LPS x NF-κB x c-Myc

The mammalian Sterile 20-like kinase 1/2 (MST1/2) belongs to the serine/threonine (GC) protein kinase superfamily. Collective studies confirm the vital role MST1/2 in inflammation and immunity. MST1/2 is closely related to the progress of inflammation. Generally, MST1/2 aggravates the inflammatory injury through MST1-JNK, MST1-mROS, MST1-Foxo3, and NF-κB pathways, as well as several regulatory factors such as tumor necrosis factor-α (TNF-α), mitochondrial extension factor 1 (MIEF1), and lipopolysaccharide (LPS). Moreover, MST1/2 is also involved in the regulation of immunity to balance immune activation and tolerance by regulating MST1/2-Rac, MST1-Akt1/c-myc, MST1-Foxos, MST1-STAT, Btk pathways, and lymphocyte function-related antigen 1 (LFA-1), which subsequently prevents immunodeficiency syndrome and autoimmune diseases. This article reviews the effects of MST1/2 on inflammation and immunity.

NF-κB transcription factors critically regulate the expression of genes which are involved in important cellular processes, including cellular proliferation and apoptosis. Abnormal activation of the NF-κB signaling pathway has been implicated in a variety of human cancers. Hyper-activation of the NF-κB signaling pathway has been found to lead to tumor survival, anti-apoptosis and invasion in the development of prostate cancer. In the present work, we identified Lycorine as a potent NF-κB inhibitor using a NF-κB activity dependent luciferase reporter in PC3 and DU145 prostate cancer cells. With this reporter gene assay, we found that Lycorine significantly suppressed the constitutive NF-κB activity as well as the NF-κB activity induced by TNF-α, LPS, PMA and IL-1β. Western blotting analysis of the NF-κB signaling pathway further showed that Lycorine inhibited IκB-α (inhibitor of κB) phosphorylation, IκB-α degradation, and p65 phosphorylation. Consistent with this, the subsequent nuclear translocation of p65 was blocked by Lycorine as evidenced in the immunofluorescence assay and western blotting. Furthermore, we observed that cell cycle was arrested at G2/M in Lycorine treated cells using FACS analysis. Western blotting analysis indicated that Lycorine increased the expression of Cyclin D1 but decreased the expression of p21. In addition, FACS analysis showed that Lycorine induced apoptosis in DU145 and PC3 cells. Western blotting analysis revealed that Lycorine decreased the expression of anti-apoptosis genes myc, survivin and Bcl-2 while increased cleavage of PARP. Finally, we observed a significant anticancer effect of Lycorine in a RM-1 prostate cancer xenograft mouse model. In agreement with its in vitro anticancer effect, Lycorine inhibited p65 phosphorylation, IKK-β phosphorylation and the expression of Ki-67, while increased the cleavage of Caspase 3 in tumor tissue. Taken together, our data demonstrated the in vitro and in vivo anti-prostate cancer activity of Lycorine by inhibiting the NF-κB signaling pathway, and highlighted it as a lead compound for further development into an effective anticancer drug.

The gram-negative bacteria secreted endotoxin, Lipopolysaccharide (LPS), plays important roles in the formation and recurrence of hepatolithiasis and chronic biliary inflammation in patients of Southeast Asia. We aimed to elucidate the anti-inflammatory effect and mechanism of local antibiotics irrigation on chronic proliferative cholangitis (CPC) and hepatolithiasis.

Escherichia coli was injected into rabbit bile ducts to induce CPC. Rabbits were divided into sham operation (SO), povidone-iodine, Metronidazole plus chlorhexidine, ofloxacin, furacillin, Neosporin® G.U., and CPC groups. Local irrigation was performed for 28 days after CPC was established. Residual E. coli and LPS, and the expression of MCP-1, CD14, COX-2, VEGF, IL-6, NF-κB, TNF-α, Fas, TGF-β1, α-SMA, Collagen-I, β-glucuronidase, PKC, C-myc, and Mucin 5AC were assessed in bile duct tissues.

The residual E. coli and LPS, and expression of MCP-1, CD14, COX-2, IL-6, NF-κB, TNF-α, Fas, TGF-β1, α-SMA, β-glucuronidase, PKC, C-myc, and Mucin 5AC in the SO, povidone-iodine, Metronidazole plus chlorhexidine, ofloxacin, and Neosporin® G.U. groups were significantly lower than those in the furacillin and CPC groups (P<0.05). VEGF and Collagen-I levels in the SO, povidone-iodine, metronidazole plus chlorhexidine, and ofloxacin groups were significantly lower than those in the furacillin, Neosporin® G.U., and CPC groups (P<0.05).

LPS affects the pathophysiology of E. coli caused chronic proliferative cholangitis and hepatolithiasis recurrence. Local antibiotics irrigation could prevent chronic proliferative cholangitis and stones formation by decreasing LPS-induced proinflammatory and profibrotic cytokines release. Povidone iodine, metronidazole plus chlorhexidine, and ofloxacin were more effective than Neosporin® G.U. and furacillin.