Prete S P, Aquino A, Masci G, Orlando L, Giuliani A, De Santis S, De Vecchis L, De Filippi R, Greiner J W, Bonmassar E, Graziani G
Department of Experimental Medicine and Biochemical Sciences, University of Rome, Tor Vergata, Italy.
J Pharmacol Exp Ther. 1996 Dec;279(3):1574-81.
Previous studies showed that 5-fluorouracil (5-FU) is capable of enhancing the membrane reactivity of the human colon carcinoma cell line HT-29 with a monoclonal antibody (COL-1) directed against carcinoembryonic antigen (CEA). In the present study, we show that short-term exposure (i.e., 1 hr) of cancer cells to 5-FU mediates a marked increase of CEA expression, that is concentration-dependent and lasts up to day 5 after treatment. This phenomenon is the result of the drug-mediated enhancement of the CEA expression, but not of the selection of the CEA-positive cells operated by the antimetabolite. This is supported by the finding that the increase of the CEA expression detected by cytofluorimetric analysis is observed not only in the parental HT-29 line, but also in its C22.20 subclone, endowed with a low basal level of CEA and with chemosensitivity to 5-FU lower than that of the parental cell line. Moreover, increase of CEA expression occurs not only in the plasma membrane, but also in the cytosolic cellular compartment, as indicated by the results of Western blot analysis. Northern blot analysis of total RNA extracted from 5-FU-treated HT-29 or C22.20 cells shows an increase in the steady-state levels of CEA and CEA-related transcripts (e.g., biliary glycoprotein). Moreover 5-FU-mediated augmentation of the CEA transcript appears to be attributable mainly to enhanced transcription rather than to increased mRNA stability. It is concluded that induction of enhanced CEA protein expression in cancer cells treated with 5-FU could be of clinical interest for the development of immunochemotherapeutic protocols based on CEA protein as the target molecule.
先前的研究表明，5-氟尿嘧啶（5-FU）能够通过一种针对癌胚抗原（CEA）的单克隆抗体（COL-1）增强人结肠癌细胞系HT-29的膜反应性。在本研究中，我们发现癌细胞短期暴露于5-FU（即1小时）会介导CEA表达显著增加，这种增加呈浓度依赖性，且在治疗后可持续至第5天。这一现象是药物介导的CEA表达增强的结果，而非抗代谢物对CEA阳性细胞的选择所致。细胞荧光分析检测到的CEA表达增加不仅在亲本HT-29细胞系中观察到，在其CEA基础水平较低且对5-FU的化学敏感性低于亲本细胞系的C22.20亚克隆中也观察到，这支持了上述结论。此外，蛋白质免疫印迹分析结果表明，CEA表达的增加不仅发生在质膜上，也发生在细胞溶质区室中。对从5-FU处理的HT-29或C22.20细胞中提取的总RNA进行的Northern印迹分析显示，CEA及CEA相关转录本（如胆汁糖蛋白）的稳态水平增加。此外，5-FU介导的CEA转录本增加似乎主要归因于转录增强，而非mRNA稳定性增加。得出的结论是，在用5-FU处理的癌细胞中诱导CEA蛋白表达增强，对于基于CEA蛋白作为靶分子的免疫化学治疗方案的开发可能具有临床意义。
