MALT1 is required for EGFR-induced NF-κB activation and contributes to EGFR-driven lung cancer progression.

The transcription factor nuclear factor kappa B (NF-κB) has been implicated in having a crucial role in the tumorigenesis of many types of human cancers. Although epidermal growth factor receptor (EGFR) can directly activate NF-κB, the mechanism by which EGFR induces NF-κB activation and the role of NF-κB in EGFR-associated tumor progression is still not fully defined. Herein, we found that mucosa-associated lymphoid tissue 1 (MALT1) is involved in EGFR-induced NF-κB activation in cancer cells, and that MALT1 deficiency impaired EGFR-induced NF-κB activation. MALT1 mainly functions as a scaffold protein by recruiting E3 ligase TRAF6 to IKK complex to activate NF-κB in response to EGF stimulation. Functionally, MALT1 inhibition shows significant defects in EGFR-associated tumor malignancy, including cell migration, metastasis and anchorage-independent growth. To further access a physiological role of MALT1-dependent NF-κB activation in EGFR-driven tumor progression, we generated triple-transgenic mouse model (tetO-EGFR(L858R); CCSP-rtTA; Malt1(-/-)), in which mutant EGFR-driven lung cancer was developed in the absence of MALT1 expression. MALT1-deficient mice show significantly less lung tumor burden when compared with its heterozygous controls, suggesting that MALT1 is required for the progression of EGFR-induced lung cancer. Mechanistically, MALT1 deficiency abolished both NF-κB and STAT3 activation in vivo, which is a result of a defect of interleukin-6 production. In comparison, MALT1 deficiency does not affect tumor progression in a mouse model (LSL-K-ras(G12D); CCSP-Cre; Malt1(-/-)) in which lung cancer is induced by expressing a K-ras mutant. Thus, our study has provided the cellular and genetic evidence that suggests MALT1-dependent NF-κB activation is important in EGFR-associated solid-tumor progression.

Effects of ethanol extract of propolis (EEP) and its flavones on inducible gene expression in J774A.1 macrophages.

Propolis, a bee-hive product, has been used in folk medicine for centuries, and recently in modern medicine as an anti-inflammatory and immunomodulatory agent. These activities would be mainly due to phenolic compounds such as flavonoids, especially flavone derivatives. The present study examined the effect of ethanol extract of propolis (EEP) and selected flavone derivatives (chrysin, galangin, kaempferol and quercetin) on interleukin-1beta (IL-1beta) and inducible nitric oxide synthase (iNOS) gene expression in lipopolysaccharide (LPS)-induced J774A.1 macrophages. Treatment of cells with EEP significantly suppressed both IL-1beta mRNA (P<0.02) and iNOS mRNA (P<0.001) expression. The concentrations of cytokine in cell culture supernatants and cell lysates and nitric oxide (NO) generation were reduced in a dose-dependent manner. The tested phenolic compounds significantly decreased the IL-1beta mRNA level and IL-1beta protein concentration (P<0.05) (excluding galangin), iNOS mRNA level and NO production (P<0.001). The most potent inhibitor of the IL-1beta synthesis and NO generation was chrysin. These results indicate that EEP exerts its inhibitory effect on the IL-1beta and iNOS gene expression in J774A.1 macrophages at the transcriptional level. Tested flavone derivatives contribute to the anti-inflammatory activity of propolis.

Effect of flavone derivatives on interleukin-1beta (IL-1beta) mRNA expression and IL-1beta protein synthesis in stimulated RAW 264.7 macrophages.

It is known that the redox status of cells affects gene expression. Flavones, as natural antioxidants, efficiently modulate this status and may play a role in the regulation of inducible gene expression of inflammatory mediators. This study was designed to investigate the effect of five flavone derivatives variously substituted with hydroxyl groups (chrysin, galangin, kaempferol, quercetin and myricetin) on interleukin-1beta (IL-1beta) gene expression in stimulated RAW 264.7 macrophages. The cells were incubated with tested hydroxyflavones and stimulated with lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma). Then, the following were estimated: the level of IL-1beta mRNA in these cells and the concentration of IL-1beta protein in cell-culture supernatants and cell lysates. Each of the tested compounds significantly decreased IL-1beta mRNA expression. The most potent inhibitor was chrysin (hydroxyflavone with two hydroxyl groups and a weak antioxidant activity). The effects of galangin and kaempferol were similar. Myricetin (hydroxyflavone with a strong antioxidant activity) significantly decreased the level of IL-1beta mRNA, but it had no effect on the IL-1beta protein synthesis. The results indicated that hydroxyflavones could modulate the IL-1beta gene expression in activated RAW 264.7 macrophages via inhibiting gene transcription. This action seems unlikely to be the result of antioxidant properties of tested compounds.

[Pseudothrombocytopenia]. / Maloplytkowosc rzekoma.

On the basis of literature data we have tried to present contemporary views on pseudothrombocytopenia (PTCP), especially EDTA-dependent pseudothrombocytopenia. False thrombocytopenia is caused by in vitro platelet clumping in EDTA-anticoagulated blood. Electronic blood count shows a low platelet count in subjects with normal platelet levels. The mechanism of this reaction appears to involve antiplatelet antibodies against glycoprotein IIb. The best technique for obtaining accurate platelet counts in PTCP subjects is to collect and examine blood sample at 37C.