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K S Chang

Publications and source records attributed to K S Chang.

At least 37 records · Page 2Linked to original sources
PubMed1999

Two candidate downstream target genes for E2A-HLF.

The E2A-HLF fusion gene, formed by the t(17;19)(q22;p13) chromosomal translocation, is thought to drive the leukemic transformation of early B-cell precursors by repressing an evolutionarily conserved apoptotic pathway. To test this hypothesis, we sought to identify downstream targets of E2A-HLF in t(17;19)+ pro-B leukemia cells (UOC-B1) that had been transfected with a zinc-inducible vector encoding a dominant-negative suppressor (E2A-HLF[dn]) of the oncoprotein. Representational difference analysis of mRNAs from E2A-HLF(dn)+ UOC-B1 cells grown with (E2A-HLF inactive) or without (E2A-HLF active) the addition of zinc yielded several differentially expressed cDNA fragments that were individually subcloned. Two of the clones, designated F-5 and G-4, hybridized with mRNAs that were upregulated by E2A-HLF. Levels of both transcripts declined sharply within 8 to 12 hours after suppression of E2A-HLF DNA-binding activity, becoming undetectable after 96 hours. The F-5 cDNA was identified as a portion of ANNEXIN VIII, whose product was expressed in promyelocytic leukemia cells and UOC-B1 cells, but not in other leukemic cell lines. A novel full-length cDNA cloned with the G-4 fragment encoded a protein that we have named SRPUL (sushi-repeat protein upregulated in leukemia). It is normally expressed in heart, ovary, and placenta, but could not be detected in leukemic cell lines other than UOC-B1. Neither protein prevented apoptosis in interleukin-3-dependent murine pro-B cells, suggesting that they have paraneoplastic roles in leukemias that express E2A-HLF, perhaps in the disseminated intravascular coagulopathy and hypercalcemia that characterize these cases.

Amino Acid Sequence↗
PubMed1999

Abciximab readministration: A single-operator community-hospital experience.

Abciximab, a monoclonal antibody to the platelet glycoprotein IIb/IIIa receptor, reduces ischemic complications of coronary interventions after first administration. In this study, We sought to determine whether readministration of abciximab is associated with equal efficacy and safety. We retrospectively reviewed the charts of 35 patients who received two doses of abciximab at separate intervals. We monitored patients clinically for recurrent ischemia, bleeding complications, and thrombocytopenia. We measured hemoglobin and platelet counts before and after readministration of abciximab. There was no cardiac-related death, myocardial infarction, or recurrent ischemia. No obvious bleeding occurred in any of the 35 patients, although 1 patient had a drop of hemoglobin >3 gm/dl. We observed one episode of severe thrombocytopenia without any complication, and this patient improved without requiring platelet transfusion. There was no profound thrombocytopenia. We conclude that readministration of abciximab was well tolerated without any evidence of altered efficacy or safety. Cathet. Cardiovasc. Intervent. 47:294-296, 1999.

Abciximab↗
PubMed1999

Soluble TNF-alpha receptor and IL-1 receptor antagonist elevation in BAL in active pulmonary TB.

Accumulating evidence suggests that patients with active pulmonary tuberculosis (TB) have an alveolar inflammation resulting in the release of tumour necrosis factor (TNF)-alpha and interleukin (IL)-1beta in bronchoalveolar epithelial fluid. It was proposed that the levels of these cytokines would correlate with clinical status parameters (extent of pulmonary involvement, fever, and body weight loss) and that their naturally occurring inhibitors would be concomitantly released in the local inflammatory sites. To test this hypothesis lung epithelial lining fluid (ELF) obtained by bronchoalveolar lavage and serum were collected from 29 patients with active pulmonary TB and 15 healthy subjects to determine the levels of these variables using a sandwich enzyme-linked immunosorbent assay (ELISA). ELF levels of TNF-alpha, soluble (s)TNF receptor I (RI), sTNF-receptor II (RII) and interleukin-1 receptor antagonist (IL-1RA) but not IL-1beta, and their serum levels except for sTNF-RII and IL-1beta were significantly higher in TB patients. Nevertheless, only ELF levels of TNF-alpha and IL-1beta were significantly correlated with disease status. No correlation was found between TNF-alpha levels and those of sTNF-RI and sTNF-RII, nor between IL-1beta and IL-1RA in ELF and serum of TB patients, although there was a significant correlation between sTNF-RI and sTNF-RII levels both in ELF and serum. These findings suggest local release of tumour necrosis factor-alpha and interleukin-1beta and a correlation with disease status. Soluble tumour necrosis factor-alpha receptors and interleukin-1beta receptor antagonist, although increased in lung epithelial lining fluid and serum in tuberculosis patients, were not correlated with tumour necrosis factor-alpha and interleukin-1beta or with disease status.

Adult↗
PubMed1999

Increased absolute number but not proportion of gamma/delta T-lymphocytes in the bronchoalveolar lavage fluid of patients with active pulmonary tuberculosis.

SETTING: The proportions and absolute cell count of gamma/delta T-lymphocytes in the peripheral blood of patients with pulmonary tuberculosis (PTB) remains controversial. Since PTB is an infections airway disease, bronchoalveolar T-lymphocytes should be a better indicator of local immune T-cell reaction after TB infection than peripheral blood T-lymphocytes. OBJECTIVE: To quantitate the absolute cell count and proportions of gamma/delta T-lymphocytes in the bronchoalveolar lavage fluid (BALF) of patients with active PTB. DESIGN: Bronchoalveolar lavage (BAL) and analysis of lymphocytes in the BALF was performed in 25 patients with active PTB and 16 normal controls. All of the patients were negative for HIV infection and none was immunocompromised. BALF and blood were prepared for cell differential count and flow cytometry analysis using monoclonal antibodies CD3, CD4, CD8, CD25, HLA-DR and gamma/delta as well as alpha/beta T-lymphocyte receptors. RESULTS: The number of cells per volume of recovered BALF was significantly higher in the patients with active PTB than in normal controls. BALF from active PTB patients also showed increased percentage of lymphocytes and neutrophils. The absolute number of total lymphocytes, CD3+ lymphocytes and CD3+ gamma/delta T-lymphocytes were significantly higher in the BALF, but not in the blood, of patients with TB, however, the proportions of CD3+ gamma/delta T-lymphocytes in BALF of patients with TB was comparable to that of normal controls. gamma/delta T-lymphocytes in the BALF rarely expressed CD4, CD25, and HLA-DR in both groups. CONCLUSION: These results suggest that gamma/delta T-lymphocytes are not the major subpopulation of CD3+ lymphocytes in the BALF that react to mycobacterial infection in the patients with clinically established active TB.

Adult↗
PubMed1999

Increased TNF-alpha, IL-1 beta and IL-6 levels in the bronchoalveolar lavage fluid with the upregulation of their mRNA in macrophages lavaged from patients with active pulmonary tuberculosis.

SETTING: We hypothesized that patients with active pulmonary tuberculosis (TB) have tubercular pneumonitis and that alveolar macrophages at these sites release proinflammatory cytokines, resulting in high levels of cytokines in alveolar epithelial lining fluid. OBJECTIVE: To measure cytokine levels in bronchoalveolar lavage fluid (BALF) and to confirm the source of any cytokines by examination of alveolar macrophage cytokine mRNA. DESIGN: Seventeen active pulmonary TB patients and 15 healthy controls were prospectively studied. Bronchoalveolar lavage (BAL) was performed, proinflammatory cytokine levels were determined and alveolar macrophages isolated from BALF were prepared for RNA extraction and Northern blot analysis. RESULTS: Compared with healthy controls, TNF-alpha, IL-1 beta and IL-6 in BALF were all significantly higher in patients with active pulmonary TB, 298.7 +/- 85.9 vs. 8.9 +/- 2.7 (P = 0.0001); 164.4 +/- 67.5 vs. 8.9 +/- 2.7 (P = 0.003); 969.2 +/- 214.2 vs. 86.4 +/- 17.0 (mean +/- SE pg/ml) (P = 0.0001), respectively. Only TNF-alpha and IL-6 levels were significantly higher in sera of active pulmonary TB patients, 92.3 +/- 28.7 vs. 3.5 +/- 1.2; 15.2 +/- 5.4 vs. 2.1 +/- 2.1, respectively. Northern blot analysis revealed increased gene expression of these alveolar macrophage cytokines in patients with active pulmonary TB compared healthy controls. CONCLUSION: Significantly higher levels of TNF-alpha, IL-1 beta and IL-6 were found in BALF from patients with active pulmonary TB, and were released by alveolar macrophages in the TB lesions.

Adult↗
PubMed1999

Enterovirus 71 from fatal and nonfatal cases of hand, foot and mouth disease epidemics in Malaysia, Japan and Taiwan in 1997-1998.

Enterovirus 71 (EV71), one of the major causative agents for hand, foot and mouth disease (HFMD), is sometimes associated with severe central nervous system diseases. In 1997, in Malaysia and Japan, and in 1998 in Taiwan, there were HFMD epidemics involving sudden deaths among young children, and EV71 was isolated from the HFMD patients, including the fatal cases. The nucleotide sequences of each EV71 isolate were determined and compared by phylogenetical analysis. EV71 strains from previously reported epidemics belonged to genotype A-1, while those from recent epidemics could be divided into two genotypes, A-2 and B. In Malaysia, genotype A-2 was more prevalent, while in Japan and Taiwan, B genotype was more prevalent. Two isolates from fatal cases in Malaysia and one isolate from a fatal case in Japan were genotype A-2. However, all isolates from three fatal cases in Taiwan belonged to genotype B. The severity of the HFMD did not link directly to certain genotypes of EV71.

DNA Primers↗
PubMed1998

Modulation of Fos-mediated AP-1 transcription by the promyelocytic leukemia protein.

The growth and transformation suppressor function of promyelocytic leukemia (PML) protein are disrupted in acute promyelocytic leukemia (APL) as a result of its fusion to the RARalpha gene by t(15;17) translocation. There is significant sequence homology between the dimerization domain of PML and the Fos family of proteins, which imply that PML may be involved in AP-1 activity. Here we show that PML can cooperate with Fos to stimulate its AP-1-mediated transcriptional activity. Cotransfection of PML with GAL4/Fos strongly induced Fos-mediated activation of GAL4-responsive reporters, indicating a functional interaction between Fos and PML in vivo. Deletion analysis of Fos and PML demonstrated that the intact C-terminal domain of Fos (containing the dimerization domain), and the RING-finger, B1 box and nuclear localization domains of PML are involved in the cooperative activity of Fos and PML. Immunoprecipitation and electrophoretic mobility shift assay showed that PML is associated with the AP-1 complex. PMLRARalpha was also found to enhance the transcriptional activity of GAL4/Fos. The addition of retinoic acid abrogated the PMLRARalpha, but not PML-induced stimulation of GAL4/Fos activity in a dose-dependent manner. This study demonstrated that PML is involved in the AP-1 complex and can modulate Fos-mediated transcriptional activity, which may contribute to its growth suppressor function.

Animals↗
PubMed1998

Recombinant PML adenovirus suppresses growth and tumorigenicity of human breast cancer cells by inducing G1 cell cycle arrest and apoptosis.

Our previous studies demonstrated that the promyelocytic leukemia gene, PML which involved in the 15;17 translocation in acute promyelocytic leukemia (APL) is a growth and transformation suppressor. In this study, recombinant PML adenovirus, Ad-PML was constructed and used to infect human breast cancer cells in vitro and in vivo, the anti-oncogenic function of PML and its mechanism of growth suppressing effect in breast cancer cells were examined. We showed that Ad-PML effectively infected the MCF-7 and SK-BR-3 cells. A high level of PML protein was expressed within 24 h post-infection and a detectable level remained at day 16. Ad-PML significantly suppressed the growth rate, clonogenicity, and tumorigenicity of breast cancer cells. Intratumoral injections of MCF-7-induced tumors by high titer Ad-PML suppressed tumor growth in nude mice by about 80%. The injection sites expressed high level of PML and associated with a massive apoptotic cell death. To elucidate the molecular mechanism of PML's growth suppressing function, we examined the effect of Ad-PML on cell cycle distribution in MCF-7 and SK-BR-3 cells. We found that Ad-PML infection caused a cell cycle arrest at the G1 phase. We further showed that G1 arrest of MCF-7 cells is associated with a significant decrease in cyclin D1 and CDK2. An increased expression of p53, p21 and cyclin E was found. The Rb protein became predominantly hypophosphorylated 48 h post-infection. These findings indicate that PML exerts its growth suppressing effects by modulating several key G1 regulatory proteins. Our study provides important insight into the mechanism of tumor suppressing function of PML and suggests a potential application of Ad-PML in human cancer gene therapy.

Adenoviridae↗
PubMed1998

Altered expression of the growth and transformation suppressor PML gene in human hepatocellular carcinomas and in hepatitis tissues.

The promyelocytic leukaemia (PML) gene, which encodes a transformation and growth suppressor, was first identified at a chromosomal translocation break point in acute promyelocytic leukaemia. To elucidate if PML may be involved in hepatocellular carcinoma (HCC), the expression of PML was analysed using immunohistochemistry in human HCC and hepatitis tissues. Our studies demonstrated overexpression of PML protein in the PML-oncogenic domain (POD) structure in 50% of HCC (11/22). Enhanced expression and cytoplasmic localisation of PML was associated with cirrhosis. Increased expression of PML was also found in liver abscesses. However, in colon metastasis to the liver, the expression of PML was moderate to low, although strong expression was seen in the surrounding interstitial cells, macrophages and lymphocytes, an indication of the inflammation process associated with tumour growth. Most interestingly, strong expression of PML was found in neoplastic cells at the periphery of the tumours, but progressively decreased in cells at the centre of the tumours, which may be associated with an altered transform phenotype or apoptosis. The altered expression of PML indicates that this nuclear protein may play an important role in cellular response to stress and inflammation, as well as in compensatory cell growth.

Carcinoma, Hepatocellular↗
PubMed1998

Studies on the binding site of the galactose-specific agglutinin PA-IL from Pseudomonas aeruginosa.

The binding properties of Pseudomonas aeruginosa agglutinin-I (PA-IL) with glycoproteins (gps) and polysaccharides were studied by both the biotin/avidin-mediated microtiter plate lectin-binding assay and the inhibition of agglutinin-glycan interaction with sugar ligands. Among 36 glycans tested for binding, PA-IL reacted best with two glycoproteins containing Galalpha1-->4Gal determinants and a human blood group ABO precursor equivalent gp, but this lectin reacted weakly or not at all with A and H active gps or sialylated gps. Among the mammalian disaccharides tested by the inhibition assay, the human blood group Pkactive Galalpha1-->4Gal, was the best. It was 7.4-fold less active than melibiose (Galalpha1-->6Glc). PA-IL has a preference for the alpha-anomer in decreasing order as follows: Galalpha1-->6 >Galalpha1-->4 >Galalpha1-->3. Of the monosaccharides studied, the phenylbeta derivatives of Gal were much better inhibitors than the methylbeta derivative, while only an insignificant difference was found between the Galalpha anomer of methyl- and p -NO2-phenyl derivatives. From these results, it can be concluded that the combining size of the agglutinin is as large as a disaccharide of the alpha-anomer of Gal at nonreducing end and most complementary to Galalpha1-->6Glc. As for the combining site of PA-IL toward the beta-anomer, the size is assumed to be less than that of Gal; carbon-6 in the pyranose form is essential, and hydrophobic interaction is important for binding.

ABO Blood-Group System↗
PubMed1998

Characterization of the ETO and AML1-ETO proteins involved in 8;21 translocation in acute myelogenous leukemia.

The AML1 and ETO genes are disrupted by the nonrandom chromosomal translocation t(8;21) in acute myelogenous leukemia (AML). While the AML1 gene encodes a transcription factor indispensable for definitive hematopoiesis, the biological function of ETO is unknown. To understand the role of ETO and AML1-ETO in the pathogenesis of AML, the full length cDNAs of ETO and AML1-ETO were cloned and antibodies against AML1 and ETO proteins have been developed in our laboratory. Western blot analysis showed that ETO and AML1-ETO were identified as 70 kDa and 94 kDa proteins, respectively, and that both proteins, like AML1, were associated with the nuclear matrix. To examine whether the t(8;21)-positive AMLs expressed a 94-kDa AML1-ETO, protein fractions isolated from leukemia blasts of 10 patients with t(8;21)-positive AML and the Kasumi-1 cells were analyzed by Western blotting. The 94 kDa AML1-ETO fusion protein was detected in all samples. However, this fusion protein was not detectable in all 40 patients with t(8;21)-negative AMLs. The biological significance of AML1-ETO was examined in K562 cells, which stably overexpress AML1-ETO. We found that AML1-ETO blocked the erythroid differentiation of K562 cells induced by low doses of Ara-C. Thus, t(8;21)-positive AMLs appear to overexpress the AML1-ETO fusion protein, which may be responsible for differentiation block and leukemogenesis in AML.

3T3 Cells↗
PubMed1998

The promyelocytic leukemia protein interacts with Sp1 and inhibits its transactivation of the epidermal growth factor receptor promoter.

The promyelocytic leukemia protein (PML) is a nuclear phosphoprotein with growth- and transformation-suppressing ability. Having previously shown it to be a transcriptional repressor of the epidermal growth factor receptor (EGFR) gene promoter, we have now shown that PML's repression of EGFR transcription is caused by inhibition of EGFR's Sp1-dependent activity. On functional analysis, the repressive effect of PML was mapped to a 150-bp element (the sequences between -150 and -16, relative to the ATG initiation site) of the promoter. Transient transfection assays with Sp1-negative Drosophila melanogaster SL2 cells showed that the transcription of this region was regulated by Sp1 and that the Sp1-dependent activity of the promoter was suppressed by PML in a dose-dependent manner. Coimmunoprecipitation and mammalian two-hybrid assays demonstrated that PML and Sp1 were associated in vivo. In vitro binding by means of the glutathione S-transferase (GST) pull-down assay, using the full-length and truncated GST-Sp1 proteins and in vitro-translated PML, showed that PML and Sp1 directly interacted and that the C-terminal (DNA-binding) region of Sp1 and the coiled-coil (dimerization) domain of PML were essential for this interaction. Analysis of the effects of PML on Sp1 DNA binding by electrophoretic mobility shift assay (EMSA) showed that PML could specifically disrupt the binding of Sp1 to DNA. Furthermore, cotransfection of PML specifically repressed Sp1, but not the E2F1-mediated activity of the dihydrofolate reductase promoter. Together, these data suggest that the association of PML and Sp1 represents a novel mechanism for negative regulation of EGFR and other Sp1 target promoters.

Binding Sites↗
PubMed1997

Transcriptional repression by the promyelocytic leukemia protein, PML.

Acute promyelocytic leukemia is characterized by the presence of a t(15; 17) chromosomal translocation which results in the expression of a chimeric gene product, PMLRAR alpha, consisting of an N-terminal-truncated retinoic acid receptor-alpha fused to a C-terminal-truncated PML. Several structural features, and regions of homology to known transcription factors, suggest that PML may be involved in the regulation of gene expression. In this study we have analyzed the transcriptional regulatory activity of PML using chimeric GAL4/PML constructs and GAL4-responsive reporter plasmids. The data presented demonstrate that PML, when fused to the DNA-binding domain of GAL4 (GAL4/PML), inhibits transcription from GAL4-responsive promoters. The magnitude of this repression is cell type and promoter dependent, and deletion studies show that the putative coiled-coil and part of the serine-rich regions of PML are required for this activity. These regions are also shown to be responsible for the repression of transcription activity from the EGFR promoter. The data presented also demonstrate that GAL4/PML can recruit PMLRAR alpha resulting in the retinoid-inducible transcriptional activation of a GAL4-responsive promoter, a function dependent on the presence of the coiled-coil region of PMLRAR alpha.

Animals↗
PubMed1997

Cell-cycle regulation of DNA damage-induced expression of the suppressor gene PML.

The promyelocytic leukemia (PML) gene, which encodes a growth- and transformation-suppressor, has been identified at the non-random chromosomal translocation break point t(15; 17)(q22; q12) of acute promyelocytic leukemia. To elucidate if PML may play a role in cellular response to DNA damage, PML expression was analyzed by immunofluorescence staining in HeLa cells treated with ionizing radiation (IR) and cisplatin. Our studies demonstrated IR at 20Gy, and cisplatin at 6 micrograms/ml caused more than 5-10 fold increases in PML protein expression in the PML Oncogenic Domain (POD) by immunofluorescent staining. Northern blotting showed that there was no gross increase in mRNA levels indicating that the induction is a post-transcriptional event. Flow cytometry showed that HeLa cells treated with IR were progressively arrested in G1, which correlates with the optimal expression of PML in the cell cycle. To determine if PML expression was under the control of the tumor suppressor p53, which is known to arrest cells in G1, HeLa cells were transfected with the wild-type p53 gene. PML expression in p53 transduced cells were 5-10 fold higher than the control, indicating that the enhanced expression of PML is apparently dependent on the p53 pathway. These data also indicate that PML may play an important role in cellular response to DNA damage such as DNA repair or apoptosis during G1 arrest.

Blotting, Northern↗
PubMed1997

Adenovirus-mediated expression of PML suppresses growth and tumorigenicity of prostate cancer cells.

Our previous studies demonstrated that the promyelocytic leukemia gene, PML, encodes a growth and transformation suppressor. Overexpression of PML inhibits cancer cell growth in vitro and in vivo. In this study, we further explored the possibility of applying PML as a potential agent for developing prostate cancer gene therapy using an adenovirus delivery system. We have constructed and produced the recombinant PML-adenovirus, Ad-PML, in which the full-length PML cDNA is driven by the strong cytomegalovirus promoter. In LNCaP, DU145, and PC-3 prostate cancer cell lines, an infection efficiency of 90% can be achieved at a concentration of 2, 10, and 100 multiplicity of infection (MOI), respectively. Western blotting and immunofluorescence staining demonstrated that the AD-PML-infected cells expressed a high level of PML protein. The protein expression peaked at days 3-4 postinfection, and a detectable level of PML was found at day 18 after viral infection. To test the effect of Ad-PML on the growth of prostate cancer cells, the DU145 and LNCaP cells were infected with 10 and 2 MOI of Ad-PML. We found that the growth rate of the Ad-PML-infected DU145 and LNCaP cells were significantly inhibited. A tumorigenicity test in nude mice showed that the Ad-PML-treated DU145 cells failed to form tumors. Most importantly, direct injection of Ad-PML into DU145-induced tumors was able to repress tumor growth in nude mice by 64%. Taken together, these data indicate that PML is a tumor growth suppressor in prostate cancer and that Ad-PML may be a potential candidate for human prostate cancer therapy.

Adenoviridae↗