RESUMO
Prohibitin (PHB) is a tumour suppressor molecule with pleiotropic activities across several cellular compartments including mitochondria, cell membrane and the nucleus. PHB and the steroid-activated androgen receptor (AR) have an interplay where AR downregulates PHB, and PHB represses AR. Additionally, their cellular locations and chromatin interactions are in dynamic opposition. We investigated the mechanisms of cell cycle inhibition by PHB and how this is modulated by AR in prostate cancer. Using a prostate cancer cell line overexpressing PHB, we analysed the gene expression changes associated with PHB-mediated cell cycle arrest. Over 1000 gene expression changes were found to be significant and gene ontology analysis confirmed PHB-mediated repression of genes essential for DNA replication and synthesis, for example, MCMs and TK1, via an E2F1 regulated pathway-agreeing with its G1/S cell cycle arrest activity. PHB is known to inhibit E2F1-mediated transcription, and the PHB:E2F1 interaction was seen in LNCaP nuclear extracts, which was then reduced by androgen treatment. Upon two-dimensional western blot analysis, the PHB protein itself showed androgen-mediated charge differentiation (only in AR-positive cells), indicating a potential dephosphorylation event. Kinexus phosphoprotein array analysis indicated that Src kinase was the main interacting intracellular signalling hub in androgen-treated LNCaP cells, and that Src inhibition could reduce this AR-mediated charge differentiation. PHB charge change may be associated with rapid dissociation from chromatin and E2F1, allowing the cell cycle to proceed. The AR and androgens may deactivate the repressive functions of PHB upon E2F1 leading to cell cycle progression, and indicates a role for AR in DNA replication licensing.
RESUMO
In order to assess clinico-radiological findings of urinary diversion, five adult healthy mongrel dogs of both sexes weighing between 25-40 kg and average age of 1.5 years, underwent continent urinary diversion surgery. In this approach fifteen centimeters of the descending colon with preservation of its mesenteric vessels was resected and this segment longitudinally was opened and flushed with an aqueous solution of povidin iodine 0.1% and the remaining colon re-anastomosed by seromuscular sutures. Then two ends of transected ureters were drawn into the resected colon by mosquito hemostatic forceps and simple interrupted sutures were placed between the ureter and the colonic mucosa for uretero-colonic anastomosis. The uretero-colonic part in a cap form transplanted to partially cystectomized bladder with one layer of cushing pattern suture. All animals survived after the operation. Clinically, all dogs were dull and depressed and passed blood tinged urine for first few postoperative days. There was pollakiuria in all of animals distinctly, but urinary incontinence was not observed. At the first few postoperative days, anorexia, nausea and vomiting were seen in three dogs. In all animals, polydipsia were seen and continued until the end of study. Intravenous urograms showed hydronephrosis and upper urinary tracts dilatation in all animals at 25th day but there were signs of improvement at 45th day distinctly. Unilateral ureteral obstruction was observed in two dogs. In regards to clinico-radiological findings can be concluded that this operation has some distinct sequela that some of them may be seen in radiographic assessments.
