Ingredient in Broccoli Boosts Cancer Drug Efficacy

An ingredient in broccoli that can alter the activity of endogenous enzymes had a positive influence on drug efficacy, a recent study found.

Researchers from the University of Zurich began studying the effects of sulforaphane on human intestinal cells. Sulforaphane is an ingredient that occurs naturally in several cruciferous vegetables, like broccoli.

During the study, researchers used sulforaphane to treat different types of colon cancer, along with intestinal cells from healthy subjects. The concentration of sulforaphane was similar to that which reaches the intestines after eating broccoli, but does not kill the cells itself.

The results of the study, published in PLOS ONE, reported that sulforaphane increases the concentration of enzymes in colon cancer cells, including enzyme AKR1C3. AKR1C3 is a biochemical actor in several metabolic pathways within the body.

However, this effect was not found in all cases. Colon cancer cells that had significant elevated concentrations of AKR1C3 as a result of the cancer, were found to have an increased concentration of the enzyme from the broccoli substance.

Colon cancer cells with very low concentrations of AKR1C3 and intestinal cells that were unaffected by cancer had no effect from sulforaphane. AKR1C3 is also central in the efficacy of the drug PR-104A, which is currently in the developmental stage in clinical testing.

PR-104A is administered in an inactive form and is converted into its active form within the cancer cells by AKR1C3.

In order to test whether sulforaphane increased the efficacy of PR-104A, researchers used cell cultures to confirm their hypothesis. Colon cancer cells pre-treated with sulforaphane needed less than one-third of the usual dose of PR-104A to kill cancerous cells.

The investigation of the influence of sulforaphane on intestinal cells was studied at the genetic and functional level.

“Since cancer drugs generally have strong side-effects, any approach that reduces the dose of medication while maintaining efficacy is always welcome,” said lead researcher Shana Sturla. “What's interesting with sulforaphane is that it occurs naturally in our food and is non-toxic in the concentrations we used. In addition, the sulforaphane-enhancing effect was seen only in cancer cells and not cells from healthy tissue, which would be very important for avoiding unwanted side-effects from the combination.”

Researchers hope to conduct a future biomarker-based study using cancer patients to determine whether sulforaphane supports a PR-104A treatment. Additionally, researchers will continue to look for other food ingredients that could have a positive effect on the efficacy of medication and accompany biomarkers that help track personalized responses.

“We assume that there are other such combinations out there,” Sturla said.