Mechanism of action of trabectedin in desmoplastic small round cell tumor cells

BMC Cancer, Feb 2017

Background Desmoplastic small round cell tumor (DSRCT) is a rare and highly aggressive disease, that can be described as a member of the family of small round blue cell tumors. The molecular diagnostic marker is the t(11;22)(p13;q12) translocation, which creates an aberrant transcription factor, EWS-WT1, that underlies the oncogenesis of DSRCT. Current treatments are not very effective so new active drugs are needed. Trabectedin, now used as a single agent for the treatment of soft tissue sarcoma, was reported to be active in some pre-treated DSRCT patients. Using JN-DSRCT-1, a cell line derived from DSRCT expressing the EWS-WT1 fusion protein, we investigated the ability of trabectedin to modify the function of the chimeric protein, as in other sarcomas expressing fusion proteins. After detailed characterization of the EWS-WT1 transcripts structure, we investigated the mode of action of trabectedin, looking at the expression and function of the oncogenic chimera. Methods We characterized JN-DSRCT-1 cells using cellular approaches (FISH, Clonogenicity assay) and molecular approaches (Sanger sequencing, ChIP, GEP). Results JN-DSRCT-1 cells were sensitive to trabectedin at nanomolar concentrations. The cell line expresses different variants of EWS-WT1, some already identified in patients. EWS-WT1 mRNA expression was affected by trabectedin and chimeric protein binding on its target gene promoters was reduced. Expression profiling indicated that trabectedin affects the expression of genes involved in cell proliferation and apoptosis. Conclusions The JN-DSRCT-1 cell line, in vitro, is sensitive to trabectedin: after drug exposure, EWS-WT1 chimera expression decreases as well as binding on its target promoters. Probably the heterogeneity of chimera transcripts is an obstacle to precisely defining the molecular mode of action of drugs, calling for further cellular models of DSRCT, possibly growing in vivo too, to mimic the biological complexity of this disease.

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Mechanism of action of trabectedin in desmoplastic small round cell tumor cells

Uboldi et al. BMC Cancer Mechanism of action of trabectedin in desmoplastic small round cell tumor cells S. Uboldi 0 3 I. Craparotta 0 3 G. Colella 2 E. Ronchetti 2 L. Beltrame 0 3 S. Vicario 0 3 S. Marchini 0 3 N. Panini 0 3 G. Dagrada 1 F. Bozzi 1 S. Pilotti 1 C. M. Galmarini 4 M. D'Incalci 0 3 R. Gatta 0 3 0 Department of Oncology, IRCCS-Istituto di Ricerche Farmacologiche 'Mario Negri' , Milan , Italy 1 Department of Pathology, Fondazione IRCCS Istituto Nazionale Tumori , Milan , Italy 2 Experimental Oncology and Pharmacogenomics, IRCCS Fondazione “Salvatore Maugeri”-Istituto di Pavia , Pavia , Italy 3 Department of Oncology, IRCCS-Istituto di Ricerche Farmacologiche 'Mario Negri' , Milan , Italy 4 Cell Biology and Pharmacogenomics Department, PharmaMar , Madrid 28770 , Spain Background: Desmoplastic small round cell tumor (DSRCT) is a rare and highly aggressive disease, that can be described as a member of the family of small round blue cell tumors. The molecular diagnostic marker is the t(11; 22)(p13;q12) translocation, which creates an aberrant transcription factor, EWS-WT1, that underlies the oncogenesis of DSRCT. Current treatments are not very effective so new active drugs are needed. Trabectedin, now used as a single agent for the treatment of soft tissue sarcoma, was reported to be active in some pre-treated DSRCT patients. Using JN-DSRCT-1, a cell line derived from DSRCT expressing the EWS-WT1 fusion protein, we investigated the ability of trabectedin to modify the function of the chimeric protein, as in other sarcomas expressing fusion proteins. After detailed characterization of the EWS-WT1 transcripts structure, we investigated the mode of action of trabectedin, looking at the expression and function of the oncogenic chimera. Methods: We characterized JN-DSRCT-1 cells using cellular approaches (FISH, Clonogenicity assay) and molecular approaches (Sanger sequencing, ChIP, GEP). Results: JN-DSRCT-1 cells were sensitive to trabectedin at nanomolar concentrations. The cell line expresses different variants of EWS-WT1, some already identified in patients. EWS-WT1 mRNA expression was affected by trabectedin and chimeric protein binding on its target gene promoters was reduced. Expression profiling indicated that trabectedin affects the expression of genes involved in cell proliferation and apoptosis. Conclusions: The JN-DSRCT-1 cell line, in vitro, is sensitive to trabectedin: after drug exposure, EWS-WT1 chimera expression decreases as well as binding on its target promoters. Probably the heterogeneity of chimera transcripts is an obstacle to precisely defining the molecular mode of action of drugs, calling for further cellular models of DSRCT, possibly growing in vivo too, to mimic the biological complexity of this disease. DSRCT; JN-DSRCT-1; Trabectedin - Background Desmoplastic small round cell tumor (DSRCT) was first described in 1989 by Gerald and Rosai [1] as a rare and highly aggressive disease that usually occurs in males during adolescence and early adulthood, with an estimated annual incidence rate of 0.1 cases/per 1 million. Only a few hundred cases have been reported worldwide. DSRCT can be described as a member of the family of small round blue cell tumors. All cases of DSRCT harbor the t(11;22)(p13;q12) translocation, leading to fusion of the Nterminal domain of Ewing’s sarcoma gene (EWS) to the Cterminal DNA binding domain of Wilms tumor suppressor gene (WT1). This unique chromosomal translocation provides the definitive molecular diagnostic marker of DSRCT and creates an aberrant transcription factor, EWS-WT1, which underlies the oncogenesis [2, 3]. The extreme rarity of the disease and the lack of prospective studies mean there is no consensus on the best treatment [4]. The three main treatment modalities are surgical resection (though complete resection is rarely possible), combination chemotherapy (response to conventional doxorubicin-based therapy is very poor), and local radiotherapy. In any case, current treatments for DSRCTs are not curative and do not give long-term survival benefits [2]. © The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Despite aggressive therapy, 3-year overall survival is estimated at 44% and the 5-year survival remains around 15%. Two case reports, one by A.M. Frezza [4] and another by A.L. Gonzalez [5], support trabectedin, which was active and safe in pre-treated DSRCT patients, all refractory (...truncated)


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S. Uboldi, I. Craparotta, G. Colella, E. Ronchetti, L. Beltrame, S. Vicario, S. Marchini, N. Panini, G. Dagrada, F. Bozzi, S. Pilotti, C. Galmarini, M. D’Incalci, R. Gatta. Mechanism of action of trabectedin in desmoplastic small round cell tumor cells, BMC Cancer, 2017, pp. 107, 17, DOI: 10.1186/s12885-017-3091-1