School of Life and Health Sciences, Aston University, Birmingham, United Kingdom.
PLoS One. 2012;7(6):e40152. doi: 10.1371/journal.pone.0040152. Epub 2012 Jun 27.
Plants have proved to be an important source of anti-cancer drugs. Here we have investigated the cytotoxic action of an aqueous extract of Fagonia cretica, used widely as a herbal tea-based treatment for breast cancer.
METHODOLOGY/PRINCIPAL FINDINGS: Using flow cytometric analysis of cells labeled with cyclin A, annexin V and propidium iodide, we describe a time and dose-dependent arrest of the cell cycle in G0/G1 phase of the cell cycle and apoptosis following extract treatment in MCF-7 (WT-p53) and MDA-MB-231 (mutant-p53) human breast cancer cell lines with a markedly reduced effect on primary human mammary epithelial cells. Analysis of p53 protein expression and of its downstream transcription targets, p21 and BAX, revealed a p53 associated growth arrest within 5 hours of extract treatment and apoptosis within 24 hours. DNA double strand breaks measured as γ-H2AX were detected early in both MCF-7 and MDA-MB-231 cells. However, loss of cell viability was only partly due to a p53-driven response; as MDA-MB-231 and p53-knockdown MCF-7 cells both underwent cell cycle arrest and death following extract treatment. p53-independent growth arrest and cytotoxicity following DNA damage has been previously ascribed to FOXO3a expression. Here, in MCF-7 and MDA-MB-231 cells, FOXO3a expression was increased significantly within 3 hours of extract treatment and FOXO3 siRNA reduced the extract-induced loss of cell viability in both cell lines.
CONCLUSIONS/SIGNIFICANCE: Our results demonstrate for the first time that an aqueous extract of Fagonia cretica can induce cell cycle arrest and apoptosis via p53-dependent and independent mechanisms, with activation of the DNA damage response. We also show that FOXO3a is required for activity in the absence of p53. Our findings indicate that Fagonia cretica aqueous extract contains potential anti-cancer agents acting either singly or in combination against breast cancer cell proliferation via DNA damage-induced FOXO3a and p53 expression.
植物已被证明是抗癌药物的重要来源。在这里，我们研究了广泛用作乳腺癌草药茶治疗的 Fagonia cretica 的水提物的细胞毒性作用。
方法/主要发现：通过用细胞周期蛋白 A、膜联蛋白 V 和碘化丙啶标记的细胞的流式细胞分析，我们描述了 MCF-7（WT-p53）和 MDA-MB-231（突变-p53）人乳腺癌细胞系中细胞周期在 G0/G1 期的时间和剂量依赖性停滞以及凋亡，而对原代人乳腺上皮细胞的影响明显较小。p53 蛋白表达及其下游转录靶标 p21 和 BAX 的分析表明，在提取物处理后 5 小时内 p53 相关生长停滞，并在 24 小时内发生凋亡。γ-H2AX 测量的 DNA 双链断裂在 MCF-7 和 MDA-MB-231 细胞中均较早检测到。然而，细胞活力的丧失仅部分归因于 p53 驱动的反应；因为 MDA-MB-231 和 p53 敲低 MCF-7 细胞在提取物处理后均经历细胞周期停滞和死亡。先前已将 DNA 损伤后的 p53 非依赖性生长停滞和细胞毒性归因于 FOXO3a 的表达。在这里，在 MCF-7 和 MDA-MB-231 细胞中，在提取物处理后 3 小时内 FOXO3a 表达显著增加，并且 FOXO3 siRNA 降低了这两种细胞系中提取物诱导的细胞活力丧失。
结论/意义：我们的研究结果首次表明，Fagonia cretica 的水提物可以通过 p53 依赖和独立的机制诱导细胞周期停滞和凋亡，激活 DNA 损伤反应。我们还表明，在没有 p53 的情况下，FOXO3a 是活性所必需的。我们的研究结果表明，Fagonia cretica 水提物含有潜在的抗癌剂，通过 DNA 损伤诱导的 FOXO3a 和 p53 表达，单独或联合作用于乳腺癌细胞增殖。
