The 41-kDa and 43-kDa mitogen-activated protein (MAP) kinases play a pivotal role in the mitogenic signal transduction pathway and are essential components of the MAP kinase cascade, which includes MAP kinase kinase (MEK) and Raf-1. As aberrant activation of signal transducing molecules such as Ras and Raf-1 has been linked with cancer, we examined whether constitutive activation of the 41-/43-kDa MAP kinases is associated with the neoplastic phenotype of 138 tumor cell lines and 102 primary tumors derived from various human organs. Constitutive activation of the MAP kinases was observed in 50 tumor cell lines (36.2%) in a rather tissue-speci®c manner: cell lines derived from pancreas, colon, lung, ovary and kidney showed especially high frequencies with a high degree of MAP kinase activation, while those derived from brain, esophagus, stomach, liver and of hematopoietic origin showed low frequencies with a limited degree of MAP kinase activation. We also detected constitutive activation of the 41-/43-kDa MAP kinases in a relatively large number of primary human tumors derived from kidney, colon and lung tissues but not from liver tissue. Many tumor cells, in which point mutations of ras genes were detected, showed constitutive activation of MAP kinases, however, there were also many exceptions to this observation. In contrast, the activation of the 41-/43-kDa MAP kinases was accompanied by the activation of Raf-1 in the majority of tumor cells and was completely associated with the activation of MEK and p90 rsk in all the tumor cells examined. These results suggest that the constitutive activation of 41-/43-kDa MAP kinases in tumor cells is not due to the disorder of MAP kinases themselves, but is due to the disorder of Raf-1, Ras, or some other signaling molecules upstream of Ras.

Liver cirrhosis is the irreversible end result of fibrous scarring and hepatocellular regeneration, characterized by diffuse disorganization of the normal hepatic structure of regenerative nodules and fibrotic tissue. It is associated with prominent morbidity and mortality, and is induced by many factors, including chronic hepatitis virus infections, alcohol drinking and drug abuse. Hepatocyte growth factor (HGF), originally identified and cloned as a potent mitogen for hepatocytes, shows mitogenic, motogenic and morphogenic activities for a wide variety of cells. Moreover, HGF plays an essential part in the development and regeneration of the liver, and shows anti-apoptotic activity in hepatocytes. In a rat model of lethal liver cirrhosis produced by dimethylnitrosamine administrations, repeated transfections of the human HGF gene into skeletal muscles induced a high plasma level of human as well as enodogenous rat HGF, and tyrosine phosphorylation of the c-Met/HGF receptor. Transduction with the HGF gene also suppressed the increase of transforming growth factor-beta1 (TGF-beta1), which plays an essential part in the progression of liver cirrhosis, inhibited fibrogenesis and hepatocyte apoptosis, and produced the complete resolution of fibrosis in the cirrhotic liver, thereby improving the survival rate of rats with this severe illness. Thus, HGF gene therapy may be potentially useful for the treatment of patients with liver cirrhosis, which is otherwise fatal and untreatable by conventional therapy.

Systemic administration of IL-18 induces polyclonal IgE responses by causing NKT cells to express CD40 ligand and to produce IL-4. Administration of IL-33 also induces IgE response, although the mechanism underlying IgE response is unclear. Here, we compared the effects of IL-18 and IL-33 on bone marrow-derived mast cells and basophils as well as non-polarized and T(h)2-polarized CD4(+) T cells in vitro. Basophils, comprising IL-18Ralpha(+) cells (14.2%) and IL-33Ralpha(+) cells (34.6%), and mast cells, comprising IL-18Ralpha(+) cells (2.0%) and IL-33Ralpha(+) cells (95.6%), produce IL-4, IL-6, IL-13, granulocyte macrophage colony-stimulating factor (GM-CSF) and chemokines (RANTES, MIP-1alpha, MIP-1beta and MCP-1), upon stimulation with IL-18 and/or IL-33 in the presence of IL-3. Only basophils strongly produce IL-4. Furthermore, compared with mast cells, basophils produce larger amounts of the above cytokines and chemokines in response to IL-33. Level of IL-33Rbeta-mRNA expression in basophils is higher than that in mast cells. Effect of IL-33 is dependent on ST2 binding, and its signal is transduced via MyD88 in vitro. We also found that IL-2 plus IL-18 or IL-33 alone stimulates non-polarized or T(h)2-polarized CD4(+) T cells to produce IL-4 and IL-13 or IL-5 and IL-13, respectively. We finally showed that administration of IL-33 into mice ST2/MyD88 dependently induces airway hyperresponsiveness (AHR) and goblet cell hyperplasia by induction of IL-4, IL-5 and IL-13 in the lungs. Furthermore, same treatment of RAG-2(-/-) mice, lacking T and B cells, more strikingly induced AHR with marked goblet cell hyperplasia and eosinophilic infiltration in the lungs. Thus, IL-33 induces asthma-like symptom entirely independent of acquired immune system.

Mitogen-activated protein kinase/extracellular signalregulated protein kinase (MAPK/ERK) is a key molecule in intracellular signal transducing pathways that transport extracellular stimuli from cell surface to nuclei. MAPK/ERK has been revealed to be involved in the physiological proliferation of mammalian cells and also to potentiate them to transform. However, its role in the outgrowth of human hepatocellular carcinoma (HCC) has yet to be clarified. Therefore, in this study, we investigated the activation of MAPK/ERK and its associated gene expression in HCC. MAPK/ERK was activated in 15 of 26 cases of HCC we examined (58%), and its activity level was significantly higher in HCC than in the adjacent non-cancerous lesions. The mitogen-activated protein kinase/extracellular signalregulated protein kinase (MAPK/ERK) was first identified as a protein serine/threonine kinase which could be activated by a number of growth factors, cytokines, and oncogenic promoters 1,2 ; the MAPK/ERK, thereafter, was revealed to be a key molecule which converges several signal transduction pathways and transduces converged signals into nuclei, resulting in various cellular responses including proliferation and differentiation. 3,4 Numerous signals through small guanosine triphosphate (GTP)-binding protein Ras, 5 protein kinase C, 6 and other signal transducing molecules both phosphorylate and activate MAPK kinase kinases. MAPK kinase kinases, in turn, phosphorylate and activate MAPK/ERK kinase. Finally, MAPK/ERK kinase activates two isozymes of MAPK/ERK, p44 ERK1 and p42 ERK2 by phosphorylation on both threonine and tyrosine residues. In this way, signals from extracellular stimuli converge upon MAPK/ERK.Once activated, MAPK/ERK translocates into nuclei, 7-9 in which it induces transcription factors, including c-Fos and c-Jun, or activate them by phosphorylation. 10 These two transcription factors consist of activator protein-1 (AP-1) 11 and bind to AP-1 binding sites of promoter regions to induce transcription of the genes, including cyclin D1, 12 which is required for cell cycle progression in the G0/G1 phase as a G1 cyclin. 13 In addition, previous works indicate that constitutive MAPK/ERK activation results in the transformation of mammalian cells, 3,14 and that its activation is necessary for oncogenic transformation. 3 In this context, alterations in expression and activity of components of the MAPK cascade have been demonstrated in human tumors. [15][16][17] With regard to human hepatocellular carcinoma (HCC), there has been only one report on five patients where MAPK expression and activity were increased in cancerous lesions over noncancerous adjacent lesions 17 ; however, little has been revealed on the involvement of MAPK/ERK in human HCCs.Therefore, the aim of this study is to determine the activation of MAPK/ERK and expression of its associated genes, i.e., transcription factors and cell-cycle related genes, in both human HCCs and their non-cancerous counterparts, and to investigate how MAPK/ERK may be involved in the p...

Listeria monocytogenes (LM), a facultative intracellular Gram-positive bacterium, often causes lethal infection of the host. In this study we investigated the molecular mechanism underlying LM eradication in the early phase of infection. Upon infection with LM, both IL-12 and IL-18 were produced, and then they synergistically induced IFN-γ production, leading to normal LM clearance in the host. IFN-γ knockout (KO) mice were highly susceptible to LM infection. IL-12/IL-18 double knockout mice were also highly susceptible. Their susceptibility was less than that of IFN-γ KO mice, but more than that of single IL-12 or IL-18 KO mice. Mice deficient in myeloid differentiation factor 88 (MyD88), an essential adaptor molecule used by signal transduction pathways of all members of the Toll-like receptor (TLR) family, showed an inability to produce IL-12 and IFN-γ following LM infection and were most susceptible to LM. Furthermore, MyD88-deficient, but not IFN-γ-deficient, Kupffer cells could not produce TNF-α in response to LM in vitro, indicating the importance of MyD88-dependent TNF-α production for host defense. As TLR2 KO, but not TLR4 KO, mice showed partial impairment in their capacity to produce IL-12, IFN-γ, and TNF-α, TLR2 activation partly contributed to the induction of IL-12-mediated IFN-γ production. These results indicated a critical role for TLRs/MyD88-dependent IL-12/TNF-α production and for IL-12- and IL-18-mediated IFN-γ production in early phase clearance of LM.

IL-18, produced as biologically inactive precursor, is secreted from LPS-stimulated macrophages after cleavage by caspase-1. In this study, we investigated the mechanism underlying caspase-1-mediated IL-18 secretion. Kupffer cells constantly stored IL-18 and constitutively expressed caspase-1. Inhibition of new protein synthesis only slightly reduced IL-18 secretion, while it decreased and abrogated their IL-1β and IL-12 secretion, respectively. Kupffer cells deficient in Toll-like receptor (TLR) 4, an LPS-signaling receptor, did not secrete IL-18, IL-1β, and IL-12 upon LPS stimulation. In contrast, Kupffer cells lacking myeloid differentiation factor 88 (MyD88), an adaptor molecule for TLR-mediated-signaling, secreted IL-18 without IL-1β and IL-12 production in a caspase-1-dependent and de novo synthesis-independent manner. These results indicate that MyD88 is essential for IL-12 and IL-1β production from Kupffer cells while their IL-18 secretion is mediated via activation of endogenous caspase-1 without de novo protein synthesis in a MyD88-independent fashion after stimulation with LPS. In addition, infection with Listeria monocytogenes, products of which have the capacity to activate TLR, increased serum levels of IL-18 in wild-type and MyD88-deficient mice but not in caspase-1-deficient mice, whereas it induced elevation of serum levels of IL-12 in both wild-type and caspase-1-deficient mice but not in MyD88-deficient mice. Taken together, these results suggested caspase-1-dependent, MyD88-independent IL-18 release in bacterial infection.

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The current study determines the prognostic factors after hepatectomy for hepatocellular carcinomas. The 295 patients who underwent hepatectomy from 1973 through 1987 were included for a univariate and a Cox multivariate analysis. The favoring conditions were determined as follows. The essential requirements are (1) the absence of tumor thrombi; (2) no intrahepatic metastasis, but even when present, it should be close to the main tumor and removed with a massive resection; and (3) retention rate of indocyanine green dye (ICG) at 15 minutes should be within 14 +/- 4.2% (M +/- SD) to allow that resection. The desired requirement is that the tumor size should preferably be less than 5 cm; a wider free margin from tumors (greater than or equal to 1 cm) is recommended, but not determining factor. The eligible patients, having no thrombi, no intrahepatic metastasis, a tumor size of 5 cm or less, negative surgical margin (greater than or equal to 1 cm), had achieved a 5-year survival of 78%. In conclusion, resection therapy is the first option for patients with those requirements.