How do we know that cancer cells contain defects in DNA repair?

Verified step by step guidance

1. Understand that DNA repair mechanisms are essential for maintaining genome integrity by correcting DNA damage that occurs naturally or due to environmental factors.
2. Recognize that cancer cells often exhibit a high rate of mutations and genomic instability, which suggests a failure in the normal DNA repair processes.
3. Examine experimental evidence where cancer cells show increased sensitivity to DNA-damaging agents, indicating defects in their ability to repair DNA.
4. Study specific genetic mutations found in cancer cells that affect key DNA repair genes, such as BRCA1 and BRCA2, which are known to be involved in homologous recombination repair.
5. Analyze laboratory assays that measure DNA repair efficiency, such as comet assays or reporter assays, which demonstrate reduced repair capacity in cancer cells compared to normal cells.

Key Concepts

DNA Repair Mechanisms

DNA repair mechanisms are cellular processes that identify and correct damage to the DNA structure. These include pathways like nucleotide excision repair, base excision repair, and mismatch repair, which maintain genomic integrity by fixing mutations that could otherwise lead to cell malfunction or disease.

Genomic Instability in Cancer Cells

Cancer cells often exhibit genomic instability, characterized by increased mutations and chromosomal abnormalities. This instability suggests defects in DNA repair pathways, as the inability to properly fix DNA damage leads to accumulation of mutations that drive cancer progression.

Experimental Evidence Linking DNA Repair Defects to Cancer

Studies show that many cancers have mutations in genes responsible for DNA repair, such as BRCA1/2. Laboratory assays demonstrate reduced repair capacity in cancer cells, and inherited DNA repair deficiencies correlate with higher cancer risk, providing direct evidence that defects in DNA repair contribute to cancer development.