Introduction: There are a lot of unmet needs in patients with triple-negative breast cancer (TNBC). Fenofibrate, a PPAR-α (Peroxisome proliferator-activated receptor alpha) agonist, has been used for decades to treat hypertriglyceridaemia and mixed dyslipidaemia and recent studies showed that it may have anti-tumor effects, however, the mechanism remains unclear. Here, we assessed the ability of fenofibrate to inhibit TNBC cells proliferation and to induce apoptosis in vitro and in vivo and explored possible involved mechanisms.

Methods: Utilization of cell count kit-8 method was to evaluate the anti-proliferation effect of fenofibrate. The percentage of apoptotic cells and distribution ratio of cell cycle was determined by flow cytometric analysis. The related protein levels were measured with Western Blotting methods. The inhibition of tumor growth in vivo was assessed using MDA-MB-231 xenograft mouse model. Terminal deoxytransferase-catalyzed DNA nick-end labeling assay was employed to estimate the proportion of apoptotic cells in tumor tissue sections. In order to evaluate the safety of fenofibrate, counts of leukocyte, erythrocyte, hemoglobin, platelet, aspartate transaminase,alanine transaminase and blood urea nitrogen in peripheral blood were detected.

Results:Fenofibrate had anti-proliferation effects on the twelve different subtype breast cancer cell lines we studied, of which the first five most sensitive ones were all TNBC cell lines. Its induction of apoptosis of MDA-MB-231 cell lines was independent on PPAR-α status with the highest apoptosis percentage of 48.0% when compared with 4.8% in the control group. It occurred in a both time- and dose-dependent manner accompanied by up-regulation of Bad, down-regulation of Bcl-xl, Survivin and activation of caspase-3 and NF-κB pathway.

Table 1:Fenofibrate induces apoptosis in MDA-MB-231 cells

Fenofibrate 0μM 12.5μM 25μM 50μM 100μM 
24H 4.8% 5.9% 7.3% 20.3% 26.0% 
48h 5.8% 7.4% 11.0% 23.7% 48.0% 
Fenofibrate 0μM 12.5μM 25μM 50μM 100μM 
24H 4.8% 5.9% 7.3% 20.3% 26.0% 
48h 5.8% 7.4% 11.0% 23.7% 48.0% 

MDA-MB-231 cells were treated with fenofibrate at different concentrations for either 24 or 48 hours. The percentage of apoptotic cells analyzed with flow cytometry are shown in the table.

Interestingly, activation of NF-κB pathway played an important role in the induction of apoptosis by fenofibtate and the apoptosis effect can be almost totally blocked by a NF-κB specific inhibitor, that is pyrrolidine dithiocarbamate(PDTC).

In addition, fenofibrate led to cell cycle arrest at G1 phase accompanied by down-regulation of Cyclin D1, Cyclin-dependent kinase4(Cdk4) and up-regulation of p21, p27/Kip1.In vivo, fenofibrate significantly inhibited tumor growth in the MDA-MB-231 xengograft mouse model and induced apoptosis with a good safety profile.

Table 2:The important role of activation of NF-κB pathway in apoptosis

  FENO 0mm FENO 50mm 
PDTC(-) 5.9±5.0% 20.5±0.9% 
PDTC(+) 3.9±1.8% 6.5±0.9% 
  FENO 0mm FENO 50mm 
PDTC(-) 5.9±5.0% 20.5±0.9% 
PDTC(+) 3.9±1.8% 6.5±0.9% 

MDA-MB-231 cels were treated with Fenofibrate at different concentrations alone or with a combination of 10nM PDTC for 24 hours. The percentage of apoptotic cells analyzed with flow cytometry are shown in the table.

Conclusions:Fenofibrate can induce apoptosis in TNBC in vitro and in vivo, and the mechanism is the activation of NF-κB pathway in a PPAR-α independent way, which may serve as a novel therapeutic drug for TNBC therapy.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-09-13.