Aboagye-Mathiesen G, Zdravkovic M, Tóth F D, Graham C H, Lala P K, Ebbesen P
Department of Virus and Cancer, Danish Cancer Society, Aarhus, Denmark.
Early Pregnancy. 1996 Jun;2(2):102-12.
The expression of the tumor suppressor/oncoprotein p53 has been investigated in normal human placental villous trophoblast, in vitro propagated invasive extravillous trophoblast, SV40 tumor antigen (Tag)-immortalized extravillous trophoblast, human cytomegalovirus (hCMV)-infected syncytiotrophoblast and malignant trophoblast (choriocarcinoma) cell lines (JAR, JEG-3 and BeWo) using quantitative enzyme-linked immunosorbent assay (ELISA) and Western immunoblot methods using monoclonal antibodies specific for wild-type and mutant p53. The normal villous and extravillous trophoblast cells expressed low levels of the wild-type p53 protein, whereas normal terminally differentiated multinucleated syncytiotrophoblast cells, as well as hCMV-infected syncytiotrophoblast, showed a higher expression of the wild-type p53 protein. SV40 Tag-immortalized invasive trophoblast cells also showed a high expression of the wild-type p53 protein which remained complexed with the Tag protein. All the choriocarcinoma cell lines over expressed the mutant form of the p53 protein. The increased expression of p53 protein in the SV40 Tag-immortalized invasive trophoblast and choriocarcinoma cells paralleled with increased expression of the mouse double minute 2 (mdm2) oncogenic protein. Transforming growth factor (TGF)-beta inhibited proliferation of normal extravillous trophoblast cells. The antiproliferative effects of TGF-beta were reduced in SV40 Tag-immortalized cells and non-detectable in choriocarcinoma cell lines JAR, BeWo and JEG-3. The inactivation of p53 owing to complexing with Tag in the immortalized premalignant trophoblast and p53 mutation in the malignant trophoblast may be responsible for their aberrant proliferation and refractoriness to antiproliferative effects of TGF-beta observed in these cells as compared to the normal trophoblast. These results may suggest the role of p53 protein in trophoblast differentiation, transformation and tumorigenesis.
采用定量酶联免疫吸附测定（ELISA）和使用针对野生型和突变型p53的单克隆抗体的Western免疫印迹方法，研究了肿瘤抑制因子/癌蛋白p53在正常人类胎盘绒毛滋养层细胞、体外培养的侵袭性绒毛外滋养层细胞、SV40肿瘤抗原（Tag）永生化的绒毛外滋养层细胞、人巨细胞病毒（hCMV）感染的合体滋养层细胞以及恶性滋养层（绒毛膜癌）细胞系（JAR、JEG-3和BeWo）中的表达情况。正常绒毛和绒毛外滋养层细胞表达低水平的野生型p53蛋白，而正常终末分化的多核合体滋养层细胞以及hCMV感染的合体滋养层细胞则显示出野生型p53蛋白较高的表达。SV40 Tag永生化的侵袭性滋养层细胞也显示出野生型p53蛋白的高表达，且该蛋白与Tag蛋白保持复合状态。所有绒毛膜癌细胞系均过度表达p53蛋白的突变形式。SV40 Tag永生化的侵袭性滋养层细胞和绒毛膜癌细胞中p53蛋白表达的增加与小鼠双微体2（mdm2）致癌蛋白表达的增加平行。转化生长因子（TGF）-β抑制正常绒毛外滋养层细胞的增殖。TGF-β的抗增殖作用在SV40 Tag永生化细胞中降低，在绒毛膜癌细胞系JAR、BeWo和JEG-3中未检测到。与正常滋养层相比，在永生化的癌前滋养层中p53因与Tag复合而失活，在恶性滋养层中p53发生突变，这可能是这些细胞异常增殖以及对TGF-β抗增殖作用产生抗性的原因。这些结果可能提示p53蛋白在滋养层分化、转化和肿瘤发生中的作用。
