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Young Kwan Sung

Publications and source records attributed to Young Kwan Sung.

13 recordsLinked to original sources
PubMed2006

Cellular changes resulting from forced expression of glypican-3 in hepatocellular carcinoma cells.

Glypican-3 (GPC3) is a member of the glypican family, which encodes cell-surface heparan-sulfate proteoglycans, and is frequently upregulated in hepatocellular carcinoma (HCC). We have recently reported that blocking endogenous GPC3 expression promotes the growth of HCC cell lines, suggesting that GPC3 plays a negative role in HCC cell proliferation. Here, we report that forced expression of GPC3 reduced the growth of HCC cells. We also found that FGF2-mediated cell proliferation was inhibited by GPC3. In addition, we observed that the adhesion of HCC cells to collagen type I and fibronectin was decreased by GPC3, whereas cellular migration and invasiveness were stimulated. Collectively, these results suggest that progression of hepatocellular carcinoma is associated with upregulation of GPC3.

Animals↗
PubMed2004

The correlation between cyclooxygenase-2 expression and hepatocellular carcinogenesis.

Overexpression of cyclooxygenase 2 (COX-2) is associated with tumorigenesis in a number of human cancers. Recently, COX-2 overexpression has also been reported in hepatocellular carcinoma (HCC), especially in well-differentiated HCC. However, doubt has been cast on these claims concerning HCC. Here we show by Western blot analysis that COX-2 protein level is higher in the adjacent chronic hepatitis liver than in the tumors themselves. We also show, by immunohistochemical staining, that the mean intensity of COX-2 expression in cirrhotic liver specimens is significantly higher than in normal livers and in moderately-differentiated HCC. In addition, the frequency and level of expression of COX-2 in poorly differentiated HCC was similar to that of well-differentiated HCC. Nevertheless all types of HCC expressed more COX-2 than normal livers, and immunofluorescence staining showed cytoplasmic expression of COX-2 in 7 out of 8 human hepatoma cell lines. Collectively, our data suggest that both chemoprevention and chemotherapy of HCC by COX-2 specific inhibitors should be considered. Our data also suggest that COX-2 may play a role in the advanced stages as well as early stages of hepatocarcinogenesis.

Blotting, Western↗
PubMed2004

NS398 inhibits the growth of Hep3B human hepatocellular carcinoma cells via caspase-independent apoptosis.

Overexpression of cyclooxygenase 2 (COX-2) is associated with the development of a number of human cancers including hepatocellular carcinoma (HCC). In addition, NS398, a selective COX-2 inhibitor, has been found to inhibit the growth of COX-2 expressing HCC cell lines. However, the mechanism of this effect remains unclear. Here, we report that NS398 inhibits the growth of the Hep 3B human HCC cell line and that inhibition results from the induction of apoptosis with no evidence of cell cycle arrest. We also show that the extent of apoptosis is greatly influenced by culture conditions. The NS398-induced apoptosis in Hep 3B cells is caspase-independent. Our data point to the feasibility of preventing HCC by means of COX-2 inhibitors, and show that the environment influences the cytotoxic effect of NS398 on cancer cells.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2003

Enhanced antitumor activity [correction for activitiy] of trans(+/-)-1,2-diaminocyclo- hexaneglutamatoplatinum(II) formulated with stealth liposome.

The antitumor platinum(II) compound, [Pt(dach)(Glu)] (dach=trans(+/-)-1,2-diaminocyclohexane, Glu=glutamate) was formulated with a stealth liposome to improve its biological activity. Liposomes were composed of PC/PEG2000-PE/CH (PC=1,2-diacyl-glycero-3-phosphocholine; PEG2000-PE=poly(ethylene glycol)2000-1,2-diacyl-glycero-3-phosphoethanolamine; CH=cholesterol) involving different acyl moieties of phospholipids such as DO (dioleoyl), DM (dimyristoyl) or DS (distearoyl) group. Among the different acyl groups in the stealth liposomes, the DM formulation was optimal for the preparation of the liposomal [Pt(dach)(Glu)] at the mole ratio of DMPC/PEG2000-DMPE/CH=50/5/45 and at the weight ratio of drug/lipid=1/20, which is represented as L-[Pt(dach)(Glu)]. In vitro cytotoxicity was examined in sensitive A2780 and ME180 and their cisplatin-resistant A2780/PDD and ME180/PDD cancer cells. L-[Pt(dach)(Glu)] was 2 approximately 3 times more cytotoxic than the free complex [Pt(dach)(Glu)] and cisplatin in sensitive cells, and 4 approximately 8 times more cytotoxic in resistant cells. Thus, the resistance index of L-[Pt(dach)(Glu)] was 1.3 approximately 2 while those of the free complex and cisplatin were 5 approximately 6, which indicates that L-[Pt(dach)(Glu)] overcome the cisplatin resistance in both resistant cells. In vivo antitumor activity was assayed against the L1210/S leukemia. The optimal activities (% T/C) of the free complex and L-[Pt(dach)(Glu)] were >459/20 and >442/200 mg/kg, respectively. Considering the amount of the platinum complex in L-[Pt(dach)(Glu)], the liposomal [Pt(dach)(Glu)] displayed 2-fold higher drug potency than the free complex. The biodistribution experiment using LE52 tumor-bearing mouse showed excellent lung targeting property of L-[Pt(dach)(Glu)].

Animals↗
PubMed2003

Growth promotion of HepG2 hepatoma cells by antisense-mediated knockdown of glypican-3 is independent of insulin-like growth factor 2 signaling.

Glypican-3 (GPC3) encodes a cell-surface heparan- sulfate proteoglycan and its expression is frequently silenced in ovarian cancer, mesotheliomas, and breast cancer cell lines and ectopic expression of GPC3 inhibited the growth of these cells, suggesting that GPC3 plays a negative role in cell proliferation. In contrast, up-regulation of GPC3 is often observed in hepatoma, neuroblastoma, and Wilms' tumor. Whether GPC3 plays the same growth inhibitory role in these tumors remains to be studied. Here we report that antisense-mediated knockdown of GPC3 in the HepG2 hepatoma cells significantly promotes the growth of hepatoma cells. In addition, we show that this growth promotion is independent of insulin-like growth factor 2 (IGF2) signaling. Our data suggest that GPC3 plays a growth-suppressing role in hepatoma and provide cell biological evidence inconsistent with the hypothesis that GPC3 acts as a growth suppressor by downregulating IGF2.

Carcinoma, Hepatocellular↗
PubMed2003

Blocking endogenous glypican-3 expression releases Hep 3B cells from G1 arrest.

Glypican-3 (GPC3) encodes a cell-surface heparan-sulfate proteoglycan mutated in type 1 Simpson-Golabi-Behmel syndrome (SGBS1), an X-linked overgrowth syndrome. The phenotype of SGBS1 patients and of GPC3 knockout mice suggests that GPC3 plays a negative role in cell proliferation, and an apoptosis-inducing role in specific tissues. Ectopic expression of GPC3 in some cell lines has supported the idea that GPC3 inhibits cell growth. Here we report that blocking endogenous GPC3 expression with an antisense transcript promotes the growth of Hep G2 and Hep 3B hepatoma cell lines. Moreover, antisense inhibition releases Hep 3B cells from cell cycle arrest. Hence, our data further support the notion that GPC3 is an inhibitor of cell proliferation and demonstrate that it modulates cell cycle progression.

Animals↗
PubMed2003

Glypican-3 is overexpressed in human hepatocellular carcinoma.

To identify candidate genes that could be used as diagnostic and therapeutic targets for hepatocellular carcinoma (HCC), we searched for the genes that are overexpressed in HCC by combining representational difference analysis and microarray. Genes such as glypican-3 (GPC3), insulin-like growth factor 2, long-chain fatty-acid-coenzyme A ligase 4, farnesyl diphosphate synthase were frequently identified in our screening. Northern blot analysis with these four genes confirmed their overexpression in HCC. Among them we found that GPC3 transcript is upregulated in six out of seven cases of HCC. Immunoblot and immunohistochemical staining using polyclonal anti-GPC3 antibodies further confirmed that GPC3 protein is indeed increased in HCC tumor samples. We also found that GPC3 is secreted into culture media from cell lines derived from HCC. We conclude that GPC3 is a good molecular marker for HCC.

Biomarkers, Tumor↗
PubMed2003

Fatty acid-CoA ligase 4 is overexpressed in human hepatocellular carcinoma.

Fatty acid-CoA ligase 4 (FACL4) is a central enzyme controlling the unesterified arachidonic acid (AA) level in cells. It has been shown that FACL4 blocks apoptosis and promotes colon carcinogenesis by lowering the cellular level of unesterified AA. Consistent with this, FACL4 is upregulated in colon adenocarcinoma. The status of FACL4 in other tumors including hepatocellular carcinoma (HCC) is not known. Here, we report that FACL4 is overexpressed in human HCC compared with adjacent normal liver tissues. FACL4 mRNA and protein were overexpressed in 5 out of 12 (41.7%) and 3 out of 8 (37.5%) cases of HCC, respectively. Immunohistochemical staining showed strong fine granular intracytoplasmic staining in tumor cells, whereas we observed occasional weak staining in normal liver tissues surrounding the tumors. We found that 14 out of 37 (37.8%) HCC expressed moderate to strong FACL4 immunostaining. Both normal adult and fetal liver tissues showed very weak to no detectable staining, whereas 3 out of 10 (30%) cirrhotic livers expressed weak staining. In addition, we found that 4 out of 8 (50%) human hepatoma cell lines expressed high levels of FACL4 by northern blot analysis. Our results show that FACL4 is a new molecular marker for HCC and suggest that the FACL4 pathway may be involved in liver carcinogenesis.

Adult↗
PubMed2002

Gene expression profile analysis in human hepatocellular carcinoma by cDNA microarray.

We performed gene expression profiling of normal and hepatocellular carcinoma (HCC) liver tissues using a high-density microarray that contained 3,063 human cDNA. The results of a microarray hybridization experiment from eight different HCC tissues were analyzed and classified by the Cluster program. Among these differentially-expressed genes, the galectin-3, serine/threonine kinase SGK, translation factor eIF-4A, -4B, -3, fibroblast growth factor receptor, and ribosomal protein L35A were up-regulated; the mRNAs of Nip3, decorin, and the insulin-like growth factor binding protein-3 were down-regulated in HCC. The differential expression of these genes was further confirmed by an RT-PCR analysis. In addition, our data suggest that the gene expression profile of HCC varies according to the histological types.

Carcinoma, Hepatocellular↗
PubMed2002

Leukemia inhibitory factor inhibits neuronal terminal differentiation through STAT3 activation.

The discovery of stem cells in the adult central nervous system raises questions concerning the neurotrophic factors that regulate postnatal neuronal development. Olfactory receptor neurons (ORNs) are a useful model, because they are capable of robust neurogenesis throughout adulthood. We have investigated the role of leukemia inhibitory factor (LIF) in postnatal neuronal development by using ORNs as a model. LIF is a multifunctional cytokine implicated in various aspects of neuronal development, including phenotype determination, survival, and in response to nerve injury. LIF-deficient mice display significant increases, both in the absolute amount and in the number of cells expressing olfactory marker protein, a marker of mature ORNs. The maturation of ORNs was significantly inhibited by LIF in vitro. LIF activated the STAT3 pathway in ORNs, and transfection of ORNs with a dominant negative form of STAT3 abolished the effect of LIF. These findings demonstrate that LIF negatively regulates ORN maturation via the STAT3 pathway. Thus, LIF plays a critical role in controlling the transition of ORNs to maturity. Consequently, a population of ORNs is maintained in an immature state to facilitate the rapid repopulation of the olfactory epithelium with mature neurons during normal cell turnover or after injury.

Animals↗