Cancer cells are devious monsters that kill people by sabotaging normal cell functions toward a path of uncontrolled cell growth. Without an effective treatment, aggressive cancers can crowd out healthy tissue and ultimately cause organ failure and death. This devastation by design makes it seem as though a cancer cell has a mind of its own, but in reality it’s all due to mindless mutations in DNA. Understanding those mutations gives scientists insight into the molecular mechanisms of cancer, which can help pinpoint targets for potential treatments.

A team at The Scripps Research Institute (TSRI) followed the trail of such a mutation in a gene called POT1. In a Cell Reports study, researchers funded in part by CIRM describe a novel mechanism of cancer progression in cells carrying the POT1 mutation and speculate about a unique therapeutic strategy.

Chromosomes go to pot without POT1

The POT1 protein is part of shelterin, a multi‑protein complex that binds and protects telomeres—the DNA caps at chromosome ends. The team found that when a mutation disrupts POT1, telomeres become vulnerable to damage, leading to chromosome instability. As a result, DNA segments rearrange, causing mutations that can speed cancer growth.

However, POT1 mutations also activate ATR, an enzyme that halts cell division and triggers programmed cell death. At first glance, this seems to oppose cancer progression. So why do POT1 mutations appear in cancers such as leukemia, melanoma, and glioma?

As TSRI Associate Professor Eros Lazzerini Denchi explained in a press release, this paradox offered an opportunity:

“Somehow those cells found a way to survive—and thrive. We thought that if we could understand how that happens, maybe we could find a way to kill those cells.”

Mutant POT1 and p53: diabolical partners in cancer progression

The team looked for answers by studying the POT1 mutation alongside a mutated form of p53, a tumor‑suppressor gene altered in over half of all human cancers. Mice with only the POT1 mutation developed no cancers. Mice with only the p53 mutation formed T‑cell lymphomas by 20 weeks and survived about 24 weeks. But mice with both mutations fared far worse, with median survival of just 17 weeks. The p53 mutation appeared to unlock the cancer‑driving potential of the POT1 mutation.

Further experiments showed that the p53 mutation blocked ATR’s programmed cell‑death signal—the same signal the POT1 mutation activated. As a result, the cells avoided programmed death. Without this fail‑safe, chromosome instability caused by the POT1 mutation had more time to generate additional cancer‑causing mutations.

Encouragingly, this harmful cooperation between mutant POT1 and p53 may offer a new treatment strategy. No cell, including cancer cells, can survive without ATR. Because POT1‑mutant cells already have reduced ATR levels, the authors suggest that low doses of ATR inhibitors—already developed for clinical use—might kill cancer cells without harming healthy ones. The team plans to test this hypothesis.

It’s heartening to know determined scientists are finding ways to outsmart cancer’s tactics. As Lazzerini Denchi noted:
“This study shows that by looking at basic biological questions, we can potentially find new ways to treat cancer.”