DNA REPAIR AND ITS ROLE IN CANCER CELLS

DNA repair is an important biological process that helps maintain the integrity of the cell's genetic code.
This mechanism is found in all organisms (prokaryotic and eukaryotic) and plays an important role in protecting DNA from damage and in the proper functioning of cells.

What is DNA repair?

DNA repair is a cell mechanism that maintains the genetic code by repairing DNA damage.
It repairs DNA damage caused by natural causes (such as oxidative stress) or external causes (such as radiation and chemicals).
This mechanism is present in both prokaryotic and eukaryotic organisms.
If DNA damage is not repaired, it can lead to mutations and diseases, especially cancer.

Base Excision Repair (BER)
- Corrects small damage to a single base of DNA.
- The enzyme DNA Glycosylase removes the damaged base and adds the correct nucleotide.
Nucleotide Excision Repair (NER)
- Removes larger damage, such as mutations caused by ultraviolet (UV) radiation.
- Helps prevent skin cancer caused by sunlight.
Homologous Recombination (HR)
- Repairs double-strand breaks (breaks in both strands of DNA).
- The BRCA1 and BRCA2 genes, useful in cancer treatment, are involved in this process.
Non-Homologous End Joining (NHEJ)
- Helps join double-strand breaks but is more prone to errors.
- It can cause irregular DNA recombination (genomic instability) in cancer cells.

Cancer cells can survive chemotherapy by activating the DNA repair system.
Scientists are now developing treatments that inhibit the TDP1 enzyme, so cancer cells cannot repair themselves and are easily killed.
Drugs like PARP inhibitors can help treat cancer by blocking DNA repair.

Cancer cells use an enzyme called TDP1 (Tyrosyl-DNA Phosphodiesterase 1) to repair DNA.
This enzyme helps repair DNA damage caused by chemotherapy drugs (such as camptothecin), which can lead to the development of treatment resistance.
TDP1 is an essential DNA repair enzyme in humans, repairing DNA by removing damaged DNA bases and maintaining cell survival.