Today’s blog is guest-written by Jana Krietsch (University of Zurich), edited by Nour Mozaffari (Promega)
Each time a cell divides, it must make an accurate copy of its entire genome—in human cells, this means roughly 6.2 billion individual DNA building blocks to duplicate. This enormous molecular task takes place inside the nucleus, a crowded, highly organized, yet remarkably dynamic environment. As the DNA-copying machinery moves along the genome, it may encounter roadblocks such as damaged DNA, sequences that are difficult to copy, tightly packed chromatin, or other molecular processes using the same DNA at the same time. These obstacles can slow or stall replication, a phenomenon known as DNA replication stress.
A Hidden Vulnerability of Cancer Cells
Cells are well equipped to deal with replication stress. Depending on the type and severity of the problem, they activate specialized signaling and repair mechanisms that protect replicating DNA. Failure of these responses can jeopardize genome integrity and result in permanent genetic changes that contribute to disease development.
In cancer, oncogenic changes and rapid proliferation places tumor cells under persistent replication stress. This promotes genome instability, a cancer hallmark, and drives tumor evolution. At the same time, it makes cancer cells hyper-dependent on replication stress response mechanisms to survive, creating a hidden vulnerability. Several treatments exploit this Achilles’ heel by increasing replication stress levels beyond what cancer cells can tolerate.
From Sequential Model to Dynamic Choreography
Many stress response pathways have been successfully reconstituted in the test tube. They are typically described as linear sequence of events triggered when an active replication site, termed replication fork, encounters a roadblock: the fork encounters an obstacle, its structure changes, signaling proteins are activated, repair factors are recruited, and DNA synthesis eventually resumes.
Continue reading “Under Pressure: The Nuclear Choreography upon Replicative Stress”






