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Medical Sciences	100%

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Stat4 and Stat6 signaling in hepatic ischemia/reperfusion injury in mice: HO-1 dependence of Stat4 disruption-mediated cytoprotection

HEPATOLOGY, Issue 2 2003
Xiu-Da Shen
Ischemia/reperfusion (I/R) injury remains an important problem in clinical organ transplantation. There is growing evidence that T lymphocytes, and activated CD4+ T cells in particular, play a key role in hepatic I/R injury. This study analyzes the role of signal transducer and activator of transcription 4 (Stat4) and Stat6 signaling in liver I/R injury. Using a partial lobar warm ischemia model, groups of wild-type (WT), T cell,deficient, Stat4-/Stat6-deficient knockout (KO) mice were assessed for the extent/severity of I/R injury. Ninety minutes of warm ischemia followed by 6 hours of reperfusion induced a fulminant liver failure in WT and Stat6 KO mice, as assessed by hepatocellular damage (serum alanine aminotransferase [sALT] levels), neutrophil accumulation (myeloperoxidase [MPO] activity) and histology (Suzuki scores). In contrast, T cell deficiency (nu/nu mice) or disruption of Stat4 signaling (Stat4 KO mice) reduced I/R insult. Unlike adoptive transfer of WT or Stat6-deficient T cells, infusion of Stat4-deficient T cells failed to restore hepatic I/R injury and prevented tumor necrosis factor , (TNF-,) production in nu/nu mice. Diminished TNF-,/Th1-type cytokine messenger RNA (mRNA)/protein elaborations patterns, along with overexpression of heme oxygenase-1 (HO-1),accompanied hepatic cytoprotection in Stat4 KO recipients. In contrast, HO-1 depression restored hepatic injury in otherwise I/R resistant Stat4 KOs. In conclusion, Stat4 signaling is required for, whereas Stat4 disruption protects against, warm hepatic I/R injury in mice. The cytoprotection rendered by Stat4 disruption remains HO-1,dependent. [source]

Targeted therapy of renal cell carcinoma: Synergistic activity of cG250-TNF and IFNg

INTERNATIONAL JOURNAL OF CANCER, Issue 1 2009
Stefan Bauer
Abstract Immunotherapeutic targeting of G250/Carbonic anhydrase IX (CA-IX) represents a promising strategy for treatment of renal cell carcinoma (RCC). The well characterized human-mouse chimeric G250 (cG250) antibody has been shown in human studies to specifically enrich in CA-IX positive tumors and was chosen as a carrier for site specific delivery of TNF in form of our IgG-TNF-fusion protein (cG250-TNF) to RCC xenografts. Genetically engineered TNF constructs were designed as CH2/CH3 truncated cG250-TNF fusion proteins and eucariotic expression was optimized under serum-free conditions. In-vitro characterization of cG250-TNF comprised biochemical analysis and bioactivity assays, alone and in combination with Interferon-, (IFN,). Biodistribution data on radiolabeled [125J] cG250-TNF and antitumor activity of cG250-TNF, alone and in combination with IFN,, were measured on RCC xenografts in BALB/c nu/nu mice. Combined administration of cG250-TNF and IFN, caused synergistic biological effects that represent key mechanisms displaying antitumor responses. Biodistribution studies demonstrated specific accumulation and retention of cG250-TNF at CA-IX-positive RCC resulting in growth inhibition of RCC and improved progression free survival and overall survival. Antitumor activity induced by targeted TNF-based constructs could be enhanced by coadministration of low doses of nontargeted IFN, without significant increase in side effects. Administration of cG250-TNF and IFN, resulted in significant synergistic tumoricidal activity. Considering the poor outcome of renal cancer patients with advanced disease, cG250-TNF-based immunotherapeutic approaches warrant clinical evaluation. © 2009 UICC [source]

Histochemical evidence of osteoclastic degradation of extracellular matrix in osteolytic metastasis originating from human lung small carcinoma (SBC-5) cells

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 2 2006
Minqi Li
Abstract The aim of this study was to assess the dynamics of osteoclast migration and the degradation of unmineralized extracellular matrix in an osteolytic metastasis by examining a well-standardized lung cancer metastasis model of nude mice. SBC-5 human lung small carcinoma cells were injected into the left cardiac ventricle of 6-week-old BALB/c nu/nu mice under anesthesia. At 25,30 days after injection, the animals were sacrificed and their femora and/or tibiae were removed for histochemical analyses. Metastatic lesions were shown to occupy a considerable area extending from the metaphyses to the bone marrow region. Tartrate resistant acid phosphatase (TRAPase)-positive osteoclasts were found in association with an alkaline phosphatase (ALPase)-positive osteoblastic layer lining the bone surface, but could also be localized in the ALPase-negative stromal tissues that border the tumor nodules. These stromal tissues were markedly positive for osteopontin, and contained a significant number of TRAPase-positive osteoclasts expressing immunoreactivity for CD44. We thus speculated that, mediating its affinity for CD44, osteopontin may serve to facilitate osteoclastic migration after their formation associated with ALPase-positive osteoblasts. We next examined the localization of cathepsin K and matrix metallo-proteinase-9 (MMP-9) in osteoclasts. Osteoclasts adjacent to the bone surfaces were positive for both proteins, whereas those in the stromal tissues in the tumor nests showed only MMP-9 immunoreactivity. Immunoelectron microscopy disclosed the presence of MMP-9 in the Golgi apparatus and in vesicular structures at the baso-lateral cytoplasmic region of the osteoclasts found in the stromal tissue. MMP-9-positive vesicular structures also contained fragmented extracellular materials. Thus, osteoclasts appear to either select an optimized function, namely secreting proteolytic enzymes from ruffled borders during bone resorption, or recognize the surrounding extracellular matrix by mediating osteopontin/CD44 interaction, and internalize the extracellular matrices. Microsc. Res. Tech. 69:73,83, 2006. © 2006 Wiley-Liss, Inc. [source]

DJ-927, a novel oral taxane, overcomes P-glycoprotein-mediated multidrug resistance in vitro and in vivo

CANCER SCIENCE, Issue 5 2003
Motoko Shionoya
DJ-927 is a novel taxane, which was selected for high solubility, non-neurotoxicity, oral bioavailability, and potent antitumor activity. In this study, we compared the in vitro and in vivo efficacy of DJ-927 with those of paclitaxel and docetaxel. DJ-927 exhibited stronger cytotoxicity than paclitaxel and docetaxel in various tumor cell lines, especially against P-glycoprotein (P-gp)-expressing cells. The cytotoxicity of DJ-927, unlike those of other taxanes, was not affected by the P-gp expression level in tumor cells, or by the co-presence of a P-gp modulator. When intracellular accumulation of the three compounds was compared, intracellular amounts of DJ-927 were much higher than those of paclitaxel or docetaxel, particularly in P-gp-positive cells. In vivo, DJ-927 showed potent antitumor effects against two human solid tumors in male BALB/c- nu/nu mice, and yielded significant life-prolongation in a murine liver metastasis model with male C57BL/6 mice, in which neither paclitaxel nor docetaxel was effective. The results demonstrate the superior efficacy of orally administered DJ-927 over intravenously administered paclitaxel or docetaxel against P-gp-expressing tumors, probably due to higher intracellular accumulation. A phase I clinical trials of DJ-927 is currently ongoing in the US. (Cancer Sci 2003; 94: 459,466) [source]

Selective Inhibition of Hepatoma Cells Using Diphtheria Toxin A under the Control of the Promoter/Enhancer Region of the Human ,-Fetoprotein Gene

CANCER SCIENCE, Issue 3 2000
Michito Kunitomi
We constructed a plasmid containing human ,-fetoprotein (AFP) promoter/enhancer to direct the cell type-specific expression of diphtheria toxin fragment A (DTA), designated as pAF-DTA, to AFP-producing hepatocellular carcinoma cells. The transfection was carried out with cationic liposomes (DMRIE-C) and the expression of the DTA gene was confirmed by a northern blot analysis. When pAF-DTA was transfected, the growth of AFP-positive HuH-7 cells was inhibited, whereas growth inhibition was not observed in AFP-negative MKN45 cells. In this experiment, the secretion of AFP was similarly suppressed, but the secretion of carcinoembryonic antigen from MKN45 was not altered. pAF-DTA could also exert its growth inhibitory effect on PLC, a cell line with a low level of AFP. However, no inhibitory effect of pAF-DTA was observed on the proliferation of primary hepatocyte cells. Furthermore, transfection experiments in which HuH-7 and splenic stromal cells were co-cultured revealed the growth inhibition by pAF-DTA to be selective in HuH-7 cells. Finally, the growth of HuH-7 transplanted on BALB/c nu/nu mice was inhibited by the direct injection of pAF-DTA/liposome complex into a tumor mass. These results suggest that use of pAF-DTA may be potentially useful as a novel approach for the selective treatment of tumor cells producing AFP even at low levels, without affecting other types of cells. [source]