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Breast Cancer Gene

November 3, 1995 at 12:00 AM EDT


CHARLAYNE HUNTER-GAULT: A new study by researchers at the University of Texas at San Antonio has found that a single gene may be linked to most breast cancers. This new research published in today’s issue of the “Journal of Science” builds on a study from last year that linked the gene primarily to inherited breast cancer. To help explain the findings and their potential impact, we turn to Dr. Francis Collins, the director of the Human Genome Project in Bethesda, Maryland. The project is a federally-funded effort throughout the country to map all 100,000 genes. Dr. Collins joins us tonight from Ann Arbor, Michigan. Dr. Collins, thank you for being with us. And in the simplest terms, can you explain the major finding and what it adds to our understanding of breast cancer.

DR. FRANCIS COLLINS, Director, Human Genome Project: (Ann Arbor) Well, I’ll give it a try. This is a very interesting new chapter in what has been a fascinating story over the course of the last year or so as we have begun to understand something about the basic molecular biology of breast cancer at least as it relates to this gene called BRCA-1. To explain this, it’s helpful to sort of make a distinction between a gene, which is like an instruction book, and the protein that it codes for. What we learned about a year ago is that about 5 percent of breast cancer comes about because people have inherited a copy of the BRCA-1 gene that has a misspelling, so the instruction book is wrong. And we were sort of surprised, because we thought when we looked at sporadic breast cancers, we would also find that their instruction book, their gene, had a glitch in it, and that was not the case. What’s being reported today by Dr. Wenwa Lee and his colleagues at San Antonio is that while the instruction book is okay, the protein product that this particular gene produces is in the wrong place in the cell. So instead of going to the place where it ought to be going to do its work, it’s in the wrong place, and, therefore, it’s not carrying out its function.

CHARLAYNE HUNTER-GAULT: And this is surprising because you thought that the only time that this gene functioned this way was when it was through an inherited line?

DR. COLLINS: I’m afraid I’ve lost the sound.

CHARLAYNE HUNTER-GAULT: You’ve lost the sound? Can you hear me now? Can you hear me, Dr. Collins? We’re going to try to see if we can restore the sound, because you have some very important information to share with us about this gene. I was talking to you about the fact that this time last year you discovered that this gene accounted for the cancers in about 5 percent of women who constituted–5 to 10 percent of women who constituted those who inherited this gene, is that right?

DR. COLLINS: That’s right.

CHARLAYNE HUNTER-GAULT: And now you’ve found that it encompasses far more women.

DR. COLLINS: Well, again, let’s try and make this distinction a little clear. It’s clear that the gene, itself, is not misspelled in most women who have breast cancer. 95 percent of them, the gene, itself, seems to have the correct spelling. But the protein product that it makes, which is sort of what carries out the action, while it’s there, it’s in the wrong place in the cell. Let me clarify that. So normally it appears–and this is what this report is showing today–this protein is in the nucleus, which is sort of the control center of the cell–but in cancer cells, instead, it’s not in the nucleus, it’s out in the cytoplasm. Something is keeping it from getting to its proper location, and that apparently is bad, because that correlates very strongly with the cancer cells, as opposed to the normal cells. You can think of it this way. You can sort of think of cancer as sort of a striking image, as a fire that’s raging where the cells are, instead of behaving themselves; they’re growing too fast. They’re burning. And BRCA-1, if you look, is like a fire extinguisher. It has the capability of putting out that fire. That’s sort of what it’s there for. In the person who’s inherited a misspelled copy of the gene, they’re kind of missing the fire extinguisher. It’s just not there, but what’s reported today is that many breast cancers, the fire extinguisher is there, it’s in the wrong part of the house. Instead of being in the kitchen where the fire is, it’s down in the basement.


DR. COLLINS: That could be good news, because it might enable us to figure out a way to get this thing back to where it should be, to locate it more properly, instead of having it in the wrong place. It’s there. It’s just not in the right part of the cell.

CHARLAYNE HUNTER-GAULT: So who is this good news for? Is it good news for the women who inherit–who have the inherited trait, or is good news for all of the women who have this misplaced gene?

DR. COLLINS: Well, I think it’s a little too soon to say exactly what this is going to amount to. Clearly, nothing has changed as of right now as far as the way that we detect or treat breast cancer. But what it could suggest is for the people who don’t have the inherited form of the gene, this same gene is, in fact, playing an indirect role, and we may be able to learn enough about that to develop therapies that are more effective than the ones we currently have. But I would hasten to say that is a number of years down the road. What this gives us is sort of a new paradigm for understanding how breast cancer comes to pass. That’s always a useful thing.

CHARLAYNE HUNTER-GAULT: So just how excited should we be? I mean, how significant is this, and does it have any practical applications at all? I mean, can women be screened for it, for example?

DR. COLLINS: I think immediately as of today the practical applications are not yet with us. What you might expect would come out of this are two things: First of all, it may be possible using this observation about whether the protein is in the wrong place or the right place, to determine whether a particular cancer is going to be a bad actor or whether it’s going to be relatively benign, and to design therapies accordingly. In the longer-term, I think this suggests strategy, a new kind of idea for cancer, where instead of trying to replace something that’s missing, you take something that’s already there, but it’s in the wrong part of the cell, and move it to where it needs to be. That kind of a strategy really couldn’t have been thought about before today. Again, I don’t think we should overstate this. It’s going to be some time before this is clarified and before it’s clear whether this does lead us to new therapies. And I think we have to be cautious about that. I’d even say it’s not absolutely clear that what the investigators have observed is a cause of cancer and not an effect. It’s also possible that the cancer cell places this protein in the wrong place for some other reason. What you’re looking at is a symptom rather than a cause. That needs to be sorted out.

CHARLAYNE HUNTER-GAULT: So how long is this going to take, and what is the next step for science, and how should we in the public be viewing all of this now?

DR. COLLINS: I think it’s important to recognize that cancer biology is going through a revolution at the basic science level, and this is another chapter in that, a very interesting one, sort of a chapter with a twist. But the timetable between taking those basic science discoveries and turning them into things that apply in clinical medicine is an unpredictable one. I would say we’re probably several years away from knowing what today’s discovery specifically means for the treatment of the disease.

CHARLAYNE HUNTER-GAULT: Well, Dr. Collins, thank you for sharing what you have with us.

DR. COLLINS: My pleasure.