Heart’s Constant Beating Suppresses Tumor Growth in Cardiac Tissues

The results of a study by researchers at the International Centre for Genetic Engineering and Biotechnology (ICGEB) suggest that the heart’s constant beating may actively suppress tumor growth in cardiac tissues. The collective findings from the team’s research in mouse models and in engineered heart tissues (EHT) suggests that this is because cellular pathways in these tissues alter gene regulation in cancer cells to keep them from proliferating.

Headed by Giulio Ciucci, PhD, and Serena Zacchigna, MD, PhD, at the ICGEB Cardiovascular Biology Laboratory, the scientists say the findings shed light on the role of mechanical forces in protecting the heart from cancer and may pave the way to new cancer therapies based on mechanical stimulation. First author Ciucci, together with senior author Zacchigna and colleagues reported on their findings in Science, in a paper titled “Mechanical load inhibits cancer growth in mouse and human hearts.” In their report the authors concluded “Collectively, the data presented in this work provide evidence that mechanical load in the heart inhibits cancer cell proliferation, likely explaining the low incidence of cardiac tumors.”

Heart cancer is very rare in mammals, but as the authors noted, “The mechanisms that protect the heart remain elusive.” The adult human heart in addition has a limited capacity for self-renewal, with cardiomyocytes regenerating at roughly 1% per year. “This suggests that the same mechanisms that halt the proliferation of cardiac cells could also inhibit the growth of cancer cells in the adult heart,” the authors continued. One proposed explanation for this loss of cardiomyocyte proliferative capacity lies in the intense mechanical demands placed on heart tissues, which must continuously pump blood against significant resistance. “We hypothesized that it could similarly hamper the proliferation of cancer cells in the heart,” the investigators reported.

Using a genetically engineered mouse model, Ciucci et al. first showed that the heart is remarkably resistant to cancer-causing mutations, even when potent oncogenic changes were introduced. To understand why, the authors developed a transplantation model in which the heart’s mechanical workload could be reduced. By grafting a donor heart into the neck of a compatible mouse, they created a “mechanically unloaded” organ, one that remained perfused with blood but did not bear physiological strain. “To assess the contribution of mechanical load to the low incidence and growth of cancer in the heart, we used a model of in vivo cardiac unloading by heterotopically transplanting a donor heart into the neck of a recipient syngeneic mouse,” they explained.

According to the study findings, mechanical forces within the tissue reshape the cancer cell genome’s regulatory landscape, influencing whether cells can proliferate. Central to this process is Nesprin-2, a protein that transmits mechanical signals from the cell surface to the nucleus. “Nesprin-2, a protein known to mediate mechanotransduction from the cytoplasm to the nucleus, emerged as a key molecule sensing mechanical forces operating in beating hearts and translating them into reduced cell proliferation,” the scientists reported.

Nesprin-2, a component of the LINC complex, senses the mechanical microenvironment of the heart and functionally alters chromatin structure and histone methylation, reducing gene activity linked to tumor cell proliferation. When Nesprin-2 was silenced in cancer cells, those cells regained the ability to grow in the mechanically active environment of the heart, forming tumors. “Silencing of Nesprin-2 in lung cancer cells prior to their implantation in the heart in vivo restored the capacity of the cells to proliferate in the presence of physiological mechanical load, resulting in the formation of large tumors,” the authors stated.

The team noted that their collective results shed light on the role of mechanical forces in protecting the heart from cancer and may pave the way to new approaches to cancer therapy. “This offers fundamental insights into the biology of cell proliferation within the myocardium, and additionally, the mechanical stimuli that operate in a beating heart could be exploited for the development of a mechanical therapy for cancer.”

The post Heart’s Constant Beating Suppresses Tumor Growth in Cardiac Tissues appeared first on GEN - Genetic Engineering and Biotechnology News.