Contrary to previous theories among scientists and doctors that heart patients are at increased risk of cancer just because of obesity, smoking, and complications of type-2 diabetes, a new Israeli study reveals that following a myocardial infarction, extracellular bubbles are secreted from the heart that increases the risk of malignant tumors.
Researchers at Tel Aviv University (TAU) and at Sheba Medical Center at Tel Hashomer have found a mechanism that is responsible for the increased risk of getting cancer among heart disease patients. They are small, extracellular vesicles (sEVs) that are secreted from the sick heart to heal it and released into the bloodstream. They encourage the growth of cancer cells throughout the body.
The researchers believe that the important discovery may in the future improve the protocols for the treatment of heart diseases so that they also take into account the increased risk of cancer.
The study was led by Prof. Jonathan Lior from TAU’s Neufeld Heart Research Institute and Medical School and Sheba’s Tamman Cardiovascular Research Institute and his research student Tal Coller at TAU. Just published in the scientific journal Circulation under the title “Small extracellular vesicles from infarcted and failing heart accelerate tumor growth,” it was funded with the assistance of the ICA and the Israel Science Foundation.
Coller explained: “In 2013, Israeli cardiologist Tal Hasin showed for the first time that there is a connection between heart failure and cancer. Heart patients are at a higher risk of getting cancer, and since heart disease is a leading cause of death (first place in the US and second, after cancer, in Israel), there are many people who are at risk. We checked what the diseased heart secretes that may be a cancer-promoting factor, and we found that the culprit is small extracellular bubbles. These are tiny particles wrapped in a membrane, which all cells secrete, but as a result of heart damage, the bubbles are released in greater quantity and contain factors related to growth, the creation of blood vessels and changes in the immune system, moving in the blood circulation and eventually reaching the malignant tumor or the pre-cancerous tissue.”
Coller added “following an infarction in the heart muscle and deterioration to heart failure, small extracellular bubbles containing growth factors and small nucleic acid molecules that encourage cell division are released. This mechanism is actually intended to heal the injured cardiac tissue, but the bubbles are released from the heart, moving in the blood circulation in the body and eventually reaching the cancerous growth as well.”
“Many theories have been proposed for the increased risk that heart patients are at for cancer. Starting with common risk factors such as smoking, diabetes and obesity, and ending with a specific protein or molecule,” said Lior. “We showed for the first time that the diseased heart secretes bubbles that contain thousands of different growth factors; they don’t encourage the growth of any tumor, but they certainly affect the immune system and may cause any tumor in the body to benefit from them.”
