Department of Medical Oncology, Fudan University Shanghai Cancer Center, 200032 Shanghai, China.
BMC Cancer. 2014 Feb 16;14:96. doi: 10.1186/1471-2407-14-96.
There are a lot of unmet needs in patients with triple-negative breast cancer (TNBC). Fenofibrate, a peroxisome proliferator-activated receptor alpha (PPAR-α) agonist, has been used for decades to treat hypertriglyceridaemia and mixed dyslipidaemia. Recent studies show that it might have anti-tumor effects, however, the mechanism remains unclear. Here, we assessed the ability of fenofibrate to induce apoptosis of TNBC in vitro and in vivo and explored involved mechanisms.
MTT method was used to evaluate the anti-proliferation effect of fenofibrate, and invert microscope to observe the apoptotic morphological changes. The percentage of apoptotic cells and distribution ratios of cell cycle were determined by flow cytometric analysis. The related protein levels were measured by Western blot method. The changes of genes and pathways were detected by gene expression profiling. The tumor growth in vivo was assessed by MDA-MB-231 xenograft mouse model. Terminal deoxytransferase-catalyzed DNA nick-end labeling (TUNEL) assay was employed to estimate the percentage of apoptotic cells in vivo. In order to evaluate the safety of fenofibrate, blood sampled from rat eyes was detected.
We found that fenofibrate had anti-proliferation effects on breast cancer cell lines, of which the first five most sensitive ones were all TNBC cell lines. Its induction of apoptosis was independent on PPAR-α status with the highest apoptosis percentage of 41.8 ± 8.8%, and it occurred in a time- and dose-dependent manner accompanied by up-regulation of Bad, down-regulation of Bcl-xl, Survivin and activation of caspase-3. Interestingly, activation of NF-κB pathway played an important role in the induction of apoptosis by fenofibtate and the effect could be almost totally blocked by a NF-κB specific inhibitor, pyrrolidine dithiocarbamate (PDTC). In addition, fenofibrate led to cell cycle arrest at G0/G1 phase accompanied by down-regulation of Cyclin D1, Cdk4 and up-regulation of p21, p27/Kip1. In vivo, fenofibrate slowed down tumor growth and induced apoptosis with a good safety profile in the MDA-MB-231 xengograft mouse model.
It is concluded that fenofibrate induces apoptosis of TNBC via activation of NF-κB pathway in a PPAR-α independent way, and may serve as a novel therapeutic drug for TNBC therapy.
三阴性乳腺癌（TNBC）患者存在大量未满足的需求。非诺贝特是一种过氧化物酶体增殖物激活受体α（PPAR-α）激动剂，已用于治疗高甘油三酯血症和混合性血脂异常数十年。最近的研究表明，它可能具有抗肿瘤作用，但机制尚不清楚。在这里，我们评估了非诺贝特在体外和体内诱导 TNBC 细胞凋亡的能力，并探讨了相关机制。
采用 MTT 法评估非诺贝特的抗增殖作用，倒置显微镜观察细胞凋亡的形态变化。通过流式细胞术分析测定细胞凋亡的百分比和细胞周期分布比。采用 Western blot 法测定相关蛋白水平。通过基因表达谱检测基因和通路的变化。采用 MDA-MB-231 异种移植小鼠模型评估体内肿瘤生长情况。采用末端脱氧核苷酸转移酶催化的 DNA 缺口末端标记（TUNEL）法测定体内细胞凋亡百分比。为评估非诺贝特的安全性，检测了大鼠眼部采血。
我们发现非诺贝特对乳腺癌细胞系具有抗增殖作用，其中前五种最敏感的细胞系均为 TNBC 细胞系。其诱导的细胞凋亡与 PPAR-α状态无关，凋亡率最高可达 41.8±8.8%，呈时间和剂量依赖性，并伴有 Bad 上调、Bcl-xl、Survivin 下调和 caspase-3 活化。有趣的是，NF-κB 通路的激活在非诺贝特诱导的细胞凋亡中起着重要作用，而 NF-κB 特异性抑制剂吡咯烷二硫代氨基甲酸盐（PDTC）几乎可以完全阻断该作用。此外，非诺贝特导致细胞周期停滞在 G0/G1 期，伴有细胞周期蛋白 D1、Cdk4 下调和 p21、p27/Kip1 上调。在体内，非诺贝特在 MDA-MB-231 异种移植小鼠模型中减缓肿瘤生长并诱导细胞凋亡，具有良好的安全性。
非诺贝特通过激活 NF-κB 通路，在不依赖 PPAR-α 的情况下诱导 TNBC 细胞凋亡，可能成为治疗 TNBC 的新型治疗药物。
