Park Hyeyoung, Im Ji Young, Kim Jeonga, Choi Wahn Soo, Kim Hyung Sik
Laboratory of Molecular Toxicology, College of Pharmacy, Pusan National University, Busan 609-735, Korea.
Int J Mol Med. 2008 Mar;21(3):325-33.
The cellular susceptibility of cancer cells to histone deacetylase (HDAC) inhibitors is increased by the etopic expression of oncogenic Ras. However, the ability of HDAC inhibitors to regulate the apoptotic pathway in human breast cancer cells is still not completely understood. In this study, the anti-proliferative effects of apicidin were compared in H-ras-transformed human breast epithelial (MCF10A-ras) and non-transformed epithelial (MCF10A) cells. MCF10A-ras cells showed a significantly higher growth rate than MCF10A cells. Apicidin significantly increased the levels of acetylated histone H3 and H4 in both cell lines. Western blot analysis and flow cytometry were used to determine if the anti-proliferative effects of apicidin in MCF10A and MCF10A-ras cells could be mediated by modulating the cell cycle. Apicidin attenuated the expression of cyclin E and CDK2 in MCF10A cells, decreased cyclin D1 and cyclin E levels in MCF10A-ras cells, and increased the levels of CDK inhibitors, p21WAF1/Cip1 and p27Kip1, in both cell lines. Notably, the levels of hyperphosphorylation of the Rb protein levels were lower in the MCF10A-ras cells after apicidin treatment. Studies on the regulation of apoptosis showed that apicidin induces the up-regulation of p53 and the downstream activation of ERK in MCF10A-ras cells. The up-regulation of p53 promoted Bax expression leading to activation of caspases-9 and -6, and eventually to apoptosis in MCF10A-ras cells. In addition, apicidin significantly increased the levels of ERK1/2 phosphorylation in MCF10A-ras cells. Therefore, the apicidin-mediated ERK pathway appears to play an important role in modulating the pro-apoptotic pathway in MCF10A-ras cells.
致癌性Ras的异位表达会增加癌细胞对组蛋白去乙酰化酶（HDAC）抑制剂的细胞敏感性。然而，HDAC抑制剂调节人乳腺癌细胞凋亡途径的能力仍未完全明确。在本研究中，比较了阿皮西丁对H-ras转化的人乳腺上皮细胞（MCF10A-ras）和未转化的上皮细胞（MCF10A）的抗增殖作用。MCF10A-ras细胞的生长速率显著高于MCF10A细胞。阿皮西丁显著提高了两种细胞系中乙酰化组蛋白H3和H4的水平。采用蛋白质免疫印迹分析和流式细胞术来确定阿皮西丁在MCF10A和MCF10A-ras细胞中的抗增殖作用是否可通过调节细胞周期来介导。阿皮西丁减弱了MCF10A细胞中细胞周期蛋白E和细胞周期蛋白依赖性激酶2（CDK2）的表达，降低了MCF10A-ras细胞中细胞周期蛋白D1和细胞周期蛋白E的水平，并提高了两种细胞系中CDK抑制剂p21WAF1/Cip1和p27Kip1的水平。值得注意的是，阿皮西丁处理后，MCF10A-ras细胞中Rb蛋白的过度磷酸化水平较低。对凋亡调节的研究表明，阿皮西丁诱导MCF10A-ras细胞中p53上调以及细胞外信号调节激酶（ERK）的下游激活。p53的上调促进了Bax表达，导致半胱天冬酶-9和-6激活，最终导致MCF10A-ras细胞凋亡。此外，阿皮西丁显著提高了MCF10A-ras细胞中ERK1/2的磷酸化水平。因此，阿皮西丁介导的ERK途径似乎在调节MCF10A-ras细胞的促凋亡途径中起重要作用。
