Jung-Hyun Shim

Both E6 and E7 Oncoproteins of Human Papillomavirus 16 Inhibit IL-18-Induced IFN-γ Production in Human Peripheral Blood Mononuclear and NK Cells

Cervical carcinoma is the predominant cancer among malignancies in women throughout the world, and human papillomavirus (HPV) 16 is the most common agent linked to human cervical carcinoma. The present study was performed to investigate the mechanisms of immune escape in HPV-induced cervical cancer cells. The presence of HPV oncoproteins E6 and E7 in the extracellular fluids of HPV-containing cervical cancer cell lines SiHa and CaSki was demonstrated by ELISA. The effect of HPV 16 oncoproteins E6 and E7 on the production of IFN-γ by IL-18 was assessed. E6 and E7 proteins reduced IL-18-induced IFN-γ production in both primary PBMCs and the NK0 cell line. FACS analysis revealed that the viral oncoproteins reduced the binding of IL-18 to its cellular surface receptors on NK0 cells, whereas there was no effect of oncoproteins on IL-1 binding to its surface IL-1 receptors on D10S, a subclone of the murine Th cell D10.G4.1. In vitro pull-down assays also revealed that the viral oncoproteins and IL-18 bound to IL-18R α-chain competitively. These results suggest that the extracellular HPV 16 E6 and E7 proteins may inhibit IL-18-induced IFN-γ production locally in HPV lesions through inhibition of IL-18 binding to its α-chain receptor. Down-modulation of IL-18-induced immune responses by HPV oncoproteins may contribute to viral pathogenesis or carcinogenesis.

Epigallocatechin Gallate Suppresses Lung Cancer Cell Growth through Ras-GTPase-Activating Protein SH3 Domain-Binding Protein 1

Green tea is a highly popular beverage globally. Green tea contains a number of polyphenol compounds referred to as catechins, and (−)-epigallocatechin gallate (EGCG) is believed to be the major biologically active compound found in green tea. EGCG has been reported to suppress lung cancer, but the molecular mechanisms of the inhibitory effects of EGCG are not clear. We found that EGCG interacted with the Ras–GTPase-activating protein SH3 domain-binding protein 1 (G3BP1) with high binding affinity (Kd = 0.4 μmol/L). We also showed that EGCG suppressed anchorage-independent growth of H1299 and CL13 lung cancer cells, which contain an abundance of the G3BP1 protein. EGCG was much less effective in suppressing anchorage-independent growth of H460 lung cancer cells, which express much lower levels of G3BP1. Knockdown shG3BP1-transfected H1299 cells exhibited substantially decreased proliferation and anchorage-independent growth. shG3BP1 H1299 cells were resistant to the inhibitory effects of EGCG on growth and colony formation compared with shMock-transfected H1299 cells. EGCG interfered with the interaction of G3BP1 and the Ras–GTPase-activating protein and further suppressed the activation of Ras. Additional results revealed that EGCG effectively attenuated G3BP1 downstream signaling, including extracellular signal-regulated kinase and mitogen-activated protein kinase/extracellular signal-regulated kinase kinase, in wild-type H1299 and shMock H1299 cells but had little effect on H460 or shG3BP1 H1299 cells. Overall, these results strongly indicate that EGCG suppresses lung tumorigenesis through its binding with G3BP1. Cancer Prev Res; 3(5); 670–9. ©2010 AACR.

Interleukin-32 monoclonal antibodies for Immunohistochemistry, Western blotting, and ELISA

The members of the IL-1 family play important roles in the development and pathogenesis of autoimmune and inflammatory diseases. Especially, IL-1 and IL-18 belong to the IL-1 family because they share structural similarity and require caspase-1 for processing. Currently, IL-18 has been studied for its biological effects in the broad spectrum of Th1- or Th2- related autoimmune diseases. IL-18 also uses a similar signaling pathway as that of IL-1 family members. Taken together these results, IL-18-inducible genes might also contribute to autoimmune and inflammatory diseases. It has recently been reported that an inducer of TNF-alpha was identified as one of IL-18 inducible genes in IL-18 responsible cells and named as a new cytokine IL-32. We have produced novel monoclonal anti IL-32 antibodies in order to help study IL-32 function and to develop improved diagnosis of IL-32-expressing tumors. Several mAbs reactive to IL-32 isoforms were prepared and characterized by the epitope analysis and Western blotting performed using various deletion mutants and IL-32 isoforms (IL-32alpha, beta, gamma, and delta). In order to optimize the sandwich ELISA for IL-32, recombinant IL-32alpha was added, followed by the addition of a biotinylated mAb KU32-52 into the microtiter plate wells pre-coated with a mAb KU32-07 or mAb KU32-56. The bound mAb was probed with a streptavidin conjugated to HRP. The epitope analysis and Western blot analysis revealed that mAb KU32-07 could detect only IL-32alpha and KU32-52 was bound to all isoforms, whereas KU32-56 were reactive to IL-32 alpha, beta, delta isoforms but not gamma isoform. These sandwich ELISAs were highly specific and had a minimal detection limit of 80 pg/ml (mean+3 SD of zero calibrator) and measuring range of up to 3000 pg/ml. An ELISA using a coating mAb KU32-07 and a capturing biotinylated mAb KU32-52 had no cross-reaction with other cytokines such as IL-32beta, IL-32gamma, IL-32delta, hIL-1alpha , IL-1beta , hIL-2, hIL-6, hIL-8, hIL-10, hIL-18, and hTNF-alpha. Intra-assay coefficients of variation were 11 to 6% (n=16) and inter-assay coefficients were 10 to 5% (n=9). Another ELISA using a coating mAb KU32-56 and a capturing biotinylated mAb KU32-52 detected both IL-32alpha and IL-32beta isoforms but not gamma and delta isoforms and had no cross-reaction with other cytokines such as hIL-1alpha , IL-1beta , hIL-2, hIL-6, hIL-8, hIL-10, hIL-18, and hTNF-alpha. One mAb KU32-09 was shown to react strongly on immunohistochemistry. Our newly established mAbs, KU32-07, KU32-09, KU32-52, KU32-56, have different and useful properties for the detection of IL-32 by immunohistochemistry, ELISA, and Western blotting.

RSK2 mediates muscle cell differentiation through regulation of NFAT3.

RSK2, an ERK downstream kinase, is a novel mediator of skeletal muscle cell differentiation through its regulation of NFAT3 activity. We found that the N-terminal (amino acids (aa) 1-68) and C-terminal (aa 416-674) kinase domains of RSK2 directly interacted with nuclear localization signal 1, the Ser/Pro repeat, and the polyproline domains (aa 261-365) of NFAT3. Upon A23187 stimulation, RSK2 induced nuclear localization of NFAT3. RSK2 phosphorylated NFAT3 in vitro (Km = 3.559 μm), and activation of NFAT3 by RSK2 enhanced the promoter activity of NFAT3 downstream target genes in vivo. Furthermore, nuclear accumulation of NFAT3 was attenuated markedly in RSK2-/- cells compared with wild-type RSK2+/+ cells. Notably, RSK2 and NFAT3 induced a significant differentiation of C2C12 myoblasts to multinucleated myotubes. Multinucleated myotube differentiation was inhibited by small interfering RNA against RSK2, ERK1/2, or NFAT3. These results demonstrate that RSK2 is an important kinase for NFAT3 in mediating myotube differentiation.

Cot, a novel kinase of histone H3, induces cellular transformation through up-regulation of c-fos transcriptional activity

Post‐translational modification of his‐tones is critical for gene expression, mitosis, cell growth, apoptosis, and cancer development. Thus, finding protein kinases that are responsible for the phosphorylation of histones at critical sites is considered an important step in understanding the process of histone modification. The serine/threonine kinase Cot is a member of the mitogen‐activated protein kinase (MAPK) kinase kinase family. We show here that Cot can phosphorylate histone H3 at Ser‐10 in vivo and in vitro, and that the phosphorylation of histone H3 at Ser‐10 is required for Cot‐induced cell transformation. We found that activated Cot is recruited to the c‐fos promoter resulting in increased activator protein‐1 (AP‐1) transactivation. The formation of the Cot‐c‐fos promoter complex was also apparent when histone H3 was phosphorylated at Ser‐10. Furthermore, the use of dominant negative mutants of histone H3 revealed that Cot was required for phosphorylation of histone H3 at Ser‐10 to induce neoplastic cell transformation. These results revealed an important function of Cot as a newly discovered histone H3 kinase. Moreover, the transforming ability of Cot results from the coordinated activation of histone H3, which ultimatelyconverges on the regulation of the transcriptional activity of the c‐fos promoter, followed by AP‐1 transactivation activity.— Choi, H. S., Kang, B. S., Shim, J. H., Cho, Y. Y., Choi, B. Y., Bode, A. M., Dong, Z. Cot, a novel kinase of histone H3, induces cellular transformation through up‐regulation of c‐fos transcriptional activity. FASEB J. 22, 113–126 (2008)

Signaling pathways implicated in α‐melanocyte stimulating hormone‐induced lipolysis in 3T3‐L1 adipocytes

Melanocortins, besides their central roles, have also recently been reported to regulate adipocyte metabolism. In this study, we attempted to characterize the mechanism underlying α‐melanocyte‐stimulating hormone (MSH)‐induced lipolysis, and compared it with that of the adrenocorticotrophin hormone (ACTH) in 3T3‐L1 adipocytes. Similar to ACTH, MSH treatment resulted in the release of glycerol into the cell supernatant. The activity of hormone‐sensitive lipase, a rate‐limiting enzyme, which is involved in lipolysis, was significantly increased by MSH treatment. In addition, a variety of kinases, including protein kinase A (PKA) and extracellular signal‐regulated kinase (ERK) were also phosphorylated as the result of MSH treatment, and their specific inhibitors caused a reduction in MSH‐induced glycerol release and HSL activity, indicating that MSH‐induced lipolysis was mediated by these kinases. These results suggest that PKA and ERK constitute the principal signaling pathways implicated in the MSH‐induced lipolytic process via the regulation of HSL in 3T3‐L1 adipocytes. J. Cell. Biochem.

Chemopreventive effect of tolfenamic acid on KB human cervical cancer cells and tumor xenograft by downregulating specificity protein 1.

Earlier studies have shown that tolfenamic acid (Tol) exhibits anticancer activity in several cancer models by inhibiting tumor growth and angiogenesis. However, the chemopreventive effect of Tol on a cervical cancer model and the underlying mechanism of action are unknown. In this study, Tol was found to inhibit cell proliferation by inducing apoptosis without affecting cyclo-oxygenase 2 expression, but ampiroxicam did not. Tol decreases the specificity protein 1 (Sp1) mRNA and its promoter activity in KB cervical cancer cells, and the downregulation of Sp1 protein by affecting several proteins that contain GC-rich sites on their promoters. Studies using small interference RNA and an Sp1-specific inhibitor (mithramycin A) confirmed that the decrease in Sp1 by Tol affects survivin and p27. Tol also inhibited tumor growth and Sp1 protein in athymic nude mice xenografts. These results show that Tol could be a potent anticervical cancer drug that acts by regulating Sp1 protein and its downstream pathways.

Hesperidin Induces Apoptosis by Inhibiting Sp1 and Its Regulatory Protein in MSTO-211H Cells

Hesperidin, a flavanone present in citrus fruits, has been studied as potential therapeutic agents that have anti-tumor activity and apoptotic effects in several cancers, but there is no report about the apoptotic effect of hesperidin in human malignant pleural mesothelioma through the specificity protein 1 (Sp1) protein. We investigated whether hesperidin inhibited cell growth and regulated Sp1 target proteins by suppressing the levels of Sp1 protein in MSTO-211H cells. The IC50 value of hesperidin was determined to be 152.3 μM in MSTO-211H cells for 48 h. Our results suggested that hesperidin (0-160 μM) decreased cell viability, and induced apoptotic cell death. Hesperidin increased Sub-G1 population in MSTO-211H cells. Hesperidin significantly suppressed mRNA/protein level of Sp1 and modulated the expression level of the Sp1 regulatory protein such as p27, p21, cyclin D1, Mcl-1, and survivin in mesothelioma cells. Also, hesperidin induced apoptotic signaling including: cleavages of Bid, caspase-3, and PARP, upregulation of Bax, and down-regulation of Bcl-xl in mesothelioma cells. These results show that hesperidin suppressed mesothelioma cell growth through inhibition of Sp1. In this study, we demonstrated that Sp1 acts as a novel molecular target of hesperidin in human malignant pleural mesothelioma.

Protective effect of oxidative stress in HaCaT keratinocytes expressing E7 oncogene

Summary.In a previous study, we established a stable cell line which constitutively expresses E7 in HaCaT human keratinocyte cell line and identified various relevant factors including oxygen modulators affected by the E7 oncogene. E7-expressing HaCaT cells (HaCaT/E7) appeared to be more resistant to H2O2-induced cell death. Here, we demonstrate how E7 oncogene would modulate oxidative stress-induced cell death. In addition, we verified the increased expression of catalase in the HaCaT/E7 by Western blot analysis. The results suggest that the E7 oncogene would induce higher resistance to ROS-induced cell injury in the E7-infected cells via the upregulation of catalase. To investigate these paradoxical effects of high concentrations of H2O2 (500 µM–1 mM), we examined their effects on receptor mediated apoptosis, cell death via the mitochondrial pathway and modulation of apoptosis related factors. Our results revealed that HaCaT keratinocytes infected with HPV 16 E7 oncogene modulated expressions of catalase, Bcl-xL, IL-18, Fas, Bad, and cytochrome c as well as NF-κB, resulting in the resistance to oxidative stress-induced cell death.

HPLC Analysis, Optimization of Extraction Conditions and Biological Evaluation of Corylopsis coreana Uyeki Flos

A method for the separation and quantification of three flavonoids and one isocoumarin by reverse-phase high performance liquid chromatography (HPLC) has been developed and validated. Four constituents present in a crude ethanolic extract of the flowers of Coryloposis coreana Uyeki, were analyzed. Bergenin, quercetin, quercitrin and isosalipurposide were used as calibration standards. In the present study, an excellent linearity was obtained with an r2 higher than 0.999. The chromatographic peaks showed good resolution. In combination with other validation data, including precision, specificity, and accuracy, this method demonstrated good reliability and sensitivity, and can be conveniently used for the quantification of bergenin, quercetin, quercitrin and isosalipurposide in the crude ethanolic extract of C. coreana Uyeki flos. Furthermore, the plant extracts were analyzed with HPLC to determine the four constituents and compositional differences in the extracts obtained under different extraction conditions. Several extracts of them which was dependent on the ethanol percentage of solvent were also analyzed for their antimicrobial and antioxidant activities. One hundred % ethanolic extract from C. coreana Uyeki flos showed the best antimicrobial activity against the methicillin-resistant Staphylococcus aureus (MRSA) strain. Eighty % ethanolic extract showed the best antioxidant activity and phenolic content. Taken of all, these results suggest that the flower of C. coreana Uyeki flos may be a useful source for the cure and/or prevention of septic arthritis, and the validated method was useful for the quality control of C. coreana Uyeki.