Susana Fraile

The PARP inhibitor olaparib enhances the sensitivity of Ewing sarcoma to trabectedin

Recent preclinical evidence has suggested that Ewing Sarcoma (ES) bearing EWSR1-ETS fusions could be particularly sensitive to PARP inhibitors (PARPinh) in combination with DNA damage repair (DDR) agents. Trabectedin is an antitumoral agent that modulates EWSR1-FLI1 transcriptional functions, causing DNA damage. Interestingly, PARP1 is also a transcriptional regulator of EWSR1-FLI1, and PARPinh disrupts the DDR machinery. Thus, given the impact and apparent specificity of both agents with regard to the DNA damage/DDR system and EWSR1-FLI1 activity in ES, we decided to explore the activity of combining PARPinh and Trabectedin in in vitro and in vivo experiments. The combination of Olaparib and Trabectedin was found to be highly synergistic, inhibiting cell proliferation, inducing apoptosis, and the accumulation of G2/M. The drug combination also enhanced γH2AX intranuclear accumulation as a result of DNA damage induction, DNA fragmentation and global DDR deregulation, while EWSR1-FLI1 target expression remained unaffected. The effect of the drug combination was corroborated in a mouse xenograft model of ES and, more importantly, in two ES patient-derived xenograft (PDX) models in which the tumors showed complete regression. In conclusion, the combination of the two agents leads to a biologically significant deregulation of the DDR machinery that elicits relevant antitumor activity in preclinical models and might represent a promising therapeutic tool that should be further explored for translation to the clinical setting.

Transcription Factors Sp1 and p73 Control the Expression of the Proapoptotic Protein NOXA in the Response of Testicular Embryonal Carcinoma Cells to Cisplatin

Background: There is little understanding of the mechanisms that explain why testicular germ cell tumors respond so well to chemotherapy. Results: Noxa is transcriptionally activated by KLF6 and TAp73 and repressed by Sp1 and ΔNp73, and its protein levels correlate with clinical prognosis. Conclusion: p73 isoforms and Sp1-like factors form a cisplatin-induced transcriptional network that regulate proapoptotic Noxa. Significance: This might help understand the transcriptional pathways of chemosensitivity. Testicular germ cell tumors (TGCTs) are highly responsive to and curable by cisplatin-based chemotherapy even in advanced stages. We have studied the molecular mechanisms involved in the induction of apoptosis in response to cisplatin, and found that proapoptotic Noxa is transcriptionally up-regulated following cisplatin exposure, even in the absence of p53, in NTERA2 cisplatin-sensitive cells but not in 1411HP-resistant cells. Blockade of Noxa reduced the apoptotic response of embryonal carcinoma (EC) NTERA2 cells to cisplatin. A detailed analysis of the Noxa promoter revealed that p73 and Sp1-like factors, Sp1 and KLF6, played key roles in the transcriptional control of this gene. Overexpression of TAp73 induced Noxa whereas the dominant negative isoform ΔNp73, reduced the levels of Noxa after cisplatin exposure in NTERA2 and 2102EP. Interestingly, down-regulation of Sp1 increased Noxa expression in response to cisplatin. However, blockade of KLF6 decreased cisplatin-induced up-regulation of Noxa in EC cell lines. In addition, tissue microarray analyses of TGCTs revealed that expression of Noxa correlates with good clinical prognosis in patients with embryonal carcinoma. Thus, our data show the transcriptional network that regulates Noxa in EC cells, which is key for their apoptotic response to cisplatin-based chemotherapy, and propose Noxa as a predictive factor of therapeutic response.

Endometrial stromal tumors: immunohistochemical and molecular analysis of potential targets of tyrosine kinase inhibitors

BackgroundThe systemic treatment of malignant endometrial stromal tumors (EST) is not well established. A few reports describe objective responses to imatinib, which suggest a novel therapeutic strategy for these tumors. Due to these facts, we aimed to perform a retrospective analysis of possible molecular targets of tyrosine kinase inhibitors (TKI) in EST: KIT, PDGFRA and EGFR.Methods52 endometrial stromal sarcomas and 13 undifferentiated endometrial sarcomas were examined and reviewed. Mutational analysis were performed for exons 9, 11, 13, and 17 of the KIT gene, exons 12 and 18 of the PDGFRA gene and exons 18, 19, 20 and 21 of the EGFR gene. The incidence and distribution of the KIT, PDGFRA, and EGFR expression were examined by immunohistochemistry, and EGFR amplification was assessed by fluorescence in situ hybridization.ResultsNo mutations in KIT, PDGFRA and EGFR genes were detected. Overexpression of KIT, PDGFRA, EGFR, was detected in 2 (3%), 23 (35.4%), 7 (10.8%) cases respectively, whereas amplification of EGFR gene was not found.ConclusionsAbsence of significant expression, amplification and activating mutations on these tyrosine kinase receptors suggest that it is unlikely that EST can benefit from therapies such as TKI on the systemic setting.

Neogene Mammal Sites in Molina de Aragón (Guadalajara, Spain): Correlation to Other Karstic Sites of the Iberian Chain, and their Geoheritage Values

Corral de Lobato, a karstic site in the area of Molina de Aragón has been studied in a preliminary way. Even though there are not many Neogene karstic sites in the Iberian Chain, they occur in four clusters, with ages ranging from latest middle Miocene (MN7/8) to early Pleistocene (MN17). Correlations between these clusters and the reference stratigraphical units of the Tagus Basin, as well as with local and global events, are proposed. These karstic sites provide a complementary source of fossil vertebrate remains to that of the stratified sites formed lowland. The Heritage significance of such sites arises from the enhanced preservation of rare taxa or associations, and the operation of biotic concentrative processes.