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cDNA expression array analysis of DNA repair genes in human glioma cells that lack or express DNA-PK
A M Galloway1, J Allalunis-Turner
1Department of Oncology, Cross Cancer Institute, Edmonton, Alberta, Canada.
Abstract:
M059J cells provide the only example of DNA-PKcs (now known as PRKDC) deficiency in a human cell line. M059K cells, derived from the same tumor specimen, express PRKDC protein and activity and, together with M059J, provide a useful model in which to study the role of DNA-PK in cellular responses to DNA-damaging agents. Because these cells are of tumor origin, we used Atlas human cancer cDNA expression arrays to investigate possible differential expression of other DNA repair genes in control and irradiated samples. cDNA array results indicated differential expression of 14 genes. Northern blotting confirmed relatively greater expression of replication factor C 37-kDa subunit mRNA in M059J cells compared to M059K cells and reduced expression of DNA ligase IV compared to ligase III in both cell lines independent of irradiation. These results suggest that other DNA repair proteins are altered in these cell lines and that repair mechanisms predicted from the study of normal tissues may be fundamentally altered in human cancer cells.
Insights
Human cancer cells exhibit altered DNA repair gene expression. M059J cells, deficient in DNA-PKcs (PRKDC), show differential expression of DNA repair genes compared to M059K cells, suggesting fundamental changes in cancer cell repair mechanisms.
Area of Science:
- Molecular Biology
- Genetics
- Cancer Research
Background:
- M059J cells are the sole human cell line lacking DNA-dependent protein kinase catalytic subunit (DNA-PKcs), now PRKDC.
- M059K cells, from the same tumor, express PRKDC, offering a model to study DNA-PK's role in DNA damage response.
- Both cell lines originate from tumors, necessitating investigation into DNA repair gene expression in cancer.
Purpose of the Study:
- To investigate differential expression of DNA repair genes in M059J and M059K cells.
- To understand how DNA repair mechanisms may be altered in human cancer cells compared to normal tissues.
Main Methods:
- Utilized Atlas human cancer cDNA expression arrays to compare gene expression profiles.
- Confirmed differential gene expression using Northern blotting.
Main Results:
- Identified differential expression of 14 genes between M059J and M059K cells.
- Observed greater replication factor C 37-kDa subunit mRNA expression in M059J cells.
- Found reduced DNA ligase IV expression relative to DNA ligase III in both cell lines, irrespective of irradiation.
Conclusions:
- DNA repair proteins are altered in these human cancer cell lines.
- DNA repair mechanisms in cancer cells may fundamentally differ from those in normal tissues.