No abstract

With regard to the nature of their bonding and reactivity, fulvmes occupy a posiiion intermediate between their benzenoid isomers and the olefins. The chemical. and physical behavior of the fulvenes is determined either by the diene character of the cross-conjugated system or by the cyclic conjugation in the five-membered ring, depending on the type of substituent at the exocyclic carbon atom. In addition to several nc. w substitution reactions, a descn'ption is given of the syntheses and reactions of Qomino-and 6-hydroxyfulvenes, isomeric with anilines andphenols, the derivatives of which can be used for the preparation of new types of nonbenzenoid cyclic conjugated systems such as carbocyclic and heterocyclic azulenes, pseudoazulenes, thiepines, dihydropyridazines, and sindacene. Mum, J. chem. Physics 17, 264 (1949); this value applies to 6,6-dielkylfulvenes. [lO]J. H. Day and Ch. Oesfreich.

In ihrem Bindungszustand und ihrer Reaktivität nehmen die Fulvene eine Mittelstellung zwischen den ihnen isomeren benzoiden Verbindungen und den Olefinen ein. In Abhängigkeit von den Substituenten am exocyclischen C‐Atom bestimmen der Diencharakter des gekreuzt konjugierten Systems oder die cyclische Konjugation im fünfgliedrigen Ring das chemische und physikalische Verhalten der Fulvene. Neben einigen neuen Substitutionsreaktionen werden besonders Synthesen und Reaktionen von den mit Anilinen und Phenolen isomeren 6‐Amino‐ und 6‐Hydroxy‐fulvenen beschrieben. Derivate dieser Verbindungen ermöglichen die Darstellung neuartiger nichtbenzoider, cyclisch konjugierter Systeme wie carbo‐ und hetero‐cyclischer Azulene, Pseudoazulene, Thiepine, Dihydropyridazine und des s‐Indacens.

63 Background: Hepatoblastoma (HB) is the most common malignant liver tumor in childhood. Although combination of neoadjuvant chemotherapy and surgery has improved the outcome of standard-risk HB-patients up to 94% the outcome of high-risk HB-patients with metastatic tumors or invasion of large hepatic veins is still dismal and only 60% of these patients survive. Therefore, the identification of biomarkers that could help early detection of high-risk HB-patients and lead to risk-adapted therapies is of utmost importance. Methods: Genomic DNA of tumor and normal liver samples from 21 HB patients was extracted with standard procedures and bisulfite-treated using EpiTect Bisulfite Kit (Qiagen). Methylation status of the Ras association (RalGDS/AF-6) domain family member 1 (RASSF1) gene was analyzed by methylation-specific-PCR. cDNA of tumor and normal liver samples was used to determine the 16-gene expression signature according to Cairo et al. (2008, Cancer Cell) using real-time PCR. Association studies of molecular and clinical data were performed with GraphPad Prism Version 3.0 using two-tailed Chi square test. Results: We identified 9/21 HB cases hypermethylated in the RASSF1 promoter region. Interestingly, RASSF1 promoter methylation was significantly associated with metastases (p=0.0166) and occurrence of this epigenetic marker was associated with a reduced overall survival of patients (p=0.0008). Moreover, we discriminated HB tumors in C1 and C2 subclasses by using the 16-gene signature and correlation of these subtypes with the methylation status of RASSF1 showed a significant association (p=0.0037) for aggressive C2 tumors (8/11), but not C1 tumors (1/10). Conclusions: RASSF1 promoter hypermethylation is a strong prognostic marker for metastasis and worse outcome and correlates with an aggressive C2 HB-tumor profile. Since the detection of tumor-derived methylated DNA in the blood stream of cancer patients is nowadays practical, our data advise RASSF1 methylation assays to be used for risk assessment in HB-patients in the future.