Project description:Development of novel PI3Ks inhibitors is an important strategy to overcome their resistance and poor tolerability in clinical trials. The quassinoid family member Brusatol shows specific inhibitory activity against hematologic malignancies. However, the mechanism of its anti-cancer activity is unknown. We studied the anti-cancer activity of Brusatol on multiple hematologic malignancies derived cell lines by RNA-Seq, mass spectrometry, biochemical pull-down assays, and CRISPR/Cas9 gene knock-out. We demonstrated that the PI3Kgamma isoform was identified as a direct target of Brusatol, and inhibition was lost on PI3Kgamma deficient cells. Novel synthetic analogs were also developed and tested in vitro and in vivo. They shared superior potency in their ability to inhibit malignant hematologic cell lines, and in a xenograft transplant mouse model. They also had minimal toxicity to normal human cells. These new analogs have enhanced potential for development as a new class of PI3K inhibitors for treatment of hematologic malignancies.
Project description:Renneville A, Gasser JA, Grinshpun DE , Jean Beltran PM, Udeshi ND, Dr. Mary E. Matyskiela , Clayton T, McConkey M, Viswanathan K, Tepper A, Guirguis AA, Sellar RS, Cotteret S, Marzac C, Saada V, de Botton S, Kiladjian J, Cayuela J, Rolfe M, Chamberlain PP, Carr SA, Ebert BL. 2021.
Thalidomide analogs exert their therapeutic effects by binding to the CRL4CRBN E3 ubiquitin ligase, promoting ubiquitination and subsequent proteasomal degradation of specific protein substrates. Drug-induced degradation of IKZF1 and IKZF3 in B-cell malignancies demonstrates the clinical utility of targeting disease-relevant transcription factors for degradation. Here, we found that avadomide (CC-122) induces CRBN-dependent ubiquitination and proteasomal degradation of ZMYM2 (ZNF198), a transcription factor involved in balanced chromosomal rearrangements with FGFR1 and FLT3 in aggressive forms of hematologic malignancies. The minimal drug-responsive element of ZMYM2 is a zinc-chelating MYM domain and is contained in the N-terminal portion of ZMYM2 that is universally included in the derived fusion proteins. We demonstrate that avadomide has the ability to induce proteasomal degradation of ZMYM2-FGFR1 and ZMYM2-FLT3 chimeric oncoproteins, both in vitro and in vivo. Our findings suggest that patients with hematologic malignancies harboring these ZMYM2 fusion proteins may benefit from avadomide treatment.
Project description:Agents targeting metabolic pathways form the backbone of standard oncology treatments, though a better understanding of differential metabolic dependencies could instruct more rationale-based therapeutic approaches. We performed a chemical biology screen that revealed a strong enrichment in sensitivity to a novel dihydroorotate dehydrogenase (DHODH) inhibitor, AG-636, in cancer cell lines of hematologic versus solid tumor origin. Differential AG-636 activity translated to the in vivo setting. Dissection of the relationship between uridine availability and response to AG-636 revealed a divergent ability of lymphoma and solid tumor cell lines to survive and grow in the setting of depleted extracellular uridine and DHODH inhibition. Metabolic characterization paired with unbiased functional genomic and proteomic screens pointed to adaptive mechanisms to cope with nucleotide stress as contributing to response to AG-636. These findings support targeting of DHODH in lymphoma and other hematologic malignancies and suggest combination strategies aimed at interfering with DNA damage response pathways.