation of ABO mRNA.
研究了人类膀胱肿瘤中导致ABO血型糖基转移酶活性丧失从而ABO抗原丢失的分子机制。在15例AB血型个体的肿瘤组织和3例正常活检组织，以及7例O血型个体的肿瘤组织和3例正常活检组织中，通过逆转录聚合酶链反应（RT-PCR）检测mRNA，并通过免疫组织学确定ABO血型结构。RT-PCR跨越ABO基因的几个内含子以排除DNA污染，并且通过双脱氧测序显示RT-PCR产物反映了ABO基因信息。ABO mRNA存在于正常尿路上皮和低级别肿瘤中，但在高级别肿瘤中消失。这种与肿瘤级别的相关性具有显著性（P<0.04）。用单克隆抗血型抗体进行免疫组织化学显示，mRNA的存在与细胞表面AB碳水化合物结构的存在完全相关。在两个基因型分别为A/-和A/A的尿路上皮细胞系中，用霍乱毒素B亚基进行生长刺激导致ABO mRNA完全丧失，表皮生长因子刺激对其中一个细胞系产生相同的效果。我们得出结论，正常和恶性尿路上皮中的ABO糖基化在mRNA水平受到调控，并且与细胞增殖相关的一种机制可能触发ABO mRNA的下调。
