Gene Expression and Environmental Health
09:00 am US Eastern Time
1. Welcome: CHE - Year in Review: Michael Lerner, Ph.D., President, Commonweal
This has been a good year for CHE, as we approach our second anniversary in March, we have 825 Individual and Organizational Partners. A year ago, we had 400. There are over 40 health-affected groups, 24 health professional and public health organizations, 17 health and environmental organizations, 35 media, philanthropic and international organizations. We've held regional meetings in New York, Boston, Seattle, Sioux Falls, and a national meeting in San Francisco. We have active working groups on Science, Learning and Developmental Disabilities, and we're developing a Health Professionals Group. We have active discussion groups on Breastmilk Monitoring and Fertility/Pregnancy Compromise. There are regional CHE groups in the Northwest and in California. We've done partnership calls on body burden, breastmilk biomonitoring, asthma, autism, the precautionary principle, birth defects, European chemical policy, and infertility. We also distributed $25,000 in mini-grants to 12 CHE Partners.
For the coming year, we're planning regional meetings in Florida, Texas, Pittsburgh, and Los Angeles. We're developing an approach to policy issues that will allow CHE Partners to find others with shared interests for collaborative action without bringing any Partners who don't want to work on policy into the process. In the science area, we hope to develop fact sheets in lay terms for greater distribution, a disease spreadsheet that shows the science on 200 conditions as they relate to environmental contaminants, and we'll continue the evaluation and dissemination of the latest science.
So, that is a brief overview of what has been done under the leadership of CHE Chairman, Dr. Phil Lee, former Assistant Secretary of Health and Chancellor Emeritus at the University of California, San Francisco, School of Medicine.
We feel that in the third year we will surely grow beyond 1000 Partners. We would like to hear from CHE Partners about what is working for you and what you'd like to see more of in the coming year.
2. Science Update: Ted Schettler, M.D., M.P.H., Science Director, Science and Environmental Health Network
I would like to comment on a study recently published in the Journal of Applied Toxicology that has received quite a bit of media and public attention. Some researchers in England analyzed the tumors of 20 breast cancer patients for a chemical called Parabens, which is used in consumer products, including underarm deodorants.
It had been demonstrated previously that parabens (a family of compounds) have estrogenic activity up to 100's to 1,000's of times less potent than naturally occurring estrogen. Depending on the compound and the assay system it can be demonstrated that they have estrogenic activity. The hypothesis is that the use of cosmetic personal care products that contain estrogenic compounds may increase breast cancer risk.
This was the first study that identified these chemicals that are present in underarm deodorant in breast cancer tissue in a small sample of people. The study was picked up by the popular media and has been read and commented on all over the world. We thought it might be useful to talk about what this study means and what it doesn't mean.
What it means is that there is a need to examine the hypothesis that foreign estrogenic agents may contribute to breast cancer incidents or severity. But the study didn't look for the same compounds in either non-cancerous tissue in these women or in women who don't have cancer. So what we don't know is whether these women with these chemicals in their breast cancer are disproportionately exposed or for some other reason tend to have higher levels of these chemicals in their breast tumors than women without breast cancer do. It also didn't confirm that underarm deodorant was the source of these compounds. It is important to note that what they actually isolated from the tumor was the parent compound and not a metabolite. So it seems likely that it was through skin absorption rather than through dietary exposure, for example that these people were exposed.
I also want to point out a few other issues that are raised by this study.
1) Skin absorption is an important root of exposure for some compounds. In particular, the skin of some parts of the body are more permeable than others including the underarms, the scalp, parts of the face, and various other areas. This is typically not taken into account when people are thinking about the skin absorption of biologically active agents.
2) We need to consider skin absorption of other components of cosmetics as well. For example some musk compounds used in fragrances have previously been isolated from breastmilk, and some are known to be estrogenic as well as carcinogenic. So this is an important area to keep in mind.
3) The regulatory framework that authorizes the Food and Drug Administration to oversee cosmetics simply does not require safety testing of ingredients that are used in cosmetics or personal care products. It does say that if their safety has not been determined then they must be so labeled. But the safety testing that would meet that obligation is minimal and really does not include comprehensive assessment of a variety of potential health affects.
The bottom line is we need to continue to look at cosmetics and personal care products as an important source of exposure to a variety of biologically active agents that may have adverse health affects.
Michael Lerner: Just as we appropriately object to the blatant misuse of science that takes place on the part of industry involved with these chemicals, so it is quite possible that a study will be done like this, that gets into the media in a somewhat distorted form and is then picked up by activists and used without any critical review, when in fact the science doesn't support the media version, or the version that the activists cite. I think one of the things that CHE can do, is to subject emerging science on the role of contaminants and the disease states that concern us, to a critical assessment. So before we go forward with the latest headline on something, we need to really take a careful look to see what the science actually says. Our goal is to stand for careful science, because the careful science itself, as we are about to hear, is infinitely powerful and our work will be much better if we stay close to what the science actually says.
Phil Lee: I just wanted to add that the Food, Drug and Cosmetic Act, was passed so there is a vehicle if the science demonstrates more action is necessary, you don’t have to start from scratch. The cosmetic side, as Ted points out, is much less rigorous in its regulation but with respect to things like the precautionary principle than we are with respect to drugs.
(for information on CHE Partners involved with this issue please see: http://users.lmi.net/wilworks/FDApetition/bkgrinfo.htm)
3. CHE Feature: Signal Disruption/Gene Expression
First Speaker: Pete Myers, Ph.D., Senior Advisor to the United Nations Foundation, Co-Author of "Our Stolen Future" and CEO of Environmental Health Sciences
Parabens have just been described as an estrogenic substance, but what does that really mean? Principally, under most circumstances, an estrogenic substance somehow is interacting with a suite of estrogen receptors and together it's affecting gene expression. It's altering the pattern of the expression of genes in ways that in this case, may or may not be increasing the likelihood of a proliferation of breast cancer cells, but are in fact involved in affecting a wide array of molecular processes that take place once gene expression is altered.
This focus on gene expression is emerging now as a huge new issue in linking environmental diseases and environmental exposure. It's truly exciting because it is both revealing the mechanisms by which low level effects can be taking place, as well as it is dramatically broadening the range of health endpoints that now are considered potentially vulnerable to environmental disruption by alterations of gene expression.
So we thought that it would be helpful to look at some of the basic issues in biology and in gene expression that are involved here because it sets up a completely new array of possibilities for disease prevention, as this science plays out. The bottom line is that when we all hear new work that comes out saying that this disease is linked to that gene, all too often we interpret that as implying that the disease therefore is under genetic control and is immune to environmental influence. This new science flips that on its head. When I hear that a disease is now linked to a gene, my first question is who's looking at patterns of alteration in gene expression, what contaminants are involved and how can we start to reduce exposures to those identified contaminants.
Second Speaker: Louis Guillette, Ph.D., Distinguished Professor of Zoology and Associate Dean for Research, University of Florida, Gainesville
If you would like to use these slides for any reason, please contact Dr. Guillette.
There's been a growing interest in the biologic community in part because of a growing ability to actually measure gene expression. In the old days we just looked at mutations. Today we realize we can actually measure the activity of specific genes, up to tens of thousands of genes at the same time, which is providing incredible breakthroughs in our understanding. (Slide 1)
For years the dogma (Slide 2) that many of us have heard is that disease is based upon genes or germs, with a little environment thrown in. We all realize that nutrition and stress, etc. affect disease states. But largely the way we've actually looked at this is that you either think of gene mutation or you think of some gene-virus interaction or you think about some virus or bacteria that causes disease. In reality, (Slide 3) the way the medical field has looked at this is almost exclusively gene mutation, or germs, as the fundamental basis of disease. Yet most of us on this call realize that the environment plays a very important role.
There were a number of studies done examining twins in Scandinavia over the last couple of years looking at cancer rates. These repeatedly show for the vast majority of cancers and other disease states that probably 60-70 or greater percentage of disease is associated with the environment somehow influencing or creating or producing that disease. We realize it's not the environment itself, but it's the environment influencing how the body functions and we believe the environment is influencing gene expression. The environment (Slide 4) plays a very large role in influencing how our genes function and whether we are susceptible to viral agents or bacterial agents, etc.
When we talk about environment (Slide 5), what exactly are we talking about? If we're talking about fetal or embryonic origins of disease, we have to think not only the environment of the embryo and the fetus, but also the external and internal environment. The internal environment (uterus, egg, etc) is controlled by the external environment (home, nest, community, ecosystem, etc). There are compounds that get into our bodies and although we don't traditionally think about them, as the egg or the sperm develops, those cells are being exposed to various kinds of contaminants and various kinds of nutritional factors, etc.
So, how does all of this relate to gene expression? When estrogen enters the cell (Slide 6) it interacts with the receptor, which then goes to very specific sites on the DNA and turns off gene expression. In some cases it may even block gene expression. In gene expression, another molecule, called messenger RNA is generated, which then goes back out into the cell and is used to produce proteins. Those proteins are everything from additional receptors to all of the enzymes and self-signaling molecules that are associated with cell function. Those enzymes are associated with breaking down and making fats, sugars, and other proteins.
Basically, your whole body is driven by signals coming in to the cell, interacting with specific receptors, turning on or shutting off gene expression. For years we have been unable to quantitatively measure gene expression. We can now tell how much a gene is turned on or shut off. We are starting to realize that that's really important.
One of the things we've been hearing about in biological literature is something called Methylation (Slide 7), which is one of the fundamental ways in which we control genes or gene expression, besides this messenger approach. Every single cell in your body has your full genome, every gene that you have. However not every single cell has the ability to express every one of those genes. How do we selectively turn on and shut off certain genes and their availability.
Methylation is a process by which a methyl group (a carbon and 3 hydrogens, bound together) is attached to the DNA. By putting on these methyl groups you actually block gene expression. The more methylation that occurs on a gene, the less gene expression there will be. We know that this is essential for normal development and we know that there are a number of enzymes that control this process and we're still trying to understand which factors control those enzymes. There's a lot of basic science that still needs to be done, but it's pretty clear that Methylation seems to be very important for normal cell development. However it is essential that you have the right methylation patterns at the right time. If you get the wrong signals during embryonic development or later in life this may lead to turning on or shutting off genes that are inappropriate at that time and therefore leads to disease.
When you expose a developing embryo to DES (diethylsilvestoral) there's a whole number of abnormalities that take place in the reproductive system. We know that that is partly due to the presence of estrogen receptors (Slide 8). Why and how do we get these abnormalities? One of the things we see with DES exposures (Slide 9) is cornification of the vaginal canal, eventually those kinds of abnormalities can lead to cancer and other abnormalities. If you have this abnormality, it's because you have the presence of an estrogen receptor. If you have an estrogen receptor and you're exposed to an estrogen at the time that you're born, for the rest of your life, you will have these abnormalities. However if you have no functional estrogen receptor and you're given DES, you don't get a response. So, estrogen plays a very important role.
Why is estrogen important (Slide 10)? There are a number of different genes that are important, and in this case it's a gene called Wnt7a. If you expose this individual to DES, you get a down regulation of this gene; it's shut off inappropriately. There's a whole series of Wnt7a genes, some are turned on, and some are shut off. What we're starting to realize is the pattern of those specific genes plays probably a central role in this persistent cornification and the other kinds of abnormalities. The interesting part is that, if you inject this female, just one time in her life, at birth you permanently change how those genes are turned on and shut off. If you don't have an estrogen receptor than you don't get the same response.
Hypospadias (Slide 11) is a relatively common birth defect, 1 in every 250 live births. We know that little boys exposed to estrogen, DES, or antiandrogens, develop hypospadias. We know that they're a very common developmental abnormality. Theo Colborn wrote a very nice article on this, published in EHP last year (please contact her if you're interested).
We've discovered a very specific receptor (Slide 12), called the Fgfr2 receptor. Where the urethra of the developing penis forms and where the urethra has to mold over and seal off, what you have is this receptor expressed. Hypospadias is an abnormal development of the urethra. Instead of the urethra forming all the way to the tip of the penis and closing off, it comes off somewhere along the underlying shaft. We now realize that receptor is there and what Marty Cohn has shown (Slide 13) is if you knock out that gene, shut it down, you have massive hypospadias - the urethra does not shut down. So if this Fgfr2 gene actually has both androgen and estrogen sites where androgen and estrogen receptors would bind to turn on or shut off this gene. So, we're hypothesizing that slight alterations in gene expressions of this receptor could in fact lead to the kinds of hypospadias that we see.
The interesting part is that there's a growing data set that suggests that a number of different phenomenon in human and wildlife health are associated, not with gene mutation, but it's simply changes in gene expression.
One final note is there's a very interesting series of studies being done by Michael Skinner (Slide 14), at Washington State, that he presented at the International Endocrine Disrupter Meeting in Japan, in December. They exposed developing male rats to methoxychlor and at birth the males looked normal until they hit puberty then they had massive abnormalities of the testis, spermatogenesis, etc. The interesting part is that they have gone through three generations and no body has been exposed since the initial exposure and they believe that it is not caused due to gene mutation, but that the methylation patterns on various genes, that they're still looking at have been altered and that the methylation pattern is being passed from generation to generation. So, if we go back to Lamarck, it's almost as if the transmittance of acquired traits in a certain generation and there are suggestions that DES exposure is doing the same thing, that there are F2 generation granddaughters that have shown similar effects.
4. Question and Answer
Theo Colborn: This new research showing methylation carrying on from generation to generation is extremely important because it's been very difficult to explain to people why this is not a mutation and this breaks that old way of thinking.
Phil Shabecoff: Lou, can you clarify the difference between a mutation and a gene expression?
Lou Guillette: That's a very good question because mutation leads to differences in gene expression as well. A gene mutation is where you've substituted one of the base pairs in the gene, so you have changed the actual composition of the gene, so it no longer either generates the right protein (messenger RNA) or it can't even function. In contrast, when we talk about gene expression we're talking about altering how much the gene is turned on or shut off. Now we talk about gene dosing, how much the gene is turned on, how much messenger RNA is being generated, how much protein, over what period of time.
Theo Colborn: This is a demonstration of what we've always said, "If we could practice prevention, we can turn this around." The gene has not actually been changed, it's just been told to do something differently. This is a very powerful message to put forth when we're talking about prevention.
Michael Lerner: Previously I had understood that if we stop being exposed to endocrine disrupting chemicals, that the problem would go away, but as I listen to what's happening with DES it sounds as though this can affect gene expression for generation after generation. Now it sounds like; 1) rather than just thinking about endocrine disruption, we should think more broadly about signal disruption, and 2) instead of thinking about something that would go away, we have something that might induce long term and even permanent modification.
Lou Guillette: There are 2 different levels of exposure; 1) if you expose a developing embryo to these compounds you may not cause gene mutation, but you are causing differences in gene expression. Some of those may lead to changes in gene expression later in life. The most important point is that just because it's a change in signaling, doesn't mean that it won't have ramifications further down through generations. But also, we can't assume that there's nothing we can do. If we stop exposure, yes we will probably still have generations affected, but more importantly, we won't affect other kids and other generations. This story is more positive than looking at it, as there is nothing you can do, it's in your genes.
Pete Myers: The methylation work that Lou described, in which it appears to be carried over, at least a couple of generations, is really new stuff and it's not clear yet how representative that is of the effect of contaminants on gene expression. It would appear, based on earlier experiments that it's probably not that common, but limited to things like DES, but we don't know the answer to that question yet. The overall message is one of hope because it dramatically expands the venues that we can push for protection.
Lin Nelson: Can any of you indicate where you think the medical school curriculum is with this?
Lou Guillette: Most medical students hear workplace environment health when they hear environment. Most physicians do not get any training in this in medical school. There may be a few medical schools that are changing this, but in general while the medical schools are behind, the physicians are starting to realize this may be important and they are now inviting us to come speak.
Ted Schettler: In the November 2003 issue of the New England Journal of Medicine, there's a review article on gene silencing and cancer associated with promoter hypermethylations.
Lou Guillette: If you google terms like methylation of genes, or fetal or embryonic origin of disease there's a number of articles and abstracts on this.
Phil Lee: The amount of teaching in relation to these kinds of issues is virtually zero. Undergraduates have much more exposure to these kinds of broader concepts, where you link the basic biology to the environment to policy. Yet in medical school, that's totally turned off. It's rare that you have centers like Phil Landrigan's. It's a tough problem, but science does influence the way people think at least in medicine, so hopefully we can begin to see some change.
Pete Myers: Typically if you talk to someone in the genetics department of a medical school about the contribution of genetics to disease, the question is what gene is linked to it and what hereditary factors are involved. If it's not simple they start looking for multiple gene hereditary issues instead of asking the kinds of questions we've been asking about. In a number of disease issues this is beginning to emerge as a really vital front for research.
Judy Herkimer: We just recently completed the 2 risk assessment peer review panels for eco and human health and Peter Defers (sp?) said that they were the 2 most damning risk assessments he's ever seen at any site. The EPA did a very good job in comprehensive studies showing that we have reproducing populations and we contended that we still have fish with obvious anomalies and fish advisories. How, with this new information do we go to the stake holders and inform them that we're now switching from endocrine disruption to signal disruption and do it in a fashion that's understandable to the lay public.
Lou Guillette: The important part to remember is we knew that we had endocrine signals that were being altered. However, from the very beginning they were also focusing on abnormalities in the brain, neurological system, immune abnormalities. What we know is that there are 3 systems in the body (immune, nervous and endocrine) that control all the functions in the body and integrate all the signaling information. So, when one goes to the public and presents it by saying, "look, we started realizing that there was endocrine abnormalities because of endocrine signals, now what we're realizing is that it is just a part of the bigger picture which involves neurological changes. It's important to realize that these systems don't stand by themselves. They all functionally talk to one another and they all have to work together.
Phil Lee: What's interesting to me is the number of students, potentially, that we could attract to this area, in terms of research, education and involvement in the community. How can we do this more effectively, because I believe there's a tremendous amount of interest among undergraduates?
Lou Guillette: You teach courses that focus on these multiple issues.
Buzzy Guillette: Many of our textbooks don't mention contamination. I have been asked to address this issue in some manner, and as more knowledge gets out, the interest is going to increase.
In Mexico, I studied pesticide and non-pesticide exposed children. Starting at age 4 these children were showing hidden deficits. They were not functioning as well, neurologically, in terms of muscle function as other children. Now, as they age we see an increase in infectious diseases and breast malformations.
Phil Lee: Students these days are very adept at using the internet. Is there some way that we can more systematically create websites that would be oriented to the students and help them to raise questions?
Lou Guillette: About seven years ago, we developed a website called environmental concepts made easy. One of the downsides of that site was that we didn't actually have lesson plans. I think today, the most effective way to get this information out is to put it on the web, but it has to be easy to access and up to date.
Buzzy Guillette: It also has to be applicable to student life.
Ted Schettler: we also need to think about the language and framing of these issues, for our general public discussions, so that we no longer accept ideas like "it's genetically determined." We need to figure out new language and terms and new ways of talking about these issues.
Michael Lerner: Thank you to our speakers and to everyone who has joined us on this call. This has been a very interesting and informative conversation. Please join us on our call next month. The topic will be Learning and Developmental Disabilities. This call will be on Thursday, February 19 at 9:00 a.m. Pacific Standard Time/ 12:00 noon Eastern Standard Time. Please RSVP to Frieda Nixdorf at ContactContact.