STEVE INSKEEP, HOST:
Scientists are trying to address a major flaw in many medical research studies. The flaw is that cells studied the laboratory often get mixed up. That means a researcher who thinks she is studying breast cancer cells might in fact be using melanoma cells. In the first of two stories, NPR's Richard Harris reports on a problem that has ruined thousands of studies of cancer and other diseases.
BOB CLARK: Hi, I'm Bob.
RICHARD HARRIS, BYLINE: Step into Bob Clark's breast cancer laboratory at Georgetown University, and you'll see technicians carrying around small, plastic flasks filled with orange-tinted liquid. Floating invisibly in that liquid are human cells, breast cancer cells.
CLARK: So these would be the stock cells that we grow up and keep them in these flasks.
HARRIS: These are all immortal lines of cells that just keep reproducing and reproducing?
CLARK: These happen to be, yes, yes. The patient who had the cancer that these cells came from - that was from the 1970s.
HARRIS: This cell line and others like it allow scientists to experiment with cancer without actually running experiments on people.
CLARK: Some things we can do in cell lines that would be technically or ethically impossible in animals and humans.
HARRIS: For example, if Clark wants to find out about a potential new drug and he has no idea how toxic it is, he certainly isn't going to put it first into a person or even a mouse.
CLARK: So we do those experiments first in cell lines, and we don't any person or animal at risk.
HARRIS: Scientists have been running this kind of experiment for many decades. Unfortunately they've also been mixing up their cells for many decades. It's easy to do. A scientist can accidentally transfer a cell from one flask to another, and if the contaminant is a fast-growing cell, it will simply take over. These days scientists can run a simple DNA test to avoid these cases of mistaken identity.
CLARK: We do it routinely because we've made the mistake ourselves in the past. We have cross-contaminated a cell line, and we didn't pick that up until after the paper was out. So then we published a paper saying, oops, sorry guys.
HARRIS: Clark told everyone who had asked for a sample of his cells to throw them away. That presumably nipped that particular problem in the bud. But there have been hundreds of cases of mistaken identity, and some have persisted for many years. Steve Ethier at the Medical University of South Carolina tells the story of a breast cancer line called MDA-435, developed in 1976. When injected in animals, these cells spread the way breast cancer metastasizes in a woman.
STEVE ETHIER: And that's not a very common feature of most breast cancer cell lines. So as a result of that people began asking for those cells. And so there are many laboratories all over the world that have published hundreds of papers using the MDA-435 cell line as a model for breast cancer metastasis.
HARRIS: Scientists published more than a thousand papers with this cell line over the years. About 15 years ago scientists using newly developed DNA tests took a close look at the cells, and they were shocked to discover that it wasn't a breast cancer cell at all. The breast cancer cell line had been crowded out by another type of cancer cell.
ETHIER: Well, we know with certainty that the MDA-435 cell line is identical to a melanoma cell line.
HARRIS: That contamination traces back for decades. Several scientists published papers about this to alert the field.
ETHIER: But nevertheless there were people out there who haven't gotten the memo apparently.
HARRIS: Ethier is associate editor of a medical journal, and every so often he still gets what's supposed to be a breast cancer study, but based on this melanoma cell line.
ETHIER: We just reject those papers and attach a polite letter explaining that the cells they're working with aren't breast cancer cells.
HARRIS: MDA-435 was so pervasive, it even ended up in Bob Clark's lab at Georgetown. He and his colleagues published a few breast cancer studies using those cells in the 1990s. A few years later, Clark was one of the scientists who helped expose these cells as being melanoma not breast cancer.
CLARK: We have much better tools now. They're much easier to use. They're much more incisive in their ability to identify what is what. It would have been very difficult early on to have spotted that problem.
HARRIS: Do you have a sense of how much that set back breast cancer research to have a thousand papers published on a cell line that people kept calling breast cancer when it was in fact melanoma?
CLARK: Yeah, that's a great question, but it's a really difficult one to answer.
HARRIS: Maybe those cells provided some useful information studying the general phenomenon of metastasis, he says. But when Clark comes across a study of MDA-435, he generally doesn't give it a second glance. Clark is the dean for research at Georgetown, co-director of the breast cancer lab and a professor of oncology. So he has to set an example when it comes to authenticating cell lines.
CLARK: If we get it wrong again, that's really our fault, and somebody should throw something at us if we do because there's really no excuse for that.
HARRIS: Still, Steve Ethier says these cell mix-ups are far too common in academic labs.
ETHIER: It's actually not a difficult problem to fix. The hard part is really overcoming a mindset in the field in terms of how people work with cell lines.
HARRIS: And tomorrow we'll explore an effort to change that mindset. Richard Harris, NPR News.
NPR transcripts are created on a rush deadline by Verb8tm, Inc., an NPR contractor, and produced using a proprietary transcription process developed with NPR. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of NPR’s programming is the audio record.