Drugs now approved to treat heart disease, bacterial infections, and other ailments hold promise as potential chemotherapies for cancer, according to new research out of the University of Montreal.

In a study published in Cancer Research, researchers found many drugs used to treat heart failure, cardiac arrhythmia, and infections suppress the growth and development of cancer cells.

"We identified a dozen or so drugs that reactivate tumor suppressor genes through an epigenetic mechanism that was never observed before", said Noël Raynal, a specialist with the research hospital CHU Sainte-Justine. "Epigenetic mechanisms control gene expression. They are highly deregulated in cancer cells. The mechanism that we discovered controls gene expression by targeting intracellular calcium levels."

All the identified drugs are U.S. Food and Drug Administration-approved.

"Since these drugs' safety and efficacy in humans are already known and proven, they may readily go through clinical validation and be made available to patients more quickly," said Raynal, who is also a professor in the Department of Pharmacology at the University of Montreal.

To reach their conclusions, the researchers screened more than 1,100 FDA-approved drugs and identified the 14 most promising anti-cancer agents. Among them: cardiac glycosides and antibiotics, whose epigenetic effects were previously unknown.

"All our drug candidates had in common their ability to act on the calcium channel and activate an enzyme essential for the anticancer effect," said Raynal. "This is consistent with epidemiological studies showing less cancer in patients treated with cardiac glycosides, and less aggressive cancers in patients that did have cancer."