The Great Cancer Cell Mix Up
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Originally published July 13, 2012
Imagine you're a scientist, trying to cure brain cancer.
One thing you’d probably want to be sure of is that the samples you’re working with actually came from a brain tumor, and not some other kind of cancer.
This sounds like a simple problem to solve, but it’s been nagging scientists for years, causing the waste of precious research dollars.
Osamu Tetsu and Janyaporn Phuchareon learned that lesson the hard way.
Tetsu and Phuchareon are scientists at the University of California San Francisco’s Department of Head and Neck Surgery. They work in a lab, studying an obscure cancer of the salivary gland called salivary adenoid cystic carcinoma.
"Bingo!" (Or not.)
Researchers working on more common cancers may have dozens of cell lines to work with. But since salivary adenoid cystic carcinoma is relatively rare, Tetsu and Phuchareon had only six cell lines to experiment on, each of which could, theoretically, be traced back to a different patient.
One day, they noticed something that surprised them: Almost all the cell samples they were working with contained a virus. It was HPV virus, which you may have heard of because it can cause cervical cancer. To Tetsu, this looked like a breakthrough.
“I thought maybe the HPV infection is the cause of this disease,” he says.
In other words, they thought, maybe the HPV virus doesn’t only, potentially, cause cervical cancer, maybe it can cause salivary gland cancer too.
“We were very excited, says Phuchareon. We thought “Bingo! We might have something!”
Then they took a closer look.
They sent the cell line samples in for DNA testing. When the results came in, they learned those cells they’d been working with had nothing to do with a salivary tumor. Four of them came from a cervical tumor.
These were HeLa cells, descendants of the infamously vigorous cervical cancer cell line that was the subject of the 2010 bestseller The Immortal Life of Henrietta Lacks.
The news was no better for the other two cell lines.
One of them, says Tetsu, didn’t show any DNA fingerprint at all. “That means this cell line is not human,” he says. They suspect both cell lines had become contaminated with mice cells somewhere along the line.
A silver lining
Six months of work, down the drain. But Phuchareon looks on the bright side. “It was bittersweet,” she says.
At least they found out before any major work had been done. They published a paper on their findings in a scientific journal, and have been able to warn other scientists who work on the same cancer.
“We think it’s important to have scientists know that this is a problem,” Phuchareon says.
The problem stems from the fact that, under a microscope, many cancer cells look the same. And since cell lines used in cancer research are anonymous, often shared informally between labs, the only way to definitively know where they came from is with DNA analysis.
The analysis is inexpensive, about $50 a sample. It’s the same technique used in crime labs. But not every scientist does it.
The steep price to science
In one 2010 case, three cell lines being used to research esophageal cancer all turned out to come from other cancers. Scientists had been working with these cells for years. They'd gotten major federal grants to do it, published more than 100 papers, even run clinical trials.
Some cell banks have estimated that as many as a third of their cell lines have been misidentified. These cell lines have been sent to labs around the world, for basic research.
Often, the results still hold. Misidentification is not a death knell for all experiments. But in many cases, cell misidentification can undermine research and waste millions of dollars, says Roland Nardone, a professor emeritus of biology at Catholic University in Washington DC.
“Money has been diverted away from useful experiments to meaningless experiments,” says Nardone.
A legacy of whistleblowers
Particularly frustrating to him is the fact that scientists have known about this problem for more than half a century.
One of the earliest scientists to call attention to it was a Bay Area researcher named Walter Nelson-Rees.
“He was a cultured man, as well as a very good biologist,” recalls Nardone.
Nelson-Rees was co-director of the Oakland-based Cell Culture Laboratory of the School of Public Health, funded by the National Cancer Institute.
In the early 1960s, he began running tests on commonly used cancer cell lines, to see how many were contaminated.
Gertrude Buehring — today, a professor of virology at UC Berkeley’s School of Public Health — worked down the hall from Nelson-Rees. She says every day, there was news of more contaminated cell lines.
“It was just one after another,” she recalls.
Many of the cell samples had been contaminated by HeLa. But not all.
“Some were interspecies contaminated, so that a human cell line actually turned out to be a mouse cell line,” she says. [Some lines that were supposedly] derived from a female turned out to be derived from a male.”
A career-ending discovery
Nelson Rees's discovery — that hundreds of cell lines had been misidentified — did not win him any friends.
Colleagues, says Buehring, “didn’t want to believe him. They fought him verbally at conferences. He was called a self-appointed vigilante and a lot of other names. One person even volunteered to send him a one way ticket to distant corners of the earth.”
Nardone says, at least initially, Nelson-Rees relished the fight.
“He was pugnacious,” says Nardone. “He recognized that he was going to be in a battlefield and he was ready for the fight.”
But, over time, the abuse took its toll.
“He seemed visibly upset that people couldn’t appreciate the service that he was doing,” says Buehring. “They were more worried about their own reputation.”
Nelson-Rees’s findings may ultimately have cost him his career.
“Without any explanation,” says Nardone, “his funds for support of his laboratory got smaller and smaller and he saw the handwriting on the wall and decided that was enough.”
Nelson-Rees became an art dealer. He died in 2009.
The search for regulation
A few years ago, Nardone decided to devote his retirement to the problem that Nelson-Rees had publicized. He joined a workgroup, led by the Virginia-based research nonprofit ATCC, to come up with a standard, one that all researchers could work by.
The standards, which came out this year, outline the correct way to authenticate cell lines, so that researchers can compare results from lab to lab. ATCC also maintains a list of misidentified cell lines on its website.
The ATCC’s Liz Kerrigan says the challenge has been getting scientific institutions to adopt the standard.
“Surprisingly to most members of the workgroup, there has been resistance to addressing or even acknowledging the problem,” she says.
A few influential science journals now require that scientists authenticate cells before they’ll publish their results. But Nardone and Kerrigan believe that’s too late.
Much better, says Nardone, would be to get the big funding institutions, particularly the National Institutes of Health, to demand that anyone who applies for funding for cell-culture research authenticate their cell lines initially.
In other words, get the cells checked out before the money’s spent.
The NIH steps back
In a statement, the NIH said doing this would be, quote, “impractical,” and that it trusts researchers to do the right thing.
Kerrigan and Nardone believe that the costs of misidentified cell lines call for greater oversight.
“The consequences of widespread misidentification of cell lines is immeasurable, really,” says Kerrigan. “In addition to the waste of millions of dollars, there’s time, intellectual resources. And then people lose confidence in published work.”
They’re hopeful stronger policies will soon emerge.Tags: ATCC, cancer cells, HeLa, misidentification, nardone, nelson-rees, Phuchareon, STR, tetsu