Carcinogenesis Advance Access originally published online on November 16, 2007
Carcinogenesis 2008 29(1):147-156; doi:10.1093/carcin/bgm261
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Lucidenic acid inhibits PMA-induced invasion of human hepatoma cells through inactivating MAPK/ERK signal transduction pathway and reducing binding activities of NF-
B and AP-1
Department of Food Science and Biotechnology, National Chung Hsing University, Taichung 40227, Taiwan
1 Institute of Biochemistry and Biotechnology
2 Institute of Medicine, Chung Shan Medical University, Taichung 40256, Taiwan
* To whom correspondence should be addressed. Tel: +886 4 2287 9755; Fax: +886 4 2285 4378; Email: gcyen{at}nchu.edu.tw
Ganoderma lucidum has been reported to be associated with suppressed motility, invasion and metastasis of several types of cancers, but its mechanism of action remains unclear. In our previous study, lucidenic acids A, B, C and N were isolated from a new strain of G.lucidum and all of them were found to have potential anti-invasive activity on phorbol-12-myristate-13-acetate (PMA)-induced HepG2 cells by suppressing the matrix metalloproteinase (MMP)-9 activity. Here, the lucidenic acid B (LAB) was used to explore its mechanisms underlying MMP-9 expression of HepG2 cells. The results showed that the LAB suppressed PMA-induced MMP-9 activity in a dose-dependent transcriptional level. The suppression of PMA-induced MMP-9 expression of HepG2 cells by LAB was through inactivating phosphorylation of extracellular signal-regulated kinase (ERK) 1/2. The treatment of mitogen-activated protein kinase kinase (MEK) inhibitors (PD98059 and U0126) and LAB to HepG2 cells could result in a synergistic reduction on the MMP-9 expression along with an inhibition on cell invasion. Moreover, LAB also strongly inhibited PMA-stimulated nuclear factor-kappa B (NF-
B) and activator protein-1 (AP-1) DNA-binding activities of HepG2 cells in dose-dependent manners. A dose-dependent inhibition on protein levels of NF-B, c-Jun and c-Fos in nuclear by LAB treatment was further observed. In conclusion, we demonstrated that the anti-invasive effects of the LAB on the PMA-induced HepG2 cells might be through inhibiting the phosphorylation of ERK1/2 and reducing AP-1 and NF-B DNA-binding activities, leading to downregulation of MMP-9 expression.
Abbreviations: AP-1, activator protein-1; DMEM, Dulbecco's modified Eagle's medium; EMSA, electrophoretic mobility shift assay; ERK, extracellular signal-regulated kinase; HCC, hepatocellular carcinoma; IK, IB kinase; JNK, c-jun N-terminal kinase; LAB, lucidenic acid B; MAPK, mitogen-activated protein kinase; MEK, mitogen-activated protein kinase kinase; MMP, matrix metalloproteinase; mRNA, messenger RNA; NF-B, nuclear factor-kappa B; PBS, phosphate-buffered saline; PI3K/Akt, phosphoinositide-3 kinase/protein kinase B; PKC, protein kinase C; PMA, phorbol-12-myristate-13-acetate; RT–PCR, reverse transcription–polymerase chain reaction; SDS–PAGE, sodium dodecyl sulfate–polyacrylamide gel electrophoresis; SPAK, stress-activated protein kinase
Received September 10, 2007; revised November 9, 2007; accepted November 9, 2007.