Examining MPS1-dependent Centrosome Amplification in Cancer
2021
Hochschulschrift
Zugriff:
The centrosome is the microtubule organizing center of the cell and is highly conserved in structure and function. The centrosome cycle mirrors the cell cycle and is tightly controlled to maintain genetic fidelity. Centrosome duplication is limited to once per cell cycle to form a normal bipolar mitotic spindle and potentiate a functional spindle assembly checkpoint (SAC) that ensures proper kinetochore attachment before the cell proceeds through anaphase. However, the presence of extra centrosomes, through a process known as centrosome amplification, threatens the fidelity of chromosome segregation and can lead to chromosomal instability (CIN). Both centrosome amplification and CIN are hallmarks of most human cancers including those characterized by constitutive activation of the mitogen activated protein kinase (MAPK) pathway. The MAPK pathway primarily controls cell proliferation and has also been implicated in control of centrosome duplication and SAC function. MPS1 is a dual-specificity protein kinase first discovered for its role in centrosome duplication and later also shown to play a critical role in the SAC. It has been shown that MAPK signaling is necessary for targeting MPS1 to kinetochores and proper SAC function, but less is known about how MPS1 and MAPK proteins interact at centrosomes and whether that relationship contributes to centrosome amplification in cancer.The present study aimed to further characterize the interaction between MPS1 and the MAPK pathway to better understand how supernumerary centrosomes form in cancer cells. To address these questions, we assessed the localization of MAPK proteins, identified binding partners, and generated constitutively active mutants used in fluorescent microscopy to identify their impact on centrosome amplification. We have shown that ERK localizes to centrosomes where it accumulates under prolonged S-phase arrest. ERK, but not its upstream activators MEK or BRAF, interacts with MPS1 in S-phase when centrosomes are duplicated. Finally, constitutively active ERK induces MPS1-dependent centrosome amplification. Further, we also performed a comparative analysis of the MPS1 small molecule inhibitor, Compound 13, with other commercially available inhibitors to explore its use as an anti-cancer agent. MPS1 is a target of cancer treatment primarily for its role in the SAC, as loss of MPS1 activity impedes SAC function and leads to cell death. However, blocking both functions of MPS1 has the potential to have a greater effect than targeting either one alone. Compound 13 was compared to the inhibitors BAY 1217389, BAY 1161909, BOS 172722, and CFI 402257 in kinase, SAC, and centriole duplication assays. We have shown that though the IC50 is a bit greater than the other inhibitors tested, Compound 13 performs comparably in blocking the activity of MPS1 in the SAC, but is unique in its ability to block centriole duplication. Only one other inhibitor blocked centriole duplication, BOS 172722, but not at lower concentrations nor to the same magnitude as Compound 13 at higher concentrations. The work presented here contributes to our understanding of how aberrant MAPK signaling interacts with MPS1 to contribute to centrosome amplification and CIN in cancer and provides support for the use of the MPS1 inhibitor, Compound 13, in cancer treatment.
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Examining MPS1-dependent Centrosome Amplification in Cancer
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Autor/in / Beteiligte Person: | Thomas, Jennifer Lynn |
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Veröffentlichung: | 2021 |
Medientyp: | Hochschulschrift |
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