Biomedical subjects

Je-Ho Lee

Publications and source records attributed to Je-Ho Lee.

33 records · Page 2Linked to original sources

PubMed2005

IFN-gamma/IRF-1-induced p27kip1 down-regulates telomerase activity and human telomerase reverse transcriptase expression in human cervical cancer.

Telomerase activation is regulated by the expression of human telomerase reverse transcriptase (hTERT) and is a key step in the development of human cancers. Interferon-gamma (IFN-gamma) signaling induces growth arrest in many tumors through multiple regulatory mechanisms. The p27 tumor suppressor protein inhibits the formation of tumors through the induction of cell cycle arrest and/or apoptosis. We demonstrate here that p27Kip1 inhibits hTERT mRNA expression and telomerase activity through post-transcriptional up-regulation by IFN-gamma/IRF-1 signaling. The ectopic expression of p27 suppressed hTERT expression and telomerase activity in human cervical cancer cell lines, HeLa and HT3. Furthermore, hTERT promoter activity of mouse embryonic fibroblasts (MEFs) deficient in p27 (p27-/- MEFs) was significantly higher than that of wild-type MEFs. Overexpression of p27 suppressed hTERT promoter activity and telomerase activity of p27-/- MEFs. In addition p27 down-regulated E7 protein expression and in transiently transfected HeLa cells, E7 increased hTERT promoter activity. In conclusion, we propose that inhibition of the hTERT expression and telomerase activity may be a novel tumor suppressor function of p27.

Cell Cycle Proteins↗

PubMed2005

Thymosin {beta}(10) inhibits angiogenesis and tumor growth by interfering with Ras function.

Thymosin beta(10) is a monomeric actin sequestering protein that regulates actin dynamics. Previously, we and others have shown that thymosin beta(10) acts as an actin-mediated tumor suppressor. In this study, we show that thymosin beta(10) is not only a cytoskeletal regulator, but that it also acts as a potent inhibitor of angiogenesis and tumor growth by its interaction with Ras. We found that overexpressed thymosin beta(10) significantly inhibited vascular endothelial growth factor-induced endothelial cell proliferation, migration, invasion, and tube formation in vitro. Vessel sprouting was also inhibited ex vivo. We further show that thymosin beta(10) directly interacted with Ras. This interaction resulted in inhibition of the Ras downstream mitogen-activated protein kinase/extracellular signal-regulated kinase kinase signaling pathway, leading to decreased vascular endothelial growth factor production. Thymosin beta(10) injected into a xenograft model of human ovarian cancer in nude mice markedly inhibited tumor growth and reduced tumor vascularity. In contrast, a related thymosin family member, thymosin beta(4), did not bind to Ras and showed positive effects on angiogenesis. These findings show that the inhibition of Ras signal transduction by thymosin beta(10) results in antiangiogenic and antitumor effects, suggesting that thymosin beta(10) may be valuable in anticancer therapy.

Actins↗

PubMed2005

Activation of Raf1 and the ERK pathway in response to l-ascorbic acid in acute myeloid leukemia cells.

L-ascorbic acid (LAA) shows cytotoxicity and induces apoptosis of malignant cells in vitro, but the mechanisms by which such effects occur have not been elucidated. In the present study, we provide evidence that the ERK MAP kinase pathway is activated in response to LAA (< 1 mM) in acute myeloid leukemia cell lines. LAA treatment of cells induces a dose-dependent phosphorylation of extracellular signal-regulated kinases (ERK) and results in activation of its catalytic domain. Our data also demonstrate that the small G protein Raf1 and MAPK-activated protein kinase 2 are activated by LAA as an upstream and a downstream regulator of ERK, respectively. Although the ERK pathway has been known to activate cell proliferation, pharmacologic inhibition of ERK reduces LAA-dependent apoptosis and growth inhibitory response of acute myeloid leukemia cell lines, suggesting that this signaling cascade positively regulates induction of apoptotic response by LAA.

Apoptosis↗

PubMed2005

Increased expression of matriptase is associated with histopathologic grades of cervical neoplasia.

Matriptase is an epithelial-derived, integral serine protease that has been implicated in the progression of epithelial tumors. We investigated whether the expression of matriptase is associated with the progression of cervical neoplasia. Using immunohistochemistry, we evaluated the matriptase expression in 89 formalin-fixed paraffin-embedded cervical tissues that included 10 normal cervical specimens, 19 low-grade squamous intraepithelial lesions, 20 high-grade squamous intraepithelial lesions, 20 invasive squamous cell carcinomas (ISCC) without lymph node (LN) metastasis, and 20 ISCC with lymph node metastasis. We also used the reverse transcriptase-polymerase chain reaction technique to determine the expression of matriptase transcripts in normal cervical and ISCC tissues. The immunohistochemical staining showed that the expression of matriptase was undetectable in all normal cervical squamous epithelia, but had cytoplasmic and membranous staining in the normal endocervical glands. Staining gradually increased in accordance with the histopathologic grades from low-grade squamous intraepithelial lesions to high-grade squamous intraepithelial lesions and ISCC ( P < .001); matriptase was detected in most cases (95%) of ISCC. In addition, matriptase transcripts were expressed in all (n = 26) of the ISCC cases by microdissection and reverse transcriptase-polymerase chain reaction, whereas none of the normal squamous epithelia cases (n = 3) expressed matriptase transcripts. These results suggest that matriptase may play a significant role in the development of cervical carcinoma and may serve as a useful marker of the malignant transformation of cervical squamous cells. Further studies could potentially lead to the development of novel approaches for early detection and therapy for this disease.

Biomarkers, Tumor↗

PubMed2005

Increased expressions of claudin-1 and claudin-7 during the progression of cervical neoplasia.

OBJECTIVES: Claudin proteins represent a large family of integral membrane proteins crucial for tight junction formation and function and they have been shown to be expressed differently in various cancers. We investigated whether the expressions of claudin-1 and claudin-7 are associated with the progression of uterine cervical neoplasia. METHODS: We analyzed 89 formalin-fixed paraffin embedded cervical tissues that included 10 normal cervical epithelium, 19 low-grade squamous intraepithelial lesion (LSIL), 20 high-grade squamous intraepithelial lesion (HSIL), 20 invasive squamous cell carcinoma (ISCC) without lymph node (LN) metastasis, and 20 ISCC with LN metastasis. The expressions of claudin-1 and claudin-7 were determined by immunohistochemistry. RESULTS: The expressions of claudin-1 and claudin-7 were undetectable in normal cervical squamous epithelium, but had variable staining in the basal layer of normal endocervical glands. The expressions of both proteins, mainly as membranous staining, gradually increased in accordance with the progression from LSIL to HSIL and ISCC (both P values are <0.001) and were detected in all cases of ISCC. CONCLUSIONS: These results suggest that claudin-1 and claudin-7 may play a significant role in tumor progression of cervical neoplasia and may represent useful markers for malignant transformation of cervical squamous cells. Further studies would likely result in the development of novel approaches for early detection and therapy for this disease.

Carcinoma, Squamous Cell↗

PubMed2005

Inkjet printer model-based halftoning.

The quality of halftone prints produced by inkjet (IJ) printers can be limited by random dot-placement errors. While a large literature addresses model-based halftoning for electrophotographic printers, little work has been done on model-based halftoning for IJ printers. In this paper, we propose model-based approaches to both iterative least-squares halftoning and tone-dependent error diffusion (TDED). The particular approach to iterative least-squares halftoning that we use is direct binary search (DBS). For DBS, we use a stochastic model for the equivalent gray-scale image, based on measured dot statistics of printed IJ halftone patterns. For TDED, we train the tone-dependent weights and thresholds to mimic the spectrum of halftone textures generated by model-based DBS. We do this under a metric that enforces both the correct radially averaged spectral profile and angular symmetry at each radial frequency. Experimental results generated with simulated printers and a real printer show that both IJ model-based DBS and IJ model-based TDED very effectively suppress IJ printer-induced artifacts.

Algorithms↗

PubMed2005

Selected adnexal cystic masses in postmenopausal women can be safely managed by laparoscopy.

The aim of this study was to assess the efficacy and safety of laparoscopic treatment for adnexal cystic masses that were predicted to be benign in postmenopausal women. Postmenopausal women found to have an adnexal cystic mass were retrospectively evaluated with transvaginal ultrasonography, and serum CA-125 levels. The selection criteria were adnexal cystic masses greater than 3 cm but less than 10 cm, the masses were in the benign range (4-8) of Sassone's scoring system for transvaginal ultrasonography, and the patients had serum CA-125 levels less than 65 IU/mL. Two hundred nineteen women fulfilled the criteria and underwent operative laparoscopy. Almost all the masses (99.5%) were accurately predicted to be benign except for one borderline ovarian tumor. Two hundreds thirteen (97.3%) women were successfully managed by operative laparoscopy and six (2.7%) required laparotomy. For the patients managed by laparoscopy, the mean operative time was 51.3 min; the mean hospital stay was 2.5 days. There was no significant morbidity and surgery-related mortality. The combination of the Sassone's scoring system for transvaginal ultrasonography and serum CA-125 level can accurately predict benign cystic masses, and operative laparoscopy is technically feasible and safe for the management of adnexal mass in postmenopausal women.

Adnexal Diseases↗

PubMed2004

L-ascorbic acid represses constitutive activation of NF-kappaB and COX-2 expression in human acute myeloid leukemia, HL-60.

There is increasing evidence that L-ascorbic acid (LAA) is selectively toxic to some types of cancer cells at pharmacological concentrations, functioning as a pro-oxidant rather than as an anti-oxidant. However, the molecular mechanisms by which LAA initiates cellular signaling leading to cell death are still unclear. In an effort to gain insight into these mechanisms, the effects of LAA on eukaryotic transcription nuclear factor NF-kappaB and cyclooxygenase-2 (COX-2) expression were investigated. In the present study, LAA suppressed DNA binding activity of NF-kappaB, composed of a p65/p50 heterodimer, through inhibition of degradation of inhibitory kappaB-alpha (IkappaB-alpha) and prevention of nuclear translocation of p65. The inhibitory effect of LAA on NF-kappaB activity was dependent upon glutathione levels in HL-60 cells, as well as generation of H2O2 but not superoxide anion. LAA also downregulated the expression of COX-2, which has a NF-kappaB binding site on its promoter, through repressing NF-kappaB DNA binding activity. Moreover, cotreatment of 1 microM arsenic trioxide (As2O3) with various concentrations of LAA enhanced an LAA-induced repression of NF-kappaB activity and COX-2 expression. In conclusion, our data suggest that LAA exerts its anti-tumor activity through downregulation of NF-kappaB activity and COX-2 expression, and these inhibitory effects can be enhanced by co-treatment with As2O3.

Apoptosis↗

PubMed2004

The interaction between E-tropomodulin and thymosin beta-10 rescues tumor cells from thymosin beta-10 mediated apoptosis by restoring actin architecture.

Thymosin beta-10 (TB10) is a small G-actin binding protein that induces depolymerization of intracellular F-actin pools by sequestering actin monomers. Previously, we demonstrated that overexpression of TB10 in ovarian tumor cells increased the rate of cell death. As an initial step to define molecular mechanism of TB10-dependent apoptotic process in ovarian tumor cells, we searched a human ovary cDNA library for a novel TB10 binding protein using a yeast two-hybrid system. The selected protein was human E-tropomodulin (E-Tmod), another component of the actin binding proteins. Subsequently, two interacting protein components were determined quantitatively. Results showed that the full-length TB10 is required to bind with E-Tmod, and the TB10 binding site on E-Tmod partially overlaps with the actin binding site on E-Tmod. Moreover, introduction of E-Tmod cDNA into a tumor cell line reversed TB10 mediated apoptosis and restored actin architectures. These results may suggest that TB10 regulates apoptotic homeostasis by not only just binding to actin but also competing or blocking the protein complex formation of E-Tmod with actin.

Actins↗

PubMed2004

L-Ascorbic acid induces apoptosis in acute myeloid leukemia cells via hydrogen peroxide-mediated mechanisms.

L-Ascorbic acid (LAA) is being investigated clinically for the treatment of patients with acute myeloid leukemia (AML) based on the observed effects of LAA on AML progenitor cells in vitro. However, the mechanism for LAA-induced cytoreduction remains to be elucidated. LAA at concentrations of 0.25-1.0 mM induced a dose- and time-dependent inhibition of proliferation in three AML cell lines and also in leukemic cells from peripheral blood specimens obtained from three patients with AML. In contrast, ovarian cancer cell lines were only minimally affected. Flow cytometric analysis showed that LAA at concentrations of 0.25-1.0 mM could significantly induce apoptosis in the AML cell lines. LAA induced oxidation of glutathione to oxidized form (GSSG) and subsequent H(2)O(2) accumulation in a concentration-dependent manner, in parallel to induction of apoptosis. The direct role of H(2)O(2) in the induction of apoptosis in AML cells was clearly demonstrated by the finding that catalase could completely abrogate LAA-induced apoptosis. Induction of apoptosis in LAA-treated AML cells involved a dose-dependent increase of Bax protein, release of cytochrome C from mitochondria to cytosol, activation of caspase 9 and caspase 3, and cleavage of poly[ADP-ribose]polymerase. In conclusion, LAA can induce apoptosis in AML cells, and this is clearly due to H(2)O(2) which accumulates intracellularly as a result of oxidation of reduced glutathione by LAA.

Apoptosis↗

PubMed2003

Recombinant FSH and pregnancy-associated plasma protein.

OBJECTIVES: To evaluate the effect of rec-FSH on the ovarian follicular environment in controlled ovarian hyperstimulation (COH) cycle, we compared the expression of the markers that have been reported to reflect the follicle health. STUDY DESIGN: A total of 31 women (<35 years) with normal ovarian function were allocated to three different COH protocols (urinary FSH (u-FSH)+hMG, rec-FSH only, or u-FSH only). E2, P4, leptin and IGF-I levels in serum or follicular fluid (FF) were measured with radioimmunoassay; cyclin D2, EGF receptor (EGF-R), and inhibin-alpha mRNA levels in luteinized granulosa cells were measured with RT-PCR; and IGFBP-4 and PAPP-A levels in FF were measured with Western blot analysis. RESULTS: There were no significant differences in serum E2, P4 and leptin levels and follicular leptin and IGF-I levels. Cyclin D2, EGF-R, and inhibin-alpha mRNA expression in luteinized granulosa cells were not different among three groups. However, follicular IGFBP-4 and PAPP-A levels in rec-FSH group were significantly higher than other groups (P<0.05). CONCLUSIONS: The use of rec-FSH increases the expression of follicular PAPP-A reflecting IGFBP-4 proteolytic activity and it may influence positively the follicular environment.

Adult↗

PubMed2003

Interferon regulatory factor-1 (IRF-1) is a mediator for interferon-gamma induced attenuation of telomerase activity and human telomerase reverse transcriptase (hTERT) expression.

Constitutive activation of the telomerase is a key step in the development of human cancers. Interferon-gamma (IFN-gamma) signaling induces growth arrest in many tumors through multiple regulatory mechanisms. In this study, we show that IFN-gamma signaling represses telomerase activity and human telomerase reverse transcriptase (hTERT) transcription, and suggest that this signaling is mediated by IRF-1. Ectopic expression of IRF-1 attenuated hTERT promoter activity. Murine embryonic fibroblasts (MEFs) genetically deficient in IRF-1 (IRF-1(-/-)) showed an elevated level (>15 times) of hTERT promoter activity as compared to the hTERT promoter activity of wild-type MEFs. The telomerase activity and hTERT expression in IRF-1(-/-) MEFs were downregulated by IRF-1 transfection. Interestingly, less extent of telomerase repression was observed in HPV E6 and E7 negative, p53 mutant HT-3 cells than in HPV 18 E6 and E7 positive HeLa cells (intact p53). These findings provide evidence that IRF-1 is a potential mediator of IFN-gamma-induced attenuation of telomerase activity and hTERT expression.

Animals↗

PubMed2002

Enhancement of the adenoviral sensitivity of human ovarian cancer cells by transient expression of coxsackievirus and adenovirus receptor (CAR).

OBJECTIVE: The coxsackievirus and adenovirus receptor (CAR) is known to be a primary receptor for attachment during adenovirus infection of target cells and thus is closely related to adenoviral infection efficiency. To extend this notion to human ovarian cancer, we investigated the difference in expression levels of CAR in human ovarian cancer cell lines and whether their adenoviral sensitivities are enhanced by transient transfection of the CAR gene. METHODS: Adenoviral infection efficiency was examined by flow cytometry analysis, beta-galactosidase staining, and beta-galactosidase activity assay. Expression of the CAR-specific mRNA and protein was analyzed by reverse transcription polymerase chain reaction and flow cytometry, respectively. RESULTS: Expression of CAR in human ovarian cancer cell lines (SKOV3, 2774, PA-1, and OVCAR3) appeared to be correlated with their susceptibilities to adenovirus-mediated gene delivery. The 2774 and PA-1 cells expressing an easily detectable level of CAR on the cell surface showed a higher susceptibility to infection with both AdCMVGFP and AdRSVbetagal than SKOV3 and OVCAR3 cells, both of which had hardly detectable levels of CAR. Ectopic expression of the CAR gene by transient transfection of these ovarian cancer cells resulted in a dramatic increase in their adenoviral sensitivities. CONCLUSION: These data show that the expression of CAR is closely related to susceptibility to adenovirus infection in human ovarian cancer cells. These results indicate that the CAR gene can be a useful tool in boosting the efficiency of adenoviral vector-mediated gene therapy against human ovarian cancer.

Adenoviridae↗

PubMed2002

Differential expressions of Fas and Fas ligand in human placenta.

To investigate the expressions of Fas and Fas ligand (FasL) in human placenta, we studied the expressions of Fas and FasL in placenta with RT-PCR, immunoblotting and immunostaining. We observed amplified products of Fas and FasL transcripts, the band of Fas (52 kDa) and multiple bands of FasL (42-52 kDa) in placenta. Fas and FasL localized mainly on fetal vessels and on syncytiotrophoblasts respectively. The differential distribution of Fas and FasL in human placenta may reflect intrinsic expressions of them by trophoblasts during differentiation. The increased expression of Fas in trophoblasts may promote apoptosis of placenta in pathologic condition such as preeclampsia.

Fas Ligand Protein↗

PubMedDate not supplied

Characterization of cyclin D2 expression in human endometrium.

OBJECTIVE: This study was undertaken to investigate cyclin D2 mRNA and protein expression in human endometrium during the menstrual cycle. METHODS: Endometrial samples were obtained from 15 premenopausal nonpregnant women who had hysterectomies for benign gynecologic reasons. They were divided into the following five groups according to histologic dating: early proliferative (n = 3), mid to late proliferative (n = 3), early secretory (n = 3), mid secretory (n = 3), and late secretory (n = 3). Cyclin D2 mRNA and protein expression were analyzed using reverse transcriptase-polymerase chain reaction, Western blotting, and immunohistochemistry. RESULTS: Cyclin D2 mRNA and protein were expressed in human endometrial tissue throughout the menstrual cycle. Cyclin D2 mRNA and protein expression of proliferative phase endometrium were significantly higher than those of secretory phase endometrium (P <.05). The staining intensity of cyclin D2 in proliferative phase endometrium was higher than that in secretory phase (P <.05). Cyclin D2 mRNA level showed good correlation with cyclin D2 protein level (R = 0.579, P <.03), and cyclin D2 protein also showed good correlation with immunohistochemical staining intensity (R = 0.562, P <.03). CONCLUSION: Cyclin D2 was expressed in human endometrium throughout the menstrual cycle. Cyclin D2 mRNA and protein were expressed at high levels in proliferative phase endometrium, especially in the early proliferative phase, and then decreased in the secretory phase.

Adult↗