Inhibition of BET bromodomain proteins with GS-5829 and GS-626510 in uterine serous carcinoma, a biologically aggressive variant of endometrial cancer

Elena Bonazzoli, Federica Predolini, Emiliano Cocco, Stefania Bellone, Gary Altwerger, Gulden Menderes, Luca Zammataro, Anna Bianchi, Francesca Pettinella, Francesco Riccio, Chanhee Han, Ghanshyam Yadav, Salvatore Lopez, Aranzazu Manzano, Paola Manara, Natalia Buza, Pei Hui, Serena Wong, Babak Litkouhi, Elena RatnerDan Arin Silasi, Gloria S. Huang, Masoud Azodi, Peter E. Schwartz, Joseph Schlessinger, Alessandro D. Santin

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: Uterine serous carcinoma (USC) is a rare and aggressive variant of endometrial cancer. Whole-exome sequencing (WES) studies have recently reported c-Myc gene amplification in a large number of USCs, suggesting c-Myc as a potential therapeutic target. We investigated the activity of novel BET bromodomain inhibitors (GS-5829 and GS-626510, Gilead Sciences Inc.) and JQ1 against primary USC cultures and USC xenografts. Experimental Design: We evaluated c-Myc expression by qRT-PCR in a total of 45 USCs including fresh-frozen tumor tissues and primary USC cell lines. We also performed IHC and Western blot experiments in 8 USC tumors. USC cultures were evaluated for sensitivity to GS-5829, GS-626510, and JQ1 in vitro using proliferation, viability, and apoptosis assays. Finally, the in vivo activity of GS-5829, GS-626510, and JQ1 was studied in USC-ARK1 and USC-ARK2 mouse xenografts. Results: Fresh-frozen USC and primary USC cell lines overexpressed c-Myc when compared with normal tissues (P ¼ 0.0009 and 0.0083, respectively). High c-Myc expression was found in 7 of 8 of primary USC cell lines tested by qRT-PCR and 5 of 8 tested by IHC. In vitro experiments demonstrated high sensitivity of USC cell lines to the exposure to GS-5829, GS-626510, and JQ1 with BET inhibitors causing a dose-dependent decrease in the phosphorylated levels of c-Myc and a dose-dependent increase in caspase activation (apoptosis). In comparative in vivo experiments, GS-5829 and/or GS-626510 were found more effective than JQ1 at the concentrations/doses used in decreasing tumor growth in both USC-ARK1 and USC-ARK2 mouse xenograft models. Conclusions: GS-5829 and GS-626510 may represent novel, highly effective therapeutics agents against recurrent/ chemotherapy-resistant USC-overexpressing c-Myc. Clinical studies with GS-5829 in patients with USC harboring chemotherapy-resistant disease are warranted.

Original languageEnglish
Pages (from-to)4845-4853
Number of pages9
JournalClinical Cancer Research
Volume24
Issue number19
DOIs
Publication statusPublished - Oct 1 2018

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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