Research on the anti-tumor effect of nordihydroguaiaretic acid targeting MyD88 / 药学学报

This study mainly explores the role of myeloid differentiation primary response protein 88 (MyD88) in tumorigenesis and development, to identify active compounds targeting MyD88. CRISPR/Cas9 system and xenograft tumor model were used to detect the effect of MyD88 deletion on tumor growth, and the experimental animal ethics review number was PZSHUTCM200828006. Microscale thermophoresis technology (MST) was used to identify compounds directly bind to MyD88 and further detect the impact of candidate small molecules on cell proliferation. Results showed that depletion of MyD88 significantly inhibited xenograft tumor growth of colon cancer, pancreatic cancer and skin cancer and the activity of NF-κB signaling pathway. MST showed that nordihydroguaiaretic acid (NDGA) bound to MyD88, with the binding dissociation constant Kd of 14.61 µmol·L-1. NDGA inhibited NF-κB reporting system activation and phosphorylation of p65, the key factor in NF-κB signal pathway. In addition, the results of colony formation assay showed that NDGA suppressed the proliferation of tumor cells. The above results show that, MyD88 is a potential therapeutic target for colon cancer, pancreatic cancer and skin cancer, NDGA directly binds to MyD88 and inhibits the activity of NF-κB signaling pathway, as well as inhibits the proliferation of pancreatic cancer, skin cancer and colon cancer cells.

TLR4-mediated activation of MyD88 signaling induces protective immune response and IL-10 down-regulation in Leishmania donovani infection.

In visceral leishmaniasis, a fragmentary IL-12 driven type 1 immune response along with the expansion of IL-10 producing T-cells correlates with parasite burden and pathogenesis. Successful immunotherapy involves both suppression of IL-10 production and enhancement of IL-12 and nitric oxide (NO) production. As custodians of the innate immunity, the toll-like receptors (TLRs) constitute the first line of defense against invading pathogens. The TLR-signaling cascade initiated following innate recognition of microbes shapes the adaptive immune response. Whereas numerous studies have correlated parasite control to the adaptive response in Leishmania infection, growing body of evidence suggests that the activation of the innate immune response also plays a pivotal role in disease pathogenicity. In this study, using a TLR4 agonist, a Leishmania donovani (LD) derived 29 kDa β 1,4 galactose terminal glycoprotein (GP29), we demonstrated that the TLR adaptor myeloid differentiation primary response protein-88 (MyD88) was essential for optimal immunity following LD infection. Treatment of LD-infected cells with GP29 stimulated the production of IL-12 and NO while suppressing IL-10 production. Treatment of LD-infected cells with GP29 also induced the degradation of IKB and the nuclear translocation of NF-kB, as well as rapid phosphorylation of p38 MAPK and p54/56 JNK. Knockdown of TLR4 or MYD88 using siRNA showed reduced inflammatory response to GP29 in LD-infected cells. Biochemical inhibition of p38 MAPK, JNK or NF-kB, but not p42/44 ERK, reduced GP29-induced IL-12 and NO production in LD-infected cells. These results suggested a potential role for the TLR4-MyD88–IL-12 pathway to induce adaptive immune responses to LD infection that culminated in an effective control of intracellular parasite replication.