Synergistic effects of Rapamycin and Fluorouracil to treat a gastric tumor in a PTEN conditional deletion mouse model.

The tumor suppressor gene phosphatase and tensin homolog (PTEN) in PI3K/Akt/mTOR pathway is essential in inhibiting tumor growth and metastasis. However, whether the mutation of PTEN gene could induce tumorigenesis and impact the treatment of gastric cancer is still unclear. The purpose of the study was to investigate the combined treatment of gastric tumorigenesis using Rapamycin and Fluorouracil (5-Fu) through interfering with the Akt/mTOR pathway in a mouse model with PTEN conditional deletion. Three groups of mice were exposed for 5 days to Rapamycin and 5-Fu separately and together. The gene expression of the Akt/mTOR pathway, the protein expression of caspase-3 and p-Akt, p-S6K and p-4EBP1, and the pathological changes in stomachs were analyzed. Our study demonstrates that the conditional PTEN deletion in the cells of glandular stomach induces hyperplastic gastric tumors in mice. The combined Rapamycin administration with 5-Fu resulted in better outcomes than their separate administration for the treatment of gastric cancer by inhibiting the mTOR signal pathway. Our study indicates that Rapamycin has a synergistic interaction with chemotherapeutic 5-Fu, and demonstrates a potential therapeutic combination treatment on glandular stomach tumor with PTEN functional absence or aberrantly activated Akt/mTOR pathway. It provides important insights into the inhibition of the Akt/mTOR pathway in gastric cancer clinical therapy.

Cytotoxicity and Apoptosis Induced by Chenopodium ambrosioides L. Essential Oil in Human Normal Liver Cell Line L02 via the Endogenous Mitochondrial Pathway Rather Than the Endoplasmic Reticulum Stress.

Chenopodium ambrosioides L. (C. ambrosioides) has been used as dietary condiments and as traditional medicine in South America. The oil of Chenopodium ambrosioides L. (C. ambrosioides) can be used as a natural antioxidant in food processing. It also has analgesic, sedating, and deworming effects, and can be used along with the whole plant for its medical effects: decongestion, as an insecticide, and to offer menstruation pain relief. This study was conducted to investigate the cytotoxicity and apoptosis effects of an essential oil from C. ambrosioides in vitro. The cytotoxicity evaluation of the essential oil from C. ambrosioides on human normal liver cell line L02 was assessed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay. AO/EB dual fluorescent staining assay and Annexin V-FITC were used for apoptosis analysis. The changes in mitochondrial membrane potential (MMP) were analyzed with 5,5,6,6'-tetrachloro-1,1,3,3,-tetraethyl-imidacarbocyanine iodide (JC-1) dye under a fluorescence microscope. The level of apoptosis related protein expression was quantified by Western blot. The L02 cells were treated with the essential oil from C. ambrosioides at 24, 48, and 72 h, and the IC50 values were 65.45, 58.03, and 35.47 µg/mL, respectively. The AO/EB staining showed that viable apoptotic cells, non-viable apoptotic cells, and non-viable non-apoptotic cells appeared among the L02 cells under the fluorescence microscope. Cell cycle arrest at the S phase and cell apoptosis increased through flow cytometry in the L02 cells treated with the essential oil. MMP decreased in a concentration-dependent manner, as seen through JC-1 staining under the fluorescence microscope. In the L02 cells as shown by Western blot and qPCR, the amount of the apoptosis-related proteins and the mRNA expression levels of cytochrome C, Bax, Caspase-9, and Caspase-3 increased, Bcl-2 decreased, and Caspase-12, which is expressed in the endoplasmic reticulum, showed no obvious changes in protein amount or mRNA expression level. The essential oil form C. ambrosioides had a cytotoxic effect on L02 cells. It could inhibit L02 cell proliferation, arrest the cell cycle at the S phase, and induce L02 cell apoptosis through the endogenous mitochondrial pathway.

[The Establishment of a Three-color Flow Cytometry Approach for the Scoring of Micronucleated Reticulocytes in Rat Bone Marrow].

OBJECTIVE: To develop and verify a flow cytometric measurement of reticulocytes (RETs) micronucleus in rat bone marrow. METHODS: In our flow cytometric protocol, reticulocytes, leukocytes and DNA were labeled by anti-CD71-fluorescein isothiocyanate (FITC), anti-CD45-phycoerythrin (PE) and DRAQ5, respectively. Sprague-Dawley (SD) rats were assigned to four treatment groups randomly, and were exposed to ethyl methanesulfonate (EMS), cyclophosphamide (CP), ethyl nitrosourea (ENU) and colchicine (COL) respectively. Each treatment group was divided into four subgroups (5 rats per subgroup) according to different exposure dosage. A exposure dose of 0 was used as vehicle control for each group. Rats were administered with testing mutagens by gavage twice with a 24 h interval. Bone marrow from both femurs were collected 24 h after the last administration. The frequency of micronucleated reticulocytes (MN-RETs) and the percentage of reticulocytes (RETs%) were determined by flow cytometric measurement established in this study. And the manual counting method with microscope (by Giemsa staining) was conducted at the same time. RESULTS: A method for detection of reticulocyte micronucleus in bone marrow based on flow cytometry was successfully established. The MN-RETs in rat bone marrow of 20 SD rats treated by vehicle (i.e., background value of MN-RETs) was 0.83‰±0.12‰ by this method. The background value of MN-RETs in manual enumeration method was 1.43‰±0.44‰. It was obvious that the flow cytometric method had lower background value and more stable results. The trend, in which MN-RETs ascended and RETs% descended with increasing dose, can be detected by both methods in rats that exposed to EMS, CP, ENU and COL. Both methods were good to detect the correlation of induced-MN-RETs with four testing mutagens (the correlation coefficients were ranged from 0.834 3 to 0.913 7). CONCLUSION: With its sensitivity, rapidity, easy operation and low background value, the three-color flow cytometric enumerative protocol established in our laboratory can be used as a good substitute for manual micronucleus counting method and used in genotoxicity assessment of chemical substances.

Delay of the onset of puberty in female rats by prepubertal exposure to T-2 toxin.

Growing evidence has revealed the deleterious influence of environmental and food contaminants on puberty onset and development in both animals and children, provoking an increasing health concern. T-2 toxin, a naturally-produced Type A trichothecene mycotoxin which is frequently found in cereal grains and products intended for human and animal consumption, has been shown to impair the reproduction and development in animals. Nevertheless, whether this trichothecene mycotoxin can disturb the onset of puberty in females remains unclear. To clarify this point, infantile female rats were given a daily intragastric administration of vehicle or 187.5 µg/kg body weight of T-2 toxin for five consecutive days from postnatal day 15 to 19, and the effects on puberty onset were evaluated in the present study. The results revealed that the days of vaginal opening, first dioestrus, and first estrus in regular estrous cycle were delayed following prepubertal exposure to T-2 toxin. The relative weights of reproductive organs uterus, ovaries, and vagina, and the incidence of corpora lutea were all diminished in T-2 toxin-treated rats. Serum levels of gonadotropins luteinizing hormone, follicle-stimulating hormone, and estradiol were also reduced by T-2 toxin treatment. The mRNA expressions of hypothalamic gonadotropin-releasing hormone (GnRH) and pituitary GnRH receptor displayed significant reductions following exposure to T-2 toxin, which were consistent with the changes of serum gonadotropins, delayed reproductive organ development, and delayed vaginal opening. In conclusion, the present study reveals that prepubertal exposure to T-2 toxin delays the onset of puberty in immature female rats, probably by the mechanism of disturbance of hypothalamic-pituitary-gonadal (HPG) axis function. Considering the vulnerability of developmental children to food contaminants and the relative high level of dietary intake of T-2 toxin in children, we think the findings of the present study provide valuable information for the health risk assessment in children.

[Study on protective effect of Tianji soft capsule on blood lipids, internal antioxidant system and vascular endothelial system in hyperlipidemia rats].

OBJECTIVE: To study the protective effects of Tianji soft capsule (TJSC) on blood lipids, internal antioxidant system and vascular endothelial system in hyperlipidemia rats. METHODS: Seventy two healthy male rats were divided into six groups. The rats in control group were administered with ordinary diet. The rats in model group were fed with high cholesterol/lipid diet to induce hyperlipidemia. The rats in TJSC and CoQ10 groups were fed with high cholesterol/lipid diet, and treated with TJSC at different doses of 83 (low-dose group, L), 250 (middle-dose group, M), 750 (high-dose group, H) mg/kg, and CoQ10 at the dose of 83 mg/kg, respectively. All animals were put to death after four weeks, effects on lipid level; antioxidant system and endothelial system were evaluated through detection of total cholesterol (TC), triglyceride (TG), very low density lipoprotein (VLDL), atherogenic index (AI), malondidehyde (MDA) and plasma endothelin (ET), HDL/TC ratio, activities of superoxide dismutase (SOD) and nitric oxide (NO). RESULTS: Compared with model group, serum TC, TG, VLDL, AI, MDA and ET reduced and the HDL/TC ratio increased, meanwhile activities of SOD and NO were enhanced. CONCLUSION: TJSC can regulate the lipid metabolism, enhance antioxidant system and protect the vascular endothelia system in hyperlipiemic rats.

[Study on the immunotoxicity of ribosome inhibiting protein of Momordica charantia].

OBJECTIVE: To separate and purify ribosome inhibiting protein (RIP) from Momordica charantia (bitter melon) seeds and to evaluate its acute toxicity and immunotoxicity in animal. METHODS: Ion exchange chromatography and gel filtration chromatography were applied in the separating and purifying of RIP from Momordica charantia seeds. Then the acute toxicity testing of RIP in mice was conducted to obtain its half lethal dose (LD50). Active systemic anaphylaxis(ASA)test in guinea pig and passive cutaneous anaphylaxis test (PCA) in rat were performed to evaluate its immunotoxicity. RESULTS: The LD50 (iv) in mice of RIP was 25.2 mg/kg in ASA, guinea pigs of the higher and lower RIP group all appeared stong allergic responses and most of them died quickly. In PCA, obvious blue dye in skin were observed in SD rats of the RIP group. CONCLUSION: RIP getting from Momordica charantia seeds had a relatively strong immunotoxicity in animals.

[Effects of amitrole on thyroid hormone-associated gene transcription in FRTL-5 cells].

OBJECTIVE: To observe the effects of amitrole on the transcription of thyroglobulin (tg), thyroid peroxidase (tpo), Na(+)/I- symporter (nis), Na(+)/I- symporter (nis), thyroid-stimulating hormone receptor (tshr), thyroid transcription factor 1 (ttf-1) and paired-domain protein-8 (pax-8) genes in FRTL-5 cells and investigate the mechanism of amitrole for intervening in thyroid hormone activity. METHODS: FRTL-5 cells were treated with amitrole at 0.001, 0.01 and 0.1 mg/ml for 24 h, respectively, after which the cells were collected for extraction of the total RNA. RT-PCR was used to examine the effects of amitrole on the transcription of tg, tpo, nis, tshr, pax-8 and ttf-1 genes in FRTL-5 cells. RESULTS: Amitrole significantly induced tg gene transcription at all the doses, but produced no obvious effects on tpo and nis gene transcription. At the concentration of 0.1 mg/ml, amitrole significantly reduced pax-8 and tshr gene transcription but increased ttf-1 gene transcription. CONCLUSION: The effects of amitrole on thyroid hormone activity may be related with its actions on tg, ttf-1, tshr and pax-8 gene transcription.

[Effect of lycopene on the proliferation of MCF-7 and MDA-MB-231 cells].

OBJECTIVE: To test the effect of lycopene on the proliferation and apoptosis of the estrogen receptor(ER)-positive MCF-7 and ER-negative MDA-MB-231 human breast cancer cell lines. METHODS: The cell proliferation was analyzed by the MTT and the H3-TdR incorporation. The effect of lycopene on the cell cycle and apoptosis of the synchronized cells was observed through flow cytometry. RESULTS: Lycopene inhibited the growth and DNA synthesis of both ER-positive MCF-7 and ER-negative MDA-MB-231 cells in a dose-dependent pattern. The maximum inhibition effect appeared after 4 days of exposure to lycopene, with an inhibition rate of 52.6% and 61.9% for the MCF-7 and MDA-MB-231 cells respectively. The flow cytometry analysis found more cells in the G0/G1 phase and less cells in the S and G2/M phase after 24 hours of exposure to lycopene. Lycopene induced apoptosis for the MDA-MB-231 cells, but not for the MCF-7 cells. CONCLUSION: Lycopene inhibits the growth of ER-positive MCF-7 cells through the inhibition of the cell cycle progression. The inhibition of ER- negative MDA-MB-231 cells by lycopene is associated not only with the G1 phase cell cycle-arrest but also the induction of apoptosis.

[Metallothionein inhibited DOX-induced cardiac apoptosis in mice].

OBJECTIVE: To investigate the inhibitive effect of metallothionein (MT) on DOX-induced cardiac apoptosis and the involved possible mechanisms. METHODS: Adult male C57BL mice (6-8 weeks old) were randomly assigned into four groups and given the following treatment: Zinc (ZnSO4, 300 micromol/kg, s.c., once a day for 2 days) or equal volume of physiological saline prior to a single dose of DOX (15 mg/kg, i.p.) or equal volume of saline. Animals were sacrificed on the 4th day after DOX administration and hearts were excised for further studies, including cadmium-hemoglobin affinity assay for MT concentration, ELISA detection of DNA fragmentation and Western blot analysis of Bax and Bcl-2. RESULTS: DOX administration decreased heart weight by 10% and caused remarkable cardiac apoptosis as demonstrated by DNA fragments, while Zinc pretreatment significantly increased the MT levels and therefore inhibited the cardiac apoptotic effect of DOX. Elevated expression of Bax was obviously observed after DOX treatment, while this elevation was prevented by MT induction by Zinc. On the contrary, Bcl-2 protein level was not altered significantly among each group. CONCLUSION: These findings suggest that metallothionein induced by Zinc exhibits protective effects on the cardiac apoptosis of DOX, which might be mediated through the prevention of Bax protein up-regulation by DOX and associated elevation of Bax/Bcl-2 ratio.

Metallothionein protects against doxorubicin-induced cardiomyopathy through inhibition of superoxide generation and related nitrosative impairment.

Metallothionein (MT) has been shown to be an effective protector against DOX-induced cardiomyopathy, however the involved precise mechanisms are still unknown. The present study was undertaken to clarify whether the inhibition of superoxide generation and related nitrosative damage were involved in the metallothionein attenuation of DOX-induced cardiac injury. MT-I/II null (MT-/-) mice and corresponding wild-type mice (MT+/+) were pretreated with either saline or zinc (300 micromol/kg, s.c., once a day for 2 days) prior to a single dose of DOX (15 mg/kg, i.p.) or equal volume of saline. Animals were sacrificed on the 4th day after DOX administration and samples were collected for further analyses. DOX caused remarkable cardiac damage in both MT+/+ and MT-/- mice as demonstrated by biochemical and histopathological alterations. Zinc pretreatment significantly increased the cardiac MT levels and therefore inhibited the cardiac toxic effects of DOX only in MT+/+ mice, but not in MT-/- mice. Furthermore, elevated formation of superoxide and peroxynitrite were obviously observed after DOX treatment, while these elevation were prevented by MT induction by zinc in MT+/+ mice, but not in MT-/- mice. These findings suggest that metallothionein induction by zinc exhibits protective effects on the cardiac toxicology of DOX, which might be mediated through the prevention of superoxide generation and related nitrosative impairment.

[Effects of soy isoflavone on levels of low-grade inflammatory peptides in rats with insulin resistance].

OBJECTIVE: To explore the effects of soy isoflavone (SIF) on low-grade inflammation in rats with high-fat diet-induced insulin resistance (IR) and explore the mechanisms of SIF in improving insulin sensitivity. METHODS: The rats with high-fat diet-induced IR were randomly divided into one model control group and 3 SIF groups gavaged with SIF water solutions at the doses of 50, 150, and 450 mg/kg, respectively. One month after the treatment, fasting blood glucose (FBG), fasting insulin (FINS), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), C-reactive protein (CRP), resistin and adiponectin in the serum were detected by enzymatic method, radioimmunoassay, or enzyme-linked immunosorbent assay. RESULTS: In the 150 and 450 mg/kg SIF groups, fasting body-weights, visceral adipose tissue deposition, FINS, resistin, TNF-alpha in serum, and IR index were lowered in comparison with the model control group, and in 450 mg/kg SIF group, serum IL-6 level was obviously lowered, and adiponectin increased. No differences were found in serum C-reactive protein levels between the 3 SIF groups. CONCLUSION: Soy isoflavone may ameliorate insulin sensitivity by decreasing visceral adipose deposition and adjusting low-grade inflammatory molecules derived from white adipose tissue.

[Effects of soy isoflavone on gene expression of resistin in insulin-resistance rats].

OBJECTIVE: To assess the effects of soy isoflavone (SIF) on improving insulin reistance (IR) status in IR rats induced by high-fat and high-sugar diet and explore the possible mechanisms. METHODS: IR rats were randomly divided into four groups according to their insulin resistance indices (IRI). The rats in one model control group and three SIF groups were fed via gavage with water solutions containing SIF at doses of 0 mg/ kg x bw, 50 mg/kg x bw, 150 mg/kg x bw, and 450 mg/kg x bw, respectively. After one month, fasting glucose, fasting insulin, resistin in serum, and resistin mRNA in adipocyte around kidney were detected by enzymologic method, radioimmunoassay, enzyme linked immunosorbent assay, and real time RT-PCR, respectively. RESULTS: Comparison between the model control group and the other groups revealed that serum resistin and resistin mRNA expression levels were lower in the 450 mg/kg x bw group, that insulin and IRI levels were lower in the 150 mg/ kg x bw group and 450 mg/kg x bw group, and that no differences in plasma glucose levels existed among the 4 groups. A positive correlation between IRI and serum resistin level (r = 0.355, P < 0.05) was observed. CONCLUSION: These results suggest that soy isoflavone may down-regulate resistin mRNA expression, decrease serum resistin level and enhance insulin sensitivity.

[Comparison of TK gene mutation assay in TK6 and TK6-E6 cell induced by vinblastin and colcemid].

OBJECTIVE: To compare TK gene mutation assay in human lymphoblastoid cell lines TK6 and TK6-E6 induced by vinblastin and colcemid. METHODS: Regular TK gene mutation assays were experimented to detect cytotoxicity and mutation frequency at tk locus after TK6 and TK6-E6 human lymphoblastoid cells were treated with vinblastin and colcemid for 24h. RESULTS: Relative survival (RS%) and Relative suspension growth (RSG%) of TK6 and TK6-E6 cells decreased when concentrations of vinblastin and colcemid increased. RS% and RSG% of TK6-E6 cells were higher than that of TK6 cells at the same doses. TK6 and TK6-E6 cells both were induced by vinblastin and colcemid. The TK6-E6's nature mutation frequency, induced mutation frequency and percentage of slow growth mutant (SG%) were lower than TK6' s at the same dose except group CCM 5.0ng/ml in MF and group CCM 0.625ng/ml in SC%. CONCLUSION: Both TK6 and TK6-E6 cell lines can be used in TK gene mutation assay, but TK6-E6 cell line was recommended to be used in the assay for its less quantity and doubling time.

[Effects of soy isoflavone on low-grade inflammation in obese rats].

OBJECTIVE: To explore the effects of soy isoflavone (SIF) on low-grade inflammation in obese rats induced by high-fat diet, and to elucidate mechanisms of SIF in improving insulin sensitivity. METHODS: Obese rats were randomly divided into 4 groups: One model control group and 3 SIF groups that were given water solutions with SIF at 0 mg/(kg x d), 50 mg/(kg x d), 150 mg/(kg x d), and 450 mg/(kg x d), respectively. After one month, fasting glucose, fasting insulin, interleukin-6, tumor necrosis factor-alpha, C-reactive protein, resistin, and adiponectin in serum were detected by enzymic method, radioimmunoassay, and enzyme linked immunosorbent assay, respectively. RESULTS: In the 150 mg/(kg x d) group and 450 mg/(kg x d) group, fasting body-weights, viscera fatty deposition, and contents of insulin, interleukin-6, and tumor necrosis factor-alpha in serum were significantly lower; serum adiponectin levels were significantly higher; and serum resistin levels were significantly lower in the 450 mg/(kg d) group than those of the model control group. There was no difference in serum C-reactive protein levels among the 3 SIF groups. CONCLUSION: Soy isoflavone may improve the insulin sensitivity by decreasing viscera fatty deposition and adjusting low-grade inflammatory molecules derived from white adipose tissues.

[Evaluation of the genotoxicity of vincristine and colchicine using mouse lymphoma tk mutation assay].

OBJECTIVE: To evaluate the genotoxicity of two mitotic inhibitors vincristine and colchicine, and to compare the detecting sensitivity of tk gene mutation assay with short-and long-term treatment by them. METHODS: Tk gene mutation assay was performed by microwell method with L5178Y mouse lymphoma cell line after exposing to vincristine and colchicine for 3 h and 24 h respectively, and the results of two different treating time were compared. RESULTS: The two chemicals didn't show positive responses in mouse lymphoma assay (MLA) with 3h treatment, but they could induce tk mutation frequency increase 1.6 to 4.8 and 2.1 to 6.2 times higher to spontaneous MF respectively after continuous treatment for 24 h. CONCLUSION: Vincristine and colchicine had mutagenic effect on tk gene with long-term treatment, which indicated that the detecting sensitivity of MLA could be enhanced by long-term treatment.

[Effects of zearalenone on proliferation and apoptosis in MCF-7 cells].

OBJECTIVE: To explore the effects of zearalenone (ZEA) on proliferation and apoptosis in estrogen-dependent human breast cancer MCF-7 cells and the likely underlying molecular mechanisms. METHODS: Cell viability was determined by MTT assay and cell cycle distribution by cytometry. Apoptosis was detected by Cell Death Detection ELISA and cytometry, respectively. The expressions of bax and bcl-2 were examined using multiple RT-PCR and Western-blot both at mRNA and protein level, respectively. RESULTS: The current study confirmed the previous studies that ZEA could stimulate proliferation in MCF-7 cells with inducing a profound increase in S phase and a modest increase in G(2)/M phase that was accompanied by a decrease in G(0)/G(1) phase. ZEA could inhibit apoptosis in MCF-7 cells following estrogen ablation at a range of concentrations of 2 nmol/L -96 nmol/L. Western blot and RT-PCR analysis revealed that the anti-apoptotic bcl-2 was upregulated at both protein and mRNA level, together with the downregulation of pro-apoptotic bax. CONCLUSION: ZEA should have possessed comparative estrogenic activity and could promote the progression of MCF-7 cells through the cell cycle by a decreasing in the G(0)/G(1) phase and by a significant increasing in S-phase. The pro-proliferative activity of ZEA was due to inhibition of apoptosis through regulation of bax/bcl-2 expression.

[Sensitivity comparison of DNA damage and repair capacity in TK6 and WTK1 cells].

OBJECTIVE: Explore the mechanisms of DNA damage and repair capacity in TK6 and WTK1 cells that are derived from the same parental cell line WI-L2 (tk+/+) human diploid lymphoblastoid cells but are different in their p53 gene status. METHODS: The TK6 and WTK1 cells treated with H2O2 were detected by single cell gel electrophoresis. Then a comparison was made on the comet cell rate, comet cell tail length and p53 protein expression level between TK6 and WTK1. RESULTS: TK6 was more sensitive to DNA damage and its repair capacity was more quick and effective when compared with WTK1. Both TK6 and WTK1 cells showed effective post-damage repair capacity in incubation time of 0.5 h to 1 h. The background level of P53 protein in WTK1 was higher than that in TK6, but the level of P53 protein in H2O2-treated TK6 increased significantly higher than that in H2O2-treated WTK1. CONCLUSION: TK6 and WTK1 cells serve as a good biological experiment system for DNA damage sensitivity and repair capacity researches in the field of toxicology. TK6 is more sensitive to DNA damage, and it increases faster and higher than WTK1 after DNA being damaged. A possible explanation is that TK6 cell is of the p53 gene wild-type and WTK1 cell is of the mutant-type and they make different responses to the same chemical.

[TK locus mutation assay: comparison of L5178Y and TK6 cell lines].

OBJECTIVE: To compare the advantages and disadvantages of utilizing L5178Y and TK6 cell lines in the TK locus mutation assay. METHODS: The two cell lines were used for detecting and assessing the mutability of four chemicals (MMS, EMS, MMC and KCl); the microwell method of TK locus mutation assay was adopted. RESULTS: The two cell lines brought about similar results in the study. The tolerance of TK6 to all four chemicals was lower than that of L5178Y, and all the relative mutation indices of TK6 were higher than those of L5178Y. CONCLUSION: Each of the two cell lines has its own strong points; nevertheless, the authors recommend the applications of TK6 cell in the assay system since this cell line comes from human.

[The effects of three plastic additives on the proliferation of MCF-7 cell].

OBJECTIVE: To explore the effect of environmental estrogens on the proliferation of breast cancer cell line MCF-7. METHODS: The tested compounds were n-4-nonyphenol, Bisphenol A and dibutylphthalate. Human estradiol-dependent MCF-7 breast cancer cells were grown in DMEM medium containing 10% bovine serum. Five days before the addition of the test compounds, the cells were washed by phosphate-buffered saline, and the medium was substituted with a phenol red-free DMEM medium containing 5% dextral charcoal-stripped FBS. The respective test compound was added in fresh medium and the control cell received only the vehicle (ethanol). The proliferation of MCF-7 was analyzed by the MTT assay, (3)H-TdR incorporation assay and flow cytometry. RESULTS: Compared with the ethanol control, the proliferation and DNA synthesis of the test cells treated with n-4-nonyphenol (8 x 10(-7) mol/L, 96 h), Bisphenol A (8 x 10(-7) mol/L, 96 h) or dibutylphthalate (32 x 10(-6) mol/L, 96 h) treatment was markedly enhanced in a time-dependent and dose-dependent manner. CONCLUSION: n-4-Nonyphenol, Bisphenol A and dibutylphthalate enhanced the proliferation of human breast cancer cell in vitro, which may demonstrate an estrogenic activity.

[Effects of genistein and zearalenone on proliferation of PEO4].

OBJECTIVE: The objective of this study was to investigate the estrogenic activity of genistein and zearalenone through their effects on the proliferative capacity of human ovarian PEO4. METHODS: Estrogen receptor-positive PEO4 cell was grown in DMEM medium containing 10% bovine serum. Five days before the addition of the test compounds, the cells were washed in phosphate-buffered saline, and the medium was substituted with a phenol red-free DMEM medium containing 5% dextran charcoal-stripped FBS. The respective test compound was added in fresh medium and the control cell received only the vehicle (ethanol). Cell proliferation was detected respectively by MTT assay, (3)H-TdR incorporation and flow cytometry. RESULTS: Compared with vehicle control, 96 x 10(-6) mol/L GS significantly inhibited PEO4 cell proliferation and DNA synthesis as measured by MTT and (3)H-TdR incorporation after treatment for 24 h. Alao, 32 x 10(-6) mol/L GS could exert inhibition on PEO4 cell growth as time extension to 48 h. 32 x 10(-6) mol/L approximately 96 x 10(-6) mol/L GS induced G(2)/M arrest. At low dose (< 8 x 10(-6) mol/L=, GS promoted proliferation in PEO4 cells. ZEA enhanced proliferation, promoted DNA synthesis and increased the S phase population in PEO4 cells. CONCLUSIONS: Genistein possess estrogenic activity and zearalenone have anti-estrogenic activity. They play different effects on the proliferation of human ovarian cancer cell. Genistein enhanced the proliferation of PEO4. Zearalenone inhibited its the proliferation. These results implied that genistein and zearalenone elicit different signal-transduction channel.