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Updated: Oct 2, 2025
Analysis of DNA Double-strand Break DSB Repair in Mammalian Cells
Published on: September 8, 2010
DLG2 impairs dsDNA break repair and maintains genome integrity in neuroblastoma
Simon Keane1, Hendrik A de Weerd2, Katarina Ejeskär1
1Translational Medicine, DHEAR, School of Health Sciences, University of Skövde, Skövde, Sweden.
Background:
In primary neuroblastoma, deletions on chromosome 11q are known to result in an increase in the total number of chromosomal breaks. The DNA double-strand break repair pathways mediated by NHEJ are often upregulated in cancer. DLG2, a candidate tumor suppressor gene on chromosome 11q, has previously been implicated in DNA repair.
Methods:
We evaluated an association between gene expression and neuroblastoma patient outcome, risk categorization, and 11q status using publicly available microarray data from independent neuroblastoma patient datasets. Functional studies were conducted using comet assay and H2AX phosphorylation in neuroblastoma cell lines and in the fruit fly with UVC-induced DNA breaks.
Results:
We show that the NHEJ genes PARP1 and FEN1 are over expressed in neuroblastoma and restoration of DLG2 impairs their gene and protein expression. When exposed to UVC radiation, cells with DLG2 over expression show less DNA fragmentation and induce apoptosis in a p53 S46 dependent manner. We could also confirm that DLG2 over expression results in CHK1 phosphorylation consistent with previous reports of G2/M maintenance.
Conclusions:
Taken together, we show that DLG2 over expression increases p53 mediated apoptosis in response to etoposide and UVC mediated genotoxicity and reduced DNA replication machinery.
Insights
DLG2 gene overexpression in neuroblastoma reduces DNA damage and enhances p53-mediated apoptosis. This finding suggests DLG2
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Chromosome 11q deletions in neuroblastoma correlate with increased chromosomal breaks.
- Non-homologous end joining (NHEJ) DNA repair pathways are frequently upregulated in cancer.
- DLG2, a tumor suppressor gene on 11q, is implicated in DNA repair mechanisms.
Purpose of the Study:
- To investigate the association between DLG2 gene expression and neuroblastoma patient outcomes.
- To analyze the correlation of DLG2 expression with tumor risk categorization and 11q status.
- To elucidate the functional role of DLG2 in DNA repair and cellular response to genotoxic stress.
Main Methods:
- Analysis of publicly available microarray data from independent neuroblastoma patient cohorts.
- Functional studies using comet assay to assess DNA fragmentation.
- Evaluation of H2AX phosphorylation and CHK1 phosphorylation in neuroblastoma cell lines and Drosophila models exposed to UVC radiation.
Main Results:
- PARP1 and FEN1, genes involved in NHEJ, are overexpressed in neuroblastoma; DLG2 restoration suppresses their expression.
- DLG2 overexpression reduces DNA fragmentation and induces p53 S46-dependent apoptosis following UVC exposure.
- DLG2 overexpression leads to CHK1 phosphorylation, indicating G2/M cell cycle checkpoint maintenance.
Conclusions:
- DLG2 overexpression enhances p53-mediated apoptosis in response to genotoxic agents like etoposide and UVC.
- DLG2 appears to modulate DNA replication machinery and DNA repair pathways.
- These findings highlight DLG2's potential role as a tumor suppressor in neuroblastoma by influencing DNA damage response.
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