Researchers at The Rockefeller University have discovered a hidden mechanical switch inside a protein complex linked to multiple cancers — and when they removed it in laboratory tests, the tumours stopped growing. The finding, published in *Genes & Development*, opens a new and potentially precise target for cancer therapies that currently don't exist.
The protein complex in question is called PRC2 — polycomb repressive complex 2. It's been connected to cancer for decades: mutations or malfunctions in PRC2 are found in breast cancer, prostate cancer, blood cancers, and skin cancers, among others. But how exactly it drives cancer, and how to stop it without disrupting normal cellular function, has remained elusive. Until now.
**The "Structural" Region That Wasn't Just Structural**
PRC2 is made up of multiple subunits. For years, one small region — called the **SBD** (Stimulation Binding Domain) — was considered essentially passive: a structural component whose job was to hold the complex together, with no known active function.
The Rockefeller team decided to test that assumption directly. What they found turned conventional understanding on its head.
*"The SBD serves as a mechanical switch necessary for both healthy embryonic development and the maintenance of certain malignancies,"* said lead author Agata Patriotis, now a postdoc at the Koch Institute for Integrative Cancer Research at MIT. *"This domain could potentially be targeted by cancer inhibitors."*
When the researchers removed the SBD from PRC2 in their experimental models, something remarkable happened: the cancers they tested stopped in their tracks. Not slowed — stopped.
**How PRC2 Works — and How It Goes Wrong**
PRC2 is an **epigenetic regulator** that controls which genes are switched on or off. It does this by adding a chemical marker to histone proteins — effectively silencing genes during embryonic development so that cells differentiate properly. It is ancient, essential, and found in organisms across the animal kingdom.
In cancer, tumour cells can hijack PRC2 to silence genes that normally suppress tumour growth. The challenge has always been: how do you target PRC2 in a cancer without disrupting its essential normal functions? The SBD discovery offers a potential answer — a target that appears to matter specifically in cancer maintenance.
**What Comes Next**
The findings are laboratory-based, and the path from target to approved therapy is long. But the identification of the SBD as a functional — not merely structural — element of PRC2 represents a fundamental advance. Drug developers already have PRC2 inhibitors in clinical development targeting a different part of the complex. The SBD represents an entirely different approach — one that might work where existing inhibitors fail.
For the millions of patients with cancers linked to PRC2 — breast, prostate, blood, skin — the discovery of a new druggable target is genuinely welcome news. Every new door opened brings the possibility of therapies that work for those for whom current treatments don't. 🧬
*Sources: Rockefeller University (rockefeller.edu) · Genes & Development (2026)*
