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NF-B-inducing kinase (NIK) has been shown to play an essential role in the NF-B activation cascade elicited by lymphotoxin ␤ receptor (LT␤R) signaling. However, the molecular mechanism of this pathway remains unclear. In this report we demonstrate that both NIK and IB kinase ␣ (IKK␣) are involved in LT␤R signaling and that the phosphorylation of the p65 subunit at serine 536 in its transactivation domain 1 (TA1) plays an essential role. We also found that NF-B could be activated in the LT␤R pathway without altering the level of the phosphorylation of IB and nuclear localization of p65. By using a heterologous transactivation system in which Gal4-dependent reporter gene is activated by the Gal4 DNA-binding domain in fusion with various portions of p65, we found that TA1 serves as a direct target in the NIK-IKK␣ pathway. In addition, mutation studies have revealed the essential role of Ser-536 within TA1 of p65 in transcriptional control mediated by NIK-IKK␣. Furthermore, we found that Ser-536 was phosphorylated following the stimulation of LT␤R, and this phosphorylation was inhibited by the kinase-dead dominant-negative mutant of either NIK or IKK␣. These observations provide evidence for a crucial role of the NIK-IKK␣ cascade for NF-B activation in LT␤R signaling.

We examined the role of p38 mitogen-activated protein (MAP) kinase in the tumor necrosis factor(IL-6) and interleukin-8 (IL-8) in fresh rheumatoid synovial fibroblast (RSF) cultures concomitantly with the induction of p38 MAP kinase activity. Pretreatment of RSF with a specific p38 MAP kinase inhibitor, SB203580, blocked the induction of IL-6 and IL-8 without affecting nuclear translocation of nuclear factor U UB (NF-U UB) or IL-6 and IL-8 mRNA levels. These findings suggest that p38 MAP kinase inhibitor may have synergistic, rather than additive, effect for the treatment of rheumatoid arthritis.z 2000 Federation of European Biochemical Societies.

No abstract

We conducted a 28-week, randomized, double-blind, parallel-group study of iguratimod in 376 Japanese patients with active rheumatoid arthritis to compare the efficacy and safety of the drug with those of placebo and salazosulfapyridine. In the American College of Rheumatology (ACR) 20 response rate, iguratimod was superior to placebo (53.8% versus 17.2%; Fisher's exact test, P < 0.001) and was not inferior to salazosulfapyridine (63.1% versus 57.7%, 95% confidence interval for the rate difference, -7.9% to 18.7%). Iguratimod began exhibiting its therapeutic effect within 8 weeks after the initiation of treatment and was effective even in patients who had a poor response to previous treatment with disease-modifying antirheumatic drugs. No statistically significant difference was noted in the incidence of adverse reactions between iguratimod and salazosulfapyridine. The study results suggest that iguratimod could become a new option for the treatment of rheumatoid arthritis.

We previously reported that endothelin-1 (ET-1) activates p42/p44 mitogen-activated protein (MAP) kinase in osteoblast-like MC3T3-E1 cells and consequently induces synthesis of interleukin-6. In the present study, we investigated the effect of ET-1 on the induction of heat shock protein 27 (HSP 27) in MC3T3-E1 cells. ET-1 time and dose dependently stimulated HSP 27 accumulation. ET-1 induced an increase in the levels of mRNA for HSP 27. Both staurosporine and calphostin C, inhibitors of protein kinase C (PKC), suppressed the ET-1-induced HSP 27 accumulation. 12-O-tetradecanoylphorbol 13-acetate (TPA), a PKC activator, induced the HSP 27 accumulation and the expression of mRNA for HSP 27. The ET-1-stimulated HSP 27 accumulation was reduced in PKC-downregulated MC3T3-E1 cells. The HSP 27 accumulation by ET-1 was not suppressed by PD-98059, an inhibitor of the upstream kinase that activates p42/p44 MAP kinase. ET-1 or TPA induced the phosphorylation of p38 MAP kinase. SB-203580, an inhibitor of p38 MAP kinase, reduced the ET-1-stimulated HSP 27 accumulation. Calphostin C and U-73122, a phospholipase C inhibitor, suppressed the ET-1-induced phosphorylation of p38 MAP kinase. U-73122 and propranolol, a phosphatidic acid phosphohydrolase inhibitor, reduced the ET-1-stimulated HSP 27 accumulation. SB-203580 suppressed the ET-1-stimulated increase in the mRNA levels for HSP 27. These results strongly suggest that ET-1 stimulates HSP 27 induction in osteoblasts and that p38 MAP kinase activation is involved in the HSP 27 induction.

No abstract

The effect of mild hyperthermia on a cultured rat malignant fibrous histiocytoma (MFH) cell line, MFH-ZNR, was imestigated. MFH cells in log-phase (growing phase) were heated at 4I0-44"C for I hr. Hyperthermic treatment at 41°C did not substantially affect cell proliferadon and treatment at 44°C caused necrosis. After hyperthermic treatment at 42" or 43"C, proliferation of MFH cells was arrested and morphological changes characteristic of apoptosis, cell shrinkage accompanying apoptotic bodies and chromatin condensation, became apparent. Hyperthermia-induced apoptosis was further confirmed by terminal deoxynucleotidyl transferase staining and a ladder pattern on agarose gel electrophoresis. Flow qtometric analysis indicated that the population in the GI phase of the cell cycle significantly decreased with a concomitant increase in apoptotic cells, indicating that apoptosis might occur mainly in the GI phase population.Q 19% Wifey-Liss, Inc.Hyperthermia is generally recognized as an effective and attractive tool in anti-tumor therapy (Dewey et al., 1989). We frequently employ hyperthermia against several malignant bone and soft tissue tumors in combination with radiation and chemotherapy. During these treatments, we noticed that malignant fibrous histiocytoma (MFH), one of the most commonly occurring malignant tumors of soft tissues, was exceptionally sensitive and susceptible to hyperthermia. From an in vitro cell biological viewpoint, it is of interest to define the unique behavior of MFH cells among other bone or soft tissue malignant tumor cells derived from osteosarcoma, rhabdomyosarcoma and liposarcoma. To date, however, little has been reported in terms of experimental studies on hyperthermiainduced anti-tumor effects on malignant tumor cells in the orthopedic field, except for an in vivo experiment using mouse fibrosarcoma (Stewart and Denekamp, 1978). Therefore, we have started to investigate the specific effect of hyperthermia on MFH cell growth in vitro. During the initial course of in vitro experiments, we found that MFH cells underwent a critical temperature-dependent cell death, including an apoptosis-like appearance at 42"43"C and necrosis-like appearance at 2 44°C. These observations prompted us to study in detail the biological changes induced by hyperthermia in the MFH cell.In the current study, we characterize the morphological and biochemical alterations of MFH cells induced by hyperthermia resulting in apoptosis and discuss the clinical advantage of hyperthermia in MFH. MATERIAL AND METHODS Cell cultureThe rat malignant fibrous histiocytoma cell line MFH-2NR was kindly provided by the Department of Oncological Pathology of Nara Medical College. MFH-NR2 was induced from rat cells by 4-hydroxyaminoquinoline l-oxide (Konishi et al., 1982(Konishi et al., , 1984 Mii et af., 1982). Primary cultures of rat fibroblasts were prepared from adult rats, and 3rd generations were used for experiments. Both cells were cultured in DMEM supplemented with 10% (v/v) FBS, 2 X 104 U/1 penicillin G and 200 mg/l st...