Floryk Daniel, Tollaksen Sandra L, Giometti Carol S, Huberman Eliezer
Gene Expression Group, Energy Systems Division and Bioscience Division, Argonne National Laboratory, Argonne, Illinois, USA.
Cancer Res. 2004 Dec 15;64(24):9049-56. doi: 10.1158/0008-5472.CAN-04-1553.
To establish a system to study differentiation therapy drugs, we used the androgen-independent human prostate PC-3 tumor cell line as a target and mycophenolic acid (MPA), tiazofurin, or ribavirin, which are inhibitors of IMP dehydrogenase, as inducers. These inhibitors evoked replication arrest, caused an increase in cell size, and triggered vacuolization of the cytoplasm. By Northern and Western blotting and immunostaining, we demonstrated MPA-induced expression of 12 proteins reported to reside in prostasomes, organelles released by secretory luminal prostate cells. Additional MPA-induced proteins were identified by two-dimensional gel electrophoresis. Among these was keratin 17, a prostate cell differentiation marker. By Northern blotting, we also demonstrated the constitutive expression of keratins 8 and 18 and induced expression of keratin 19, three other prostate cell differentiation markers. In addition, we established that cells were committed to differentiate after the 2nd day of MPA treatment using guanosine, which can abrogate the effects of MPA. Based on the expression patterns of prostasomal proteins and keratins and the presence of tentative secretory vacuoles, we hypothesize that IMP dehydrogenase inhibitors induce androgen-independent PC-3 cells to mature into cells with a phenotype that resembles normal prostate luminal cells, but at their intermediate state of differentiation.
为建立一个研究分化治疗药物的系统，我们以雄激素非依赖性人前列腺PC-3肿瘤细胞系为靶点，使用肌苷单磷酸脱氢酶（IMP dehydrogenase）抑制剂霉酚酸（MPA）、噻唑呋林或利巴韦林作为诱导剂。这些抑制剂引起复制停滞，导致细胞体积增大，并引发细胞质空泡化。通过Northern印迹法、Western印迹法和免疫染色，我们证明了MPA诱导了12种据报道存在于前列腺小体中的蛋白质的表达，前列腺小体是分泌性管腔前列腺细胞释放的细胞器。通过二维凝胶电泳鉴定出了其他MPA诱导的蛋白质。其中包括角蛋白17，一种前列腺细胞分化标志物。通过Northern印迹法，我们还证明了角蛋白8和18的组成性表达以及角蛋白19的诱导性表达，角蛋白19是另外三种前列腺细胞分化标志物。此外，我们证实，使用鸟苷（可消除MPA的作用）后，细胞在MPA处理的第2天后开始分化。基于前列腺小体蛋白和角蛋白的表达模式以及临时分泌空泡的存在，我们推测IMP脱氢酶抑制剂可诱导雄激素非依赖性PC-3细胞成熟为具有类似于正常前列腺管腔细胞表型的细胞，但处于其分化的中间状态。
