Cancer Helper

Protein Found that Helps Cancer Cells

Tatiana Matveeva, "Scientific Russia"

In a new study, scientists from the University of Copenhagen (Denmark) have discovered two important functions of a protein called RTEL1 during cell division, thanks to which cancer cells survive. The discovery may help to find new cancer treatments, the press service of the university reports (Researchers find protein that helps cancer cells to survive).

The results of the work are published in the scientific journal Nature Structural & Molecular Biology (Wu et al., RTEL1 suppresses G-quadruplex-associated R-loops at difficult-to-replicate loci in the human genome).

One of the most important processes of the body is cell division, which occurs throughout life. Normal cells have only a limited number of divisions, while in cancer cells, cell division is not controllable.

The cycle of cell division contains several phases. The two most important are the S-phase, when the DNA of a cell is duplicated, and mitosis, when the duplicated DNA is divided equally between two daughter cells. A new study shows that a special protein RTEL1 plays an important role in both the S-phase and mitosis of cancer cells.

At the S-phase, RTEL1 can prevent destructive collisions between DNA replication and transcription processes (when RNA is produced), which otherwise can cause DNA damage and chromosome instability. This is due to the elimination of "certain unusual structures that can form between DNA and RNA, called R-loops," the authors note.

The second feature is that RTEL1 is the engine of a process called MiDAS (mitotic DNA synthesis), which occurs at an early stage of mitosis and helps cells complete DNA replication, which did not complete in the S-phase. It was discovered in 2015.

Then, about five years ago, it turned out that cancer cells use this unusual form of DNA replication much more often than normal cells, because cancer cells experience severe "replication stress" in the S-phase due to a violation of the cell division cycle, which is caused by excessive activity of oncogenes.

If MiDAS does not occur, it leads to cell death or mutations in the surviving cells. In the case of cancer, this means that the tumor cell can become even more abnormal due to new mutations.

In the new study, scientists looked at various types of cancer cells, including bone, cervical and colon cancers. They saw that the RTEL1 protein helps cancer cells use MiDAS. Now scientists will be able to use it as a target for cancer treatment, blocking the work of the protein.

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