Biomedical subjects

Jau-Hong Lee

Publications and source records attributed to Jau-Hong Lee.

7 recordsLinked to original sources

PubMed2006

Berberine induces cell cycle arrest and apoptosis in human gastric carcinoma SNU-5 cell line.

AIM: To investigate the relationship between the inhibited growth (cytotoxic activity) of berberine and apoptotic pathway with its molecular mechanism of action. METHODS: The in vitro cytotoxic techniques were complemented by cell cycle analysis and determination of sub-G1 for apoptosis in human gastric carcinoma SNU-5 cells. Percentage of viable cells, cell cycle, and sub-G1 group (apoptosis) were examined and determined by the flow cytometric methods. The associated proteins for cell cycle arrest and apoptosis were examined by Western blotting. RESULTS: For SNU-5 cell line, the IC50 was found to be 48 micromol/L of berberine. In SNU-5 cells treated with 25-200 micromol/L berberine, G2/M cell cycle arrest was observed which was associated with a marked increment of the expression of p53, Wee1 and CDk1 proteins and decreased cyclin B. A concentration-dependent decrease of cells in G0/G1 phase and an increase in G2/M phase were detected. In addition, apoptosis detected as sub-G0 cell population in cell cycle measurement was proved in 25-200 micromol/L berberine-treated cells by monitoring the apoptotic pathway. Apoptosis was identified by sub-G0 cell population, and upregulation of Bax, downregulation of Bcl-2, release of Ca2+, decreased the mitochondrial membrane potential and then led to the release of mitochondrial cytochrome C into the cytoplasm and caused the activation of caspase-3, and finally led to the occurrence of apoptosis. CONCLUSION: Berberine induces p53 expression and leads to the decrease of the mitochondrial membrane potential, Cytochrome C release and activation of caspase-3 for the induction of apoptosis.

Amino Acid Chloromethyl Ketones↗

PubMed2005

Effect of inhibition of aloe-emodin on N-acetyltransferase activity and gene expression in human malignant melanoma cells (A375.S2).

Arylamine carcinogens and drugs are N-acetylated by cytosolic N-acetyltransferase (NAT), which uses acetyl-coenzyme A as a cofactor. NAT plays an initial role in the metabolism of these arylamine compounds. 2-Aminofluorene is one of the arylamine carcinogens which have been demonstrated to undergo N-acetylation in laboratory animals and humans. Our previous study showed that human cancer cell lines (colon cancer, colo 205; liver cancer, Hep G2; bladder cancer, T24; leukemia, HL-60; prostate cancer, LNCaP; osteogenic sarcoma, U-2 OS; malignant melanoma, A375.S2) displayed NAT activity, which was affected by aloe-emodin in human leukemia cells. The purpose of this study was to determine whether aloe-emodin could affect the enzyme activity and gene expression of NAT at the mRNA and protein levels in malignant human melanoma A375.S2 cells. The results showed that aloe-emodin inhibited NAT1 activity (decreased N-acetylation of 2-aminofluorene) in intact cells in a dose-dependent manner. The effect of aloe-emodin on NAT1 at the protein level was determined by Western blotting and the mRNA levels were examined by polymerase chain reaction (PCR) and cDNA microarray. These results clearly indicate that aloe-emodin inhibits the mRNA expression and enzyme activity of NAT1 in A375.S2 cells.

2-Acetylaminofluorene↗

PubMed2003

3-D US frame positioning using speckle decorrelation and image registration.

In this paper, a new positioning system is proposed for the 3-D ultrasound (US). This system combines the image registration technique and speckle decorrelation algorithm to accurately position sequential ultrasonic images without any additional positioning hardware. The speckle decorrelation algorithm estimates the relative distance of two neighboring frames and the image registration technique gets the range of the whole 3-D ultrasonic data set and makes slight modification on each frame's position. The image registration technique is based on the reference image, which is perpendicular to the 3-D ultrasonic data set. This reference image intersects each frame of the 3-D ultrasonic data set in a line. For each frame, the intersectional line is first found and then the location in the reference image can be used to estimate the position of this frame. This system uses the data set of consecutive 2-D freehand-scanned US B-mode images to construct the 3-D US volume data, and it can be integrated into the 3-D US volume rendering system.

Algorithms↗

PubMedDate not supplied

Effects of ellagic acid by oral administration on distribution and metabolism of 2-aminofluorene in Sprague-Dawley rats.

The effects of ellagic acid on the in vivo N-acetylation and metabolism of 2-aminofluorene (2-AF) were investigated in bladder, blood, colon, kidney, liver, feces and urine samples from male Sprague-Dawley rats. Major metabolites such as 1-OH-2-AAF, 8-OH-2-AAF and 9-OH-2-AAF were found in bladder tissues, 1-OH-2-AAF, 5-OH-2-AAF and 8-OH-2-AAF were found in blood samples, 1-OH-2-AAF, 3-OH-2-AAF, 5-OH-2-AAF, 8-OH-2-AAF and 9-OH-2-AAF were found in colon tissues, 1-OH-2-AAF, 3-OH-2-AAF and 9-OH-2-AAF were found in kidney tissues, 1-OH-2-AAF, 3-OH-2-AAF and 8-OH-2-AAF were found in liver tissues, 1-OH-2-AAF, 3-OH-2-AAF, 5-OH-2-AAF and 8-OH-2-AAF were found in feces samples and 1-OH-2-AAF, 3-OH-2-AAF, 5-OH-2-AAF and 8-OH-2-AAF were also found in urine samples after rats had been orally treated with 2-AF (50 mg/kg) for 24 h. Pretreatment of male rats with ellagic acid (10 mg/kg) 24 h prior to the administration of 2-AF (50 mg/kg) resulted in absence of 8-OH-2-AAF in bladder tissues, and there were significant decreases of 8-OH-2-AAF in blood and urine samples. In blood samples, amounts of 2-AAF and 8-OH-2-AAF were significantly decreased; in colon tissues, amounts of 2-AF, 1-OH-2-AAF and 3-OH-2-AAF, in liver tissues, amounts of 2-AAF, 1-OH-2-AAF and 3-OH-2-AAF, and in urine samples, amounts of 2-AF and 8-OH-2-AAF were significantly decreased in 24-h ellagic acid (EA)-treated rats before 2-AF was added to the diet. However, significantly increased 1-OH-2-AAF concentrations were found in urine samples in 24-h EA-treated rats before 2-AF was administered. In the EA and 2-AF rats, in the same time treated groups, bladder, colon and liver tissues, and feces and urine samples showed significant differences when compared to the ones without EA co-treatment. We saw significant decreases of the amounts of 2-AF and 1-OH-2-AAF in colon tissues. The feces samples showed increased amounts of 2-AAF in EA- and in 2-AF- treated rats in the same time groups, but urine samples showed a decreased amount of 8-OH-2-AAF in both EA-treated groups. The total amounts of 2-AF metabolites in bladder, blood, kidney and liver tissues showed significant difference between control and the group which was EA-treated 24 h before 2-AF was added. The total amounts of 2-AF metabolites in the liver, feces and urine showed significant decreases between control and EA-treated at the same time with 2-AF groups. This is the first report of EA affecting the N-acetylation and metabolism of 2-AF in rat tissues in vivo.

2-Acetylaminofluorene↗

PubMedDate not supplied

(-)-Menthol inhibits DNA topoisomerases I, II alpha and beta and promotes NF-kappaB expression in human gastric cancer SNU-5 cells.

It has been reported that (-)-Menthol can inhibit the growth of rat liver epithelial tumor cells and is a potent chemopreventive agent. The purpose of the present experiment was to examine and identify cellular processes leading to cell death which are affected by (-)-Menthol in human gastric SNU-5 cancer cells. Cell death (cytotoxicity) was examined and analyzed by trypan blue stain and flow cytometric methods. It was shown that (-)-Menthol inhibited the proliferation of the cells in a dose- and time-dependent manner, inhibited topoisomerase I, IIa and IIbeta, but promoted the levels of NF-kappaB gene expression based on the Western blot and polymerase chain reaction (PCR) and cDNA microarray methods. These data suggest that (-)-Menthol may induce cytotoxicity through inhibiting gene expression of topoisomerase I, IIalpha and IIbeta and promoting the gene expression of NF-kappaB in SNU-5 cells.

Antigens, Neoplasm↗

PubMedDate not supplied

Ketoprofen-inhibited N-acetyltransferase activity and gene expression in human colon tumor cells.

The activation of ketoprofen, which inhibits the outgrowth of azoxymethane-induced aberrant crypt foci in the rat colon, on the inhibition of arylamine N-acetyltransferase (NAT) activity (N-acetylation of substrates), gene expression (mRNA NAT) and 2-aminofluorene (AF)-DNA adduct formation was studied in a human colon tumor (adenocarcinoma) cell line (colo 205). Cellular cytosols (9000 xg supernatant) and intact colon tumor cells were used. The NAT activity in colo 205 cells was inhibited by ketoprofen in a dose- and time -dependent manner in both examined systems. The data also indicated that ketoprofen decreased the apparent value of V(max) of NAT enzymes, being a competitive inhibitor of NAT enzymes. The AF-DNA adduct formation in colo 205 cells was also decreased by ketoprofen. Based on the results from PCR, it was shown that ketoprofen affected mRNA NAT expression in human colon colo 205 cells. The cells were stained with anti-NAT antibody, then analyzed by flow cytometry. The results showed that ketoprofen decreased the percentage of cells stained by anti-NAT. This report is the first to demonstrate that ketoprofen inhibits human colon tumor cell NAT activity, gene expression and DNA adduct formation.

2-Acetylaminofluorene↗

PubMedDate not supplied

Gypenosides induced apoptosis in human colon cancer cells through the mitochondria-dependent pathways and activation of caspase-3.

The effects of the gypenosides (Gyp), a component of Gynostemma pentaphyllum Makino, on the cell viability, cell cycle and induction of apoptosis were investigated in human colon cancer colo 205 cells. Gyp was cytotoxic to colo 205 cells with an IC50 of 113.5 microg/ml. The decreasing number of viable cells appeared to be due to the induction of cell cycle arrest and apoptotic cell death, since Gyp induced morphological changes and internucleosomal DNA fragmentation and increased the sub-G1 group. The production of reactive oxygen species and Ca2+ and the depolarization of mitochondrial membrane potential were observed, dose- and time-dependently, after treatment with various concentrations of Gyp. Gyp treatment also gradually decreased the expression of the anti-apoptotic proteins Bcl-2 and Bcl-xl, but increased the expression of the pro-apoptotic protein Bax. Gyp increased the levels of p53 and promoted the release of cytochrome c and the activation of caspase-3 before leading to apoptosis. These results provide information towards an understanding of the mechanisms by which Gyp induces cell cycle arrest and apoptosis in human colon cancer cells.

Apoptosis↗