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Scientists Look for Link Between Stress and Disease
Produced by Lynette Kalsnes on Wednesday, October 31, 2007
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Dr. Suzanne Conzen and Professor Sarah Gehlert |
A lot of us think of our genes as sort of this immutable force. We’re born with our DNA, and it doesn’t change. But genes can be turned on or off. Or they can even be turned up or down, so they work with the intensity of a spotlight, or the dimness of a candle. As part of our DNA Files series on genetics, we learn why some scientists think our environment can activate this system and affect our genes.
The fancy term for it, is gene-environment interaction.
CONZEN: We know that small changes in the interactions of the proteins and the genes are very, very important.
Dr. Suzanne Conzen is an oncologist and researcher at University of Chicago.
CONZEN: A lot of the systems in your body work through systems like a dimmer switch. And those dimmer switches in turn interact with other dimmer switches, and so there’s a feedback. And you can imagine that small changes can have big repercussions.
For scientists like Conzen, environment doesn’t just mean the industrial plant that dumps chemicals in your water, or the congested highway next door, that has you breathing exhaust all day.
She works with Sarah Gehlert at the university’s Center for Interdisciplinary Health Disparities Research. Sarah Gehlert:
GEHLERT: I don’t think people really do have a good idea of how social circumstances, just the quality of your neighborhood, things that are less morphous, impact health.
That’s a puzzle that researchers at the University of Chicago are trying to solve. They know African American women in Chicago are 68 percent more likely to die of breast cancer than white women. Gehlert and Conzen want to find out if a woman’s living conditions can affect her genes. Do crime, isolation and stress have anything to do with why young African-American women disproportionately get a nasty form of breast cancer?
GEHLERT: We really haven’t grasped the significance of just that almost baseline violence, that baseline stress, that goes on everyday.
To find out, researchers are studying African-American women with breast cancer in 15 neighborhoods on the South Side. They’re analyzing the women’s DNA, and also their living conditions, including crime stats from their neighborhoods.
ambi: neighborhood streets
Lori Booker lives in one of these neighborhoods. She joined the study after she found a lump in her breast. Her apartment’s about three miles south of the university, but that’s a world away. She points to a house that’s kitty-corner from her apartment.
BOOKER: You can tell the crack walk. I don’t know what that stuff does to them, but it makes ‘em walk real fast, and they’re thin. And they’ll come over, get whatever they have to get and leave right out.
She’s found gun casings behind her building. Sometimes there are fights. So she tries not to go outside at night. Some scientists think crime and isolation – and the stress they cause – are taking a toll on the health of Booker and women like her. Nearly one-fifth of the women in the U of C study live alone. Twenty-two percent of them are clinically depressed. Booker says she struggles with depression.
BOOKER: I feel like a basket case sometimes. I think about, you always hear people on TV, they sound so positive and so forth. I’m like, are they lying, or do they really feel like me?
Booker wonders if her health would be better, if she lived in a different neighborhood, felt less isolated, and had less stress at work.
BOOKER: Well, if my life was different, instead of being single, 34, a cat, mostly by myself for days on end, and just talking to people on the telephone, how would it have been different? Could I have avoided breast cancer? |
It’s really too early to tell what, if any, role these social conditions play in human breast cancer. But let’s go to the lab, to see what happens, when mice and rats live alone
CONZEN: What we’re going to do is we’re going to go into the mouse room.
Here in this sterile white laboratory at U of C, there are cages of white mice that are genetically identical. Dr. Suzanne Conzen is trying to create conditions that lead to isolation and a sense of vigilance. So some of her mice grow up in groups. Others live completely alone. And then she exposes them to stress, to see what happens to gene expression, and their tumors.
CONZEN: If you’d like, we can go in and see the testing area.
She picks up a demonstration mouse that lives in a group and releases it into a box. It immediately starts exploring. The isolated mice?
CONZEN: They often stay there for 3 to 5 minutes without moving out, and you’ll see them sort of peering outside their bowl. What’s intriguing is the isolated mice have a higher level of stress hormone after the experiments. And Conzen says this stress hormone latches onto its receptors inside the breast cancer cells, and appears to help these cells survive, so the tumors can keep growing.
Now that’s mice. It’s unclear what this means for humans. But we do know that some people handle stress better than others. And researcher Eva Redei wants to find out why.
REDEI: Stressful events are all around us, and that’s just going to increase, so we need to know how we can control it.
Redei’s a psychiatry professor at Northwestern University who studies rats. She wants to know if it’s HOW we cope with stress that changes our genes.
ambi: lab
KALSNES: You just scooped a little brown object out of a tube. What is this?
REDEI: Well, that is the rat brain.
Before Redei dissects the rats, she puts the live ones into a box with a device that administers a small shock. When normal rats get a shock, they bury the device in bedding. But the depressed or passive rats? They stand in a corner, or even go back for another shock.
KALSNES: It almost makes me think of a pessimistic, a depressed pessimist, who’s expecting everything is going to be bad, and so doesn’t feel it necessarily, or doesn’t expect it will change.
REDEI: Exactly. And that is exactly what we think is happening.
There are people who, when under stress, act very much like these rats. And studies have shown they have an increased risk for getting conditions like hypertension. Redei hopes that eventually, there will be a genetic test to predict for depression and this way of dealing with stress. And if you could reach these people early on, you could help them avoid falling into these behavior patterns. And that would be a good thing, right?
ZOLOTH: If you could, you would have people all living lives like some version of Club Med, I suspect, right?
Laurie Zoloth, a bioethicist at Northwestern, says that might not be as good as it sounds.
ZOLOTH: We used to think of the soul as ourself, but now we think of, boy, if that DNA, that double helix, as the essential self. And when you think about altering that in some way, it’s a little bit like the Faustian notion of you could make this deal, but you would lose the essence of your being.
Zoloth raises another ethical issue that’s a little more down-to-earth, and no easier to solve. If scientists do find that our living conditions alter our DNA, and make us sick, what obligation do we have to fix our neighborhoods?
Thanks to the DNA Files Public Radio Documentary Series for their support. Visit dnafiles.org. It’s a project of SoundVision Productions, Berkeley, California. You can chat on-line with scientists about their work and debate the ethical questions we’ve covered in our DNA Files series.
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