15-Keto prostaglandin E2 induces heme oxygenase-1 expression through activation of Nrf2 in human colon epithelial CCD 841 CoN cells

Prostaglandin E-2 (PGE(2)) plays a key role in inflammation-associated carcinogenesis. NAD(+)-dependent 15-hydroxyprostaglandin dehydrogenase (15-PGDH) catalyzes the oxidation of the 15(S)-hydroxyl group of PGE(2) to generate 15-keto PGE(2). 15-PGDH has been known as a tumor suppressor in various malignancies including colon cancer. However, the molecular mechanisms underlying the tumor-suppressive function of 15-PGDH remain largely unresolved. In this study, we found that 15-keto PGE(2) upregulated the expression of heme oxygenase-1 (HO-1), a representative antioxidative and anti-inflammatory enzyme, at both transcriptional and translational levels, in human colon epithelial CCD 841 CoN cells. A redox-sensitive transcription factor, NF-E2-related factor (Nrf2) plays a critical role in the regulation of HO-1 and other cytoprotective proteins. 15-Keto PGE(2) induced translocation of Nrf2 into the nucleus and antioxidant response element-driven luciferase activity. Furthermore, the silencing of the Nrf2 gene abolished 15-keto PGE(2)-induced HO-1 expression in CCD 841 CoN cells. 15-Keto PGE(2) activated AKT signaling, and the pharmacological AKT inhibitor, LY294002 suppressed the 15-keto PGE(2)-induced HO-1 expression. 15-Keto PGE(2) generates the reactive oxygen species which is suppressed by the general antioxidant N-acetyl-L-cysteine. N-acetyl-L-cysteine treatment attenuated the 15-keto PGE(2)-induced phosphorylation of GSK3 beta, transcriptional activity of Nrf2, and subsequently HO-1 expression. However, 13,14-dihydro-15-keto PGE(2) lacking the alpha,beta-unsaturated carbonyl moiety failed to induce intracellular production of reactive oxygen species, HO-1 expression and nuclear translocation of Nrf2. In conclusion, 15-keto PGE(2) induces HO-1 expression through Nrf2 activation in human colon epithelial cells.

Novel involvement of leukotriene B4 receptor 2 through ERK activation by PP2A down-regulation in leukotriene B4-induced keratin phosphorylation and reorganization of pancreatic cancer cells

AbstractPerinuclear reorganization via phosphorylation of specific serine residues in keratin is involved in the deformability of metastatic cancer cells. The level of leukotriene B4 is high in pancreatic cancers. However, the roles of LTB4 and its cognate receptors in keratin reorganization of pancreatic cancers are not known. LTB4 dose-dependently induced phosphorylation and reorganization of Keratin 8 (K8) and these processes were reversed by LY255283 (BLT2 antagonist). BLT2 agonists such as Comp A and 15(S)-HETE also induced phosphorylation of serine 431 in K8. Moreover, Comp A-induced K8 phosphorylation and reorganization were blocked by LY255283. Gene silencing of BLT2 suppressed Comp A-induced K8 phosphorylation and reorganization in PANC-1 cells. Over-expression of BLT2 promoted K8 phosphorylation. Comp A promoted the migration of PANC-1 cells in a dose-dependent manner, and LY255283 blocked Comp A-induced migration, respectively. PD98059 (ERK inhibitor) suppressed Comp A-induced phosphorylation of serine 431 and reorganization of K8. Gene silencing of BLT2 suppressed the expression of pERK, and over-expression of BLT2 increased the expression of pERK even without Comp A. Comp A induced the expression of active ERK (pERK) and BLT2. These inductions were blocked by PD98059. Comp A decreased PP2A expression and hindered the binding of PP2A to the K8, leading to the activation of ERK. PD98059 suppressed the Comp A-induced migration of PANC-1 cells and BLT2 over-expression-induced migration of PANC-1 cells. Overall, these results suggest that BLT2 is involved in LTB4‐induced phosphorylation and reorganization through ERK activation by PP2A downregulation, leading to increased migration of PANC‐1 cells

Interaction of testisin with maspin and its impact on invasion and cell death resistance of cervical cancer cells

AbstractPrevious studies have shown that testisin promotes malignant transformation in cancer cells. To define the mechanism of testisin-induced carcinogenesis, we performed yeast two-hybrid analysis and identified maspin, a tumor suppressor protein, as a testisin-interacting molecule. The direct interaction and cytoplasmic co-localization of testisin with maspin was confirmed by immunoprecipitation and confocal analysis, respectively. In cervical cancer cells, maspin modulated cell death and invasion; however, these effects were inhibited by testisin in parallel experiments. Of interest, the doxorubicin resistance was dramatically reduced by testisin knockdown (P=0.016). Moreover, testisin was found to be over-expressed in cervical cancer samples as compared to matched normal cervical tissues. Thus, we postulate that testisin may promote carcinogenesis by inhibiting tumor suppressor activity of maspin.Structured summaryMINT-7712215, MINT-7712176: Testisin (uniprotkb:Q9Y6M0) binds (MI:0407) to Maspin (uniprotkb:P36952) by pull down (MI:0096)MINT-7712188: Testisin (uniprotkb:Q9Y6M0) and Maspin (uniprotkb:P36952) colocalize (MI:0403) by fluorescence microscopy (MI:0416)MINT-7712115: Testisin (uniprotkb:Q9Y6M0) physically interacts (MI:0915) with Maspin (uniprotkb:P36952) by two-hybrid (MI:0018)MINT-7712162, MINT-7712128: Maspin (uniprotkb:P36952) physically interacts (MI:0915) with Testisin (uniprotkb:Q9Y6M0) by anti bait co-immunoprecipitation (MI:0006)MINT-7712147: Testisin (uniprotkb:Q9Y6M0) physically interacts (MI:0915) with Maspin (uniprotkb:P36952) by anti tag co-immunoprecipitation (MI:0007

Development of Monoclonal Antibodies Against Human IRF-5 and Their Use in Identifying the Binding of IRF-5 to Nuclear Import Proteins Karyopherin-α1 and -β1

PURPOSE: IRF-5 is a direct transducer of virus-mediated and TLR-mediated signaling pathways for the expression of cytokines and chemokines which form homodimers or heterodimers with IRF-7. However, direct IRF-5-specific monoclonal antibodies (mAbs) are not available at present. These could be used to further evaluate the functions of IRF-5. In this study, we produced and characterized three mouse mAbs to human IRF-5. The binding of IRF-5 to nuclear import proteins was first identified using a mAb. MATERIALS AND METHODS: His-tagged human IRF-5 protein spanning amino acid residues 193-257 was used as an antigen and three mAbs were produced. The mAbs were tested with ELISA, Western blot analysis (WB), immunofluorescent staining (IF), and immunoprecipitation (IP). In addition, the nuclear import protein which carried phosphorylated IRF-5 was identified using one of these mAbs. RESULTS: MAbs 5IRF8, 5IRF10 and 5IRF24 which reacted with the recombinant His-IRF-5(193-257) protein were produced. All mAbs bound to human IRF-5, but not to IRF-3 or IRF-7. They could be used for WB, IF, and IP studies. The binding of phosphorylated IRF-5 to karyopherin-alpha1 and -beta1 was also identified. CONCLUSION: Human IRF-5-specific mAbs are produced for studying the immunologic roles related to IRF-5. Phosphorylated IRF-5 is transported to the nucleus by binding to nuclear import proteins karyopherin-alpha1 and -beta1.ope

Identification of Domains Directing Specificity of Coupling to G-proteins for the Melanocortin MC3 and MC4 Receptors

The melanocortin receptors, MC3R and MC4R, are G protein-coupled receptors that are involved in regulating energy homeostasis. Using a luciferase reporter gene under the transcriptional control of a cAMP-responsive element (CRE), the coupling efficiency of the MC4R and MC3R to G-proteins was previously shown to be different. MC4R exhibited only 30-50% of the maximum activity induced by MC3R. To assess the role of the different MC3R and MC4R domains in G-protein coupling, several chimeric MC3R/MC4R receptors were constructed. The relative luciferase activities, which were assessed after transfecting the chimeric receptors into HEK 293T cells, showed that the i3 (3rd intracellular) loop domain has an essential role in the differential signaling of MC3R and MC4R. To reveal which amino acid residue was involved in the MC4R-specific signaling in the i3 loop, a series of mutant MC4Rs was constructed. Reporter gene analysis showed that single mutations of Arg220 to Ala and Thr232 to either Val or Ala increased the relative luciferase activities, which suggests that these specific amino acids, Arg220 and Thr232, in the i3 loop of MC4R play crucial roles in G-protein coupling and the subtype-specific signaling pathways. An examination of the inositol phosphate (IP) levels in the cells transfected with either MC3R or MC4R after being exposed to the melanocortin peptides revealed significant stimulation of IP production by MC3R but no detectable increase in IP production was observed by MC4R. Furthermore, none of the MC4R mutants displayed melanocortin peptide-stimulated IP production. Overall, this study demonstrated that MC3R and MC4R have distinct signaling in either the cAMP- or the inositol phospholipid-mediated pathway with different conformational requirements

Three-way Translocation of MLL/MLLT3, t(1;9;11)(p34.2;p22;q23), in a Pediatric Case of Acute Myeloid Leukemia

The chromosome band 11q23 is a common target region of chromosomal translocation in different types of leukemia, including infantile leukemia and therapy-related leukemia. The target gene at 11q23, MLL, is disrupted by the translocation and becomes fused to various translocation partners. We report a case of AML with a rare 3-way translocation involving chromosomes 1, 9, and 11: t(1;9;11)(p34.2;p22;q23). A 3-yr-old Korean girl presented with a 5-day history of fever. A diagnosis of AML was made on the basis of the morphological evaluation and immunophenotyping of bone marrow specimens. Flow cytometric immunophenotyping showed blasts positive for myeloid lineage markers and aberrant CD19 expression. Karyotypic analysis showed 46,XX,t(1;9;11)(p34.2;p22;q23) in 19 of the 20 cells analyzed. This abnormality was involved in MLL/MLLT3 rearrangement, which was confirmed by qualitative multiplex reverse transcription-PCR and interphase FISH. She achieved morphological and cytogenetic remission after 1 month of chemotherapy and remained event-free for 6 months. Four cases of t(1;9;11)(v;p22;q23) have been reported previously in a series that included cases with other 11q23 abnormalities, making it difficult to determine the distinctive clinical features associated with this abnormality. To our knowledge, this is the first description of t(1;9;11) with clinical and laboratory data, including the data for the involved genes, MLL/MLLT3