Student researcher tests theory that plant sterols can block cancer

BRADFORD, Pa. -- What if certain foods could block cancer? Andrew McRandal spent his summer trying to answer that question, using tiny fruit flies as guinea pigs.  

The sophomore University of Pittsburgh at Bradford pre-medicine student from Pittsburgh learned that this was a complex process. It involved the precise timing of fly fertility, administration of carbon dioxide and deftly tapping on a beaker of fruit flies, a trick that should make them all fall to the bottom for easy separation.  

McRandal is conducting research overseen by Dr. Lauren Yaich, associate professor of biology. Yaich has long worked with fruit flies because they are inexpensive and produce a new generation every 10 days.  

Her newest research involves a promising hypothesis that compounds found in plants may be able to reduce cancer risk. Food derivatives such as wheat germ and rice bran oil are full of phytosterols currently used to lower cholesterol in humans, she explained.  

“Because a lot of people think phytosterols could also lower cancer risk, we thought it would be interesting to look at,” she said.  

She returned to her knowledge of fruit flies to design an experiment that could be performed by a student researcher. The first step was to breed flies that would develop cancer without intervention.  

To carry out the breeding experiments, two fly lines were obtained from Dr. Ross Cagan at Mt. Sinai School of Medicine. One line carried a tumor-causing gene. The other line produces a protein that could activate the tumor-causing gene. By themselves, each fly line looked perfectly normal. But when mated together, their offspring would grow tumors on their eyes.  

To make things even trickier, the experiment required that the female flies be virgins. Here, the sped-up life cycle of the flies becomes an advantage. A beaker full of male and female flies was allowed to reproduce, then the females laid their eggs in a food medium (to simulate fruit) in the bottom of the container. Once females laid their eggs, McRandal tapped the beaker, the adult flies fell to the bottom, and he collected and removed them.  

The lifecycle of a fruit fly is similar to that of a butterfly. Once the eggs hatched, the larvae ate the food medium until they were ready to climb the sides of the beaker and undergo metamorphosis inside a pupa, changing into an adult fly. When the virgin flies emerged from their pupae, McRandal had eight hours from the time the flies hatched until they reached sexual maturity. As the new adult flies emerged, he collected them, saving the virgin females and tossing the males.

Once virgin females from one line were obtained, they were then mated with males from the other line in vials containing either regular food as a control or food that was rich in phytosterols. From this cross, McRandal would then examine the tumors in the offspring under a microscope.

McRandal gave each fly a score based on whether it had developed a tumor and what size it was, scoring about 200 fruit flies in an hour.

“It can be therapeutic,” McRandal said about the meditation-like mindset needed to score hundreds of fruit flies.

“I love the research,” he said, adding that he has been helping with lab work in the chemistry department as well as a student worker.

McRandal said that while he learns a lot from reading, the research helps him make better sense of what he is reading.  

Currently, he is reading a lot. Having just collected results, he will synthesize his results with background information from other scientists into a paper that he hopes to present at several undergraduate research conferences this year. He has not yet formed definite conclusions for the research.

“What is the most rewarding part of research is when you collect the results,” McRandal said.

Yaich agreed. “Sometimes, you're the only person in the world who knows what you've found out - until you share it.”