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Biomedical subjects

T C Hsieh

Publications and source records attributed to T C Hsieh.

50 records · Page 3Linked to original sources
PubMed1995

The synthetic retinoid N-(4-hydroxyphenyl) retinamide (4-HPR) exerts antiproliferative and apoptosis-inducing effects in the androgen-independent human prostatic JCA-1 cells.

A significant reduction in JCA-1 cell proliferation was observed as a result of treatment with 4-HPR. This was accompanied by the down-regulated expression of the proliferating cell nuclear antigen PCNA, cyclins D and E, and p34cdc2. Unexpectedly, p53 and pRB was also suppressed in response to 4-HPR. A prolonged exposure to 4-HPR (6 days) promoted the appearance of non-adherent cells showing morphological features and DNA fragmentation patterns indicative of apoptosis.

Androgens↗
PubMed1995

Changes in cell growth, cyclin/kinase, endogenous phosphoproteins and nm23 gene expression in human prostatic JCA-1 cells treated with modified citrus pectin.

Modified citrus pectin (MCP) added to the media of cultured androgen-independent human prostatic JCA-1 cells reduced cell growth and correspondingly [3H]thymidine incorporation into DNA, which was correlated with the down-regulation of cyclin B and p34cdc2 MCP also induced distinct increases in specific endogenous phosphoproteins, including a cAMP-stimulated 52,000 (52-kDa) protein. Since metastatis has been inversely correlated with nm23 gene expression in some cancer cells and was reportedly inhibited by MCP in a rat prostate model, we investigated steady state level changes in the nm23 protein in JCA-1 cells and found it to be unexpectedly suppressed as a result of exposure to MCP.

Animals↗
PubMed1990

Induction of tumor necrosis factor and cytotoxicity by macrophages exposed to lactoperoxidase and microperoxidase.

Peroxidases are involved in a number of cytotoxic reactions. Murine thioglycollate-induced peritoneal macrophages were exposed to either lactoperoxidase or microperoxidase in vitro. At a concentration of 17.7 microM, both of these enzymes induced between 100 and 200 units of tumor necrosis factor (TNF) per 0.1 ml. Furthermore, these substances were able to stimulate macrophages to kill 3T12 target cells in a dose dependent manner at concentrations of 0.177 microM to 17.7 microM. Per cent cytotoxicity varied from 20% up to 75% at the higher concentrations. It was concluded that these enzymes can induce macrophages to secrete TNF and become activated to the cytotoxic state.

Animals↗
PubMed1989

Peroxidases enhance macrophage-mediated cytotoxicity via induction of tumor necrosis factor.

Tumor necrosis factor (TNF) is a monokine which is involved in macrophage-mediated cytotoxicity (MMC). We have previously reported that peroxidases can activate thioglycollate-induced macrophages to the tumoricidal state in vitro. The present study was undertaken in an attempt to correlate peroxidase-induced MMC with production of TNF. Horseradish peroxidase (HRP) was used as the principal model for these studies. Resident and thioglycollate-induced macrophages exposed to peroxidases were examined for both MMC against 3T12 cells and production of TNF. Thioglycollate-induced macrophages exposed to HRP, bovine lactoperoxidase, or human myeloperoxidase demonstrated enhanced secretion of TNF. When exposed to HRP, both resident and thioglycollate-induced macrophages secreted significant amounts of TNF and acquired the ability to lyse 3T12 cells. However, resident macrophages were considerably less efficient in both their cytotoxic activity and TNF secretion. Macrophage-mediated cytotoxicity was eliminated by the addition of specific antisera to TNF. In addition, replacement of culture supernatants within 24 hr after exposure of the macrophages to HRP increased tumor cell killing in the absence of additional detectable TNF production, suggesting that other factors may be involved in peroxidase-induced MMC. These results indicate that TNF is intimately associated with peroxidase-induced MMC and suggest a possible role for peroxidases as immunomodulators via augmentation of macrophage capacities and functions.

Animals↗
PubMed1987

Occurrence of an unusual amount of an odd-numbered fatty acid in glycosphingolipids from human cataracts.

Human cataractous glycosphingolipids were isolated and purified according to previously established procedures. Fatty acid analyses of the purified glycosphingolipid revealed the presence of a significant amount of an odd-chain fatty acid. This was confirmed by methane (CH4) chemical ionization mass spectrometry, which showed characteristic ions at m/z 397, 425, 437, and 365. These ions facilitated the determination of molecular weight and the assignment of C25:0 (n-pentacosanoic acid) to this fatty acid in question. This may be the first time that such an unusual distribution of a single odd-chain fatty acid has been shown to occur in glycosphingolipid from any tissue.

Brain↗
PubMed1986

Structures of the asparagine-linked sugar chains of laminin.

This investigation describes the isolation and characterization of oligosaccharides of the basement membrane glycoprotein, laminin. Pronase-released glycopeptides of isolated laminin, from a mouse Engelbreth-Holm-Swarm tumor, were fractionated using a combination of gel permeation chromatography and Con A-Sepharose affinity chromatography. The glycopeptides were analyzed for sugar linkage patterns by methylation analysis. Glycopeptides and hydrazine-released oligosaccharides were further analyzed using endo-beta-galactosidase, endo-beta-N-acetylglucosaminidase H and specific exoglycosidases in conjunction with calibrated gel permeation chromatography. Based on these experiments, murine tumor laminin was shown to contain asparagine-linked oligosaccharides with the following structures: bi-, tri- and tetraantennary complex-type oligosaccharides; polylactosaminyl side chains containing Gal(beta 1----4)GlcNAc(beta 1----3) repeating units attached to the trimannose core portion of the bi-, tri- and tetraantennary complex-type oligosaccharides; unusual complex-type oligosaccharides terminated at the nonreducing end with sialic acid, alpha-galactose, beta-galactose and beta-N-acetylglucosamine; alpha-galactosyl residues linked to N-acetyllactosamine sequences; high-mannose-type oligosaccharides. These results, in conjunction with analytical data, indicate that most of the carbohydrate of this laminin is N-linked to asparagine and that there are about 43 such N-linked oligosaccharides per laminin molecule.

Animals↗
PubMed1981

Glycophosphoceramides from plants. Purification and characterization of a novel tetrasaccharide derived from tobacco leaf glycolipids.

A glycophosphoceramide concentrate prepared from tobacco leaves was shown to contain a mixture of related lipids (Kaul, K., and Lester, R. L. (1975) Plant Physiol. 55, 120-129; Kaul, K., and Lester, R. L. (1978) Biochemistry 17, 3569-3575) with the simplest and most abundant components having the structure GlcN(+/- Ac)(alpha 1 leads to 4)GlcUA(alpha 1 leads to 2)myoinositol-1-O-phosphorylceramide (Hsieh, T. C.-Y., Kaul, K., Laine, R. A., and Lester, R. L. (1978) Biochemistry 17, 3575-3579). To determine the structure of the more complex members of this series, a mixture of oligosaccharides was prepared from a carboxyl-reduced glycophosphoceramide concentrate by alkali-catalyzed hydrolysis and alkaline phosphatase treatment. A combination of reverse-phase high pressure liquid chromatography (Wells, G. B., and Lester, R. L. (1979) Anal. Biochem. 97, 184-190), normal-phase high pressure liquid chromatography, and thin layer chromatography were used to resolve several oligosaccharides as acetylated derivatives. Products of methylation analysis, CrO3 oxidation, and deacetylation-deamination were identified using chemical ionization mass spectrometry to give the following novel structures. A major tetrasaccharide was completely characterized as Gal(alpha 1 leads to 4)GlcNAc(alpha 1 leads to 4)GlcUA(alpha 1 leads to 2)myoinositol. An additional structure of a minor tetrasaccharide was partially characterized as GlcNAc(alpha 1 leads to 4)GlcUA(alpha 1 leads to ?)myoinositol(O leads from 1 alpha)Man. These are representatives of a class of acidic glycolipids from plants, possibly analogous to the acidic gangliosides found in animal cell membranes.

Carbohydrate Conformation↗
PubMed1978

Structure of a major glycophosphoceramide from tobacco leaves, PSL-I: 2-deoxy-2-acetamido-D-glucopyranosyl(alpha1 leads to 4)-D-glucuronopyranosyl(alpha1 leads to 2)myoinositol-1-O-phosphoceramide.

The chemical structure of a major glycophosphoceramide from tobacco leaves, called PSL-I [K. Kaul and R. L. Lester (1975), Plant Physiol. 55, 120], has now been characterized as 2-deoxy-2-acetamido-D-glucopyranosyl(alpha1 leads to 4)D-glucuronopyranosyl(alpha1 leads to 2)myoinositol-1-O-phosphoceramide. Sites of glycoside linkage were determined by (1) methylation analysis on a trisaccharide isolated by degradation of carboxyl-reduced PSL-I and (2) periodate oxidation experiments on PSL-I. The resulting products were identified with gas chromatography/mass spectrometry. Anomeric configurations were determined by resistance of the sugars in the peracetylated trisaccharide to chromium trioxide treatment.

Glycosphingolipids↗
PubMedDate not supplied

Control of human vascular smooth muscle cell proliferation by sera derived from 'experimentally stressed' individuals.

Recently we reported that individuals with high scores in standardized hostility evaluation tests, when placed in a environment, may have an association with increases in a blood-borne mitogenic substance(s) for arterial smooth muscle cells. To further investigate the molecular basis for such an association, PDS [plasma derived serum with platelet derived growth factor (PDGF) removed] from individuals showing the greatest differential pre/post-stress mitogenic activity, were tested for ability to modulate changes in the steady state of the c-myc mRNA in cultured VSMC (vascular smooth muscle cells) by Northern blot analysis. Post-stress PDS resulted in a significant increase in c-myc mRNA, when compared with pre-stress PDS of the same individual. These results give further experimental support for the notion that stress (even in the form of transient, episodic psychological challenges) may affect the cardiovascular system via rapid elicited rises in serum mitogenic activity for VSMC.

Cell Division↗
PubMedDate not supplied

Grape-derived chemopreventive agent resveratrol decreases prostate-specific antigen (PSA) expression in LNCaP cells by an androgen receptor (AR)-independent mechanism.

Trans-resveratrol, a polyphenol present in red wines and various human foods, inhibited the proliferation of LNCaP cells and the expression of a prostate specific gene, PSA. A 4-day treatment with resveratrol reduced the levels of intracellular and secreted PSA by approximately 80%, as compared to controls. To test whether this decrease was coordinated with changes in AR expression, levels of AR were assayed by Western blot analysis, using the cognate antibody, or by binding with the radioactive ligand methyltrienolone [3H]R1881. With either assay, little or no change in AR expression could be detected between control and resveratrol-treated cells. Thus, it would appear that the prostate tumor marker PSA is down regulated by resveratrol, by a mechanism independent of changes in AR.

Adenocarcinoma↗
PubMedDate not supplied

Control of renal carcinoma TC-1 growth, cyclin/kinase and nm23 expression by IFN-gamma and TGF-beta.

To gain mechanistic insights into the growth control of renal cell carcinoma cells by IFN-gamma and TGF-beta, a recently established human renal carcinoma TC-1 cell line was treated with different concentrations of IFN-gamma and TGF-beta. Cell growth and changes in specific gene expression were evaluated. IFN-gamma exerted an antimitogenic effect on TC-1 cells, whereas TGF-beta was essentially without effect. The growth-suppressed cells had reduced expression of proliferating cell nuclear antigen (PCNA), the G2/M cell cycle transition regulatory proteins cyclin B/p34cdc2, the tumor suppressor gene pRB, and the antimetastatic gene nm23. However, levels of other cell cycle regulatory protein molecules such as cyclin D and p53 were unaffected by IFN-gamma. Thus, the antimitogenic effect of IFN-gamma may be mediated by its ability to modulate specific oncogene changes.

Carcinoma, Renal Cell↗
PubMedDate not supplied

Growth control of human prostatic cancer cells by the phorbol ester TPA: possible involvement of protein kinases.

To gain insights into the involvement of kinases in the growth control of prostate carcinoma cells by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), immunoblot analysis and in vitro phosphorylation assays were performed using kinase discriminating effectors and extracts prepared from the androgen-dependent LNCaP and the androgen-independent JCA-1 human prostate cells. The down-regulation of PKC-alpha and -beta in JCA-1 cells was correlated with the effects of TPA. In LNCaP cells, proliferation may involve DNA-PK, proposed to act possibly via phosphorylation of the androgen receptor.

Cell Cycle↗
PubMedDate not supplied

Effects of microtubule inhibitors-taxol, vinblastine and estramustine on the growth and p53 gene expression in the hormone independent human prostatic JCA-1 cells.

Treatment of the JCA-1 prostate cells with different concentrations of microtubule inhibitors-taxol (paclitaxel) vinblastine, and estramustine-was accompanied by reduced cell growth and, correspondingly, characteristic morphological changes. The reduction of cellular proliferation was unlikely to be attributable to an inhibitory effect of the antimicrotubule agents on cell cycling, but was correlated with the decreased expression of the p53 gene. These results suggest that antimicrotubule agents may be considered as potentially complementary treatment modalities for patients with hormonally independent prostate cancer.

Antineoplastic Agents↗