sodium-bicarbonate and Melanoma

Excision with or without adjuvant cryotherapy or brachytherapy is the treatment of choice in conjunctival melanoma. Adjuvant rinsing with alcohol or sodium hypochlorite peroperatively (Dakin's solution) is used in some centers to prevent seeding of melanoma cells. The purpose of this research is to compare the cytotoxicity of sodium hypochlorite (NaOCl) with other potential cytotoxic solutions in the treatment of conjunctival melanoma.. Three uveal melanoma cell lines (OCM8, Mel285, and Mel270) and one conjunctival melanoma cell line (CM2005.1) were tested in a proliferation test (CellTiter 96 AQueous One Solution Cell Proliferation Assay, Promega, Madison, WI). The 96-well plates were coated with melanoma cells and treated with sodium hypochlorite 0.5%, sodium bicarbonate (1.4% and 8.4%), ethanol 99%, or sodium chlorite during 3, 5, or 15 minutes. Each solution was tested in several dilutions.. In all cell lines, no surviving cells were observed after treatment of 3 minutes with sodium hypochlorite. Ethanol 99% had a similar effect. A reduction of 70% of viable cells could be reached using sodium bicarbonate 1.4% or 8.4%. Water reduced the amount of viable cells by 40%.. Sodium hypochlorite is cytotoxic for melanocytic cells in vitro. Its use may reduce local seeding of tumor cells and may decrease metastasis after extirpation of an extended ocular tumour. Further in vivo evaluation of sodium hypochlorite is required.

Topics: Cell Line, Tumor; Cell Proliferation; Chlorides; Cytotoxins; Ethanol; Eye Neoplasms; Humans; Melanoma; Sodium Bicarbonate; Sodium Hypochlorite; Time Factors; Water

A novel inhibitor of dihydroorotate dehydrogenase (DHO-DH) has been discovered using data from the National Cancer Institute's in vitro drug screen. Upon analysis of cytotoxicity results from the sixty tumor cell lines used in this screen, the COMPARE program predicted that NSC 665564 was likely to have the same mechanism of inhibition as brequinar, a known potent inhibitor of DHO-DH. We validated this prediction experimentally using MOLT-4 lymphoblast and found the IC50 of brequinar (0.5 microM) and NSC 665564 (0.3 microM) were comparable and that this induced cytotoxicity was reversed by either uridine or cytidine. The enzyme target of NSC 665564 was shown to be identical to that of brequinar when incubation with each drug followed by a 1 h pulse with [14C] sodium bicarbonate resulted in cellular accumulation of [14C]N-carbamyl-L-aspartic acid and [14C]L-dihydroorotic acid, with concurrent marked depletion of CTP and UTP. The Ki's for NSC 665564 and brequinar were 0.14 and 0.24 microM, respectively, when partially purified MOLT-4 mitochondria (the site of DHO-DH) were used. These results show that mechanistic predictions obtained using correlations from the COMPARE algorithm are independent of structure since the structure of NSC 665564 is dissimilar to that of other established DHO-DH inhibitors.

Topics: Antineoplastic Agents; Aspartic Acid; Biphenyl Compounds; Breast Neoplasms; Carbolines; Carcinoma, Non-Small-Cell Lung; Central Nervous System Neoplasms; Colonic Neoplasms; Dihydroorotate Dehydrogenase; Enzyme Inhibitors; Female; Humans; Kidney Neoplasms; Kinetics; Leukemia; Lung Neoplasms; Male; Melanoma; Mitochondria; Orotic Acid; Ovarian Neoplasms; Oxidoreductases; Oxidoreductases Acting on CH-CH Group Donors; Prostatic Neoplasms; Ribonucleotides; Sodium Bicarbonate; Software; Tumor Cells, Cultured