No abstract

This study: (i) investigated the in vitro cytotoxicity and mode of action of lurbinectedin (PM01183) and ZalypsisV R (PM00104) compared with trabectedin in cell lines deficient in specific mechanisms of repair, (ii) evaluated their in vivo antitumor activity against a series of murine tumors and human xenografts. The antiproliferative activity, the DNA damage and the cell cycle perturbations induced by the three compounds on tumor lines were very similar. Nucleotide Excision Repair (NER) deficient cells were approximately fourfold more resistant to trabectedin, lurbinectedin and ZalypsisV R . Cells deficient in non-homologous end joining (NHEJ), MRN complex and translesion synthesis (TLS) were slightly more sensitive to the three compounds (approximately fivefold) while cells deficient in homologous recombination (HR) were markedly more sensitive (150-200-fold). All three compounds showed a good antitumor activity in several in vivo models. Lurbinectedin and trabectedin had a similar pattern of antitumor activity in murine tumors and in xenografts, whereas ZalypsisV R appeared to have a distinct spectrum of activity. The fact that no relationship whatsoever was found between the in vitro cytotoxic potency and the in vivo antitumor activity, suggests that in addition to direct cytotoxic mechanisms other host-mediated effects are involved in the in vivo pharmacological effects.Trabectedin (ET-743; YondelisV R ) is a natural marine compound isolated from the Caribbean tunicate Ecteinascidia turbinata in the late 1960 and now produced synthetically.

Purpose Epithelial ovarian tumors (EOTs) are amongst the most lethal of malignancies in women. We have previously identified ZIC2 as expressed at a higher level in samples of a malignant form (MAL) of EOT than in samples of a form with low malignant potential (LMP). We have now investigated the role of ZIC2 in driving tumor growth and its association with clinical outcomes. Experimental Design ZIC2 expression levels were analysed in two independent tumor tissue collections of LMP and MAL. In vitro experiments aimed to test the role of ZIC2 as a transforming gene. Cox models were used to correlate ZIC2 expression with clinical endpoints. Results ZIC2 expression was about 40-fold in terms of mRNA and about 17-fold in terms of protein in MAL (n = 193) versus LMP (n = 39) tumors. ZIC2 mRNA levels were high in MAL cell lines, but undetectable in LMP cell lines. Over-expression of ZIC2 was localized to the nucleus. ZIC2 over-expression increases the growth rate and foci formation of NIH 3T3 cells, and stimulates anchorage-independent colony formation; down-regulation of ZIC2 decreases the growth rate of MAL cell lines. Zinc finger domains 1 and 2 are required for transforming activity. In stage I MAL ZIC2 expression was significantly associated with overall survival in both univariate (p = 0.046), and multivariate model (p = 0.049). Conclusions ZIC2, a transcription factor related to the sonic hedgehog pathway, is a strong discriminant between MAL and LMP tumors: it may be a major determinant of outcome of EOT.