novobiocin and Melanoma

The aim of this study was to determine the efficacy of novobiocin and rifampin as oral antibiotic prophylaxis for the prevention of catheter-related infection in melanoma patients treated with interleukin-2 (IL-2) plus interferon-alpha and chemotherapy (biochemotherapy).. Patients with advanced melanoma who were treated with biochemotherapy at the University of Texas M. D. Anderson Cancer Center were randomized in a crossover study to receive either oral antibiotic prophylaxis consisting of novobiocin and rifampin or observation alone over a 35-day course period. Patients were subsequently "crossed over" to the opposite arm of the study for an additional 35-day period, with each serving as his or her own control.. Twenty-six patients were enrolled. Nine patients (35%) failed to tolerate oral antibiotics because of severe nausea and vomiting; 17 patients (65%) were crossed over and considered evaluable. During the control patient courses, 71% of evaluable patients had infectious complications, 41% had a catheter-associated bacteremia, and 53% had a local catheter infection. In contrast, of the patients treated with antibiotic prophylaxis, only 12% had an infectious complication (P = 0.001), 12% had a local catheter infection (P = 0.008), and 6% had catheter-associated bacteremias (P = 0.04). Thirty-six episodes of catheter infections occurred during the 17 control courses, whereas only 3 episodes occurred during antibiotic prophylaxis (P < 0.001).. Although more than one-third of patients receiving IL-2 treatment with biochemotherapy failed to tolerate novobiocin and rifampin, this oral antibiotic regimen was efficacious in preventing the infectious complications, especially those associated with vascular catheters, in this high risk patient population.

Topics: Administration, Oral; Adult; Anti-Bacterial Agents; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Bacteremia; Bacterial Infections; Catheterization, Central Venous; Catheterization, Peripheral; Catheters, Indwelling; Chemoprevention; Cross-Over Studies; Equipment Contamination; Female; Humans; Immunologic Factors; Interferon-gamma; Interleukin-2; Male; Melanoma; Middle Aged; Nausea; Novobiocin; Prospective Studies; Rifampin; Vomiting

Heat shock protein 90 (Hsp90) is differentially expressed in tumor cells including melanoma and involved in proper folding, stabilization and regulation of cellular proteins. We investigated a novobiocin-derived Hsp90 C-terminal inhibitor, KU135, for anti-proliferative effects in melanoma cells. The results indicate that KU135 reduced cell viability and cell proliferation in melanoma cells and IC(50) values for A735(DRO), M14(NPA), B16F10 and SKMEL28 cells were 0.82, 0.92, 1.33 and 1.30μM respectively. KU135 induced a more potent anti-proliferative effect in most melanoma cells versus N-terminal Hsp90 inhibitor 17AAG. KU135 induced apoptosis in melanoma cells, as indicated by annexin V/PI staining, reduction in the mitochondrial membrane potential, mitochondrial cytochrome C release and caspase 3 activation. KU135 reduced levels of Hsp90 client proteins Akt, BRAF, RAF-1, cyclin B and cdc25. Additionally, levels of Hsp90 and Hsp70 did not increase, while the levels of phosphorylated HSF1 levels decreased. KU135 induced strong G2/M cell cycle arrest, associated with decreased expression of cdc25c, cyclin B and increased phosphorylation of cdc25c. These finding show that KU135 reduced cell survival, proliferation, and induces apoptosis in melanoma cells. We suggest that KU135 may be a potential candidate for cancer therapy against melanoma.

Topics: Antineoplastic Agents; Apoptosis; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Flow Cytometry; Humans; Inhibitory Concentration 50; Melanoma; Membrane Potentials; Mitochondria; Novobiocin

The effect of novobiocin on the formation of DNA replication intermediates in human melanoma cells was investigated. This drug reduces DNA synthesis in all probability by interfering with the DNA gyrases (enzymes that are involved in the supercoiling of the DNA). The single-stranded DNA replication intermediates were released from the parental DNA by lysing the cells in dilute alkali and were then fractionated by agarose gel electrophoresis. In the untreated cells one can detect replication intermediates ranging in size from Okazaki-fragments up to 10 kb. However, in novobiocin-treated cells, apart from the already known intermediates, formation of a new replication intermediate with the size of about 20 kb was also detected. The 20-kb DNA shows a similar discrete appearance in the agarose gel as the 10-kb DNA intermediate.

Topics: Cells, Cultured; DNA; DNA Replication; DNA Topoisomerases, Type II; DNA, Neoplasm; Electrophoresis, Agar Gel; Humans; Hydroxyurea; Melanoma; Novobiocin