nystatin-a1 and Ovarian-Neoplasms

Ovarian cancer is the most lethal gynecologic malignancy, often diagnosed at advanced stage leading to poor prognosis. In the study reported here, magnetic resonance imaging and near-infrared reflectance imaging were applied for in vivo analysis of two competing endocytic pathways affecting retention of bifunctional daidzein-bovine serum albumin (BSA)-based contrast media by human epithelial ovarian carcinoma cells. Suppression of caveolae-mediated uptake using nystatin or by BSA competition significantly enhanced daidzein-BSA-GdDTPA/CyTE777 uptake by tumor cells in vitro. In vivo, perivascular myofibroblasts generated an effective perivascular barrier excluding delivery of BSA-GdDTPA/CyTE777 to tumor cells. The ability to manipulate caveolae-mediated sequestration of albumin by perivascular tumor myofibroblasts allowed us to effectively overcome this tumor-stroma barrier, increasing delivery of daidzein-BSA-GdDTPA/CyTE777 to the tumor cells in tumor xenografts. Thus, both in vitro and in vivo, endocytosis of daidzein-BSA-GdDTPA/CyTE777 by ovarian carcinoma cells was augmented by albumin or by nystatin. In view of the cardinal role of albumin in affecting the availability and pharmacokinetics of drugs, this approach could potentially also facilitate the delivery of therapeutics and contrast media to tumor cells.

Topics: Animals; Antineoplastic Agents; Biological Transport; Endocytosis; Female; Humans; Isoflavones; Mice; Mice, Nude; Nystatin; Ovarian Neoplasms; Pentetic Acid; Serum Albumin, Bovine; Tissue Distribution

The human copper transporter 1 (hCTR1), the major transporter responsible for copper influx, mediates one component of the cellular accumulation of cisplatin (DDP). Both copper and DDP cause rapid down-regulation of hCTR1 expression in human ovarian carcinoma cells. In this study, we investigated the mechanism of this effect using digital deconvolution microscopy and Western blot analysis of cells stained with antibodies directed at both ends of the protein. Treatment of 2008 cells with DDP in combination with inhibitors of various endosomal pathways (amiloride, cytochalasin D, nystatin, and methyl-beta-cyclodextrin) showed that hCTR1 degradation was blocked by amiloride and cytochalasin D, indicating that hCTR1 was internalized primarily by macropinocytosis. Expression of transdominant-negative forms of dynamin I and Rac showed that loss of hCTR1 was not dependent on pathways regulated by either of these proteins. DDP-induced loss of hCTR1 was blocked by the proteasome inhibitors lactacystin, proteasome inhibitor 1, and MG132. This study confirms that DDP triggers the rapid loss of hCTR1 from ovarian carcinoma cells at clinically relevant concentrations. The results indicate that DDP-induced loss of hCTR1 involves internalization from the plasma membrane by macropinocytosis followed by proteasomal degradation. Because hCTR1 is a major determinant of early DDP uptake, prevention of its degradation offers a potential approach to enhancing tumor sensitivity.

Topics: Amiloride; beta-Cyclodextrins; Cation Transport Proteins; Cell Line, Tumor; Cisplatin; Copper Transporter 1; Cytochalasin D; Female; HeLa Cells; Humans; Immunohistochemistry; Microscopy, Confocal; Nystatin; Ovarian Neoplasms; Pinocytosis; Proteasome Endopeptidase Complex; Proteasome Inhibitors

The experiments in vitro have demonstrated that an application of 0.1 mg/ml of nistatine into ascitic cells suspension would result in swelling of cells and 80% loss of intracellular potassium, associated with a considerable reduction of Na+K+-ATP-ase activity, the intensity of respiration and glycosis being changed but insignificantly. Thus, the influence of a polyene antibiotic - nistatine on the water-salt balance of ascitic cells under study is likely to be somewhat related with inhibition of NA+K+-dependent ATP-ase.

Topics: Adenosine Triphosphatases; Animals; Antibiotics, Antineoplastic; Ascitic Fluid; Carcinoma, Ehrlich Tumor; Carcinoma, Hepatocellular; Female; Glycolysis; In Vitro Techniques; Liver Neoplasms; Mice; Neoplasms, Experimental; Nystatin; Ovarian Neoplasms; Oxygen Consumption; Potassium; Sodium