Q78 — Cellular Response to DNA Damage in Cancer

Theoretical 2 Real exam question — full text reproduced under IBO's CC BY-NC-SA 4.0 license

Cell response to DNA damage is intricately regulated and can lead to different pathways. On one hand, cells try to repair the breaks in the DNA helix, on the other hand, they proceed to apoptosis and mitotic arrest, if it fails. Cancer cells are typically treated with DNA-damaging agents like irradiation and many chemotherapeutics lead to proliferation inhibition and ultimately cell death. To escape this fate, some cancer cells develop various resistance mechanisms that allow them to survive and proliferate further.

Flow diagram of the DNA damage response: DNA damage is detected by sensor proteins (ATM/ATR), which activate downstream effectors. These effectors can trigger apoptosis, cell cycle checkpoints, DNA repair, changes in metabolism, or senescence, depending on the extent of damage and the cell’s ability to repair it. Diagram of the DNA damage response pathway: sensors, effectors, and the possible downstream outcomes (apoptosis, cell cycle checkpoints, DNA repair, metabolism, senescence).

Using this information, determine whether the following statements are true or false.

A. Genetic diseases that lead to genomic instability often contain defects in DNA repair mechanisms and may lead to cancer.

B. If the DNA damage is not repaired, normal cells will be arrested in the cell cycle but cancer cells will not.

C. Cancer cells carrying mutations in the DNA-damage sensing proteins may escape apoptosis.

D. DNA damage is more dangerous for the cells in G0 phase when compared to S or M phase.

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Question reproduced from IBO 2022, Theoretical Paper 2, licensed under CC BY-NC-SA 4.0 — attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)