Cytotoxic activity of nemorosone in neuroblastoma cells

• Published in: Journal of cellular and molecular medicine Vol. 12; no. 6b; pp. 2598 - 2608
• Main Authors: Díaz‐Carballo, D., Malak, S., Bardenheuer, W., Freistuehler, M., Reusch, H. P.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.12.2008; John Wiley & Sons, Inc
• Subjects: 5-Fluorouracil; AKT protein; Akt/PKB; Apoptosis; Benzophenones - isolation & purification; Benzophenones - pharmacology; Cancer; Caspase 3 - metabolism; Caspase-3; Cell cycle; Cell Cycle - drug effects; Cell Death - drug effects; Cell growth; Cell Line, Tumor; Cells; Chemoresistance; Chemotherapy; Children; Children & youth; Chromatography; Cisplatin; Clusia rosea; Cyclin-dependent kinase inhibitor p21; Cytotoxicity; Dephosphorylation; Disease resistance; DNA Damage; DNA fragmentation; Drug resistance; Drug Screening Assays, Antitumor; Drug Synergism; Enzymatic activity; Enzyme Activation - drug effects; ERK1/2; Etoposide; Extracellular signal-regulated kinase; Fibroblasts; Humans; Inhibitory Concentration 50; isobologram; Kinases; Liquid chromatography; MAP kinase; MAP Kinase Kinase 1 - antagonists & inhibitors; MAP Kinase Kinase 2 - antagonists & inhibitors; Medical prognosis; Myc protein; MYCN; N-Myc protein; N-Myc Proto-Oncogene Protein; nemorosone; Neuroblastoma; Neuroblastoma - enzymology; Neuroblastoma - pathology; Neuroblasts; Nuclear Proteins - metabolism; Oncogene Proteins - metabolism; Oncology; Phosphorylation - drug effects; Population studies; Protein Kinase Inhibitors - pharmacology; Proto-Oncogene Proteins c-akt - antagonists & inhibitors; Proto-Oncogene Proteins c-raf - antagonists & inhibitors; Resins; Signal transduction; Signal Transduction - drug effects; Tumors; Florida; United States > US; Germany
• ISSN: 1582-1838; 1582-4934
• DOI: 10.1111/j.1582-4934.2008.00232.x

Neuroblastoma is the second most common solid tumour during childhood, characterized by rapid disease progression. Most children with metastasized neuroblastoma die despite intensive chemotherapy due to an intrinsic or acquired chemotherapy resistance. Thus, new therapeutic strategies are urgently needed. Here, we demonstrate that the novel compound nemorosone isolated from alcoholic extracts of Clusia rosea resins by reverse phase high pressure liquid chromatography (RP‐HPLC) exerts cytotoxic activity in neuroblas‐toma cell lines both parental and their clones selected for resistance against adriamycin, cisplatin, etoposide or 5‐fluorouracil. Cell cycle studies revealed that nemorosone induces an accumulation in G0/G1‐ with a reduction in S‐phase population combined with a robust up‐regulation of p21Cip1. Furthermore, a dose‐dependent apoptotic DNA laddering accompanied by an activation of caspase‐3 activity was detected. Nemorosone induced a significant dephosphorylation of ERK1/2 in LAN‐1 parental cells probably by the inhibition of its upstream kinase MEK1/2. No significant modulation of signal transducers JNK, p38 MAPK and Akt/PKB was detected. The enzymatic activity of immunoprecipitated Akt/PKB was strongly inhibited in vitro, suggesting that nemorosone exerts its anti‐proliferative activity at least in part by targeting Akt/PKB in the cell lines studied. In addition, a synergistic effect with Raf‐1 inhibitor BAY 43‐9006 was found. Finally, nemorosone induced a considerable down‐regulation of N‐myc protein levels in parental LAN‐1 and an etoposide resistant sub‐line at the same drug‐concentrations.