Norcantharidin facilitates LPS-mediated immune responses by up-regulation of AKT/NF-κB signaling in macrophages.

Norcantharidin (NCTD), a demethylated analog of cantharidin, is a common used clinical drug to inhibit proliferation and metastasis of cancer cells. But the role of NCTD in modulating immune responses remains unknown. Here, we investigated the function and mechanism of NCTD in regulation of TLR4 associated immune response in macrophages. We evaluated the influence of NCTD on host defense against invaded pathogens by acute peritonitis mouse model, ELISA, Q-PCR, nitrite quantification, phagocytosis assay and gelatin zymography assay. Our data showed that the survival and the serum concentrations of IL-6 and TNF-α were all enhanced by NCTD significantly in peritonitis mouse model. Accordingly, LPS-induced cytokine, nitric oxide and MMP-9 production as well as the phagocytosis of bacteria were all up-regulated by NCTD in a dose dependent manner in both RAW264.7 cells and bone marrow-derived macrophages (BMMs). Then we further analyzed TLR4 associated signaling pathway by Western blot, Immunofluorescence and EMSA in the presence or absence of LPS. The phosphorylation of AKT and p65 at serine 536 but not serine 468 was enhanced obviously by NCTD in a dose dependent manner, whereas the degradation of IκBα was little effected. Consequently, the nuclear translocation and DNA binding ability of NF-κB was also increased by NCTD obviously in RAW264.7 cells. Our results demonstrated that NCTD could facilitate LPS-mediated immune response through promoting the phosphorylation of AKT/p65 and transcriptional activity of NF-κB, thus reprofiling the traditional anti-tumor drug NCTD as a novel immune regulator in promoting host defense against bacterial infection.

Nitidine Chloride inhibits breast cancer cells migration and invasion by suppressing c-Src/FAK associated signaling pathway.

Nitidine is a benzophenanthridine alkaloid, which has been shown to have anti-tumor properties. Here, we demonstrated that Nitidine Chloride (NC) could inhibit breast cancer cells migration and invasion both in vitro and in vivo. Meanwhile, the protrusion formation and partial proteolytic activity of MMP-9 and MMP-2 were attenuated by NC in a dose-dependent manner in MDA-MB-231 cells. Furthermore, addition NC to cells significantly decreases PDGF induced phosphorylation of c-Src, FAK, MAPKs, activation of RhoA, Rac1 and AP-1 transcriptional activity. Taken together, our results indicate that NC could have potential as a novel anti-metastasis drug to breast cancer.

Cudratricusxanthone G inhibits human colorectal carcinoma cell invasion by MMP-2 down-regulation through suppressing activator protein-1 activity.

Cudratricusxanthone G (CTXG), a natural bioactive cudratricusxanthone extracted from C. tricuspidata, has shown anti-cancer properties. However, the function and mechanism of CTXG in tumor invasion have not been elucidated to date. In this study, we investigated the inhibitory effect of CTXG on the proliferation, migration and invasion of SW620 cells. We found that MMP-2, a pivotal factor in tumor invasion, was suppressed in both expression and activation by CTXG in a dose-dependent manner. The suppression of MMP-2 expression by CTXG led to an inhibition of SW620 cells invasion and migration by inactivating Rac1 and Cdc42 but not RhoA GTPase. Furthermore, CTXG also inhibited the transcriptional activity of AP-1 (activator protein-1). In conclusion, our data demonstrate that CTXG exerted anti-invasion action in SW620 cells by targeting MMP-2 though regulating the activities of Rac1, Cdc42 and their downstream transcriptional factor AP-1. These results are the first to reveal the novel functions of CTXG in cancer cell invasion and its molecular basis for the anti-cancer action.

CADPE inhibits PMA-stimulated gastric carcinoma cell invasion and matrix metalloproteinase-9 expression by FAK/MEK/ERK-mediated AP-1 activation.

Metastasis is one of the main causes of death for patients with malignant tumors. Aberrant expression of matrix metalloproteinase-9 (MMP-9) has been implicated in the invasion and metastasis of various cancer cells. Here, we found that caffeic acid 3,4-dihydroxy-phenethyl ester (CADPE) could inhibit the migration and invasion of human gastric carcinoma cells in Transwell migration assays. To understand the underlying mechanism, we showed that CADPE significantly inhibited phorbol 12-myristate 13-acetate (PMA)-induced increases in MMP-9 expression and activity in a dose-dependent manner. The inhibitory effect of CADPE on MMP-9 expression correlated well with the suppression of MMP-9 promoter activity and the reduction of MMP-9 mRNA. Reporter gene assay and electrophoretic mobility shift assay showed that CADPE inhibited MMP-9 expression by suppressing the activation of the nuclear transcription factor activator protein-1 (AP-1) and c-Fos, but not NF-κB. Moreover, CADPE inhibited PMA-induced phosphorylation of protein kinases involved in AP-1 activation, such as focal adhesion kinase (FAK), mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK), and ERK1/2, whereas CADPE had little effect on the phosphorylation of p38 and c-jun NH(2)-terminal kinase. Taken together, our findings indicate that CADPE could be a unique antitumor agent that specifically inhibits MMP-9 activity by targeting the activation of FAK/MEK/ERK protein kinases and AP-1 transcription factor.