Biomedical subjects

H L Lin

Publications and source records attributed to H L Lin.

At least 19 recordsLinked to original sources

PubMed2004

Chemoprevention of gastric cancer by celecoxib in rats.

BACKGROUND: Overexpression of cyclooxygenase 2 (COX-2) is frequently detected in gastric cancer and is believed to play a crucial role in gastric carcinogenesis. AIM: We examined the chemopreventive effect of a COX-2 inhibitor in an animal model of stomach carcinogenesis. METHODS: Eighty six male Wistar rats were divided into six different treatment groups: group A, water alone (n = 5); group B, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG 100 micro g/ml) (n = 16); group C, indomethacin (3 mg/kg/day) (n = 16); group D, celecoxib (5 mg/kg/day) (n = 17); group E, celecoxib (10 mg/kg/day) (n = 16); and group F, celecoxib (20 mg/kg/day) (n = 16). Group B-F animals were treated with 10% sodium chloride (in the initial six weeks) and MNNG in drinking water to induce adenocarcinoma in the stomach. All animals received treatment for 40 weeks, and were sacrificed after death or at 48 weeks. Gastric neoplasm was evaluated by histology. RESULTS: The incidences of gastric cancer were 0% in group A, 75% in group B, 68.8% in group C, 70.6% in group D, 18.8% in group E, and 31.3% in group F (p = 0.002, ANOVA). Compared with MNNG controls, treatment with celecoxib 10 mg/kg/day also showed lower tumour multiplicity (0.19 (0.40) v 1.00 (0.73); p = 0.004) and lower mean tumour volume (2.4 v 2805 mm(3); p = 0.02). Although tumours had significantly higher COX-2 expression than their adjacent normal tissues (p<0.02), there was no significant difference in COX-2 levels among tumours in the different treatment groups. The lowest tumour prostaglandin E(2) level was found in the indomethacin treated group, suggesting that the chemopreventive effect of celecoxib may be mediated by a COX independent pathway. CONCLUSION: While treatment with indomethacin had no significant effect on tumour development, treatment with celecoxib reduced gastric cancer incidence and growth in rats.

Analysis of Variance↗

PubMed2001

2-Methoxyestradiol-induced caspase-3 activation and apoptosis occurs through G(2)/M arrest dependent and independent pathways in gastric carcinoma cells.

BACKGROUND: 2-Methoxyestradiol (2-Me), one of the estrogen metabolites, has recently been found to possess anti-angiogenesis activity in vivo. Many chemotherapeutic agents, such as taxol, docetaxel, and vinblastine, interact with microtubules and then induce apoptosis. It has been suggested that 2-Me acts on microtubules and results in G(2)/M-cycle arrest of tumor cells. Whether 2-Me induces apoptosis in gastric carcinoma cell lines is not known. Moreover, reactive oxygen species (ROS) produced by 2-Me may be involved in cytotoxicity of tumor cells. Thus, another objective of this study was to evaluate the relation between cell cycle arrest, ROS formation, and caspase activity levels after 2-Me treatment in gastric carcinoma cells. METHODS: It was determined whether 2-Me directly induced apoptosis in two gastric carcinoma cell lines (SC-M1 and NUGC-3) through caspase-3 and caspase-8 activation and, eventually, induced DNA fragmentation. To clarify the effect of 2-Me-induced G(2)/M arrest in apoptosis, calcium ionophore, A23187, and thapsigargin were used to modulate 2-Me-induced cell cycle responses. Moreover, the role of 2-Me-induced ROS formation in the cell cycle responses also was evaluated. RESULTS: It was found that 2-Me treatment resulted in G(2)/M-cycle arrest, caspase-8 and caspase-3 activation, and DNA fragmentation. In addition, the 2-Me induced, concomitant increases of peroxide and superoxide anions were correlated with G(2)/M-cycle arrest. Treatment with calcium ionophore A23187 and thapsigargin partially reversed the 2-Me-induced G(2)/M-cycle arrest, with a concomitant decrease in both peroxide and superoxide levels. Moreover, A23187 blocked the 2-Me-induced caspase-3 activation, whereas thapsigargin had no effect. Treatment with calcium channel blockers did not affect 2-Me-induced cell cycle arrest or caspase-3 activation. CONCLUSIONS: These results suggest that the 2-Me-induced apoptosis of gastric carcinoma cells by DNA fragmentation accompanied caspase activation. Elevation of free radicals was associated with G(2)/M-cycle arrest. The induction of G(2)/M-cycle arrest is not a prerequisite for caspase activation.

2-Methoxyestradiol↗

PubMed2001

Folate depletion and elevated plasma homocysteine promote oxidative stress in rat livers.

This study was designed to determine whether nutritional folate depletion exerts hepatic oxidative stress in relation to elevated plasma homocysteine. To mimic various extents of folate depletion status in vivo, male Wistar rats were fed an amino acid-defined diet containing either 8 (control), 2, 0.5, or 0 mg folic acid/kg diet. After a 4-wk feeding period, the plasma and hepatic folate concentrations of the rats decreased significantly with each decrement of dietary folate. Folate depletion did not significantly affect two major liver antioxidants: reduced glutathione and alpha-tocopherol. Conversely, folate depletion decreased Cu-Zn superoxide dismutase and glutathione peroxidase activities, but had no effect on catalase activity in liver homogenates. Lipid peroxidation products, as measured by thiobarbituric acid-reactive substances, were significantly higher in livers of folate-depleted rats than in those of the controls. This occurrence of hepatic oxidative stress in folate-depleted rats was confirmed by demonstrating an increased susceptibility of livers of folate-depleted rats to lipid peroxidation induced by additional H2O2 or Fe(2+) treatments compared with the controls. Decreasing dietary folate intake resulted in graded increases in plasma homocysteine concentrations of folate-depleted rats. Elevated plasma homocysteine and decreased plasma and hepatic folate concentrations in folate-depleted rats were all strongly and significantly correlated with increased liver lipid peroxidation (/r/ > or = 0.58, P < 0.0003). These data demonstrate that folate depletion and elevated plasma homocysteine promote oxidative stress in rat livers.

Animals↗

PubMed2001

Molecular cloning and expression of woodchuck granulocyte-macrophage colony stimulating factor.

Granulocyte-macrophage colony stimulating factor (GM-CSF) has immunoregulatory and antiviral effects, and may thus be promising for the treatment of chronic hepatitis B. Using woodchuck hepatitis virus (WHV)-infected woodchuck as an animal model to test the efficacy and safety of GM-CSF on the therapy of chronic hepatitis B, woodchuck GM-CSF will be required due to the apparent species-specific activity of GM-CSF. The cDNA of woodchuck GM-CSF was cloned using reverse transcription-polymerase chain reaction (RT-PCR) with primers deriving from highly conserved regions of GM-CSF genes from other species. The deduced amino acids, including the signal peptide, is 138 in length and its identities to human, murine, canine and bovine GM-CSFs are 63, 49, 63, and 63% respectively. The genomic DNA of woodchuck GM-CSF was also cloned by PCR. Its organization is highly homologous to that of human and murine GM-CSF genes, consisting of four exons and three introns. Cloned woodchuck GM-CSF was expressed transiently in 293T cells. The recombinant protein expressed was found to stimulate the growth and differentiation of woodchuck bone marrow cells, indicating the protein expressed by the cloned gene is functional. These results pave the way for future studies on the potential role of GM-CSF for the treatment of chronic hepatitis B by using this animal model.

Amino Acid Sequence↗

PubMed2000

Comparison of 2-methoxyestradiol-induced, docetaxel-induced, and paclitaxel-induced apoptosis in hepatoma cells and its correlation with reactive oxygen species.

BACKGROUND: Previously, the authors observed that paclitaxel treatment of hepatoma cells resulted in differential cytotoxicity. Whether other antimicrotubule agents (docetaxel and 2-methoxyestradiol) are more effective than paclitaxel is not clear. Moreover, whether the modulation of reactive oxygen species (ROS) is involved in the drug-induced growth inhibition of hepatoma cells is not known. METHODS: The authors examined the effects of 2-methoxyestradiol, paclitaxel, and docetaxel on HepG2, Hep3B, HA22T/VGH, and Hepa1-6 hepatoma cell lines. The parameters examined included cell viability, cell membrane permeability, cell cycle distribution, DNA fragmentation, and ROS generation. RESULTS: Docetaxel and paclitaxel inhibited the growth of hepatoma cells at submicromolar concentrations, whereas that of 2-methoxyestradiol was within a micromolar range. This drug-induced growth inhibition was cell cycle dependent. 2-Methoxyestradiol-treated (10-50 microM) cells resulted in G2/M block prior to apoptosis. High dose (0.1 microM) docetaxel- and paclitaxel-treated cells resulted in a G2/M arrest followed by generation of polyploidy or apoptosis; however, low dose (0.01 microM) treatment induced apoptosis without G2/M arrest. The low dose effect was more significant in docetaxel-treated cells than in paclitaxel-treated cells. Although these antimicrotubule agents increased the formation of ROS, antioxidant treatment did not block drug-induced cell cycle and growth inhibition effects. CONCLUSIONS: The current results suggest that the growth inhibition of hepatoma cells induced by 2-methoxyestradiol, paclitaxel, and docetaxel was mediated through G2/M-phase arrest, caspase activation, and DNA fragmentation. The drug-induced apoptosis was independent of ROS formation. Docetaxel was more effective than paclitaxel in killing hepatoma cells. The potential of using 2-methoxyestradiol and docetaxel for the treatment of patients with hepatoma is worthy of further study.

2-Methoxyestradiol↗

PubMed2000

Differentiation of hair growth cycle from scalp hair roots for the diagnosis of glucose-6-phosphate dehydrogenase deficiency in neonates.

Hair analysis can be used as a screening tool in the diagnosis of genetic diseases. The scalp hair roots of 67 normal neonates and 39 neonates with glucose-6-phosphate dehydrogenase (G6PD) deficiency were analysed using Fourier transform infrared (FT-IR) microspectroscopy to differentiate the stages of the hair growth cycle and to diagnose the genetic disorder on the basis of spectral differences. We have demonstrated that FT-IR microspectroscopy is a rapid and effective noninvasive diagnostic method to differentiate scalp hair roots of normal neonates into the anagen, catagen or telogen phases of the hair growth cycle, using IR spectral differences within the 3000-2800 cm(-1) region and the IR peak area ratio of 2854 cm(-1)/2873 cm(-1) or 1084 cm(-1)/amide II band (p<0.001). Moreover, G6PD-deficient neonates could be accurately diagnosed from telogen phase hair roots owing to significant differences in IR peak area ratios of 2854 cm(-1)/2873(-1) or 1084 cm(-1)/amide II band compared to normal values in healthy neonates. The result suggests that the application of FT-IR microspectroscopy may be capable not only of differentiating the hair growth cycle into anagen, categen or telogen phases but also of detecting G6PD deficiency. Hair root analysis promises to be a useful complement to serum and urine analysis in the diagnosis of genetic diseases.

Female↗

PubMed2000

Effect of skin-penetrating enhancers on the thermophysical properties of cholesteryl oleyl carbonate embedded in a thermo-responsive membrane.

The effect of skin-penetrating enhancers such as propylene glycol (PG), Azone and ethanol on the thermophysical properties of cholesteryl oleyl carbonate (COC) was investigated using differential scanning colorimetry (DSC) and microscopic Fourier-transform infrared (FT-IR) spectroscopy. The results indicate that PG did not influence the DSC thermograms and IR spectra of COC in the different ratios of COC and PG mixture; whereas Azone interacted with COC not only to lower the semectic-cholesteric phase transition temperature of COC but also to induce a new IR spectral peak at 1653 cm(-1) which shifted from the carbonyl stretching band (1636 cm(-1)) of Azone. Ethanol did not interact with COC, but it influenced the IR spectral peak intensity of COC at 1253 cm(-1). The peak intensity at 1253 cm(-1) gradually rose with the time of ethanol evaporation and was similar to that of the temperature effect. The solubility parameter was also used to explain the miscibility and interaction between COC and PG, Azone or ethanol.

Journal Article↗

PubMed2000

Effects of ICAM-1 antisense oligonucleotide on the tubulointerstitium in mice with unilateral ureteral obstruction.

UNLABELLED: Effects of ICAM-1 antisense oligonucleotide on the renal tubulointerstitium in mice with unilateral ureteral obstruction. BACKGROUND: To extend our previous study of the therapy of the renal lesions of unilateral ureteral obstruction (UUO) in mice by an inhibitor of intercellular adhesion molecule-1 (ICAM-1), we investigated the blocking effects of ICAM-1 antisense oligonucleotides (ASONs) on the ICAM-1 expression in mouse kidney. METHODS: First, ICAM-1 ASON was transducted into mouse renal tubular epithelial cells to investigate the effects of ICAM-1 ASON in vitro. Second, fluorescein isothiocyanate (FITC)-labeled ICAM-1 ASON was injected intravenously to determine the distribution of the ASON in vivo. Third, the expression of ICAM-1 in kidney and the changes of renal morphology were observed to investigate the therapeutic effects of ICAM-1 ASON on the UUO mice in vivo. RESULTS: The expressions of ICAM-1 in the epithelial cells induced by interleukin-1beta were inhibited by ICAM-1 ASON at the dosages of 100 and 200 nmol/L. Twenty-four hours after an introvenous injection with FITC-labeled ICAM-1 ASON, the highest level of fluorescein was detected within the proximal tubules in mouse kidney. Results of immunohistology and Northern blot showed that the ICAM-1 expression was markedly reduced in the obstructed kidney after treatment with ICAM-1 ASON. The ASON also alleviated the infiltration of inflammatory cells and accumulation of the extracellular matrix in the tubulointerstitium of UUO mice without apparent side effects. CONCLUSION: Our data demonstrate that ICAM-1 ASON is taken up primarily by the proximal tubular cells of mouse kidney. ICAM-1 ASON can selectively inhibit the ICAM-1 expression of the renal tubular cells both in vitro and in vivo.

Animals↗

PubMed2000

Male predominance in hepatocellular carcinoma: new insight and a possible therapeutic alternative.

Hepatocellular carcinoma is one of the most common cancers in the world. The male to female ratio is 3-6 to 1 in patients with hepatocellular carcinoma. Although steroid hormones and receptors have been examined extensively for their role in the growth regulation of hepatocellular carcinoma, the direct stimulation of hepatocellular carcinoma by steroid hormones still awaits elucidation. On the other hand, clinical trials using antagonists for steroid hormones to treat hepatocellular carcinoma were found to be mostly ineffective. Recently it has been found that 2-methoxyestradiol - an estrogen metabolite - is effective in growth inhibition of various tumor cells as well as in angiogenesis inhibition. Since estrogen is metabolized in the liver, it is conceivable that females with menstruation cycles have more estrogen metabolized in their liver, consequently more 2-methoxyestradiol produced which could inhibit tumor growth in situ. We propose that the low incidence and mortality of hepatocellular carcinoma found in females may have resulted from the high levels of 2-methoxyestradiol produced in the liver during their reproductive years. Consequently, the growth of hepatocellular carcinoma in females is delayed significantly as compared to males. The potential of using 2-methoxyestradiol for treatment of patients with hepatocellular carcinoma after resection of tumor should be explored.

2-Methoxyestradiol↗

PubMed2000

Combination of angiogenesis inhibitor TNP-470 with cytotoxic drugs in experimental therapy of nasopharyngeal carcinoma.

This study was conducted to evaluate the effectiveness of angiogenesis inhibitor 6-O-(N-chloroacetyl-carbamoyl)-fumagillol (TNP-470. AGM-1470) in the treatment of nasopharyngeal carcinoma (NPC) alone and in combination with cytotoxic agents. Forty-two male BALB/c nude mice bearing human NPC cell line CNE-2 were randomized into 6 groups: those treated with saline solution, TNP-470, cisplatin (DDP), fluorouracil (5-FU), TNP-470 + DDP, and TNP-470 + 5-FU, respectively. In every treatment group, tumor growth was suppressed significantly. The combination of 5-FU with TNP-470 showed significant enhancement in antitumor efficacy. TNP-470 also enhanced the inhibitory effect of DDP, although not to statistical significance. All animals gained in body weight, although treatment with 5-FU caused slight, reversible diarrhea of 2 to 3 days' duration. The results showed that TNP-470 suppressed the growth of the human NPC cell line and enhanced the antitumor effect of 5-FU without increasing its toxicity. The combination of angiogenesis inhibitors with conventional cytotoxic agents is promising in the treatment of NPC.

Angiogenesis Inhibitors↗

PubMed1999

N-Nitrosodimethylamine-mediated cytotoxicity in a cell line expressing P450 2E1: evidence for apoptotic cell death.

N-Nitrosodimethylamine (NDMA) is an acute hepatotoxin and potent carcinogen. The metabolic activation of NDMA to reactive metabolites is a critical step for the expression of its toxic and carcinogenic potential. We have previously demonstrated a strong correlation between methylation of cellular macromolecules and NDMA-mediated cytotoxicity, and we have demonstrated that reactive oxygen species may partially contribute to the toxic effects in P450 2E1-expressing cells. The mode of cell death in NDMA-treated monolayer cultures exhibited the following characteristics: (i) condensation of nuclear chromatin as demonstrated by using Hoechst 33258 staining, (ii) DNA fragmentation as detected by combining pulsed field and conventional agarose gel electrophoresis, and (iii) DNA double strand breaks determined by using the in situ terminal deoxynucleotidyl transferase assay and flow cytometric analysis. These results indicate that reactive metabolites of NDMA trigger activation of the signal pathway for apoptotic cell death in these P450-expressing cells. The NDMA-mediated cell death was partially prevented by the endonuclease inhibitor, aurintricarboxylic acid, as well as the caspase inhibitors, acetyl-Asp-Glu-Val-Asp-CHO and acetyl-Tyr-Val-Ala-Asp-CHO. The cell cycle distribution was altered in NDMA-treated cells resulting in an increase in the G2/M phase and a decrease in the G1 phase. Our results suggest that DNA degradation, the inability to complete DNA repair, the biochemical events associated with G2/M arrest, and the process of apoptotic death all result from P450 2E1-catalyzed metabolism of NDMA.

Apoptosis↗

PubMed1999

Up-regulation of multidrug resistance transporter expression by berberine in human and murine hepatoma cells.

BACKGROUND: Berberine, one of the major constitutents of alkaloids of Coptis chinensis is frequently utilized in the treatment of inflammation and liver-related diseases. In Chinese herbal medicine, Coptis chinensis is used as a prophylactic drug to treat gastrointestinal disorders. In a previous study, the authors found that berberine reduced cell proliferation and alpha-fetoprotein expression in human hepatoma HepG2 cells. Multidrug resistance transporter (pgp-170) is known to be overexpressed in HepG2 cells. Whether berberine regulates the expression of pgp-170 in HepG2 and other hepatoma cell lines is unknown and worthy of investigation. METHODS: Human and murine hepatoma cells were treated with berberine (0.32, 3.2, 32, and 320 microM), tamoxifen (1 microM), or verapamil (10 microM) for 24 hours. Flow cytometry was used to measure retention of a fluorescence dye, rhodamine 123, and the level of immunoreactive pgp-170 in berberine-treated hepatoma cells. RESULTS: Berberine up-regulated the expression of pgp-170 in three human hepatoma cell lines. The function of pgp-170 was blocked by tamoxifen and verapamil, resulting in increased retention of rhodamine 123. Retention of rhodamine 123 was significantly reduced in berberine-treated hepatoma cells. CONCLUSIONS: Berberine modulates the expression and function of pgp-170 in hepatoma cells. These results suggest that treatment of tumor cells with berberine may result in reduced retention of chemotherapeutic agents.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1999

Berberine modulates expression of mdr1 gene product and the responses of digestive track cancer cells to Paclitaxel.

Berberine is the major constituent of Coptis chinese and is commonly used in Chinese herbal medicine to treat patients with gastrointestinal disorders. In this study, using flow cytometry, we have found that a 24-h berberine treatment up-regulated the multidrug-resistant transporter (pgp-170) expression in two oral (KB, OC2), two gastric (SC-M1, NUGC-3) and two colon (COLO 205, CT 26) cancer cell lines. Decreased retention of rhodamine 123 was observed in berberine-treated cells as compared to vehicle control. To examine whether the berberine modulated pgp-170 expression in cancer cells is associated with changes in drug resistance, we determined the cytotoxicity, cell cycle progression and cell morphology of Paclitaxel-treated cells. Paclitaxel (1 nM-10 microM) treatment for 24 h induced cytotoxicity in OC2, SC-M1 and COLO 205 cells in a dose-dependent manner. Pretreatment of cells with 32 microM berberine for 24 h prior to Paclitaxel treatment resulted in increased viability as compared to that of Paclitaxel-treated cells. In addition, Paclitaxel-induced apoptosis and/or G2/M arrest in these three cancer cell lines. Pretreatment of cells with berberine prior to Paclitaxel blocked the Paclitaxel-induced cell cycle responses and morphological changes. These results together suggest that berberine modulated the expression and function of pgp-170 that leads to reduced response to Paclitaxel in digestive track cancer cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1999

Folate deficiency induces a cell cycle-specific apoptosis in HepG2 cells.

The human hepatoma HepG2 cell line was chosen as a representative of solid tissue-derived cell systems in which folate metabolism and apoptosis induction have not been thoroughly investigated. HepG2 cells were cultivated in the control or folate-deficient media (control media lacking of folate, glycine, thymidine and hypoxanthine) for 4 wk. This resulted in a decrease in intracellular folate levels to 32% of the control within 1 wk, which was followed by growth arrest and greater cell death rates. These disturbances of folate deficiency coincided with apoptotic induction, as characteristically shown by nucleosomal DNA fragmentation of 180-200 base pair multimers, nuclear chromatin condensation and positive terminal transferase-mediated dUTP nick end labeling assay. Apoptosis coincided with an accumulation of cells in S-phase, a subsequent G2/M phase block and a significant increase in mean protein content as evaluated by flow cytometric analyses employing a double-staining method. The growth and cell cycle arrest under folate-deficient conditions was independent of a change of p53 expression as measured by an enzyme-linked immunosorbent assay. Supplementation of 2 micromol/L folate normalized cell cycles and diminished DNA fragmentation. Taken together, these data indicate that HepG2 cells cultivated in folate-deficient medium have a low folate concentration, decreased growth and viability, and increased apoptotic propensity. This occurrence of apoptosis was associated with a cell cycle-specific mechanism and independent of p53-mediated pathway.

Apoptosis↗

PubMed1999

Anti-tumor effect of angiogenesis inhibitor TNP-470 on the human nasopharyngeal carcinoma cell line NPC/HK1.

The efficacy and targeting cells of angiogenesis inhibitor TNP-470 on human squamous cell nasopharyngeal carcinoma (NPC) were investigated. The colorimetric MTT assay was used to evaluate the IC50 values of NPC/HK1 cells and human dermal microvascular endothelial cells (HDMEC) for TNP-470. An NPC human tumor model was built by tumor-bearing nude mice using the NPC cell line of NPC/HK1. TNP-470 (30 mg/kg s.c.) was injected every other day. The results showed that the IC50 of NPC/HK1 cells for TNP-470 was 3.8 times higher than that of HDMEC. A significant difference in tumor volume between control and treatment groups was found after 7 days of treatment and increased thereafter. At the end of the treatment, tumor volume was 773.7 +/- 287.1 mm3 (n = 8) in the control group versus 454.5 +/- 132.8 mm3 (n = 8) in the treatment group (p = 0. 013); the ratio of the mean tumor volume in treated animals to that of control animals was 0.587, resulting a 41.3% decrease in tumor growth. The necrotic area was larger in the treatment group. Physical toxicity did not result from the treatment. These studies suggest that angiogenesis inhibitor TNP-470 is effective in the treatment of squamous cell NPC without obvious toxicity.

Antibiotics, Antineoplastic↗

PubMed1998

Primary study in experimental antiangiogenic therapy of nasopharyngeal carcinoma with AGM-1470 (TNP-470).

OBJECTIVE: To evaluate the efficacy of the angiogenesis inhibitor AGM-1470 for the experimental treatment of nasopharyngeal carcinoma (NPC). METHODS: A NPC human tumour model was built by tumour-bearing nude mice using the NPC cell line CNE-2. Twenty-one BALB/c nude mice bearing CNE-2 xenografts were randomized into a treatment group and a control group. In the treatment group, AGM-1470 was injected 30 mg/kg subcutaneously every other day; while the vehicle (three per cent ethanol solution in 0.9 per cent saline) was given to the mice in control group. Tumour volumes and animal weights were measured every third day. Autopsy was performed after 18 days of treatment. The tumour tissue as well as the murine tissues of heart, kidney, and liver in each mouse were removed for formalin fixation and routine HE staining. Pathological evaluation was performed in these tissues. RESULTS: There was a significant difference in tumour volume between the two groups at day 9 of treatment and this increased thereafter. At day 15 of treatment, the tumour volume was 4251 +/- 559 mm3 (n = 10) in the control group versus 3122 +/- 967 mm3 (n = 11) in the AGM-1470 treated group (p = 0.004); and T:C ratio (mean tumour volume of treated/mean tumour volume of control) was 0.73, resulting in a 27 per cent decrease in tumour growth. Central necrosis and consequential shrinkage of tumours occurred in both groups at the end of experiment. Physical toxicity and histological toxicity of heart, liver, and kidney did not result from AGM-1470 therapy. CONCLUSIONS: AGM-1470 suppresses the growth of the human NPC cell line CNE-2. Treatment by AGM-1470 has no physical nor histological toxicity. Angiogenesis inhibitors may be effective in the treatment of the local lesion of NPC.

Animals↗

PubMed1998

Heterologous expression of rat P450 2E1 in a mammalian cell line: in situ metabolism and cytotoxicity of N-nitrosodimethylamine.

GM0637, a human fibroblast cell line, was transfected with pCMV2E1, an expression vector containing the full length cDNA for rat cytochrome P450 2E1 (P450 2E1), and with pCMVneo, which contained vector alone, and the selected clones were designated GM2E1 and GMneo, respectively. Western blot analysis showed that GM2E1, but not GMneo, expressed a protein that reacted with anti-human P450 2E1 antibody. The 7-ethoxycoumarin O-deethylase,p-nitrophenol hydroxylase, and N-nitrosodimethylamine (NDMA) demethylase activities of the P450 in these cells were measured in monolayer cell cultures without preparing microsomes. Exposure of the GM2E1 cells to NDMA for 4 days caused severe decreases in cell viability, as determined by crystal violet uptake, and showed a sigmoidal dose-response curve with a median lethal dose of 17 microM. In contrast, the viability of GMneo cells was not altered by NDMA even at concentrations up to 10 mM. Time- and concentration-dependent methylation of DNA, RNA and protein by [14C]NDMA was only observed in cells expressing P450 2E1. Inhibitors of P450 2E1 activity such as ethanol, 4-methylpyrazole, and isoniazid caused a 90% decrease in the methylation of cellular macromolecules and also completely protected the cells against NDMA-mediated toxicity. The cytotoxicity due to exposure to NDMA was partially inhibited by antioxidants such as N-acetylcysteine, ascorbic acid, butylated hydroxyanisole and N-t-butyl-alpha-phenylnitrone but was not potentiated upon glutathione depletion. These results document the ability of rat P450 2E1 to metabolize NDMA to toxic reactive intermediates and demonstrate that this cell line provides a useful model for studying the mechanisms of metabolism-mediated toxicity and carcinogenesis.

Animals↗

PubMed1997

Nitric oxide regulates nitric oxide synthase-2 gene expression by inhibiting NF-kappaB binding to DNA.

Treatment of astroglial cells with interleukin 1beta and interferon gamma transcriptionally activates the nitric oxide synthase (NOS)-2 gene. The duration of mRNA expression is brief because of transcript instability. In addition, NO donors reduce the expression of NOS-2 mRNA dramatically by reducing the rate of transcription. In this study we observed that the NO donor, spermine NONOate did not inhibit the activation and translocation of NF-kappaB, a key transcription factor in the induction of NOS-2, but inhibited formation of the NF-kappaB-DNA complex. This effect was reversed by methaemoglobin (acting as an NO trap) and by the reducing agent dithiothreitol. Formation of the interferon-regulatory factor-DNA complex was unaffected by NO. These results suggest that NO can modulate its own production by interfering with NF-kappaB interaction with the promoter region of the NOS gene, a negative feedback effect that may be important for limiting NO production in vivo.

Animals↗