St. Jude Children's Research Hospital scientists have discovered that a protein used by cancer cells to evade death also plays a vital role in heart health. This dual role complicates efforts to develop cancer drugs that target the protein, but may lead to new therapies for heart muscle damage. The research appeared in the June 15 edition of the scientific journal Genes & Development.
The protein, MCL1, is currently the focus of widespread cancer drug development efforts. MCL1 is best known as an inhibitor of death via the cell's suicide pathway in a process called apoptosis. The protein is elevated in a variety of cancers, and a number of MCL1 inhibitors are in the cancer drug development pipeline worldwide. The protein has also been linked to drug resistance in cancer patients. Until now, however, MCL1's role in heart muscle cells was unclear.
"Our study shows that MCL1 is required for normal cardiac function and that the protein may be critical in protecting the heart from apoptosis," said Joseph Opferman, Ph.D., an associate member of the St. Jude Department of Biochemistry and the paper's corresponding author. Unlike skin or blood cells, heart muscle cells cannot be replaced, so even a small loss through apoptosis can be devastating. In this study, knocking out MCL1 in mice led to death from cardiomyopathy within weeks.
"These findings suggest that cancer-related drug development efforts should focus on reducing MCL1 expression in target cells rather than eliminating the protein's function completely," Opferman said.
The results also have implications for treating heart muscle damage following heart attacks or other insults. While limiting MCL1 in cancer cells might aid in destroying them, providing higher levels of the protein in heart muscle cells might benefit a patient recovering from a heart attack or other heart damage. "These findings have broad implications for human health," Opferman said.
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St. Jude Children's Research Hospital