Hazlewood J, Fonagy A, Henning D, Freeman J W, Busch R K, Busch H
Department of Pharmacology, Baylor College of Medicine, Houston, TX 77030.
Cancer Commun. 1989;1(1):29-34. doi: 10.3727/095535489820875426.
A monoclonal antibody to a human tumor nucleolar 120 kD protein was developed by Freeman et al. (Cancer Res. 48: 1244-1251, 1988). Its complementary DNA (cDNA) has been isolated and sequenced (Fonagy et al., submitted). To determine the relative messenger RNA (mRNA) level for protein p120, cellular mRNA was extracted, slot-blotted onto nitrocellulose filters, and hybridized to radioactive p120 cDNA fragments. Human tumor cells contained 15-60 times more p120 mRNA than human term placenta. The rat Novikoff hepatoma ascites cell mRNA hybridized to the p120 cDNA probes, but the p120 monoclonal antibody did not react with the Novikoff hepatoma proteins. Novikoff hepatoma mRNA contained 8 times as much p120 mRNA as normal rat liver. As a control, a cDNA was used for protein B23, an abundant nucleolar protein; there were 3.5, 29, and 14 times more B23 mRNA than p120 mRNA in normal rat liver, Novikoff hepatoma ascites cells, and HeLa cells, respectively. Whereas the increased levels of the mRNA and protein B23 reflect increased activity of the nucleolus for any increment of nucleolar function, the increased levels of p120 mRNA and the p120 protein reflect the activity of the G1 phase of the cell cycle. The elevated level of p120 mRNA in tumors may reflect the heightened G1 cascade in transformed cells.
弗里曼等人研制出了一种针对人类肿瘤核仁120 kD蛋白的单克隆抗体（《癌症研究》48: 1244 - 1251, 1988）。其互补DNA（cDNA）已被分离并测序（福纳吉等人，待发表）。为了确定蛋白质p120的相对信使RNA（mRNA）水平，提取细胞mRNA，点样到硝酸纤维素滤膜上，然后与放射性p120 cDNA片段杂交。人类肿瘤细胞中的p120 mRNA比足月胎盘多15至60倍。大鼠诺维科夫肝癌腹水细胞的mRNA与p120 cDNA探针杂交，但p120单克隆抗体不与诺维科夫肝癌蛋白发生反应。诺维科夫肝癌mRNA中的p120 mRNA含量是正常大鼠肝脏的8倍。作为对照，使用了一种针对丰富的核仁蛋白B23的cDNA；在正常大鼠肝脏、诺维科夫肝癌腹水细胞和人宫颈癌HeLa细胞中，B23 mRNA分别比p120 mRNA多3.5倍、29倍和14倍。虽然mRNA和蛋白质B23水平的升高反映了核仁功能任何增量时核仁活性的增加，但p120 mRNA和p120蛋白水平的升高反映了细胞周期G1期的活性。肿瘤中p120 mRNA水平的升高可能反映了转化细胞中G1期级联反应的增强。
