Single-Strand Annealing in Cancer
1Department of Molecular Genetics, Faculty of Biology and Environmental Protection, University of Lodz, 90-236 Lodz, Poland.
Abstract:
DNA double-strand breaks (DSBs) are among the most serious forms of DNA damage. In humans, DSBs are repaired mainly by non-homologous end joining (NHEJ) and homologous recombination repair (HRR). Single-strand annealing (SSA), another DSB repair system, uses homologous repeats flanking a DSB to join DNA ends and is error-prone, as it removes DNA fragments between repeats along with one repeat. Many DNA deletions observed in cancer cells display homology at breakpoint junctions, suggesting the involvement of SSA. When multiple DSBs occur in different chromosomes, SSA may result in chromosomal translocations, essential in the pathogenesis of many cancers. Inhibition of RAD52 (RAD52 Homolog, DNA Repair Protein), the master regulator of SSA, results in decreased proliferation of BRCA1/2 (BRCA1/2 DNA Repair Associated)-deficient cells, occurring in many hereditary breast and ovarian cancer cases. Therefore, RAD52 may be targeted in synthetic lethality in cancer. SSA may modulate the response to platinum-based anticancer drugs and radiation. SSA may increase the efficacy of the CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)/Cas9 (CRISPR associated 9) genome editing and reduce its off-target effect. Several basic problems associated with SSA, including its evolutionary role, interplay with HRR and NHEJ and should be addressed to better understand its role in cancer pathogenesis and therapy.
Insights
Single-strand annealing (SSA) repairs DNA double-strand breaks but can cause deletions and translocations. Inhibiting RAD52, a key SSA regulator, shows promise for cancer therapy, especially in BRCA1/2-deficient cancers.
Area of Science:
- Molecular Biology
- Genetics
- Cancer Research
Background:
- DNA double-strand breaks (DSBs) are critical DNA lesions repaired by pathways like non-homologous end joining (NHEJ) and homologous recombination repair (HRR).
- Single-strand annealing (SSA) is an alternative DSB repair pathway that utilizes homologous repeats, but it is error-prone, leading to deletions and potentially chromosomal translocations implicated in cancer.
- Homology at breakpoint junctions in cancer DNA deletions suggests SSA's involvement in tumorigenesis.
Purpose of the Study:
- To explore the role of SSA in DNA repair and its implications in cancer pathogenesis.
- To investigate RAD52 (RAD52 Homolog, DNA Repair Protein) as a potential therapeutic target in cancer, particularly in BRCA1/2 (BRCA1/2 DNA Repair Associated)-deficient cells.
- To assess the potential of SSA modulation in cancer treatment strategies and genome editing technologies.
Main Methods:
- Review of existing literature on DNA repair mechanisms, focusing on SSA, NHEJ, and HRR.
- Analysis of the role of RAD52 in SSA and its impact on cancer cell proliferation.
- Examination of SSA's influence on responses to platinum-based drugs, radiation, and CRISPR/Cas9 genome editing.
Main Results:
- SSA contributes to DNA deletions and chromosomal translocations, which are significant in cancer development.
- Inhibition of RAD52 reduces proliferation in BRCA1/2-deficient cancer cells, highlighting a synthetic lethality approach.
- SSA influences sensitivity to genotoxic cancer therapies and can affect the efficiency and accuracy of CRISPR/Cas9 genome editing.
Conclusions:
- SSA is a critical, albeit error-prone, DNA repair pathway with a significant role in cancer pathogenesis.
- Targeting RAD52 presents a promising synthetic lethality strategy for treating BRCA1/2-deficient cancers.
- Further research into SSA's fundamental mechanisms and interactions with other repair pathways is crucial for advancing cancer therapy and genome editing.
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