UC San Diego Discovers How Body Blocks Breast Cancer Spread

Scientists have discovered a powerful ally hiding in plain sight: a protein that acts as the body's own breast cancer defense system.

Researchers at UC San Diego found that a protein called TYK2 works like a cellular gatekeeper, stopping breast cancer cells from breaking away and spreading throughout the body. When tissues are healthy and soft, TYK2 sits on the cell membrane and keeps cancer cells locked in place.

The breakthrough came from studying how cancer cells respond to their physical environment. In stiffer tissue, which is common in tumors, TYK2 loses its protective position and spreads throughout the cell. This shift allows cancer cells to break free and invade other tissues, leading to metastasis.

"This study reveals how extracellular matrix stiffness regulates breast cancer metastasis through TYK2," said Dr. Zhimin Hu, lead author and project scientist at UC San Diego Moores Cancer Center. The research team tested their findings in mice and confirmed that when TYK2 was blocked, cancer spread more aggressively.

The discovery matters beyond basic science. Pharmaceutical companies are currently developing TYK2-inhibiting drugs to treat autoimmune diseases like psoriasis and inflammatory bowel disease. The new findings suggest these medications could accidentally increase breast cancer risk in some patients.

The Ripple Effect

This research is already changing how doctors think about cancer screening. Patients with certain types of noninvasive breast cancer who take TYK2 inhibitors may need enhanced monitoring to catch any signs of progression early.

The team's work also opens exciting possibilities for new cancer treatments. By understanding exactly how TYK2 prevents metastasis, scientists can now explore ways to boost its protective effects or develop therapies that mimic its action.

Dr. Jing Yang, professor of pharmacology at UC San Diego School of Medicine and corresponding author, emphasized the broader implications. "Our findings underscore the importance of considering the mechanical microenvironment in cancer therapy," she said.

The research highlights how our bodies already have sophisticated systems for fighting cancer. The more scientists understand these natural defenses, the better they can design treatments that work with our biology rather than against it.

This discovery joins a growing body of research showing that the physical properties of tissues matter just as much as their chemical makeup in cancer development.