Scientists may have discovered another way the human body tries to protect itself from cancer. New research on mice suggests that the heart's constant beating may prevent tumour growth in cardiac tissue. Most organs are vulnerable to cancer, but the heart is something of an anomaly. While cancer can spread from other parts of the body to the heart, tumours rarely start there. It's a medical mystery that has puzzled scientists for years.

Researchers  suspected that it may have something to do with mechanical load and physical forces of the heartbeat, so they decided to investigate. That is, the physical stress the heart muscle is under as it constantly contracts and relaxes to pump blood could be what helps protect the heart from cancer growth.

The study is published in the journal Science, as well as a Perspective.

The team first transplanted a donor mouse heart into the neck of another mouse. This second heart had a blood supply but was not mechanically pumping blood around the body. Then they injected cancer cells into both hearts to compare tumour behaviour. While tumour cells spread aggressively in the transplanted heart, cancer cells replaced only about 20% of the tissue in the original beating heart.

To understand what could be happening at the cellular level, the scientists created engineered heart tissue (EHT) in the lab. They varied the mechanical load on the tissue by stretching and altering pressure to monitor its effect on the growth of human lung cancer cells. The more pressure they put on the EHT, the slower the cancer cells grew.

"Mechanical forces in the beating heart protect it from cancer by halting cancer cell proliferation," they wrote in their paper.

The research team also analyzed cell samples of patients whose cancer had spread to the heart and compared them with tumours in other parts of the body. According to the study's findings, mechanical forces alter how cells organize their DNA by interacting with the protein Nesprin-2.
When the heart squeezes, Nesprin-2 senses the pressure and helps transmit that mechanical signal to the cell's nucleus. In response, the packaging of DNA in a structure called chromatin changes. It becomes less compact, which makes it easier for the cell to access and activate genes that slow cancer cell growth.

When researchers silenced the Nesprin-2 protein in those cancer cells, they couldn't sense the mechanical pressure and began to grow and multiply. "Nesprin-2 is a key molecule sensing these forces and translating them into reduced cell proliferation."

If scientists could mimic these mechanical forces with drugs or technology, they could potentially stop cancer cells in their tracks.

Giulio Ciucci et al, Mechanical load inhibits cancer growth in mouse and human hearts, Science (2026). DOI: 10.1126/science.ads9412

Wyatt G. Paltzer et al, The heart puts pressure on cancer growth, Science (2026). DOI: 10.1126/science.aeg8798