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Targeting TRIM37-driven centrosome dysfunction in 17q23-amplified breast cancer.

ABSTRACT: Genomic instability is a hallmark of cancer, and has a central role in the initiation and development of breast cancer^1,2. The success of poly-ADP ribose polymerase inhibitors in the treatment of breast cancers that are deficient in homologous recombination exemplifies the utility of synthetically lethal genetic interactions in the treatment of breast cancers that are driven by genomic instability³. Given that defects in homologous recombination are present in only a subset of breast cancers, there is a need to identify additional driver mechanisms for genomic instability and targeted strategies to exploit these defects in the treatment of cancer. Here we show that centrosome depletion induces synthetic lethality in cancer cells that contain the 17q23 amplicon, a recurrent copy number aberration that defines about 9% of all primary breast cancer tumours and is associated with high levels of genomic instability^4-6. Specifically, inhibition of polo-like kinase 4 (PLK4) using small molecules leads to centrosome depletion, which triggers mitotic catastrophe in cells that exhibit amplicon-directed overexpression of TRIM37. To explain this effect, we identify TRIM37 as a negative regulator of centrosomal pericentriolar material. In 17q23-amplified cells that lack centrosomes, increased levels of TRIM37 block the formation of foci that comprise pericentriolar material-these foci are structures with a microtubule-nucleating capacity that are required for successful cell division in the absence of centrosomes. Finally, we find that the overexpression of TRIM37 causes genomic instability by delaying centrosome maturation and separation at mitotic entry, and thereby increases the frequency of mitotic errors. Collectively, these findings highlight TRIM37-dependent genomic instability as a putative driver event in 17q23-amplified breast cancer and provide a rationale for the use of centrosome-targeting therapeutic agents in treating these cancers.

SUBMITTER: Yeow ZY

PROVIDER: S-EPMC7597367 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Amplification of chromosome 17q23 is a frequent genomic event that occurs in ~ 11% of human breast cancers. The 17q23 amplification is enriched in HER2+ breast cancers, which is significantly correlated with poor clinical outcomes. Previous studies have identified the oncogenic phosphatase WIP1 gene in the amplicon, which functions as a master inhibitor in DNA damage response. While the possibility of any other protein-coding oncogenes in the WIP1-containing 17q23 amplicon was ruled out, our analysis of human breast cancer genomics uncovered an oncogenic microRNA gene, MIR21, in a majority of the WIP1-containing amplicons. Interestingly, DEAD-box helicase 5 (DDX5), co-amplified with WIP1 and MIR21 in the 17q23 amplicon, facilitates the essential processing of primary miR-21 transcripts. Accordingly, the 17q23 amplification results in aberrant expression of WIP1 and miR-21, which not only promotes breast tumorigenesis, but also leads to resistance to anti-HER2 therapies. Inhibiting WIP1 and miR-21 using small molecular inhibitor against WIP1 (GSK2830371) and anti-miR-21 oligonucleotides selectively inhibits the proliferation, survival and tumorigenic potential of HER2+ breast cancer cells harboring 17q23 amplification. However, the in vivo bioavailability of the two agents in their free form is poor. To overcome the resistance of trastuzumab-based therapies in vivo, we developed pH-sensitive nanoparticles for specific co-delivery of the two agents into breast tumors. The nanoparticles consist of four materials approved by the Food and Drug Administration (FDA) for medical use: Poly (d,l-lactide-co-glycolide) (PLGA), Pluronic F127 (PF127), chitosan, and 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine (DPPC). Moreover, chitosan was modified with guanidine to form chitosan-guanidine (CG), which not only can improve the encapsulation efficiency of anti-miR-21 oligonucleotides but also effectively capture carbon dioxide (CO2) into the nanoparticle to achieve the ‘nano-bomb’ effect for triggered drug release under the reduced pH in tumors. The two agents (inhibitors of miR-21 and WIP1)-laden nanoparticles can be used to efficiently kill trastuzumab-resistant HER2+ breast cancer cells, leading to a profound reduction of the tumor growth in vivo. These results demonstrate the great potential of the combined treatment of WIP1 and miR-21 inhibitors for the HER2+ breast cancers resistant to anti-HER2-based therapies.

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Targeting TRIM37-driven centrosome dysfunction in 17q23-amplified breast cancer.

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