ABSTRACT
<p><b>AIM</b>To further uncover the possible mechanism of quercetin-mediated inhibitory effect on prostate cancer cells.</p><p><b>METHODS</b>The 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.</p><p><b>RESULTS</b>Quercetin 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.</p><p><b>CONCLUSION</b>Overexpression 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.</p>
Subject(s)
Humans , Male , Antineoplastic Agents, Phytogenic , Pharmacology , CREB-Binding Protein , Genetics , Metabolism , Physiology , Cell Line, Tumor , Immunoprecipitation , Prostatic Neoplasms , Metabolism , Pathology , Protein Binding , Proto-Oncogene Proteins c-jun , Genetics , Metabolism , Physiology , Quercetin , Pharmacology , Receptors, Androgen , Genetics , Physiology , TransfectionABSTRACT
<p><b>AIM</b>To study the effect of curcumin on the apoptosis of prostate cancer cell line LNCaP and regulation of expression of maspin gene.</p><p><b>METHODS</b>MTT and DNA electrophoresis were used to examine the cell growth and apoptosis of prostate cancer cell line LNCaP after treated with different doses of curcumin. The expression of maspin gene at transcription level and translation level was also detected by RT-PCR and Western blotting. pGL3-maspin luciferase expression vector, containing 847 bp (- 764 -/+ 83) DNA of maspin gene 5' promoter region, was transient transfected into LNCaP cell. Through detecting the activity of luciferase, the effect of curcumin on the promoter of maspin was studied.</p><p><b>RESULTS</b>Curcumin inhibited cell growth, induced the apoptosis and enhanced the expression of maspin gene in LNCaP cells.</p><p><b>CONCLUSION</b>Curcumin up-regulated expression of maspin gene in LNCaP cells through enhancing the transcription activity of promoter of maspin gene.</p>
Subject(s)
Humans , Male , Androgen Receptor Antagonists , Apoptosis , Cell Line, Tumor , Cell Proliferation , Curcumin , Pharmacology , Gene Expression Regulation, Neoplastic , Promoter Regions, Genetic , Prostatic Neoplasms , Drug Therapy , Genetics , Pathology , RNA, Messenger , Receptors, Androgen , Genetics , Serpins , GeneticsABSTRACT
<p><b>AIM</b>To study the regulatory effects of 9-cis retinoic acid (RA) on the expression of human homeobox gene NKX3.1 in prostate cancer cell line LNCaP.</p><p><b>METHODS</b>Flow cytometry, reverse transcriptase polymerase chain reaction and Western blotting were performed to evaluate the effects of 9-cis RA on NKX3.1 expression and cell cycle of LNCaP cells. To identify a regulatory region within the NKX3.1 promoter contributing to the regulation induced by 9-cis RA, we have constructed an NKX3.1 promoter-reporter plasmid, pGL3-1040bp, and its 5'-deletion mutants, which were transfected into LNCaP cells with treatment of 9-cis RA in indicated concentrations.</p><p><b>RESULTS</b>With the treatment of 9-cis RA, the NKX3.1 promoter activity was increased in reporter gene assay and NKX3.1 expression was enhanced at both mRNA and protein levels in LNCaP cells. We found that the region between -936 and -921 in the upstream of NKX3.1 gene involved the inducible regulation by 9-cis RA treatment. In flow cytometry, 9-cis RA treatment caused accumulation of cells in the G(1) phase of the cell cycle and a fewer cells pass through to G(2)/M.</p><p><b>CONCLUSION</b>Our results demonstrated that 9-cis RA as a differentiating agent can arrest prostate cancer cells in G(1) phase and reduce cell mitosis, and upregulate the expression of human homeobox gene NKX3.1, which is thought to play an important role in prostate differentiation and to act as a tumor suppressor gene in the prostate.</p>