ZURICH, July 5 — Against this backdrop of a decades-long struggle to outwit cancer’s most evasive strategy, a team in Switzerland has built a molecule that can be switched on and off with flashes of light, offering a new way to reach sleeping tumor cells. Cancer has a dirty trick: it can put itself to sleep. When tumor cells slip into a kind of biological hibernation, they become hard to kill, shrugging off treatment and lying low until conditions improve, then waking up and bringing the disease back.
For decades, researchers have struggled to shut down this hiding strategy without causing serious harm elsewhere in the body. Behind this cellular sleep state, at least in certain cancers, sits a protein called the glucocorticoid receptor, a sensor inside cells that reacts to stress hormones.
When it switches on, it can push cancer cells, especially in some solid tumors such as lung cancer, into a drug-resistant, dormant state. The obvious fix would be to destroy the receptor outright, but there is a catch. The same receptor does important jobs all over the body, including calming inflammation.
Removing it everywhere would cause real damage. What was needed was a way to hit the receptor inside a tumor and leave the rest of the body alone.
That is what the team set out to build. Their solution, described in the journal Proceedings of the National Academy of Sciences, is a class of molecules called photoPROTACs: drug-like compounds engineered to destroy the stress hormone receptor, but only when a specific color of light switches them on. Shine the right light on them, and they go to work.
Keep the light off, and they remain inert. The research was led by Erick M. Carreira and Katharina Gapp of ETH Zürich.
What is at stake here is the ability to probe, and possibly disrupt, the way sleeping cancer cells hide from treatment. The wider picture is one of precision.
In the corridors of oncology research, the challenge has long been how to attack a tumor without collateral damage. This light-activated approach represents a step toward that goal, giving scientists a precise new tool that can be turned on and off at will. For now, the work remains in the laboratory.
But the principle — a molecular kill switch triggered by light — opens a door that has been closed for decades. Consult your doctor for medical advice.
