Bi-steric mTORC1 inhibitors induce apoptotic cell death in tumor models with hyperactivated mTORC1
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA992119 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR25179942_1.fastq.gz | Fastqsanger.gz | |||
| SRR25179942_2.fastq.gz | Fastqsanger.gz | |||
| SRR25179943_1.fastq.gz | Fastqsanger.gz | |||
| SRR25179943_2.fastq.gz | Fastqsanger.gz | |||
| SRR25179944_1.fastq.gz | Fastqsanger.gz |
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2023-11-08 | GSE236742 | GEO
Project description:Activation of the PI3K-mTOR pathway is central to breast cancer pathogenesis including resistance to many targeted therapies. The mTOR kinase forms two distinct complexes, mTORC1 and mTORC2, and understanding which is required for the survival of malignant cells has been limited by tools to selectively and completely impair either subcomplex. To address this, we used RMC-6272, a bi-steric molecule with a rapamycin-like moiety linked to an mTOR active-site inhibitor that displays >25-fold selectivity for mTORC1 over mTORC2 substrates. Complete suppression of mTORC1 by RMC-6272 causes apoptosis in ER+/HER2- breast cancer cell lines, particularly in those that harbor mutations in PIK3CA or PTEN, due to inhibition of the rapamycin resistant, mTORC1 substrate 4EBP1 and reduction of the pro-survival protein MCL1. RMC-6272 reduced translation of ribosomal mRNAs, MYC target genes, and components of the CDK4/6 pathway, suggesting enhanced impairment of oncogenic pathways compared to the partial mTORC1 inhibitor everolimus. RMC-6272 maintained efficacy in hormone therapy-resistant acquired cell lines and patient derived xenografts (PDX), showed increased efficacy in CDK4/6 inhibitor treated acquired resistant cell lines versus their parental counterparts, and was efficacious in a PDX from a patient experiencing resistance to CDK4/6 inhibition. Bi-steric mTORC1-selective inhibition may be effective in overcoming multiple forms of therapy-resistance in ER+ breast cancers.
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Project description:A bi-steric mTORC1-selective inhibitor overcomes drug resistance in breast cancer
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Project description:The clinical benefit of current mTOR inhibitors is limited, perhaps reflecting their intrinsic pharmacological profiles. Rapamycin analogs selectively inhibit mTORC1, but fail to suppress phosphorylation of the mTORC1 substrate 4EBP1, a translational repressor that is a key driver of oncogenic mTORC1 signaling. mTOR kinase active-site inhibitors fully suppress mTORC1 and phosphorylation of its substrates, but are active against mTORC2 and additional kinases, potentially contributing to tolerability limitations. The prototype bi-steric inhibitor RapaLink-1 exploits the selective mTORC1 interactions of rapamycin and the broad mTOR kinase inhibitory effects of an active-site inhibitor, through covalent linkage of the two pharmacophores to achieve complete mTORC1/2 inhibition. We demonstrate that the anti-proliferative activity of RapaLink-1 is dependent upon mTORC1 and suppression of 4EBP1 phosphorylation. Using a rational design strategy, we tuned the affinities of the rapamycin core and ATP-mimetic moieties to create novel bi-steric inhibitors with enhanced mTORC1 selectivity and potency against 4EBP1 phosphorylation. mTORC1-selective bi-steric compounds produced durable inhibition of 4EBP1 phosphorylation in vitro and in vivo, and drove tumor regressions at well-tolerated doses in xenograft models of breast cancer.
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Project description:mTORC1-driven noninflammatory HCC and provide insight into further development of a protective strategy against noninflammatory HCC. Background & Aims: Mammalian target of rapamycin complex 1 (mTORC1) is frequently hyperactivated in hepatocellular carcinoma (HCC). Cases of HCC without inflammation and cirrhosis are not rarely seen in clinics. However, the molecular basis of noninflammatory HCC remains unclear. Methods: Spontaneous noninflammatory HCC in mice was triggered by constitutive elevation of mTORC1 by liver-specific Tsc1 knockout (LTsc1KO). A multi-omics approach was utilized on tumor tissues to better understand the molecular basis for the development of HCC in the LTsc1KO model. Results: We showed that LTsc1KO in mice triggered spontaneous noninflammatory HCC, with molecular characteristics similar to those of diethylnitrosamine-mediated noncirrhotic HCC. Mitochondrial and autophagy defects, as well as hepatic metabolic disorder were manifested in HCC development by LTsc1KO. mTORC1 activation on its own regulated an oncogenic network (DNA-damage-inducible transcript 4, nuclear protein 1 and fibroblast growth factor 21), and mTORC1–signal transducer and activator of transcription pathway crosstalk that altered specific metabolic pathways contributed to the development of noninflammatory HCC. Conclusion: Our findings reveal the mechanisms of mTORC1-driven noninflammatory HCC and provide insight into further development of a protective strategy against noninflammatory HCC.
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Project description:Histone monoaminylation is a new class of chromatin post-translational modification whereby glutamines are transamidated by tissue transglutaminase 2 (TGM2). Initial studies of these marks have identified serotonylation and dopaminylation on H3Q5, suggesting the modification is a marker of active chromatin. However, little work has been conducted to understand the regulation of TGM2-mediated monoaminylation of chromatin. Here, we employed a highly sensitive TGM2 assay using the small molecule biotin-cadaverine as an acyl-acceptor substrate. In doing so, we discovered that, in addition to H3Q5, H3Q19 and H2A.ZQ123 and Q124 are glutaminyl substrates for TGM2 in vitro. Modification of these residues occurs in a sequence independent manner, with the primary determining factor for substrate selectivity being steric accessibility. We demonstrated that moving substrate glutamines near the histone fold domain turns them into non-substrates. Furthermore, we found that steric accessibility of glutamines appears to be controlled by higher order chromatin structures. Using nucleosome arrays as substrates, we successfully showed that formation of chromatin fibers in vitro reduces levels of monoaminylation. We then successfully extended these findings to a cell based system, showing that TGM2 is not enriched in heterochromatin and that H3Q5 serotonylation and H3K9me3 are mutually exclusive marks. In total, our results strongly suggest that TGM2, and monoaminylation, are excluded from heterochromatin based on steric accessibility
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