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1,25-(OH)2 vitamin D3 (1,25-(OH)2D3) exerts antiproliferative effects via cell cycle regulation in a variety of tumor cells, including prostate. We have previously shown that in the human prostate cancer cell line LN-CaP, 1,25-(OH)2D3 mediates an increase in cyclin-dependent kinase inhibitor p27Kip1 levels, inhibition of cyclin-dependent kinase 2 (Cdk2) activity, hypophosphorylation of retinoblastoma protein, and accumulation of cells in G1. In this study, we investigated the mechanism whereby 1,25-(OH)2D3 increases p27 levels. 1,25-(OH)2D3 had no effect on p27 mRNA levels or on the regulation of a 3.5-kb fragment of the p27 promoter. The rate of p27 protein synthesis was not affected by 1,25-(OH)2D3 as measured by luciferase activity driven by the 5'- and 3'-untranslated regions of p27 that regulate p27 protein synthesis. Pulse-chase analysis of 35S-labeled p27 revealed an increased p27 protein half-life with 1,25-(OH)2D3 treatment. Because Cdk2-mediated phosphorylation of p27 at Thr187 targets p27 for Skp2-mediated degradation, we examined the phosphorylation status of p27 in 1,25-(OH)2D3-treated cells. 1,25-(OH)2D3 decreased levels of Thr187 phosphorylated p27, consistent with inhibition of Thr187 phosphorylation-dependent p27 degradation. In addition, 1,25-(OH)2D3 reduced Skp2 protein levels in LNCaP cells. Cdk2 is activated in the nucleus by Cdk-activating kinase through Thr160 phosphorylation and by cdc25A phosphatase via Thr14 and Tyr15 dephosphorylation. Interestingly, 1,25-(OH)2D3 decreased nuclear Cdk2 levels as assessed by subcellular fractionation and confocal microscopy. Inhibition of Cdk2 by 1,25-(OH)2D3 may thus involve two mechanisms: 1) reduced nuclear Cdk2 available for cyclin binding and activation and 2) impairment of cyclin E-Cdk2-dependent p27 degradation through cytoplasmic mislocalization of Cdk2. These data suggest that Cdk2 mislocalization is central to the antiproliferative effects of 1,25-(OH)2D3. 相似文献
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Whitlatch LW Young MV Schwartz GG Flanagan JN Burnstein KL Lokeshwar BL Rich ES Holick MF Chen TC 《The Journal of steroid biochemistry and molecular biology》2002,81(2):135-140
The hormone 1alpha,25-dihydroxyvitamin D (1alpha,25(OH)(2)D) inhibits growth and induces differentiation of prostate cells. The enzyme responsible for 1alpha,25(OH)(2)D synthesis, 25-hydroxyvitamin D (25(OH)D)-1alpha-hydroxylase (1alpha-OHase), has been demonstrated in human prostate cells. We compared the levels of 1alpha-OHase activity in prostate cancer cell lines, LNCaP, DU145 and PC-3 and in primary cultures of normal, cancerous and benign prostatic hyperplasia (BPH) prostate cells. We observed a marked decrease in 1alpha-OHase activity in prostate cancer cells, including an undetectable level of activity in LNCaP cells. Transient or stable transfection of 1alpha-OHase cDNA into LNCaP cells increased 1alpha-OHase activity from undetectable to 4.95pmole/mg+/-0.69pmole/mg and 5.8pmole/mg+/-0.7pmole/mg protein per hour, respectively. In response to 25(OH)D, the prohormone of 1alpha,25(OH)(2)D, the transfected LNCaP cells showed a significant inhibition of 3H-thymidine incorporation (37%+/-6% and 56%+/-4% at 10(-8)M for transiently and stably transfected cells, respectively). These findings support an important autocrine role for 1alpha,25(OH)(2)D in the prostate and suggest that the re-introduction of the 1alpha-OHase gene to prostate cancer cells, in conjunction with the systemic administration of 25(OH)D, constitutes an endocrine form of gene therapy that may be less toxic than the systemic administration of 1alpha,25(OH)(2)D. 相似文献
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Burnstein RM Foltynie T He X Menon DK Svendsen CN Caldwell MA 《The international journal of biochemistry & cell biology》2004,36(4):702-713
Human neural progenitor cells (HNPCs) can be expanded in large numbers for significant periods of time to provide a reliable source of neural cells for transplantation in neurodegenerative disorders such as Parkinson's disease (PD). In the present study, HNPCs isolated from embryonic cortex were expanded as neurospheres in cell culture for 10 months. Just prior to transplantation, a proportion of the HNPCs were treated in a "predifferentiation" protocol in combination with the neurotropic factor NT4, in order to yield significant numbers of neurons. For transplantation, either undifferentiated HNPCs, or predifferentiated HNPCs were transplanted into the substantia nigra of a rat model of Parkinson's disease. At 12 weeks, there was good survival with proliferation of transplanted HNPCs occurring after transplantation but ceasing before the animals were sacrificed. Transplants of predifferentiated cells contained a higher proportion of neurons. The presence of a lesion in the striatum had a significant influence on the migration of transplanted cells from the substantia nigra into the striatum. There was no significant behavioural recovery or effect of transplanted HNPCs on the loss of dopaminergic cells from the host brain. In conclusion, HNPCs may provide a source of cells for use in the treatment of Parkinson's disease. 相似文献
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Fortunato Ferrara Sara D’Angelo Tiziano Gaiotto Leslie Naranjo Hongzhao Tian Susanne Gr?slund Elena Dobrovetsky Peter Hraber Fridtjof Lund-Johansen Silvia Saragozza Daniele Sblattero Csaba Kiss Andrew RM Bradbury 《MABS-AUSTIN》2015,7(1):32-41
Only a small fraction of the antibodies in a traditional polyclonal antibody mixture recognize the target of interest, frequently resulting in undesirable polyreactivity. Here, we show that high-quality recombinant polyclonals, in which hundreds of different antibodies are all directed toward a target of interest, can be easily generated in vitro by combining phage and yeast display. We show that, unlike traditional polyclonals, which are limited resources, recombinant polyclonal antibodies can be amplified over one hundred million-fold without losing representation or functionality. Our protocol was tested on 9 different targets to demonstrate how the strategy allows the selective amplification of antibodies directed toward desirable target specific epitopes, such as those found in one protein but not a closely related one, and the elimination of antibodies recognizing common epitopes, without significant loss of diversity. These recombinant renewable polyclonal antibodies are usable in different assays, and can be generated in high throughput. This approach could potentially be used to develop highly specific recombinant renewable antibodies against all human gene products. 相似文献
56.
Lúcia de Paula Célio L Silva Daniela Carlos Camila Matias-Peres Carlos A Sorgi Edson G Soares Patrícia RM Souza Carlos RZ Bladés Fábio CS Galleti Vânia LD Bonato Eduardo DC Gonçalves Érika VG Silva Lúcia H Faccioli 《Genetic vaccines and therapy》2007,5(1):1-7
The great challenges for researchers working in the field of vaccinology are optimizing DNA vaccines for use in humans or large animals and creating effective single-dose vaccines using appropriated controlled delivery systems. Plasmid DNA encoding the heat-shock protein 65 (hsp65) (DNAhsp65) has been shown to induce protective and therapeutic immune responses in a murine model of tuberculosis (TB). Despite the success of naked DNAhsp65-based vaccine to protect mice against TB, it requires multiple doses of high amounts of DNA for effective immunization. In order to optimize this DNA vaccine and simplify the vaccination schedule, we coencapsulated DNAhsp65 and the adjuvant trehalose dimycolate (TDM) into biodegradable poly (DL-lactide-co-glycolide) (PLGA) microspheres for a single dose administration. Moreover, a single-shot prime-boost vaccine formulation based on a mixture of two different PLGA microspheres, presenting faster and slower release of, respectively, DNAhsp65 and the recombinant hsp65 protein was also developed. These formulations were tested in mice as well as in guinea pigs by comparison with the efficacy and toxicity induced by the naked DNA preparation or BCG. The single-shot prime-boost formulation clearly presented good efficacy and diminished lung pathology in both mice and guinea pigs. 相似文献
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Aileen?G?RowanEmail author Koichiro?Suemori Hiroshi?Fujiwara Masaki?Yasukawa Yuetsu?Tanaka Graham?P?Taylor Charles?RM?Bangham 《Retrovirology》2014,11(1):116