Su-Hyung Hong

MicroRNA profiling in the mouse hypothalamus reveals oxytocin-regulating microRNA.

Oxytocin (Oxt), produced in the hypothalamic paraventricular and supraoptic nuclei for transport to and release from the posterior pituitary, was originally discovered through its role in lactation and parturition. Oxt also plays important roles in the central nervous system by influencing various behaviors. MicroRNAs (miRNAs), endogenous regulators of many genes, are a class of small non‐coding RNAs that mediate post‐transcriptional gene silencing. We performed miRNA expression profiling of the mouse hypothalamus by deep sequencing. Among the sequenced and cross‐mapped small RNAs, expression of known miRNAs and unknown miRNAs candidates were analyzed. We investigated in detail one miRNA, miR‐24, and found that it is a novel regulator of Oxt and controls both transcript and peptide levels of Oxt. These results provide insights into potential neurohypophysial hormone regulation mediated by miRNAs.

Phosphatase of regenerating liver-3 promotes migration and invasion by upregulating matrix metalloproteinases-7 in human colorectal cancer cells

Phosphatase of regenerating liver (PRL)‐3, a member of a subgroup of protein tyrosine phosphatases that can stimulate the degradation of the extracellular matrix, is over‐expressed in metastatic colorectal cancer (CRC) relative to primary tumors. To determine whether PRL‐3‐induced enhancement of migration and invasion is dependent on the expression of matrix metalloproteinases (MMPs), PRL‐3 was expressed in DLD‐1 human CRC cells. The motility, migration and invasion characteristics of the cells were examined, and metastasis to the lung was confirmed in a nude mouse using PRL‐3‐overexpressing DLD‐1 cells [DLD‐1 (PRL‐3)]. Migration and invasion of the cells were inhibited by phosphatase and farnesyltransferase inhibitors. Expression of MMPs was enhanced 3‐ to 10‐fold in comparison to control cells, and migration and invasion were partially inhibited by small interfering RNA (siRNA) knockdown of MMP‐2, ‐13 or ‐14. Importantly, siRNA knockdown of MMP‐7 completely inhibited the migration and invasion of DLD‐1 (PRL‐3) cells, whereas overexpression of MMP‐7 increased migration. The expression of MMP‐7 was also downregulated by phosphatase and farnesyltransferase inhibitors. It was found that PRL‐3 induced MMP‐7 through oncogenic pathways including PI3K/AKT and ERK and that there is a relationship between the expression of PRL‐3 and MMP‐7 in human tumor cell lines. The expression of MMP‐13 and ‐14 was very sensitive to the inhibition of farnesyltransferase; however, the migration and invasion of DLD‐1 (PRL‐3) cells did not strongly depend on the expression of MMP‐13 or ‐14. These results suggest that the migration and invasion of PRL‐3‐expressing CRC cells depends primarily on the expression of MMP‐7.

Possible involvement of DNA methylation in NKCC1 gene expression during postnatal development and in response to ischemia

J. Neurochem. (2010) 114, 520–529.

Effect of garlic on bacterial biofilm formation on orthodontic wire.

OBJECTIVE To examine the effect of garlic extract on the biofilm formation by Streptococcus mutans on orthodontic wire and on glucosyltransferase gene expression. MATERIALS AND METHODS Growth inhibition of oral bacteria was tested after 50 µL of garlic extract was placed on an agar plate. The minimum inhibitory concentration (MIC) of garlic extract on S mutans growth was first determined. After cultivating streptococci in biofilm medium (BM)-sucrose with garlic extract and orthodontic wire, adenosine triphosphate (ATP) measurement and viable cell counting was performed from the bacteria attached on the wire. Scanning electron microscopy (SEM) analysis of morphology was observed on bacterial cells attached to orthodontic wire. The effect of garlic extract on gene expression was evaluated using quantitative real-time polymerase chain reaction (PCR) of glucosyltransferase. RESULTS Though garlic extract had a clear antibacterial effect on all microorganisms, it also enhanced S mutans attachment on orthodontic wire. Low concentration of garlic extract also increased glucosyltransferase gene expression of S mutans. CONCLUSIONS Despite its antibacterial function, garlic extract increases biofilm formation by S mutans to orthodontic wire, likely through upregulation of glucosyltransferase expression. Garlic extract may thus play an important role in increased bacterial attachment to orthodontic wires.

2-Hydroxycinnamaldehyde inhibits the epithelial-mesenchymal transition in breast cancer cells

Since epithelial-mesenchymal transition (EMT) plays a critical role in cancer progression and in maintaining cancer stem cell properties, EMT is emerging as a therapeutic target for inhibiting the metastatic progression of cancer cells. 2′-Hydroxycinnamaldehyde (HCA) and its derivative, 2′-benzoyloxycinnamaldehyde, have recently been suggested as promising therapeutic candidates for cancer treatment. The purpose of this study is to investigate the anti-metastatic effect of HCA on breast cancer and the molecular mechanisms by which HCA regulates the transcriptional program during EMT. HCA induces epithelial reversion at nanomolar concentrations by suppressing Snail via the nuclear translocalization of GSK-3β, which results in the transcriptional upregulation of E-cadherin. HCA also activates the transcription factor KLF17, which suppresses Id-1, indicating that HCA inhibits EMT by multiple transcriptional programs. Further, HCA treatment significantly inhibits lung metastasis in a mouse orthotopic breast cancer model. This study demonstrates the anti-metastatic effect of the non-toxic natural compound HCA through attenuation of EMT in a breast cancer model.

2-Hydroxycurcuminoid induces apoptosis of human tumor cells through the reactive oxygen species–mitochondria pathway

2-Hydroxycinnamaldehyde (HCA) and curcumin have been reported to have antitumor effects against various human tumor cells in vitro and in vivo by generation of ROS. Aldehyde-free HCA analogs were synthesized based on the structure of curcumin, which we have called 2-hydroxycurcuminoids. The hydroxyl group of curcuminoids enhances the ability to generate ROS. 2-Hydroxycurcuminoid (HCC-7) strongly inhibited the growth of SW620 colon tumor cells with a GI(50) value of 7μM, while the parent compounds, HCA and curcumin, displayed GI(50) values of 12 and 30μM, respectively. HCC-7 was found to induce apoptosis through the reactive oxygen species-mitochondria pathway and cell cycle arrest at G2/M phase.

PPAR γ partial agonist, KR-62776, inhibits adipocyte differentiation via activation of ERK

Abstract.Indenone KR-62776 acts as an agonist of PPARγ without inducing obesity in animal models and cells. X-ray crystallography reveals that the indenone occupies the binding pocket in a different manner than rosiglitazone. 2-Dimensional gel-electrophoresis showed that the expression of 42 proteins was altered more than 2.0-fold between KR-62776- or rosiglitazone-treated adipocyte cells and control cells. Rosiglitazone down-regulated the expression of ERK1/2 and suppressed the phosphorylation of ERK1/2 in these cells. However, the expression of ERK1/2 was up-regulated in KR-62776-treated cells. Phosphorylated ERK1/2, activated by indenone, affects the localization of PPARγ, suggesting a mechanism for indenone-inhibition of adipogenesis in 3T3-L1 preadipocyte cells. The preadipocyte cells are treated with ERK1/2 inhibitor PD98059, a large amount of the cells are converted to adipocyte cells. These results support the conclusion that the localization of PPARγ is one of the key factors explaining the biological responses of the ligands.

DJ-1 upregulates breast cancer cell invasion by repressing KLF17 expression

Background:DJ-1 (PARK7) was reported as an oncogene in a Ras-dependent manner. Recent studies have shown that DJ-1 stimulates cell proliferation, cell invasion, and cancer metastasis. However, the molecular mehchanism by which DJ-1 induces cancer cell invasion and metastasis remains unclear.Methods:Breast cancer cells were transfected with DJ-1 siRNA or DJ-1 overexpression to investigate the effect of DJ-1 on KLF17 expression. ID-1 luciferase promoter assay was performed to evaluate DJ-1-dependent KLF17 expression changes. In addition, Epistasis analysis of DJ-1 and KLF17 was performed to evaluate their regulatory interactions. Ras inhibitors were pretreated to determine whether DJ-1 regulates cell invasion in a Ras-dependent manner.Results:In the present study, we found increased DJ-1 expression in highly invasive breast cancer cells as compared with non-metastatic cells. Furthermore, DJ-1 promoted breast cancer cell invasion by downregulating E-cadherin and increasing Snail expression. Interestingly, exogenous DJ-1 overexpression markedly decreased mRNA and protein expression of KLF17, the EMT negative regulator. These data were confirmed by ID-1 promoter activity, which is directly regulated by DJ-1-dependent KLF17 transcription factor. Epistasis analysis showed that KLF17 overexpression overcomes increased cell invasion by DJ-1, suggesting that KLF17 might be one of the downstream signalling molecules of DJ-1. Acceleration of cell invasion by DJ-1 was alleviated by Ras inhibitors, suggesting that DJ-1 cooperates with Ras to increase cell invasion.Conclusion:Altogether, these data suggest for the first time that DJ-1 acts as an EMT-positive regulator in breast cancer cells via regulation of the KLF17/ID-1 pathway.

Up-Regulation of microRNA* Strands by Their Target Transcripts

During microRNA (miRNA) biogenesis, one strand of a 21–23 nucleotide RNA duplex is preferentially selected for entry into an RNA-induced silencing complex (RISC). The other strand, known as the miRNA* species, is typically thought to be degraded. Previous studies have provided miRNA* selection models, but it remains unclear how the dominance of one arm arises during the biogenesis of miRNA. Using miRNA sponge-like methods, we cloned four tandem target sequences (artificial target) of miR-7b* and then measured miR-7b* expression levels after transfection of the artificial target. miR-7b* levels were found to significantly increase after transfection of the artificial target. We postulate that the abundance of target transcripts drives miRNA arm selection.

Cinnamaldehydes in Cancer Chemotherapy.

Cinnamaldehyde and cinnamaldehyde‐derived compounds are candidates for the development of anticancer drugs that have received extensive research attention. In this review, we summarize recent findings detailing the positive and negative aspects of cinnamaldehyde and its derivatives as potential anticancer drug candidates. Furthermore, we describe the in vivo pharmacokinetics and metabolism of cinnamaldehydes. The oxidative and antioxidative properties of cinnamaldehydes, which contribute to their potential in chemotherapy, have also been discussed. Moreover, the mechanism(s) by which cinnamaldehydes induce apoptosis in cancer cells have been explored. In addition, evidence of the regulatory effects of cinnamaldehydes on cancer cell invasion and metastasis has been described. Finally, the application of cinnamaldehydes in treating various types of cancer, including breast, prostate, and colon cancers, has been discussed in detail. The effects of cinnamaldehydes on leukemia, hepatocellular carcinoma, and oral cancer have been summarized briefly. Copyright