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Updated: Aug 20, 2026
Conditional Knockdown of Gene Expression in Cancer Cell Lines to Study the Recruitment of Monocytes/Macrophages to the Tumor Microenvironment
Published on: November 23, 2017
[An exploratory study on mechanism of PPARalpha activators-induced plasminogen activator inhibitor-1 expression in
Ping Ye1, Yan-li He, Qiong Wang
1Department of Geriatric Cardiology, PLA General Hospital, Beijing 100853, China. yeping@sina.com.
Objective:
To investigate the influence of peroxisome proliferator-activated receptor alpha activators on plasminogen activator inhibitor-1 (PAI-1) expression in HepG-2 cells and the mechanism possibly involved.
Methods:
Linoleic acid and fenofibrate were used in the treatment of HepG-2 cell culture. PAI-1 activity and mRNA expression were determined with colorimetric assay and reverse transcription-polymerase chain reaction, respectively. Using gene recombination techniques, two types of chloramphenicol acetyl transferase (CAT) reporter gene plasmid containing different deletions in PAI-1 promoter were constructed and transiently transfected into HepG-2 cells, respectively. Linoleic acid and fenofibrate were added to induce the transfected cells. CAT activity was measured to demonstrate the transcriptional activity of PAI-1 gene in HepG-2 cells.
Results:
The mRNA expression and protein activity of PAI-1 was significantly induced by linoleic acid, but was obviously suppressed by fenofibrate. In the HepG-2 cells transfected with PAI-pCAT promoter constructs the PAI-1 transcription activity was significantly induced by linoleic acid, but suppressed by fenofibrate. The level of PAI-1 transcription was also significantly increased when co-transfected with PAI-pCAT promoter construct and PPAR alpha-pSG5 expression plasmid to HepG-2 cells. Furthermore, in the condition of transfection with NF-kappaB-response element-deletion-pCAT construct, both linoleic acid and fenofibrate increased the PAI-1 transcriptional activity, whereas in those cells transfected with VLDL/fatty acid response element-deletion-pCAT construct, fenofibrate significantly reduced PAI-1 transcriptional activity, but no change in PAI-1 transcription activity was found with linoleic acid stimulation.
Conclusions:
Linoleic acid induces PAI-1 activity and mRNA expression in HepG-2 cells. PPAR alpha may be one of transcription factors playing a role in the upregulation of PAI-1 gene expression. The inhibition of NF-kappaB signaling pathway may be involved in the downregulation of PAI-1 gene expression by fenofibrate.
