Plants could deliver potent anti-tumor agents

In Vicki Vance’s lab, the expression “You are what you eat” might soon take on new meaning.

The veteran molecular plant scientist thinks genetically modified plants could become useful weapons in the war against human cancer. To test the idea, she’s turning plants into bio-factories that make tumor-suppressing micro-RNA (miRNA).

“There are about 2,000 types of miRNA that control every major physiological process in the body at the cellular level, but they can get out of balance,” Vance said. “For example, when the type of miRNA that suppresses tumors is diminished, a cell’s ability to divide rapidly can go unchecked.”

Cancer scientists have been eager to use miRNA to control cancer, but it’s not so easy. Previous research has shown that synthetically manufactured miRNA rapidly degrades in the bloodstream and doesn’t infiltrate cells very well.

Putting the miRNA in nanoparticles and chemically modifying it to make it more stable has yielded better results, but the accompanying toxicity can cancel out the benefits.

“That’s where our research comes in,” Vance said. Her team’s previous work in the field of gene silencing involved using miRNA to genetically manipulate plants to express desired traits. Vance developed a patented process for making any type of miRNA in plants.

Her research team has modified a common cruciferous plant called Arabidopsis to make three tumor-suppressing miRNAs. This fall, the team plans to feed the plants to mice that have been bred with a propensity for digestive tumors. Earlier proof-of-concept experiments in her lab showed significant potential for reducing the rodents’ tumor burden.

This is Vance’s first foray into cancer research and was sparked about three years ago after reading the findings of a Chinese research team that found evidence of plant miRNA affecting mammals that ingested it. The paper stirred scientific debate, and Vance saw immediate opportunity for additional research.

“We asked ourselves, ‘What if we made tumor suppressor miRNA in a plant and fed it to an organism with cancer?’ ” she said.

Vance has secured a small grant from the National Institutes of Health and institutional funding from the Office of Research, but she is hopeful for bigger things if this fall’s experiments go well.

“I have high hopes,” she said. “This research looks so promising. If you can just eat something that helps fight cancer, how can we not invest more time and resources to learn more?”

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