| 1. |
- D'Incalci, Maurizio, et al.
(författare)
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Unique features of the mode of action of ET-743.
- 2002
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Ingår i: The oncologist. - 1083-7159. ; 7:3, s. 210-6
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Forskningsöversikt (refereegranskat)abstract
- This paper describes the current knowledge of the primary mode of action of a natural product, ecteinascidin 743 (ET-743), derived from the marine tunicate Ecteinascidia turbinata. ET-743 was initially selected for preclinical development because of its potent antitumor activity observed against several human solid tumor types. In vitro, the drug is cytotoxic in the nanomolar range, and in the case of some very sensitive cell lines, in the picomolar range. The large potency differences observed among several solid tumor types indicate that this compound possesses some tumor selectivity, but the molecular basis of these differential effects remains to be elucidated. The present studies were undertaken to evaluate the mechanism of action of ET-743 in this context. The available information on ET-743 binding to DNA and its effects on transcriptional regulation point to a unique behavior of this drug, as it independently affects specific gene transcription in a promoter-dependent way. In addition, ET-743 shows a peculiar pattern of selectivity in cells with different defects in their DNA-repair pathways. These results highlight a unique property of ET-743, possibly explaining why it possesses antitumor activity against tumors that are refractory to standard anticancer drugs, all of which certainly act by mechanisms that are different from that of ET-743.
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| 2. |
- Forni, Claudia, et al.
(författare)
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Trabectedin (ET-743) promotes differentiation in myxoid liposarcoma tumors.
- 2009
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Ingår i: Molecular cancer therapeutics. - 1535-7163. ; 8:2, s. 449-57
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Tidskriftsartikel (refereegranskat)abstract
- Differentiation is a complex set of events that can be blocked by rearrangements of regulatory genes producing fusion proteins with altered properties. In the case of myxoid liposarcoma (MLS) tumors, the causative abnormality is a fusion between the CHOP transcription factor and the FUS or EWS genes. CHOP belongs to and is a negative regulator of the large CAAT/enhancer binding protein family whose alpha, beta, and delta members are master genes of adipogenesis. Recent clinical data indicate a peculiar sensitivity of these tumors to the natural marine compound trabectedin. One hypothesis is that the activity of trabectedin is related to the inactivation of the FUS-CHOP oncogene. We find that trabectedin causes detachment of the FUS-CHOP chimera from targeted promoters. Reverse transcription-PCR and chromatin immunoprecipitation analysis in a MLS line and surgical specimens of MLS patients in vivo show activation of the CAAT/enhancer binding protein-mediated transcriptional program that leads to morphologic changes of terminal adipogenesis. The activity is observed in cells with type 1 but not type 8 fusions. Hence, the drug induces maturation of MLS lipoblasts in vivo by targeting the FUS-CHOP-mediated transcriptional block. These data provide a rationale for the specific activity of trabectedin and open the perspective of combinatorial treatments with drugs acting on lipogenic pathways.
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| 3. |
- Tavecchio, Michele, et al.
(författare)
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Multi-parametric flow cytometric cell cycle analysis using TO-PRO-3 iodide (TP3): detailed protocols.
- 2008
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Ingår i: Acta histochemica. - : Elsevier BV. - 0065-1281. ; 110:3, s. 232-44
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Tidskriftsartikel (refereegranskat)abstract
- TO-PRO-3 iodide (TP3), a monomeric cyanine nucleic acid stain with a peak absorbance at 642 nm and emission at 661 nm, is best excited by a helium-neon (HeNe) laser (633nm). It was tested in monocytes and different cell lines under conditions of different fixatives, dye concentrations, labeling kinetics and RNAse concentrations for mono-, bi- and tri-parametric flow cytometric cell cycle analysis to establish the best protocol for DNA analysis in terms of G1 peak CV, G2/G1 ratio and minimal amount of debris. A linear increase in G1 peak position was found from 0.1 to 2 microM TP3 concentrations. Fixatives 70% ethanol or 1% methanol-free formaldehyde, followed by 70% ethanol, resulted in the best DNA histograms. Although different protocols were found to be cell-type specific, in general, excellent results were obtained with 30 min incubation with 0.5 microM TP3 plus RNAse in almost all cell lines tested. These data show that TP3 is an alternative method to propidium iodide (PI), the most commonly used DNA-specific probe in flow cytometry. The most important advantage of using TP3 in combination with other fluorochromes, such as fluorescein isothiocyanate (FITC) or phycoerythrin (PE) in bi- or tri-parametric flow cytometric analysis, is that there is no need for fluorescence compensation for the TP3 signals.
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| 4. |
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| 5. |
- Tognon, Gianluca, 1976, et al.
(författare)
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Induction of resistance to Aplidin in a human ovarian cancer cell line related to MDR expression.
- 2005
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Ingår i: Cancer biology & therapy. - 1538-4047. ; 4:12, s. 1325-30
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Tidskriftsartikel (refereegranskat)abstract
- Aplidin-resistant IGROV-1/APL cells were derived from the human ovarian cancer IGROV-1 cell line by exposing the cells to increasing concentration of Aplidin for eight months, starting from a concentration of 10 nM to a final concentration of 4 microM. IGROV-1/APL cell line possesses five fold relative resistance to Aplidin. IGROV-1/APL resistant cell line shows the typical MDR phenotype: (1) increased expression of membrane-associated P-glycoprotein, (2) cross-resistance to drugs like etoposide, doxorubicin, vinblastine, vincristine, taxol, colchicin and the novel anticancer drug Yondelis (ET-743). The Pgp inhibitor cyclosporin-A restored the sensitivity of IGROV-1/APL cells to Aplidin by increasing the drug intracellular concentration. The resistance to Aplidin was not due to the other proteins, such as LPR-1 and MRP-1, being expressed at the same level in resistant and parental cell line. The finding that cells over-expressing Pgp are resistant to Aplidin was confirmed in CEM/VLB 100 cells, that was found to be 5-fold resistant to Aplidin compared to the CEM parental cell line.
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