Lee Sooyong, Yoon Seunghee, Kim Dong-Hyun
Bioanalysis and Biotechnology Research Center, Korea Institute of Science and Technology, Seoul 136-791, South Korea.
Gynecol Oncol. 2007 Feb;104(2):338-44. doi: 10.1016/j.ygyno.2006.08.040. Epub 2006 Oct 4.
The aim of this study was to elucidate the role of ERK1/2 on cisplatin resistance in human ovarian cancer cells.
The relationship between nuclear levels of ERK2 and cisplatin-induced apoptosis in human ovarian carcinoma cell line, OVCAR-3, and in cells of the cisplatin-resistant subclone, OVCAR-3/CDDP, was examined using immunoblotting and immunocytochemistry.
Cisplatin treatment resulted in the activation of ERK2, both in OVCAR-3 and OVCAR-3/CDDP cells. However, considerable levels of activated ERK2 existed in the nuclei of OVCAR-3/CDDP cells during serum starvation and in the early period (1-3 h) after cisplatin treatment. Conversely, phospho-ERK2 was marginally detected in the nuclei of OVCAR-3 cells prior to cisplatin treatment. These phenomena were confirmed by immunofluorescence staining of the phosphorylated ERK2 in the nuclei of both cells. High basal phospho-ERK2 in the nuclei of OVCAR-3/CDDP cells contributed to cisplatin resistance, and was supported by several observations; (1) treatment of U0126, an inhibitor of MEK/ERK signaling pathway, partially sensitized OVCAR-3/CDDP cells to cisplatin; (2) pretreatment of OVCAR-3 cells with phorbol 12-myristate 13-acetate (PMA), an activator of ERK, induced nuclear translocation of activated ERK2, which led to the suppression of cisplatin-induced apoptosis.
These results collectively indicate that prelocalization of activated ERK2 in the nuclei contribute to cisplatin resistance in OVCAR-3/CDDP cells.
本研究旨在阐明细胞外信号调节激酶1/2（ERK1/2）在人卵巢癌细胞顺铂耐药中的作用。
采用免疫印迹法和免疫细胞化学法，检测人卵巢癌细胞系OVCAR-3及其顺铂耐药亚克隆OVCAR-3/CDDP细胞中ERK2的核水平与顺铂诱导凋亡之间的关系。
顺铂处理可导致OVCAR-3和OVCAR-3/CDDP细胞中ERK2激活。然而，在血清饥饿期间及顺铂处理后的早期（1-3小时），OVCAR-3/CDDP细胞核中存在相当水平的活化ERK2。相反，在顺铂处理前，OVCAR-3细胞核中仅能检测到少量磷酸化ERK2。通过对两种细胞细胞核中磷酸化ERK2的免疫荧光染色证实了上述现象。OVCAR-3/CDDP细胞核中高水平的基础磷酸化ERK2导致顺铂耐药，以下几点观察结果支持这一结论：（1）MEK/ERK信号通路抑制剂U0126处理可使OVCAR-3/CDDP细胞对顺铂部分敏感；（2）用佛波酯12-肉豆蔻酸酯13-乙酸酯（PMA，一种ERK激活剂）预处理OVCAR-3细胞，可诱导活化ERK2的核转位，进而抑制顺铂诱导的凋亡。
这些结果共同表明，活化ERK2在细胞核中的预定位导致了OVCAR-3/CDDP细胞的顺铂耐药。
