How a Tiny Molecule Inside Our Cells Might Explain Why Cancer Spreads
When we think about cancer, most of us picture a single tumor. But the truth is, most cancer deaths don’t come from the original tumor itself — they happen because the cancer spreads, a process called metastasis.
For decades, scientists have been trying to answer a huge question: what exactly gives cancer cells the ability to break free, travel through the body, and set up camp in new places?
Now, researchers at Rockefeller University have found a surprising clue — hidden inside the cell’s power plant, the mitochondria. And it all revolves around a molecule you may have heard of before: glutathione.
The Cell’s Powerhouse Has a Dark Side
Mitochondria are usually described as the “powerhouse of the cell”, the structures that keep everything running by producing energy. But they don’t just make energy — they also generate metabolites, the small molecules that keep cells alive and flexible.
Scientists have long suspected that mitochondria play a role in cancer’s spread. After all, tumors aren’t just energy-hungry; they also need special chemical tricks to survive in new environments. The big mystery has been figuring out which specific mitochondrial metabolites are responsible for metastasis.
Enter Glutathione
Out of thousands of possible molecules, one stood out: glutathione. Normally, glutathione is famous for its role as an antioxidant — reducing oxidative stress, supporting detoxification, and helping the immune system.
It’s often talked about in the context of health supplements and wellness trends.
But in this case, glutathione wasn’t just hanging around. Researchers discovered that it was found in highly elevated levels inside the mitochondria of breast cancer cells that had already spread to the lungs.
To confirm this, the team used a high-tech method called spatial metabolomics, which allowed them to actually map where glutathione was sitting inside lung tissues filled with metastatic cancer cells.
The Transporter That Unlocks the Mystery
Finding glutathione was just the start. The next step was figuring out how it gets into mitochondria in the first place. Here’s where a protein called SLC25A39 enters the picture. This protein acts like a transporter, shuttling glutathione across the mitochondrial membrane.
The researchers showed that without this transporter, glutathione can’t reach the mitochondria — and cancer cells lose their ability to spread. That’s a pretty strong link: glutathione plus its transporter equals metastasis.
Not About Antioxidants After All
Here’s the twist: glutathione wasn’t helping cancer spread by acting as an antioxidant. Instead, it was sending signals that triggered a survival program in the cancer cells. Specifically, it activated a factor called ATF4, which helps cancer cells cope with stressful conditions like low oxygen.
This signaling was especially important during the early stages of metastasis, when cancer cells are just trying to survive in a brand-new environment. In other words, glutathione gives these cells the boost they need to settle down in distant tissues.
Why This Discovery Matters
This finding is more than just a cool piece of cell biology. It could have real-world implications. The researchers noticed that breast cancer patients whose tumors had spread to the lungs often had higher levels of SLC25A39. Even more striking, higher expression of this transporter was linked to poorer overall survival.
That means that, in the future, a drug that blocks glutathione’s entry into mitochondria might be able to prevent cancer from spreading — without the harsh side effects of treatments that disrupt general cell functions.
A Bigger Picture of Cancer Metabolism
This discovery also fits into a growing shift in how scientists study cancer. Instead of just asking “which molecules go up or down,” they’re digging deeper into where these molecules act inside the cell. By zooming in on specific organelles like mitochondria, researchers can uncover hidden pathways that were invisible before.
As one of the study’s leaders put it, it’s about making our understanding of metabolism more precise. And precision could be the key to designing smarter, more targeted therapies in the future.
Cancer research often feels like a long, winding puzzle, but every once in a while, a new piece clicks into place. In this case, that piece is glutathione, a molecule we thought we knew well, but which turns out to have a hidden role in one of cancer’s most devastating tricks.
