Inhibitory effect of dihydrohinokiflavone on tumor cell growth, invasion, and metastasis

Abstract

Matrix metalloproteinases (MMPs) inhibitors were screened from Metasequoia glyptostroboides and one potent inhibitor, dihydrihinokiflavone (DHHF), a biflavonoid, was selected. DHHF inhibited proliferation of HT1080, human fibrosarcoma cells in a dose-dependent manner. Noncytotoxic levels of DHHF dramatically decreased MMP-9 and MMP-2 production in unstimulated cells, but did not change the level of tissue inhibitor of metalloproteinase (TIMP-1), an inhibitor of MMP-9. DHHF further inhibited phorbol 12-myristate 13-acetate (PMA)-induced MMP-9 overproduction and proMMP-2 activation. In HT1080 cells, which express wild ?type p53 and Rb, DHHF treatment induced G1 cycle arrest. The G1 arrest in cell cycle progression was associated with a marked decreased in cdk2, cdk4, and phospho-Rb. DHHF increased the levels of p53, a key protein for cell cycle arrest and overexpression if mutant p53 blocked the growth inhibitory effect of DHHF. These results indicate that DHHF inhibits cell growth through p53-dependent pathways. DHHF inhibited critical mediators for cell survival, Akt, phospho-Akt, and Bcl-2. This inhibition was associated with MMP-9 downregulation and partly responsible for G1 arrest. Furthermore, DHHF upregulated phospho-JNK, a key factor for cell death, and increased cell death susceptibility in the presence of hydrogen peroxide. DHHF showed marked inhibition of in vitro HT1080 and B16F10 melanoma cell growth, invasion and motility, and further was effective to inhibit in vivo tumor growth and metastasis. All these results suggest that DHHF can be a good therapeutic compound for anti-tumor including chemoprevention and anti-metastasis.