Assessing the ability of DNA damage response inhibitors to prevent escape from a telomere crisis

Damo, Angelos 2023. Assessing the ability of DNA damage response inhibitors to prevent escape from a telomere crisis. PhD Thesis, Cardiff University. Item availability restricted.

Preview	PDF - Accepted Post-Print Version Download (8MB) | Preview
	PDF (Cardiff University Electronic Thesis and Dissertation Form) - Supplemental Material Restricted to Repository staff only Download (358kB)

Abstract

Telomere crisis is a cellular state induced by telomere deprotection and characterised by genomic instability and cell death. Escape from telomere crisis is linked with the development of malignant tumours. Previous work in our lab has demonstrated that inhibition of the PARP1-induced DNA damage response can selectively kill cells undergoing crisis. The aim of this thesis is to examine if inhibition of other DNA damage response pathways can affect the ability of cells to escape a telomere induced crisis and to examine how this would influence cell cycle progression, apoptosis, telomere length and dynamics and DNA damage. We used colorectal cancer cells expressing a dominant-negative telomerase (DN-hTERT) that undergo a well-defined period of crisis from which they escape and we treated them with DNA damage response inhibitors (RAD51, RAD52, ATR, CHK1, DNA-PK, WEE1, ATM, DNA Ligase I, III and IV). We selected three inhibitors (ATR, CHK1, DNA-PK) and treated primary fibroblasts that undergo a well-defined period of crisis from which they do not escape. We assessed how the inhibitors affected cellular functions before and during crisis. Among the DNA damage response inhibitors tested, 50nM Rabusertib (CHK1i) consistently prevented cells escaping crisis and 50nM AZD6738 (ATRi) dramatically slowed down escape from crisis in colorectal cancer cells. The inhibitors activated the DNA damage response and they reduced cell growth, increased apoptosis and altered cell cycle progression during crisis. They did not affect the rate of telomere erosion before and during crisis, but Rabusertib increased telomere fusion during deep crisis. Primary fibroblasts undergoing telomere crisis were sensitive to 50nM Rabusertib but not to 50nM AZD6738. We propose that the ATR-CHK1 pathway is crucial in keeping cells alive during crisis and suggest further clinical evaluation of Rabusertib as a potential treatment for patients with tumours that exhibit short dysfunctional telomeres.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Medicine
Date of First Compliant Deposit:	20 May 2024
Last Modified:	20 May 2024 13:05
URI:	https://orca.cardiff.ac.uk/id/eprint/169035

Actions (repository staff only)

Edit Item