Inhibition of 12-lipoxygenase reduces proliferation and induces apoptosis of hepatocellular carcinoma cells in vitro and in vivo

Hepatobiliary Pancreat Dis Int. 2012 Apr;11(2):193-202. doi: 10.1016/s1499-3872(12)60147-7.


Background: 12-lipoxygenase (12-LOX) has been reported to be an important gene in cancer cell proliferation and survival, and tumor metastasis. However, its role in hepatocellular carcinoma (HCC) cells remains unknown.

Methods: Expression of 12-LOX was assessed in a diethyl-nitrosamine-induced rat HCC model, and in SMMC-7721, HepG2 and L-02 cells using immunohistochemical staining and reverse transcriptase-polymerase chain reaction (RT-PCR). GST-π and Ki-67 were determined in vivo by immunohistochemical staining. Apoptosis was evaluated by TUNEL assay. Cell viability and apoptosis were determined by MTT assay and flow cytometry, respectively. Apoptosis-related proteins in SMMC-7721 and HepG2 cells were detected by Western blotting.

Results: Immunohistochemical staining and RT-PCR showed that 12-LOX was over-expressed in rat HCC and two HCC cell lines, while the expression was inhibited by baicalein, a specific inhibitor of 12-LOX. Baicalein inhibited cell proliferation and induced apoptosis in rat HCC and both cell lines in a dose- and time-dependent manner. Our in vivo study demonstrated that baicalein also reduced neoplastic nodules. Mechanistically, baicalein reduced Bcl-2 protein expression coupled with a slight increase of the expression of Bax and activation of caspase-3. Furthermore, baicalein inhibited the activation of ERK-1/2 (phosphorylated). Interestingly, the effects of baicalein were reversed by 12(S)-HETE, a metabolite of 12-LOX.

Conclusions: Inhibition of 12-LOX leads to reduced numbers of HCC cells, partially caused by increased apoptosis. 12-LOX may be a potential molecular target for HCC prevention and treatment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects*
  • Arachidonate 12-Lipoxygenase / drug effects*
  • Arachidonate 12-Lipoxygenase / metabolism
  • Carcinoma, Hepatocellular / metabolism
  • Carcinoma, Hepatocellular / pathology*
  • Caspase 3 / metabolism
  • Cell Line, Tumor
  • Cell Proliferation / drug effects*
  • Disease Models, Animal
  • Dose-Response Relationship, Drug
  • Flavanones / pharmacology*
  • Humans
  • In Vitro Techniques
  • Lipoxygenase Inhibitors / pharmacology*
  • Liver Neoplasms / metabolism
  • Liver Neoplasms / pathology*
  • Male
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • Rats
  • Rats, Wistar
  • Time Factors
  • bcl-2-Associated X Protein / metabolism


  • Flavanones
  • Lipoxygenase Inhibitors
  • Proto-Oncogene Proteins c-bcl-2
  • bcl-2-Associated X Protein
  • baicalein
  • Arachidonate 12-Lipoxygenase
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Caspase 3