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Checkpoint-Dependent Sensitivities to Nucleoside Analogues Uncover Specific Patterns of Genomic Instability
Zainab Burhanuddin Kagalwala1,2, Mohammed Ayan Chhipa1,3, Zohreh Kianfard1,3
1Department of Chemistry and Biology, Faculty of Science, Toronto Metropolitan University, Toronto, ON M5B 2K3, Canada.
Abstract:
Nucleoside analogues are used as drugs and as labels in laboratory-based research. However, the effect of different nucleoside analogue mechanism(s) on cell sensitivity or mutagenesis is unclear. This is particularly important in cancer treatments where checkpoint proteins and DNA damage factors are often mutated. We tested six nucleoside analogues in fission yeast, Schizosaccharomyces pombe. We found that the mutations in the DNA replication checkpoint cause unique sensitivity profiles towards chemotherapeutic nucleoside analogues (gemcitabine, 5-fluorouracil, cytarabine) and the non-clinical analogue bromodeoxyuridine. Antiretroviral compounds, zidovudine and lamivudine, did not alter cell growth. We compared half-maximal inhibitory concentration (IC50) doses between checkpoint deficient yeast strains, examining culture growth and DNA mis-segregation. Intriguingly, gemcitabine and bromodeoxyuridine doses above the IC50 promoted better growth. Above each compound's IC50 dose we saw that cells were insensitive to nucleoside analogue re-exposure, particularly in DNA replication checkpoint mutants (cds1∆, rad3∆). Thus, pairing nucleoside analogue use with personal genomics may inform drug choice, dose, and schedule. Finally, these data indicate that resistance may be predictable, informing clinical strategy.
Insights
DNA replication checkpoint mutations create unique sensitivities to nucleoside analogues. Understanding these profiles can predict drug resistance and personalize cancer treatment strategies.
Area of Science:
- Molecular Biology
- Genetics
- Cancer Research
Background:
- Nucleoside analogues are vital in medicine and research, but their impact on cell sensitivity and mutagenesis remains unclear.
- This knowledge gap is critical for cancer therapy, especially when DNA damage response pathways are compromised.
Purpose of the Study:
- To investigate how DNA replication checkpoint mutations affect sensitivity to various nucleoside analogues.
- To explore the potential for predicting drug resistance and informing clinical strategies.
Main Methods:
- Tested six nucleoside analogues in the fission yeast model organism, *Schizosaccharomyces pombe*.
- Compared growth inhibition and DNA mis-segregation across different checkpoint-deficient yeast strains.
- Determined half-maximal inhibitory concentration (IC50) values for each analogue.
Main Results:
- Checkpoint mutations conferred unique sensitivities to chemotherapeutic (gemcitabine, 5-fluorouracil, cytarabine) and non-clinical (bromodeoxyuridine) analogues.
- Antiretroviral nucleoside analogues (zidovudine, lamivudine) did not significantly affect cell growth.
- Doses of gemcitabine and bromodeoxyuridine above IC50 paradoxically promoted growth and led to resistance upon re-exposure, particularly in DNA replication checkpoint mutants (*cds1∆*, *rad3∆*).
Conclusions:
- DNA replication checkpoint status significantly influences cellular response to nucleoside analogues.
- Resistance to nucleoside analogues can be predictable, especially in specific mutant backgrounds.
- Integrating nucleoside analogue sensitivity data with personal genomics could optimize cancer drug selection, dosage, and scheduling.
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