Eun Myoung Shin

Secreted frizzled related proteins: Implications in cancers

The Wnt (wingless-type) signaling pathway plays an important role in embryonic development, tissue homeostasis, and tumor progression becaluse of its effect on cell proliferation, migration, and differentiation. Secreted frizzled-related proteins (SFRPs) are extracellular inhibitors of Wnt signaling that act by binding directly to Wnt ligands or to Frizzled receptors. In recent years, aberrant expression of SFRPs has been reported to be associated with numerous cancers. As gene expression of SFRP members is often lost through promoter hypermethylation, inhibition of methylation through the use of epigenetic modifying agents could renew the expression of SFRP members and further antagonize deleterious Wnt signaling. Several reports have described epigenetic silencing of these Wnt signaling antagonists in various human cancers, suggesting their possible role as tumor suppressors. SFRP family members thus come across as potential tools in combating Wnt-driven tumorigenesis. However, little is known about SFRP family members and their role in different cancers. This review comprehensively covers all the available information on the role of SFRP molecules in various human cancers.

DEAD-box helicase DP103 defines metastatic potential of human breast cancers

Despite advancement in breast cancer treatment, 30% of patients with early breast cancers experience relapse with distant metastasis. It is a challenge to identify patients at risk for relapse; therefore, the identification of markers and therapeutic targets for metastatic breast cancers is imperative. Here, we identified DP103 as a biomarker and metastasis-driving oncogene in human breast cancers and determined that DP103 elevates matrix metallopeptidase 9 (MMP9) levels, which are associated with metastasis and invasion through activation of NF-κB. In turn, NF-κB signaling positively activated DP103 expression. Furthermore, DP103 enhanced TGF-β-activated kinase-1 (TAK1) phosphorylation of NF-κB-activating IκB kinase 2 (IKK2), leading to increased NF-κB activity. Reduction of DP103 expression in invasive breast cancer cells reduced phosphorylation of IKK2, abrogated NF-κB-mediated MMP9 expression, and impeded metastasis in a murine xenograft model. In breast cancer patient tissues, elevated levels of DP103 correlated with enhanced MMP9, reduced overall survival, and reduced survival after relapse. Together, these data indicate that a positive DP103/NF-κB feedback loop promotes constitutive NF-κB activation in invasive breast cancers and activation of this pathway is linked to cancer progression and the acquisition of chemotherapy resistance. Furthermore, our results suggest that DP103 has potential as a therapeutic target for breast cancer treatment.

microRNAs in breast cancer: regulatory roles governing the hallmarks of cancer

A large number of etiological factors and the complexity of breast cancers present challenges for prevention and treatment. Recently, the emergence of microRNAs (miRNAs) as cancer biomarkers has added an extra dimension to the ‘molecular signatures’ of breast cancer. Bioinformatic analyses indicate that each miRNA can regulate hundreds of target genes and could serve functionally as ‘oncogenes’ or ‘tumour suppressor’ genes, and co‐ordinate multiple cellular processes relevant to cancer progression. A number of studies have shown that miRNAs play important roles in breast tumorigenesis, metastasis, proliferation and differentiation of breast cancer cells. This review provides a comprehensive overview of miRNAs with established functional relevance in breast cancer, their established target genes and resulting cellular phenotype. The role and application of circulating miRNAs in breast cancer is also discussed. Furthermore, we summarize the role of miRNAs in the hallmarks of breast cancer, as well as the possibility of using miRNAs as potential biomarkers for detection of breast cancer.

Anti-Inflammatory Activity of Angelica keiskei Through Suppression of Mitogen-Activated Protein Kinases and Nuclear Factor-κB Activation Pathways

Angelica keiskei has been shown to exhibit antitumor, antioxidant, and antidiabetic activities, and the fresh leaves and dry powder are used for health food. In spite of several beneficial effects, however, the molecular mechanism or mechanisms behind anti-inflammatory activities of A. keiskei remain unclear. Thus, we investigated the effects of A. keiskei on the activities of inducible nitric oxide (NO) synthase (iNOS) and cyclooxygenase-2 (COX-2) in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. We found that the n-hexane fraction of A. keiskei (HAK) significantly inhibited LPS-induced NO and prostaglandin E(2) production and tumor necrosis factor-alpha secretion. HAK also inhibited the expression of LPS-induced iNOS and COX-2 proteins and their mRNA levels. Furthermore, we hypothesize that anti-inflammatory effects by HAK can be linked to interference with the signaling pathway of mitogen-activated protein kinases (MAPKs) and the activation pathway of nuclear factor kappaB (NF-kappaB). HAK suppressed LPS-induced c-Jun NH(2)-terminal kinase, p38, and p44/p42 MAPK activation. We also found that the cell-based assay system showed that HAK suppressed LPS-induced NF-kappaB activity in transfectant RAW 264.7 cells. In addition, the electrophoretic mobility shift assay showed the same result as in the cell-based assay system. Our data suggest that the anti-inflammatory effect of HAK is mediated through down-modulation of iNOS and COX-2 gene products by blocking the signaling pathways of MAPKs and NF-kappaB.

Targeted Inhibition of Multiple Proinflammatory Signalling Pathways for the Prevention and Treatment of Multiple Myeloma

Radhamani Kannaiyan1, Rohit Surana1,2, Eun Myoung Shin2, Lalitha Ramachandran1, Gautam Sethi1,2,* and Alan Prem Kumar1,2,3,* 1Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, 2Cancer Science Institute of Singapore, National University of Singapore, 3School of Anatomy and Human Biology, The University of Western Australia, Crawley, Perth, Western Australia 1,2Singapore 3Australia

Anti-Inflammatory activity of Angelica keiskei through suppression of mitogen-activated protein kinases and nuclear factor-kappaB activation pathways.

Angelica keiskei has been shown to exhibit antitumor, antioxidant, and antidiabetic activities, and the fresh leaves and dry powder are used for health food. In spite of several beneficial effects, however, the molecular mechanism or mechanisms behind anti-inflammatory activities of A. keiskei remain unclear. Thus, we investigated the effects of A. keiskei on the activities of inducible nitric oxide (NO) synthase (iNOS) and cyclooxygenase-2 (COX-2) in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. We found that the n-hexane fraction of A. keiskei (HAK) significantly inhibited LPS-induced NO and prostaglandin E(2) production and tumor necrosis factor-alpha secretion. HAK also inhibited the expression of LPS-induced iNOS and COX-2 proteins and their mRNA levels. Furthermore, we hypothesize that anti-inflammatory effects by HAK can be linked to interference with the signaling pathway of mitogen-activated protein kinases (MAPKs) and the activation pathway of nuclear factor kappaB (NF-kappaB). HAK suppressed LPS-induced c-Jun NH(2)-terminal kinase, p38, and p44/p42 MAPK activation. We also found that the cell-based assay system showed that HAK suppressed LPS-induced NF-kappaB activity in transfectant RAW 264.7 cells. In addition, the electrophoretic mobility shift assay showed the same result as in the cell-based assay system. Our data suggest that the anti-inflammatory effect of HAK is mediated through down-modulation of iNOS and COX-2 gene products by blocking the signaling pathways of MAPKs and NF-kappaB.

Ikk2 regulates cytokinesis during vertebrate development

NFκB signaling has a pivotal role in regulation of development, innate immunity, and inflammation. Ikk2 is one of the two critical kinases that regulate the NFκB signaling pathway. While the role of Ikk2 in immunity, inflammation and oncogenesis has received attention, an understanding of the role of Ikk2 in vertebrate development has been compounded by the embryonic lethality seen in mice lacking Ikk2. We find that despite abnormal angiogenesis in IKK2 zygotic mutants of zebrafish, the maternal activity of Ikk2 supports embryogenesis and maturation of fertile animals and allows to study the role of IKK2 in development. Maternal-zygotic ikk2 mutants represent the first vertebrates globally devoid of maternal and zygotic Ikk2 activity. They are defective in cell proliferation as evidenced by abnormal cytokinesis, nuclear enlargement and syncytialisation of a significant portion of blastoderm. We further document that reduced phosphorylation of Aurora A by Ikk2 could underlie the basis of these defects in cell division.

RNA helicase DP103 and TAK1: a new connection in cancer.

Cancer Science Institute of Singapore; National University of Singapore; Singapore; Institute of Molecular and Cellular Biology; A*STAR, Singapore; Institute of Bioengineering and Nanotechnology; A*STAR; Singapore; Department of Paediatrics; Yong Loo Lin School of Medicine; National University of Singapore; Singapore; International Research Center for Medical Sciences; Kumamoto University; Kumamoto, Japan; Department of Pharmacology; Yong Loo Lin School of Medicine; National University of Singapore; Singapore; National University Cancer Institute; Singapore; School of Biomedical Sciences; Faculty of Health Sciences; Curtin University; Perth, Western Australia, Australia; Department of Biological Sciences; University of North Texas; Denton, TX USA; Department of Biochemistry; Yong Loo Lin School of Medicine; National University of Singapore; Singapore

PRDM15 safeguards naive pluripotency by transcriptionally regulating WNT and MAPK-ERK signaling

The transcriptional network acting downstream of LIF, WNT and MAPK–ERK to stabilize mouse embryonic stem cells (ESCs) in their naive state has been extensively characterized. However, the upstream factors regulating these three signaling pathways remain largely uncharted. PR-domain-containing proteins (PRDMs) are zinc-finger sequence-specific chromatin factors that have essential roles in embryonic development and cell fate decisions. Here we characterize the transcriptional regulator PRDM15, which acts independently of PRDM14 to regulate the naive state of mouse ESCs. Mechanistically, PRDM15 modulates WNT and MAPK–ERK signaling by directly promoting the expression of Rspo1 (R-spondin1) and Spry1 (Sprouty1). Consistent with these findings, CRISPR–Cas9-mediated disruption of PRDM15-binding sites in the Rspo1 and Spry1 promoters recapitulates PRDM15 depletion, both in terms of local chromatin organization and the transcriptional modulation of these genes. Collectively, our findings uncover an essential role for PRDM15 as a chromatin factor that modulates the transcription of upstream regulators of WNT and MAPK–ERK signaling to safeguard naive pluripotency.

Anti-Inflammatory Activity ofAngelica keiskeiThrough Suppression of Mitogen-Activated Protein Kinases and Nuclear Factor-κB Activation Pathways

Angelica keiskei has been shown to exhibit antitumor, antioxidant, and antidiabetic activities, and the fresh leaves and dry powder are used for health food. In spite of several beneficial effects, however, the molecular mechanism or mechanisms behind anti-inflammatory activities of A. keiskei remain unclear. Thus, we investigated the effects of A. keiskei on the activities of inducible nitric oxide (NO) synthase (iNOS) and cyclooxygenase-2 (COX-2) in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. We found that the n-hexane fraction of A. keiskei (HAK) significantly inhibited LPS-induced NO and prostaglandin E(2) production and tumor necrosis factor-alpha secretion. HAK also inhibited the expression of LPS-induced iNOS and COX-2 proteins and their mRNA levels. Furthermore, we hypothesize that anti-inflammatory effects by HAK can be linked to interference with the signaling pathway of mitogen-activated protein kinases (MAPKs) and the activation pathway of nuclear factor kappaB (NF-kappaB). HAK suppressed LPS-induced c-Jun NH(2)-terminal kinase, p38, and p44/p42 MAPK activation. We also found that the cell-based assay system showed that HAK suppressed LPS-induced NF-kappaB activity in transfectant RAW 264.7 cells. In addition, the electrophoretic mobility shift assay showed the same result as in the cell-based assay system. Our data suggest that the anti-inflammatory effect of HAK is mediated through down-modulation of iNOS and COX-2 gene products by blocking the signaling pathways of MAPKs and NF-kappaB.