THE EFFECT OF ALL-TRANS RETINOIC ACID ON GAP JUNCTIONAL INTERCELLULARCOMMUNICATION AND CONNEXIN 43 GENE EXPRESSION IN GLIOMA CELLS

To illuminate the regulating effect of all trans retinoic acid (ATRA ) on gap junctional intercellular communication (GJIC) and connexin 43 (Cx43) ge ne expression in glioma cells, which is tissue and organ specific. Method. Rat C6 glioma cells were exposed to ATRA at a concentration of 1, 10, 10 0 μmol/L respectively, and the GJIC function of the cells was examined with scr ape loading dye transfer assay 24 hours, 48 hours and 72 hours after ATRA treat ment. The effect of ATRA on Cx43 gene expression was measured with semiquantitat ive reverse transcription polymerase chain reaction (RT PCR) 24 hours after ATR A exposure. Results. The GJIC function of C6 glioma cells was significantly increased by ATR A at each concentration applied. The dye passed 4 to 5 rows of cells from the sc raping edge in ATRA treated cells, but only 1 or 2 rows in the control. The augm ent effect was observed 24 hours after each concentration ATRA treatment, and la sted till 72 hours after treatment with 1μmol/L and 10μmol/L ATRA. Forty eigh t hours after exposed to 100μmol/L ATRA, the enhancement of GJIC was less obvi ous. There was no significant increase induced by ATRA on the transcription of C x43 gene, as demonstrated by semiquantitative RT PCR. Conclusion. ATRA turned out to be a potent enhancer on GJIC function in C6 gliom a cells, and the enhancement effect was most probable at post transcriptional l evel.

Synthesis and anti-tumor activity of all-trans retinoic acid derivatives

A series of retinoate and retinamide derivatives were designed, synthesized, and their anti-tumor activities were investigated in NB4 by MTT and flow cytometry assays （FCM）. All compounds showed cytotoxicity, especially compounds la and ld exhibited a higher cytotoxicity than other derivatives and all-trans rethaoic acid （ATRA）. Furthermore, compound 1d could induce NB4 cell lines differentiation efficiently. O 2009 Fei Hu Chert. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Inhibition of matrix metalloproteinases expression in human dental pulp cells by all-trans retinoic acid

All-trans retinoic acid（ATRA） inhibits matrix metalloproteinase（MMP）-2 and MMP-9 in synovial fibroblasts, skin fibroblasts,bronchoalveolar lavage cells and cancer cells, but activates MMP-9 in neuroblast and leukemia cells. Very little is known regarding whether ATRA can activate or inhibit MMPs in human dental pulp cells（HDPCs）. The purpose of this study was to determine the effects of ATRA on the production and secretion of MMP-2 and-9 in HDPCs. The productions and messenger RNA（mRNA） expressions of MMP-2 and-9 were accessed by gelatin zymography and real-time polymerase chain reaction（PCR）, respectively. ATRA was found to decrease MMP-2 level in a dose-dependent manner. Significant reduction in MMP-2 mRNA expression was also observed in HDPCs treated with 25 mmol？L21ATRA. However, HDPCs treated with ATRA had no effect on the pattern of MMP-9 produced or secreted in either cell extracts or conditioned medium fractions. Taken together, ATRA had an inhibitory effect on MMP-2 expression in HDPCs,which suggests that ATRA could be a candidate as a medicament which could control the inflammation of pulp tissue in vital pulp therapy and regenerative endodontics.

All-trans Retinoic Acid Diminishes Collagen Production in a Hepatic Stellate Cell Line via Suppression of Active Protein-1 and c-Jun N-terminal Kinase Signal

Following acute and chronic liver injury,hepatic stellate cells (HSCs) become activated to undergo a phenotypic transformation into myofibroblast-like cells and lose their retinol content,but the mechanisms of retinoid loss and its potential roles in HSCs activation and liver fibrosis are not understood.The influence of retinoids on HSCs and hepatic fibrosis remains controversial.The purpose of this study was to evaluate the effects of all-trans retinoid acid (ATRA) on cell proliferation,mRNA expression of collagen genes [procollagen α1 (Ⅰ),procollagen α1 (Ⅲ)],profibrogenic genes (TGF-β 1,CTGF,MMP-2,TIMP-1,TIMP-2,PAI-1),fibrolytic genes (MMP-3,MMP-13) and the upstream element (JNK and AP-1) in the rat hepatic stellate cell line (CFSC-2G).Cell proliferation was evaluated by measuring BrdU incorporation.The mRNA expression levels of collagen genes [procollagen α1 (Ⅰ),procollagen α1 (Ⅲ)],profibrogenic genes (TGF-β 1,CTGF,MMP-2,TIMP-1,TIMP-2,PAI-1),and fibrolytic genes (MMP-3,MMP-13) were quantitatively detected by using real-time PCR.The mRNA expression of JNK and AP-1 was quantified by RT-PCR.The results showed that ATRA inhibited HSCs proliferation and diminished the mRNA expression of collagen genes [procollagen α1 (Ⅰ),procollagen α1 (Ⅲ)] and profibrogenic genes (TGF-β 1,CTGF,MMP-2,TIMP-1,TIMP-2,PAI-1),and significantly stimulated the mRNA expression of MMP-3 and MMP-13 in HSCs by suppressing the mRNA expression of JNK and AP-1.These findings suggested that ATRA could inhibit proliferation and collagen production of HSCs via the suppression of active protein-1 and c-Jun N-terminal kinase signal,then decrease the mRNAs expression of profibrogenic genes (TGF-β 1,CTGF,MMP-2,TIMP-1,TIMP-2,PAI-1),and significantly induce the mRNA expression of MMP-3 and MMP-13.

Effect of All-trans Retinoic Acid on Liver Fibrosis Induced by Common Bile Duct Ligation in Rats

The aim of this study was to investigate the effect and possible mechanism of all-trans retinoic acid （ATRA） on liver fibrosis induced by common bile duct ligation （CBDL） in rats. Fifty-three female Wistar rats were randomly divided into 5 groups： sham operation group （group J, 5 animals） and groups A, B, C and D （12 animals in each group）. The rats in groups A, B, C and D were subjected to CBDL to induce liver fibrosis, while those in group J to sham operation. From the 3rd week the rats in groups B, C and D respectively received daily administration of ATRA via gas- tric tube at three different doses [0.1, 1.5 and 7.5 mg/kg body weight （BW）]. Animals were sacrificed at 6th week. Rats＇ liver tissues were observed for pathologic changes under a light microscope. The protein levels of type Ⅰ collagen （COLⅠ）, matrix metalloproteinase-2 （MMP2）, MMP13 and tissue inhibitors of metalloproteinase-1 （TIMP-1） in liver tissues were determined by immunohistochemical techniques. The expression levels of TGF-β1 and CTGF mRNA in liver tissues were detected by semi-quantitative reverse transcription-polymerase chain reaction （RT-PCR）. The results showed that loss of normal hepatic architecture and formation of obvious fibrosis were observed in group A, while ATRA treatment for 4 weeks notably alleviated the pathological changes of hepatocytes. The expres- sion of COL Ⅰ and TIMP-1 proteins in group A was increased, while decreased in ATRA-treated CBDL groups （P〈0.05）. ATRA （1.5 and 7.5 mg/kg BW） reduced the expression levels of COLⅠ protein more greatly than that of 0.1 mg/kg BW （P〈0.05）. ATRA treatment increased the protein levels of MMP2 and MMP13. The expression levels of TGF-β1 and CTGF mRNA in group A were increased. In comparison with group A, the mRNA levels of TGF-β1 and CTGF in ATRA-treated CBDL groups were significantly decreased （P〈0.05）. It was concluded that ATRA could inhibit CBDL-induced liver fibrosis in rats by suppressing the expression of TGF-β1 and CTGF so as to di- minish the inhibition of TIMP-1 on MMP2 and MMP13 and increase the activity of MMP2 and MMP13.

Potential role of nuclear receptor ligand all-trans retinoic acids in the treatment of fungal keratitis

·Fungal keratitis(FK) is a worldwide visual impairment disease. This infectious fungus initiates the primary innate immune response and, later the adaptive immune response. The inflammatory process is related to a variety of immune cells, including macrophages, helper T cells, neutrophils, dendritic cells, and Treg cells, and is associated with proinflammatory, chemotactic and regulatory cytokines. All-trans retinoic acids(ATRA)have diverse immunomodulatory actions in a number of inflammatory and autoimmune conditions. These retinoids regulate the transcriptional levels of target genes through the activation of nuclear receptors.Retinoic acid receptor α(RAR α), retinoic acid receptor γ(RAR γ), and retinoid X receptor α(RXR α) are expressed in the cornea and immune cells. This paper summarizes new findings regarding ATRA in immune and inflammatory diseases and analyzes the perspective application of ATRA in FK.

All-trans retinoic acid upregulates VEGF expression in glioma cells in vitro

All-trans retinoid acid （ATRA） is one of the most potent and most thoroughly studied differentiation inducers that induce the differentiation and apoptosis of glioma cells. However, the effect of ATRA on angiogenesis of glioma re- mains poorly understood. We examined the effect of ATRA on the expression of vascular endothelial growth fac- tor （VEGF） in different glioma cell lines and investigated the underlying mechanism, intending to partially reveal the effects of ATRA on angiogenesis of glioma. Glioma cells were treated by ATRA at 5 and 10 μmol/L. The VEGF mRNA transcript levels were determined by real-time RT-PCR and the protein levels of VEGF in glioma cells were evaluated by Western blotting assays. Moreover, hypoxia-inducible factor-1α （HIF-la） mRNA expression was analyzed by using real-time RT-PCR. After treatment with 5 and 10 μmol/L ATRA, the VEGF mRNA tran- script levels in glioma cells increased remarkably, compared with that in the control group, and the relative protein expression of VEGF was also up-regulated. Meanwhile, the HIF-la mRNA expression also increased. ATRA in- creases the expression of VEGF in glioma cells at both transcriptional and translational levels.

Identification of target genes of transcription factor CEBPB in acute promyelocytic leukemia cells induced by all-trans retinoic acid

Objective:To indentify target genes of transcription factor CCA AT enhancer-binding protein P(CEBPB) in acute proinyelocytie leukemia cells induced by all-tram retinoie acid.Methods: A new strategy for high—throughput identification of direct target genes was established by combining chromatin immunoprecipitation(ChIP) with in vitro selection.Then,106 potential CKBPB binding fragments from the genome of the all-trans retinoie acid(ATRA)-treated NB4 cells were identified.Results:Of them,82 were mapped in proximity to known or previously predicted genes;7 were randomly picked up for further confirmation by ChlP-PCR and 3 genes (CALM,1TPR2 and 0RM2) were found to be specificaUy up-regulated in the ATRA-treated NB4 cells,indicating that they might lie the down-stream target genes of ATKA.Conclusions:Our results provided new insight into the mechanisms of ATRA-induced granulocytic differentiation.

The Effects of All-Trans Retinoic Acid on Vasculogenic Mimicry Formation Ability in CD133+ Glioma Stem Cells and Its Mechanisms

Objective: to investigate the effects of all-trans retinoic acid (ATRA) on vasculogenic mimicry formation in glioma stem cells. Methods: U87 stem cells were harvested through a suspension culture assay from the U87 cells, identified by CD133 and nestin, and counted by a flow cytometry. To investigate the VM formation ability of U87 stem cells with the treatment of various concentrations of ATRA, a Matrigel-based tube formation assay was used in the present study in vitro and tube-like structure (typical tube, TT;atypical tube AT) was observed and counted. Then the expressions of VEGF, VEGFR-2 and CD133 were measured throughout real time q-PCR, western blotting and immunofluorescence techniques. The data, presented as the mean ± standard deviation, were analyzed using SPSS software. One-way analysis of variance was used to compare groups and Fisher’s least significant difference tests were performed for subsequent comparisons between groups. P Results: Most of the harvested spheroid cells were positive for nestin and 88.4% were positive forCD133. The CD133+ U87 cells were cultured into tube like structure loaded on the top of Matrigel and the quantity of tubes was decreased under the treatment of ATRA. In addition, the expressions of VEGF, VEGFR-2 and CD133 were significantly reduced under the treatment of ATRA, particularly in the higher concentration groups (20 and 40 μmol, P Conclusions: ATRA may inhibit the establishment of VM differing from stem cells in glioma, and these effects may attribute to the effects of ATRA’s promotion of the differentiation of stem cells and/or down regulation of the expressions of proangiogenic factors VEGF and its receptor VEGFR-2. Thus, the results of the present study indicated a novel idea for the treatment of GBM and enriched the anti-glioma mechanisms of ARTA.

VARIATION OF SERUM G-CSF LEVEL IN APL TREATED WITH ALL-TRANS RETINOIC ACID

Objective: To detect the level of serum G-CSF. from patients with acute promyelocytic leukemia pre- or post-treatment with ATRA and analyze the relationship between serum G-CSF and hyperleukocytosis. Methods: Enzyme-linked immunosorbent assay (ELISA) method was developed and used in detecting serum G-CSF. Linear correlation test and Spearman rank order correlation coefficient were used as the statistical analytical method. Results: The levels of serum G-CSF increased in 11.4% (4/35) of APL patients (equal of more than 0.095 ng/ml). It was also found that serum G-CSF level in 25 APL patients started to increase from the 6th day to 12th day and then gradually declined after treatment with ATRA. Both serum G-CSF and WBC numbers increase in 72% (18/25) patients; no obvious variation of WBC and increase of serum G-CSF and augmentation of WBC were seen in 12% (3/25) of the cases with APL. It was also demonstrated that serum G-CSF level was statistically related to the WBC number (r=0.275,P<0.05), promyelocytes (r=0.2015,P<0.05) or more matured granulocytes (r=0.2055P<0.05) by Spearman rank correlation analysis. Conclusion: The results of this study strongly indicate that G-CSF variation in patients with APL after treatment with ATRA plays an important role in hyperleukocytosis of WBC increase.

Effect of All-trans Retinoic Acid on Airway Inflammation in Asthmatic Rats and Its Mechanism

Summary: The inhibitive effects of all-trans retinoic acid (ARTA) on airway inflammation in asthmatic rats and its mechanism on the basis of the regulation of nuclear factor kappaB (NF-κB) were explored. Thirty-two SD rats were randomly divided into 4 groups: control group, asthma group, dexamethasone treatment group and retinotic acid treatment group. The total and differential cell counts in the collected bronchoalveolar lavage fluid (BALF) were measured. The pathological changes in lung tissues were estimated by scoring. The expression of NF-κB inhibitor (IκBa), NF-κB, intercellular adhering molecule-1 (ICAM-1) in lung tissue was detected by immunohistochemical method. The results showed that in the two treatment groups, the total cell counts and proportion of inflammatory cells in BALF were significantly reduced, but there was no significant difference in differential cell counts in BALF between them. The pathological changes in lung tissues in the treatment groups were significantly attenuated as compared with asthma group. Except the epithelial injury in retinotic acid treatment group was milder than in dexamethasone treatment group, the remaining lesions showed no significant difference between them. In the two treatment groups, the expression of IκBa was increased, while the expression of NF-κB and ICAM-1 decreased with the difference between the two groups being not significant. It was concluded that the similar anti-inflammatory effects and mechanism of ATRA on airway in asthmatic rats to those of dexamethasone were contributed to the increase of cytoplasmic IκBa content and suppression of NF-κB activation and expression.

MGMT is down-regulated independently of promoter DNA methylation in rats with all-trans retinoic acidinduced spina bifida aperta

O6-methylguanine DNA methyltransferase(MGMT), a DNA repair enzyme, has been reported in some congenital malformations, but it is less frequently reported in neural tube defects. This study investigated MGMT mRNA expression and methylation levels in the early embryo and in different embryonic stages, as well as the relationship between MGMT and neural tube defects. Spina bifida aperta was induced in rats by a single intragastric administration of all-trans retinoic acid on embryonic day(E) 10, whereas normal control rats received the same amount of olive oil on the same embryonic day. DNA damage was assessed by detecting γ-H2 A.X in spina bifida aperta rats. Real time-polymerase chain reaction was used to examine mRNA expression of MGMT in normal control and spina bifida aperta rats. In normal controls, the MGMT mRNA expression decreased with increasing embryonic days, and was remarkably reduced from E11 to E14, reaching a minimum at E18. In the spina bifida aperta model, γ-H2 A.X protein expression was increased, and mRNA expression of MGMT was markedly decreased on E14, E16, and E18. Bisulfite sequencing polymerase chain reaction for MGMT promoter methylation demonstrated that almost all CpG sites in the MGMT promoter remained unmethylated in both spina bifida aperta rats and normal controls, and there was no significant difference in methylation level between the two groups on either E14 or E18. Our results show that DNA damage occurs in spina bifida aperta rats. The mRNA expression of MGMT is downregulated, and this downregulation is independent of promoter DNA methylation.

Interon-gamma Enhances the Antitumor Effect of All-trans Retinoic Acid on Hepatocellular Carcinoma Cells by Inhibiting the Expression of Nuclear Factor-kappaB

Objective： To explore the combination effects of all-trans retinoic acid （ATRA） with interferon-gamma （IFN-γ） on human hepatocarcinoma cell line SMMC-7721 and the mechanism of action. Methods： SMMC-7721 cells were divided into treated group and control group. The cells were treated with ATRA or ATRA＋ IFN-γ in the former and added with PBS in the latter. The inhibition rate of SMMC-7721 cell proliferation was detected by MTT, the cell change in morphology was observed by electron microscope. The apoptosis was detected by flow cytometry and the expression changes of nuclear factor-kappaB （NF-κB） was analyzed by Western blotting when the SMMC-7721 cells were treated with ATRA and IFN-γ. Results： The SMMC-7721 cell proliferation was suppressed and apoptosis was induced after the cells were treated with ATRA treatment, and these effects were enhanced when ATRA was combined with IFN-γ. The expression of NF-κB was reduced after SMMC-7721 cell was treated with ATRA, and reduced significantly when the cells were treated with the combination of ATRA and IFN-γ. Conclusion： IFN-γ can enhance the inhibiting effects of ATRA on cell proliferation and inducing apoptosis on SMMC-7721 cell and these effects might be mediated by inhibiting the expression of NF-κB.

Identification of tumor invasion-related differentially expressed genes in different grades and all-trans retinoic acid-treated astrocytoma cell lines

BACKGROUND： Although several genetic aberrations and gene expressional changes have been shown to exist in tumors and different grades of astrocytomas, as well as in normal tissues, the gene profiling and genetic pathways associated with malignant transformation and progression remain unclear. OBJECTIVE： To identify differentially expressed genes related to tumor invasion from various grades and all-trans retinoic acid （ATRA）-treated astrocytoma cell lines by cDNA microarray. DESIGN, TIME AND SETTING： In vitro gene experiment was performed at the Department of Neurobiology, Third Military Medical University of Chinese PLA from January to October 2007. MATERIALS： Two different grades of astrocytoma cell lines CHG-5 （WHO grade II ） and SHG-44 （WHO grade IV） were developed by our laboratory; a cell differentiation-inducing agent ATRA and a human cDNA microarray technology were used to determine differentially expressed genes （City University of Hong Kong）. METHODS： Total RNA was extracted using the Trizol test kit. Reverse transcription was performed using Superscript 11 reverse transcriptase. The cDNA product （target DNA） was marked with fluorochromes Cy3 （normal SHG-44） and Cy5 （CHG-5 or ATRA-treated SHG-44）, followed by chip hybridization. MAIN OUTCOME MEASURES： Gene expression profiles of CHG-5 vs. SHG-44 and ATRA-treated vs. normal SHG-44 were performed to identify differentially expressed genes. Several of these genes were randomly selected for Northern Blot analysis. The identification of genes that were similarly regulated （overlapping） was performed by comparing gene expression profiles between CHG-5 and SHG-44 cells, and between SHG-44 cells with or without treatment with ATRA. RESULTS： No significant differences were observed between CHG5 and SHG-44 cell line morphology. Under confocal microscopy, GFAP staining intensity of CHG5 cells was greater than SHG-44 cells （t = 6.078 P = 0.004）. Growth curve analysis demonstrated that the speed of SHG-44 cell growth was greater than CHG5 cells. Flow cytometry analysis showed that the number of ATRA-treated SHG-44 cells at G0/G1 stage increased by 15%, compared with normal SHG-44 cells （P 〈 0.05）. A total of 31 known genes with altered expression were identified in this study. Among them, 20 genes were upregulated and 11 were downregulated in CHG-5 compared with SHG-44 cells, and ATRA-treated SHG-44 compared with untreated SHG-44 ceils. Four of these reported genes （CD151, G3BP, UGB, and CSTB） were shown to be involved in tumor invasion. Validation of a selection of differentially expressed genes was perfonlaed by Northern blot. CONCLUSION： A total of 31 known genes were demonstrated by cDNA microarray to relate to the malignant progression of astrocytomas, and four differentially expressed genes （CD151, G3BP, UGB, and CSTB） were shown to relate to tumor invasion.

Apoptosis of Glioblastoma U251 Cells Induced by Carmustine Combined All-trans Retinoic Acid via Regulating Cyclin E and p27kip 1

The effect and mechanism of carmustine（BCNU） combined with all-trans retinoic acid（ATRA） on the apoptosis of human glioblastoma U251 cells were investigated by means of 3-（4,5-dimethylthiazol-2-yl）-2,5-diphe- nyltetrazolium bromide（MTT） assay, flow cytometry, reverse transcription-polymerase chain reaction（RT-PCR） and Western blot analysis. The results show that BCNU or ATRA shows time- and dose-dependent inhibition effects on human glioblastoma U251 cells and the combination of BCNU with ATRA shows an synergistic inhibition effect on human glioblastoma U251 cells, and the combined BCNU and ATRA can significantly inhibit the proliferation of human glioblastoma U251 cells, and induce the apoptosis of them, making the cells arrest in the stage of G1 phase, the stage of S and G2 phases decline, the rate of the apoptosis of human glioblastoma U251 cells increase, the corresponding mRNA expression of cyclin E and cyclin-dependent kinase 2（CDK2） downregulated and the correspon- ding mRNA expression of p27kip 1 unregulated. In addition, the combined BCNU and ATRA reduced the protein expression of nuclear factor kappa B（NF-κB）. Taken together, these results suggest that the treatment of human glioblastoma U251 cells with a combination application of ATRA and BCNU can exert synergistic effect, the course of this kind of combination chemotherapy may likely be associated with multiple molecular mechanisms for apoptosis, furthermore, the cyclin E and p27kip 1 should be considered as novel targets for controlling the growth of glioblastoma cells.

COMPARISON OF CLINICAL OBSERVATIONS BETWEEN PATIENTS WITH ACUTE PROMYELOCYTIC LEUKEMIA TREATED WITH ALL-TRANS RETINOIC ACID AND CHEMOTHERAPY

Clinical observations were retrospectively compared between 2 matched groups of patients with acute promyelocytic leukemia (APL) each 20. The first group were treated with chemotherapy, the other with all-tram retinoic acid (ATRA) alone at a dose of 45-60mg/M^2/d. The complete remission (CR) rate of ATRA group was significantly higher than that of chemotherapy (90% vs 55%). The time for obtaining CR as well as the duration of fever and hospitalization were shorter and the amount of blood transfused was less in the former than in the latter group. Seven cases were complicated by DIC and 4 died in the group of chemotherapy, while no case was by of DIC or death in the ATRA group. The mechanism was discussed. ATRA is an alternative effective drug for remission induction therapy in APL with high rate of CR.

Apoptosis of Human Pancreatic Carcinoma Cells Induced By All-Trans Retinoic Acid and Interferon

Objective： To investigate the apoptosis of human pancreatic carcinoma PC3 cells induced by the combination of all-trans retinoic acid （ATRA） with interferon alpha （IFN-α）. Methods： PC3 cells were treated with ATRA and IFN-α. The inhibitory rate of PC3 cell proliferation was detected using MTT method. Cellular apoptosis was determined with flow cytometry. The percentage of PC3 cell apoptosis was assayed using TUNEL methods. Results： ATRA and IFN-α could inhibit cellular proliferation and induces cellular apoptosis of PC3 cells. The inhibitory effect was stronger when the ATRA and IFN-α were combined as a therapy. Conclusion： ATRA inhibits the proliferation of PC3 cells and induce the apoptosis of PC3 cells. The combination of IFN-α with ATRA may enhance these effects on PC3 cells.

Effects of All-trans Retinoic Acid (ATRA) against Bacterial Infection in Chickens

In order to investigate the effects of all-trans retinoic acid （ATRA） against bacterial infection in chickens, 35 3-day-old AA broiler chickens were fed adaptively for two days and randomly divided into five groups, including Escherichia coli experimental group （ group 1 ）, Escherichia coli control group （group 2）, blank control group （ group 3 ）, PasteureUa experimental group （ group 4）, and PasteureUa control group （ group 5 ）. At 5 days of age, the chickens in group 1 and group 4 were drenched with 5 p.mol/kg ATRA for seven consecutive days according to their weight; the chickens in group 2, group 3 and group 5 were drenched with an equal volume of dimethyl sulfoxlde （DMSO）. The clinical symptoms and weight changes in each group were observed and recorded. Seven days later, the chickens were euthanized and dissected to determine the immune organ indexes. The results showed that there were significant differences in body weight between ATRA-administrated chickens and non-administrated chickens after bacterial infection （P 〈 0.05 ） ; moreover, the immune organ indexes of ATRA-administrated chickens exhibited significant differences compared with control group （P 〈 0.05 ）, indicating that ATRA could promote the development of immune organs of poultry, thereby enhancing the body immunity against bacterial infection.

All-TRANS RETINOIC ACID INTERFERES DEVELOPMENT OF PULMONARY HYPERTENSION INDUCED BY MONOCROTALINE IN RATS

Objective To determine whether all-trans retinoic acid (atRA) affects the metabolism of collagen in main pulmonary artery and exerts an inhibitory effect in rats with pulmonary hypertension induced by monocrotaline. Methods All rats (n = 72) were divided into 3 groups as control, model, and atRA. in model and atRA groups, rats (n =48) were assigned at random to be given a single subcutaneous injection of monocrotaline (60mg/kg) and administrated with either atRA (30mg· kg-1·d-1) for atRA group or saline through oral-gastro intubation for model group. in control group, rats (n =24) received a single subcutaneous injection of an equal volume of 0. 9% saline. On day 7, 14, 21 and 28 after monocrotaline or saline injection, cardiovascular catheters were inserted into the pulmonary artery of rats in each group to examine their mean pulmonary artery pressure, in addition with their hydroxyproline content determined by chromometry. Results In comparison with the control rats, the mean pulmonary artery p ressure of rats in model group in-creased significantly on day 21 and up to the peak on day 28 (P <0. 01), while their hydroxyproline contents decreased significantly on day 14 (P< 0. 05) and increased significantly on day 21 and 28. The atRA group when compared with the model group show reduction in the content of hydroxyproline and the mean pulmonary artery pressure (P < 0. 01). Conclusion The atRA inhibits the accumulation of collagen in main pul-monary artery and interferes the development of pulmonary hypertension which might elicit favorable geometric remodeling of rat pulmonary hypertension induced by monocrotaline.

Study of Bcl-2 siRNA Enhancement of Sensitivity of HL-60 Cells to All Trans Retinoic Acid

OBJECTIVE To study whether siRNA targeting against the Bcl-2 gene can enhance sensitivity of HL-60 cells to all trans retinoic acid(ATRA). METHODS siRNA,which is a leading sequence selected by previous experiments,was transferred into HL-60 cells.At 6 h after transfection,the cells were cultured with ATRA.The cell growth of the HL-60 cells was measured by the MTT assay at 24, 48,72 h.The level of the Bcl-2 protein and ROS(reactive oxygen species)as well as membrane potential of the mitochondria were determined by flowcytometry. RESULTS siRNA significantly increased the inhibitory effect of ATRA on growth of the HL-60 cells.The combination of siRNA with ATRA resulted in a decrease in the Bcl-2 protein level and an increase in the ROS level as well as significantly lowering the mitochondrial membrane potential of the HL-60 cells(P<0.05). CONCLUSION Effective siRNA targeting of Bcl-2 increases the sensitivity of HL-60 leukemic cells to ATRA by inhibiting the expression of the Bcl-2 protein.