yk-4-279 and Bone-Neoplasms

Ewing sarcomas (ES) are aggressive pediatric cancers of bone and soft tissues characterized by in frame chromosomal translocations giving rise to chimeric transcription factors, such as EWS-FLI1. An emerging strategy to block EWS-FLI1 activity is represented by the small molecule YK-4-279, which binds to EWS-FLI1 and alters its transcriptional activity. The specific effectors of the anti-oncogenic activity of YK-4-279 are still largely unknown. Herein, by performing a high-throughput screening we identify the lncRNA HULC (Highly Upregulated in Liver Cancer) as a prominent target of YK-4-279 activity in ES cells. High levels of HULC correlate with ES aggressiveness, whereas HULC depletion reduces ES cell growth. Mechanistically, we find that HULC promotes the expression of TWIST1 oncogene by sponging miR-186. Downregulation of HULC upon treatment with YK-4-279 reduces the expression of TWIST1 by unleashing miR-186 and favoring its binding to TWIST1 transcripts. Notably, high levels of miR-186 and low levels of TWIST1 correlate with better prognosis in ES patients. Our results disclose a novel oncogenic regulatory circuit mediated by HULC lncRNA that is disrupted by the small molecule YK-4-279, with promising therapeutic implications for ES treatment.

Topics: Bone Neoplasms; Cell Line, Tumor; Cell Proliferation; Computational Biology; Datasets as Topic; Disease-Free Survival; Down-Regulation; Drug Resistance, Neoplasm; Gene Expression Regulation, Neoplastic; Humans; Indoles; Kaplan-Meier Estimate; MicroRNAs; Nuclear Proteins; Prognosis; RNA, Long Noncoding; Sarcoma, Ewing; Twist-Related Protein 1

EWS-FLI1 is an oncogenic fusion protein implicated in the development of Ewing's sarcoma family tumors (ESFT). Using our previously reported lead compound 2 (YK-4-279), we designed and synthesized a focused library of analogues. The functional inhibition of the analogues was measured by an EWS-FLI1/NR0B1 reporter luciferase assay and a paired cell screening approach measuring effects on growth inhibition for human cells containing EWS-FLI1 (TC32 and TC71) and control PANC1 cell lines devoid of the oncoprotein. Our data revealed that substitution of electron donating groups at the para-position on the phenyl ring was the most favorable for inhibition of EWS-FLI1 by analogs of 2. Compound 9u (with a dimethylamino substitution) was the most active inhibitor with GI50 = 0.26 ± 0.1 μM. Further, a correlation of growth inhibition (EWS-FLI1 expressing TC32 cells) and the luciferase reporter activity was established (R(2) = 0.84). Finally, we designed and synthesized a biotinylated analogue and determined the binding affinity for recombinant EWS-FLI1 (Kd = 4.8 ± 2.6 μM).

Topics: Aniline Compounds; Antineoplastic Agents; Bone Neoplasms; Cell Proliferation; Crystallography, X-Ray; Gene Expression Regulation, Neoplastic; Humans; Indoles; Luciferases; Models, Molecular; Molecular Structure; Oncogene Proteins, Fusion; Proto-Oncogene Protein c-fli-1; RNA-Binding Protein EWS; Sarcoma, Ewing; Structure-Activity Relationship; Tumor Cells, Cultured

Translocations involving ETS-transcription factors, most commonly leading to the EWSR1-FLI1 fusion protein, are the hallmark of Ewing sarcoma. Despite knowledge of this driving molecular event, an effective therapeutic strategy is lacking. To test potential treatment regimes, we established a novel Ewing sarcoma zebrafish engraftment model allowing time-effective, dynamic quantification of Ewing sarcoma progression and tumour burden in vivo, applicable for screening of single and combined compounds. In Ewing sarcoma the tumour-suppressor gene TP53 is commonly found to be wild-type, thus providing an attractive target for treatment. Here, we study TP53 wild-type (EW7, CADO-ES1 and TC32) and TP53-deleted (SK-N-MC) Ewing sarcoma cell lines to investigate the potentiating effect of p53 reactivation by Nutlin-3 on treatment with YK-4-279 to block transcriptional activity of EWSR1-FLI1 protein. Blocking EWSR1-FLI1 transcriptional activity reduced Ewing sarcoma tumour cell burden irrespective of TP53 status. We show that simultaneous YK-4-279 treatment with Nutlin-3 to stabilize p53 resulted in an additive inhibition of TP53 wild-type Ewing sarcoma cell burden, whilst not affecting TP53-deleted Ewing sarcoma cells. Improved inhibition of proliferation and migration by combinatorial treatment was confirmed in vivo by zebrafish engraftments. Mechanistically, both compounds together additively induced apoptosis of tumour cells in vivo by engaging distinct pathways. We propose reactivation of the p53 pathway in combination with complementary targeted therapy by EWSR1-FLI1 transcriptional activity disruption as a valuable strategy against p53 wild-type Ewing sarcoma.

Topics: Animals; Antineoplastic Agents; Bone Neoplasms; Cell Line, Tumor; Cells, Cultured; Disease Models, Animal; Drug Synergism; Heterografts; Humans; Imidazoles; Indoles; Piperazines; RNA-Binding Protein EWS; RNA-Binding Proteins; Sarcoma, Ewing; Signal Transduction; Transcription, Genetic; Tumor Suppressor Protein p53; Zebrafish; Zebrafish Proteins