AIMTo further uncover the possible mechanism of quercetin-mediated inhibitory effect on prostate cancer cells.

METHODSThe cell extracts treated with quercetin or without treatment were used for checking protein expression levels of c-Jun and cAMP response element binding protein (CREB)-binding protein (CBP) by Western blotting assay. Regulatory effects of c-Jun and CBP on the function of androgen receptor (AR) were examined by cotransfection experiment. Finally, a physical interaction of c-Jun and the AR was investigated by coimmunoprecipitation.

RESULTSQuercetin dramatically induced the protein expression of c-Jun which in turn inhibited the AR function. Meanwhile, quercetin had no detectable effect on CBP expression, and the results of transient transfection demonstrated that the ectopic CBP stimulated the transcriptional activity of AR, whereas CBP-mediated stimulation could be attenuated by quercetin. Furthermore, physical interaction of c-Jun and the AR was confirmed by coimmunoprecipitation result.

CONCLUSIONOverexpression of c-Jun induced by quercetin had inhibitory effect on the function of AR protein, and increased CBP expression did not reverse the inhibition by quercetin. Together, quercetin-mediated inhibition on the AR function might be not by competition with limited amount of CBP in the cell, but through a direct association of c-Jun and the AR.

Antineoplastic Agents, Phytogenic ; pharmacology ; CREB-Binding Protein ; genetics ; metabolism ; physiology ; Cell Line, Tumor ; Humans ; Immunoprecipitation ; Male ; Prostatic Neoplasms ; metabolism ; pathology ; Protein Binding ; drug effects ; Proto-Oncogene Proteins c-jun ; genetics ; metabolism ; physiology ; Quercetin ; pharmacology ; Receptors, Androgen ; genetics ; physiology ; Transfection

BACKGROUNDCD4(+) T cells play a crucial role in the pathogenesis of aplastic anaemia. However, the mechanisms of over-proliferation, activation, infiltration of bone marrow and damage to haematopoietic cells of CD4(+) T cells in aplastic anaemia are unclear. Therefore, we screened differentially expressed genes of bone marrow CD4(+) T cells of aplastic anaemia patients and normal donors by suppressive subtractive hybridization to investigate the pathogenesis of aplastic anaemia.

METHODSThe bone marrow mononuclear cells of a first visit aplastic anaemia patient and a healthy donor of the same age and sex were isolated using lymphocyte separating medium by density gradient centrifugation. With the patients as "tester" and donor as "driver", their CD4(+) T cells were separated with magnetic bead sorting and a cDNA library established by suppressive subtractive hybridization. Then 15 of the resulting subtracted cDNA clones were randomly selected for DNA sequencing and homological analysis. With semiquantitative RT-PCR, bone marrow samples from 20 patients with aplastic anaemia and 20 healthy donors assessed the expression levels of differentially expressed genes from SSH library.

RESULTSPCR detected 89 clones in the library containing an inserted fragment of 100 bp to 700 bp. Among 15 sequenced clones, 12 were known genes including 3 repeated genes. Compared with normal donors, there were 9/12 genes over-expressed in bone marrow CD4(+) T cells of patients with aplastic anaemia. The effects of these genes included protein synthesis, biology oxidation, signal transduction, proliferative regulation and cell migration. Not all these genes had been reported in the mechanisms of haematopoietic damage mediated by CD4(+) T cells in aplastic anaemia.

CONCLUSIONSScreening and cloning genes, which regulate functions of CD4(+) T cells, are helpful in elucidating the mechanisms of over proliferation, activation, infiltrating bone marrow and damaging haematopoietic cells of CD4(+) T cells in aplastic anaemia.

Adult ; Anemia, Aplastic ; genetics ; Bone Marrow Cells ; metabolism ; CD4-Positive T-Lymphocytes ; metabolism ; CREB-Binding Protein ; genetics ; Gene Library ; Humans ; Male ; Nucleic Acid Hybridization ; methods ; Reverse Transcriptase Polymerase Chain Reaction ; T Cell Transcription Factor 1 ; genetics

Leptin is an adipocytokine that regulates body weight, and maintains energy homeostasis by promoting reduced food intake and increasing energy expenditure. Leptin expression and secretion is regulated by various factors including hormones and fatty acids. Butyrate is a short-chain fatty acid that acts as source of energy in humans. We determined whether this fatty acid can play a role in leptin expression in fully differentiated human adipocytes. Mature differentiated adipocytes were incubated with or without increasing concentrations of butyrate. RNA was extracted and leptin mRNA expression was examined by Northern blot analysis. Moreover, the cells were incubated with regulators that may affect signals which may alter leptin expression and analyzed with Northern blotting. Butyrate stimulated leptin expression, and stimulated mitogen activated protein kinase (MAPK) and phospho-CREB signaling in a time-dependent manner. Prior treatment of the cells with signal transduction inhibitors as pertusis toxin, Gi protein antagonist, PD98059 (a MAPK inhibitor), and wortmannin (a PI3K inhibitor) abolished leptin mRNA expression. These results suggest that butyrate can regulate leptin expression in humans at the transcriptional level. This is accomplished by: 1) Gi protein-coupled receptors specific for short-chain fatty acids, and 2) MAPK and phosphatidylinositol-3-kinase (PI3K) signaling pathways.
Adipocytes/*metabolism ; Azo Compounds ; Butyric Acid/*pharmacology ; CREB-Binding Protein/genetics/metabolism ; Cell Differentiation ; Cells, Cultured ; Gene Expression Regulation/*drug effects/physiology ; Humans ; Leptin/genetics/*metabolism ; Mitogen-Activated Protein Kinase Kinases/genetics/metabolism ; Phosphatidylinositol 3-Kinases/genetics/metabolism ; RNA, Messenger/genetics/metabolism ; Signal Transduction/*physiology ; Staining and Labeling

OBJECTIVE: To determine the inhibitory effect of miRNA-381 on renal carcinoma invasion and to explore the underlying mechanisms.
 METHODS: After up-regulation of miRNA-381, the inhibitory effect of miR-381 on cell invasion was investigated. We screened the target genes of miRNA-381 in a database (starBase) through combination of five programs including targetscan, picTar, RNA22, PITA and miRanda. Then, the predicted targeting genes were verified by the dual luciferase reporter assay. We also examined the expression of miRNA-381 and its target genes in renal cancer cells and tissues.
 RESULTS: Transfection and up-regulation of miRNA-381 resulted in a significant decrease in trans-membrane cell numbers and the ability of renal cell invasion. Bioinformatics analysis showed that CREB binding protein (CBP), β-catenin and lymphoid enhancer binding factor-1 (LEF-1) were the potential targets of miRNA-381. In the luciferase reporter gene system, co-transfection of miRNA-381 with the 3'UTR of wild-type target gene led to a significant decrease in luciferase activity. The expression of miRNA-381 was decreased in various renal cancer cells, and it was particularly lower in highly metastatic cell lines (786-OHM). On the contrary, the expression levels of miRNA-381 target genes (CBP, β-catenin and LEF-1) were significantly increased in cells and tissues.
 CONCLUSION MiRNA-381 can inhibit cell invasion in renal cancer by block the function of CBP, β-catenin and LEF-1.
3' Untranslated Regions ; CREB-Binding Protein ; metabolism ; Carcinoma, Renal Cell ; pathology ; Cell Line, Tumor ; Computational Biology ; Gene Expression Regulation, Neoplastic ; Humans ; Kidney Neoplasms ; pathology ; Lymphoid Enhancer-Binding Factor 1 ; metabolism ; MicroRNAs ; genetics ; Neoplasm Invasiveness ; genetics ; Transfection ; Up-Regulation ; beta Catenin ; metabolism