PHA-680626 Is an Effective Inhibitor of the Interaction between Aurora-A and N-Myc

by Selleckchem | Nov 16 2023

Neuroblastoma is a severe childhood disease, accounting for ~10% of all infant cancers. The amplification of the MYCN gene, coding for the N-Myc transcription factor, is an essential marker correlated with tumor progression and poor prognosis. In neuroblastoma cells, the mitotic kinase Aurora-A (AURKA), also frequently overexpressed in cancer, prevents N-Myc degradation by directly binding to a highly conserved N-Myc region. As a result, elevated levels of N-Myc are observed. During recent years, it has been demonstrated that some ATP competitive inhibitors of AURKA also cause essential conformational changes in the structure of the activation loop of the kinase that prevents N-Myc binding, thus impairing the formation of the AURKA/N-Myc complex. In this study, starting from a screening of crystal structures of AURKA in complexes with known inhibitors, we identified additional compounds affecting the conformation of the kinase activation loop. We assessed the ability of such compounds to disrupt the interaction between AURKA and N-Myc in vitro, using Surface Plasmon Resonance competition assays, and in tumor cell lines overexpressing MYCN, by performing Proximity Ligation Assays. Finally, their effects on N-Myc cellular levels and cell viability were investigated. Our results identify PHA-680626 as an amphosteric inhibitor both in vitro and in MYCN overexpressing cell lines, thus expanding the repertoire of known conformational disrupting inhibitors of the AURKA/N-Myc complex and confirming that altering the conformation of the activation loop of AURKA with a small molecule is an effective strategy to destabilize the AURKA/N-Myc interaction in neuroblastoma cancer cells.

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The passage you provided describes a study focused on the potential therapeutic approach to treat neuroblastoma, a severe childhood cancer. Here's a breakdown of the key points in the study:

1. **Neuroblastoma and MYCN Amplification**: Neuroblastoma is a childhood cancer that accounts for about 10% of all infant cancers. In this type of cancer, the amplification of the MYCN gene is associated with tumor progression and poor prognosis. The MYCN gene codes for the N-Myc transcription factor.

2. **AURKA and N-Myc Interaction**: The study focuses on the interaction between two proteins, Aurora-A (AURKA) and N-Myc, in neuroblastoma cells. AURKA is a mitotic kinase that is often overexpressed in cancer. It has been found that AURKA prevents the degradation of N-Myc by directly binding to a specific region of N-Myc. This interaction leads to elevated levels of N-Myc, which is associated with cancer progression.

3. **Inhibition of AURKA**: The study explores the use of small molecules that inhibit AURKA. Some of these inhibitors not only inhibit the kinase activity of AURKA but also induce conformational changes in the activation loop of the kinase.

4. **Disruption of AURKA/N-Myc Interaction**: The researchers screened crystal structures of AURKA in complexes with known inhibitors to identify compounds that affect the conformation of the kinase activation loop. These compounds were tested to assess their ability to disrupt the interaction between AURKA and N-Myc.

5. **Experimental Methods**: The study used Surface Plasmon Resonance (SPR) competition assays to test the compounds' ability to disrupt the AURKA/N-Myc interaction in vitro. Proximity Ligation Assays were conducted in tumor cell lines that overexpress MYCN to confirm the disruption of the interaction in a cellular context.

6. **Identification of PHA-680626**: The results of the study identified PHA-680626 as an amphosteric inhibitor, meaning it has dual functionality, both inhibiting AURKA activity and disrupting the AURKA/N-Myc interaction.

7. **Impact on Cancer Cells**: The study also investigated the effects of these compounds on N-Myc levels within cancer cells and their impact on cell viability. This likely involved assessing whether the disruption of the AURKA/N-Myc interaction had a therapeutic effect on neuroblastoma cells.

8. **Conclusion**: The study concludes that altering the conformation of the activation loop of AURKA with small molecules, such as PHA-680626, is an effective strategy to destabilize the AURKA/N-Myc interaction in neuroblastoma cancer cells. This approach may have potential as a therapeutic strategy for treating neuroblastoma, especially in cases where MYCN is overexpressed.

In summary, this study highlights a potential new avenue for developing targeted therapies for neuroblastoma by disrupting the interaction between AURKA and N-Myc, which plays a critical role in cancer progression.