Abstract 4793
Background
ATM is an important cell cycle checkpoint kinase. This protein is an controller of cell cycle checkpoint that is required for cell response to DNA damage and for genome stability. The spindle assembly checkpoint (SAC) controls accurate chromosome segregation to maintain genome stability. All kinetochores correctly attach to the spindle, which allow mitosis to proceed. Bub3 is the mainly component of the SAC, in which its kinase activity can stabilize the correct kinetochore–microtubule attachments. Genomic stability is a hallmarks of breast cancer, and the level of Bub3 in breast cancer are higher than that in normal tussue. Understanding how the ATM-Bub3 signal contributes to kinetochore-based signaling may help us to recognize the occurrence of breast cancer.
Methods
Stable Isotope Labeling with Amino Acid in Cell Culture (SILAC) to identify ATM interation protein in breast cancer. Bioinformatics analyze the phosphorylation site of Bub3. Biacore assay and in vitro kinase assay to validate the phosphorylation site. Flow cytometry assay to check the mitotic index. Mutation of the phosphorylation site of bub3 and Co-IP were proformed to identify the interation of Bub3 and Bub1 or ZNF207, and western blot to be used to test the activity of Bub1.
Results
Through Stable Isotope Labeling with Amino Acid in Cell Culture (SILAC), we identified additional mitotic proteins that interact and can be phosphorylated by mitotically activated ATM kinase. We provide both in vitro and in vivo evidence that ATM phosphorylates Bub3 on Serine 135. This phosphorylation event promotes Bub1 activity in the mitotic spindle checkpoint. Further, we find that phosphorylation of Bub3 on Ser135 is required for formation of the Bub3-Bub1 complex, which is essential for Bub1 Ser314 phosphorylation. Mutation of Ser135 to alanine of Bub3 resulted in an enhanced interaction with BuGZ/ZNF207 and reduced interaction with Bub1, which lead to a spindle checkpoint defect.
Conclusions
Our findings highlight the functional significance of ATM-mediated kinetochore protein phosphorylation and elucidate a detailed regulatory mechanism of the SAC in breast cancer.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
5465 - Proof of concept clinical study by US-guided intratumor injection of VCN-01, an oncolytic adenovirus expressing hyaluronidase in patients with pancreatic cancer
Presenter: Manuel Hidalgo
Session: Poster Display session 1
Resources:
Abstract
2555 - A Phase 1a/b first-in-human, open-label, dose-escalation, safety, PK and PD study of TP-0903 in solid tumors
Presenter: John Sarantopoulos
Session: Poster Display session 1
Resources:
Abstract
3533 - First in human phase 1/2a study of PEN-866, a Heat Shock Protein 90 (HSP90) ligand – SN38 conjugate for patients with advanced solid tumors: Phase 1 results
Presenter: Johanna Bendell
Session: Poster Display session 1
Resources:
Abstract
4114 - A Phase I Open-Label, Non-Randomized Study of Recombinant Super-Compound Interferon (rSIFN-co) In Patients with Advanced Solid Tumors
Presenter: Amanda Seet
Session: Poster Display session 1
Resources:
Abstract
2537 - Evaluation of Pharmacodynamic (PD) Biomarkers in Advanced Cancer Patients Treated with Oxidative Phosphorylation (OXPHOS) Inhibitor, OPC-317 (OPC)
Presenter: Jie Qing Eu
Session: Poster Display session 1
Resources:
Abstract
5764 - Pharmacokinetic (PK) assessment of BT1718: A phase 1/2a study of BT1718, a first in class Bicycle Toxin Conjugate (BTC), in patients (pts) with advanced solid tumours
Presenter: Natalie Cook
Session: Poster Display session 1
Resources:
Abstract
2683 - A phase I open label dose escalation trial evaluating VT1021 in patients with advanced solid tumors.
Presenter: Wael Harb
Session: Poster Display session 1
Resources:
Abstract
3609 - Interim Results from Trial of SL-801, a Novel XPO-1 Inhibitor, in Patients with Advanced Solid Tumors
Presenter: Judy Wang
Session: Poster Display session 1
Resources:
Abstract
3485 - Phase 1 Trial of Fruquintinib in Patients with Advanced Solid Tumors: Results of the Dose Escalation Phase
Presenter: Andrea Wang-Gillam
Session: Poster Display session 1
Resources:
Abstract
4085 - A Phase 1, Open-Label, Dose-Escalation Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Antitumor Activity of ADCT-601 in Patients with Advanced Solid Tumors
Presenter: Anthony Tolcher
Session: Poster Display session 1
Resources:
Abstract