The hexane fraction of Naematoloma sublateritium extract suppresses the TNF-α-induced metastatic potential of MDA-MB-231 breast cancer cells through modulation of the JNK and p38 pathways.

Naematoloma sublateritium (Fr.) P. Karst is a basidiomycete that has been used as traditional medicine. N. sublateritium produces a triterpenoid antitumor compound, clavaric acid, but, in general, the effects of N. sublateritium constituents against tumor invasion and metastasis have been poorly studied. To investigate the inhibitory effect of N. sublateritium constituents on highly invasive and metastatic tumor cells, the TNF-α-stimulated human breast cancer cell line, MDA-MB‑231 was treated with the hexane fraction of an N. sublateritium extract (HFNS). Non-cytotoxic concentrations of HFNS markedly inhibited the invasion and migration of the MDA-MB‑231 cells in the Matrigel invasion assay and wound-healing analysis, respectively. Gelatin zymography showed that HFNS suppressed the activity of MMP-9, but not of MMP-2. Immunoblotting demonstrated that treatment with HFNS had decreased the level of MMP-9 and urokinase plasminogen activator-1 (uPA-1), but had upregulated expression of the endogenous inhibitor proteins, including TIMP-1,-2, and PAI-1, in a dose-dependent manner. Furthermore, HFNS suppressed the phosphorylation of p38 and JNK1/2, but not that of ERK1/2. This was confirmed by pretreatment of cells with specific inhibitors prior to stimulation with TNF-α. HFNS treatment also led to a dose-dependent inhibition of the DNA-binding activities of AP-1 and NFκB, which are downstream targets of JNK and p38. These data suggested that HFNS inhibits the metastatic potential of MDA-MB‑231 cells by inhibiting the phosphorylation of JNK/p38 and reducing AP-1 and NFκB DNA-binding activities. Therefore, HFNS may be a potential therapeutic agent against metastasis of breast cancer.