Hsiao Wen Chen

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The chemical synthesis and metabolic characteristics of the lanosterol analogue, 15 alpha-fluorolanost-7-en-3 beta-ol, are described. The 15 alpha-fluorosterol is shown to be a competitive inhibitor of the lanosterol 14 alpha-methyl demethylase (Ki = 315 microM), as well as substrate for the demethylase enzyme. Metabolic studies show that the 15(More)
A system for the assay of 3-hydroxy-3-methyglutaryl (HMG) coenzyme A (CoA) reductase in digitonin-permeabilized Chinese hamster ovary cells is described. Under these conditions, HMG-CoA reductase remained intact and associated with the endoplasmic reticulum, and values for Km (HMG-CoA), Ki (mevinolin), and active/total activity were similar to those seen in(More)
Relatively few studies have been conducted to examine cholesterol as a nutrient for cell growth. Clonal growth and serial passage of several cell lines have been reported to be promoted or even dependent on the availability of exogenous cholesterol. Most cells, however, are capable of synthesizing cholesterol. Even in the presence of serum, a certain amount(More)
Chloroquine inhibits the incorporation of [14C]acetate into sterols at a concentration of 10 microM or more in mouse L cells but has no effect on fatty acid synthesis and CO2 production from the same substrate even at a 10-fold higher concentration of the drug. The site of inhibition is distal to the formation of mevalonate since chloroquine also inhibits(More)
A Chinese hamster ovary cell mutant, AR45, was selected for amphotericin B resistance after treatment with the mutagen ethyl methanesulfonate. The mutant is a cholesterol auxotroph with a deficiency in cholesterol biosynthesis. Whole cell experiments demonstrate that the mutant accumulates the C30 sterols, lanosterol and dihydrolanosterol, under culture(More)
With sequence homology to the SV40 T antigen-binding domain of the retinoblastoma protein (Rb), p107 and p130 constitute two additional members of the Rb family. To explore the potential function of p130 in mouse development, we cloned the full-length mouse cDNA for p130 and characterized p130 mRNA expression in mice. The deduced mouse p130 protein sequence(More)
The lanosterol 14 alpha-methyl demethylase inhibitors miconazole and ketoconazole have been used to assess their effects upon cholesterol biosynthesis in cultured Chinese hamster ovary cells. In Chinese hamster ovary cells treated with either agent, an initial accumulation of lanosterol and dihydrolanosterol has been observed. At elevated concentrations,(More)
HER2/neu, a transmembrane glycoprotein overexpressed in several types of human cancers, is a potential target for active immunotherapy. However, this protein and especially its extracellular domain (ECD(HER2)), is weakly immunogenic and is poorly processed by dendritic cells (DCs). Previously, we showed that anti-HER2/neu IgG3-(IL-2) and anti-HER2/neu(More)
Aphidicolin, a fungal metabolite which is a specific inhibitor of DNA polymerase alpha, inhibited the incorporation of [14C]acetate into desmosterol in mouse L cells by 50% at a concentration of 8.8 microM. It had no effect on acetate metabolism into fatty acids or CO2. The site of inhibition was determined to be distal to the formation of mevalonic acid(More)
The mRNA levels for HMG-CoA reductase were measured in Chinese hamster lung Dede cells or ovary CHO cells by Northern blot analysis. It was observed that 25-hydroxycholesterol decreased the level of reductase mRNA by 40 to 70% in a 6 hour treatment. Inclusion of cycloheximide in the culture prevented the decrease observed with 25-hydroxycholesterol alone.(More)