Interdisciplinary Program of Toxicology, Texas A&M University, College Station, TX 77843, USA.
Breast Cancer Res Treat. 2012 Nov;136(1):21-34. doi: 10.1007/s10549-012-2224-0. Epub 2012 Sep 2.
Several studies have demonstrated that polyphenolics from pomegranate (Punica granatum L.) are potent inhibitors of cancer cell proliferation and induce apoptosis, cell cycle arrest, and also decrease inflammation in vitro and vivo. There is growing evidence that botanicals exert their cytotoxic and anti-inflammatory activities, at least in part, by decreasing specificity protein (Sp) transcription factors. These are overexpressed in breast tumors and regulate genes important for cancer cell survival and inflammation such as the p65 unit of NF-κB. Moreover, previous studies have shown that Pg extracts decrease inflammation in lung cancer cell lines by inhibiting phosphatidylinositol-3,4,5-trisphosphate (PI3K)-dependent phosphorylation of AKT in vitro and inhibiting the activation of NF-kB in vivo. The objective of this study was to investigate the roles of miR-27a-ZBTB10-Sp and miR-155-SHIP-1-PI3K on the anti-inflammatory and cytotoxic activity of pomegranate extract. Pg extract (2.5-50 μg/ml) inhibited growth of BT-474 and MDA-MB-231 cells but not the non-cancer MCF-10F and MCF-12F cells. Pg extract significantly decreased Sp1, Sp3, and Sp4 as well as miR-27a in BT474 and MDA-MB-231 cells and increased expression of the transcriptional repressor ZBTB10. A significant decrease in Sp proteins and Sp-regulated genes was also observed. Pg extract also induced SHIP-1 expression and this was accompanied by downregulation of miRNA-155 and inhibition of PI3K-dependent phosphorylation of AKT. Similar results were observed in tumors from nude mice bearing BT474 cells as xenografts and treated with Pg extract. The effects of antagomirs and knockdown of SHIP-1 by RNA interference confirmed that the anti-inflammatory and cytotoxic effects of Pg extract were partly due to the disruption of both miR-27a-ZBTB10 and miR-155-SHIP-1. In summary, the anticancer activities of Pg extract in breast cancer cells were due in part to targeting microRNAs155 and 27a. Both pathways play an important role in the proliferative/inflammatory phenotype exhibited by these cell lines.
已有多项研究表明，石榴（Punica granatum L.）中的多酚类化合物是癌细胞增殖的有效抑制剂，可诱导细胞凋亡、细胞周期停滞，并减少体内外的炎症。越来越多的证据表明，植物药发挥其细胞毒性和抗炎活性，至少部分是通过降低特异性蛋白（Sp）转录因子来实现的。这些因子在乳腺癌肿瘤中过度表达，并调节与癌细胞存活和炎症相关的重要基因，如 NF-κB 的 p65 亚单位。此外，先前的研究表明，Pg 提取物通过抑制体外 AKT 的磷脂酰肌醇-3,4,5-三磷酸（PI3K）依赖性磷酸化以及抑制体内 NF-kB 的激活，来减少肺癌细胞系中的炎症。本研究的目的是研究 miR-27a-ZBTB10-Sp 和 miR-155-SHIP-1-PI3K 在石榴提取物抗炎和细胞毒性活性中的作用。Pg 提取物（2.5-50μg/ml）抑制 BT-474 和 MDA-MB-231 细胞的生长，但不抑制非癌 MCF-10F 和 MCF-12F 细胞。Pg 提取物显著降低了 BT474 和 MDA-MB-231 细胞中的 Sp1、Sp3 和 Sp4 以及 miR-27a，并增加了转录抑制因子 ZBTB10 的表达。Sp 蛋白和 Sp 调节基因的表达也明显下降。Pg 提取物还诱导了 SHIP-1 的表达，同时伴随着 miRNA-155 的下调和 AKT 的 PI3K 依赖性磷酸化的抑制。在作为异种移植物的 BT474 细胞裸鼠肿瘤中也观察到了类似的结果，并接受了 Pg 提取物的治疗。通过反义寡核苷酸和 RNA 干扰敲低 SHIP-1 的实验结果证实，Pg 提取物的抗炎和细胞毒性作用部分是由于破坏了 miR-27a-ZBTB10 和 miR-155-SHIP-1。总之，Pg 提取物在乳腺癌细胞中的抗癌活性部分归因于靶向 microRNAs155 和 27a。这两个途径在这些细胞系表现出的增殖/炎症表型中都起着重要作用。
