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Megan Johnstone

The Affect of Nutrition on Cancer Growth

By Jennifer Brouner

Undergraduate researcher Megan Johnstone spends nearly all of her time at the University of Tennessee in the Jessie Harris Building. After climbing up three flights of stairs and entering into one of the uppermost rooms of the building, Johnstone begins her daily routine.

At 8:30 a.m., Johnstone starts by thoroughly washing her hands—making sure that she scrubs every inch of them clean. She then tugs on a pair of blue rubber gloves, and afterwards, she squirts her now blue hands with ethanol.

Finally satisfied that she has killed any dangerous substances that may pose a threat to her research project, she turns to her left and opens the door to what appears to be a refrigerator. But what she pulls out does not look very appetizing. In her clean blue hands, she holds a glass flask where a bright red liquid sloshes back and forth. Johnstone has just pulled out yesterday’s harvest: a new generation of melanoma cells that she has been cultivating.

Megan JohnstoneThe storage container that looks like a refrigerator is called an incubator. In it are many other jars containing different kinds of melanoma cells. It doesn’t take much work to grow melanoma cells, admits Johnstone. “I can thaw cells, plate them, and the next day they can be ready to go,” she says.

Different types of cancers grow at different rates, but the melanoma cells that Johnstone studies double in number in about eight hours. “I find that a little bit scary,” Johnstone confesses. “That is skin cancer after all.”

Johnstone joined Dr. Michael Zemel’s lab after listening to him speak in one of her nutrition classes about his research, which focuses on the study of energy metabolism within cells and organisms. Johnstone approached Dr. Zemel, Professor of Nutrition and Medicine at the University of Tennessee, about conducting research in his lab. He was more than happy to accept her as his newest undergraduate researcher in the spring of 2010.

After entering the lab, Johnstone was taught proper lab technique, but that was not what made her research experience a unique opportunity. “Technique is just a series of tasks. Research is about the thought that goes into the experiment,” says Dr. Zemel. Undergraduate research has taught Johnstone how to synthesize and voice new ideas about research, and also how to design and conduct an experiment.

After working alongside graduate students for the first few months, Johnstone was ready to be given an independent project. Dr. Zemel wanted her to attempt to alter the metabolism of the melanoma cells, some of which exhibit an increased reliance on glucose for growth. This metabolic shift is referred to as the Warburg Effect.

A normal cell uses highly efficient machines called mitochondria, explains Johnstone. Nearly 16 times more energy per glucose molecule is produced when the mitochondria is used.

However, for reasons that still baffle scientists, some types of cancer cells rely on a much less efficient method of energy production—one that does not involve the mitochondria at all. This type of energy production causes the cells to always desire more glucose.

“It’s like a high school boy that has a bottomless pit for a stomach. He just eats and eats and eats and eats,” Johnstone says. “Melanoma cells have no control, so these cancer cells just grow exponentially, as opposed to normal cells that have systems to prevent uncontrolled cellular growth.”

Johnstone tests these melanoma cells by exposing them to differing concentrations of glucose and amino acids (the building blocks of proteins), and observing the genetic effects on cellular metabolism. In 2010, she exposed the melanoma cells to incredibly high levels of glucose. This summer, she is exposing them to lower levels of glucose to see if they will respond differently. After treating the cells, she analyzes their genetic responses by observing the production of messenger RNA, which is simply a movable copy of DNA.

Dr. Zemel and Johnstone discuss her research at least once a week—brainstorming new ideas together and determining the best way to test the ideas they come up with. “Megan has sufficient self confidence to be willing to challenge and question me,” says Dr. Zemel. “Scientists have to be willing to put a wrong idea out there. That’s the only way we get to the right one.”

The goal of Johnstone’s research is to find a way to cause the cancerous cells to go into cell cycle arrest, which means she wants to prevent the cell from growing exponentially. “If we can learn to manipulate this growth,” says Johnstone, “then hopefully some doctor somewhere will be able to use this and potentially help somebody live longer until a cure can be found. That’s my idealistic sugar-coated dream.”

This breakthrough is at best years away, possibly decades, cautions Dr. Zemel. There is also a chance that this line of research will be totally ineffective when dealing with cancer.

Despite this, Johnstone works nearly 30 hours a week in the summer and manages to spare 20 hours or more a week during the school year studying the metabolism of cancerous melanoma cells. “It’s a lot of hard work, and it’s frustrating sometimes when I have to give up a Friday night or a Saturday morning to come in and take care of my research,” says Johnstone, “but at the end of the day I feel better about myself.”

Undergraduate research can be time consuming, but Johnstone has no regrets. “Undergraduate research easily defines my college experience,” she says. “The time I have spent here has defined what I want to do with the rest of my life … Work is work, but it is so much fun to just go in and do what I like and what I understand.”

Dr. Zemel is very proud of his undergraduate researcher. “Megan is bright, inquisitive, and a pleasure to work with,” says Dr. Zemel. “She’s not afraid to challenge me, and that’s a good trait to have. The quality of her work pretty early in her undergraduate career suggests this is only going to get better.”

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