UC San Diego Study Identifies TYK2 Protein as Critical Sensor Regulating Breast Cancer Metastasis Through Tissue Stiffness

Researchers at UC San Diego discover the TYK2 protein suppresses breast cancer metastasis by sensing tissue stiffness, raising concerns over TYK2 inhibitors.

By: AXL Media

Published: Apr 1, 2026, 9:07 AM EDT

Source: Information for this report was sourced from University of California - San Diego

The Mechanics of Cancerous Invasion

The process by which cancer cells transition from a localized tumor to a metastatic disease is heavily influenced by the physical properties of the tumor microenvironment. Scientists at UC San Diego have identified a biological mechanism known as mechanotransduction, where cells sense and adapt to the stiffness of the extracellular matrix—the "scaffold" that connects and supports cells. This research highlights that the physical environment is not just a passive backdrop but an active participant in cancer progression. By understanding how cells interpret these physical cues, the medical community can develop more effective strategies to arrest the spread of breast cancer before it reaches vital organs.

TYK2 as a Biological Barrier to Metastasis

At the center of this discovery is a protein called TYK2, which has traditionally been associated with the body's inflammatory response. The study reveals that TYK2 serves as a critical suppressor of metastasis, essentially acting as a lock that prevents cancer cells from breaking away. When the extracellular matrix maintains a low level of stiffness, TYK2 remains stationed on the cell membrane, effectively blocking the pathways that allow cancer cells to invade neighboring tissues. This finding suggests that the protein’s location and activity are directly governed by the structural integrity of the tissue surrounding the tumor.

The Impact of Tissue Rigidity on Protein Function

The research team found that as a tumor grows and the surrounding tissue becomes increasingly rigid or "high stiffness," the behavior of TYK2 changes dramatically. In these high-stiffness environments, the protein is inactivated and disperses throughout the cell rather than remaining on the membrane. This displacement removes the natural barrier to invasion, providing cancer cells with the opportunity to migrate and metastasize. Lead author Zhimin Hu, PhD, noted that this specific transition explains why denser, stiffer tumors are often associated with more aggressive forms of breast cancer and a higher likelihood of spreading.