About a year ago, we wrote about the retraction of a paper in Oral Oncology that highlighted a big issue in oncology research: Widespread contamination of cancer cell lines by other lines, making findings difficult to interpret.
One of the common contaminants is HeLa cells. HeLa, of course, stands for Henrietta Lacks, the subject of Rebecca Skloot’s bestseller The Immortal Life of Henrietta Lacks. As we noted last year,
scientists began realizing that Lacks’s cells, now known as the HeLa cell line and used in labs around the world, were so good at proliferating that they had taken over many other cell lines researchers use to study human disease.
Now, in a study published in the Journal of Urology, a group of researchers has taken stock of a supposed bladder cancer cell line, KU7, and confirmed that it, too, is actually HeLa.
Some background on KU7 from the paper:
One of the most popular bladder cancer cell lines has been KU7, which was isolated from a patient with low-grade papillary bladder cancer at the Keio University (KU) in 1980. KU7 has been widely used due to its robust growth in vitro, its amenability to molecular manipulation, and its reliable growth characteristics in xenograft models.
As the paper’s title, “Hiding in plain view,” suggests, there have been clues, the authors write:
Interestingly, KU7 has behaved over many years as a highly invasive and rapidly growing cell line, which is quite disparate to its original description as being derived from a low grade papillary tumor. This discrepancy, however, was not recognized until we had already determined the true identity of KU7. This highlights the importance of bearing the disease context of cell lines in mind when using them for pre-clinical modeling. The widespread contamination of KU7 clones determined here makes us believe that all KU7 in the urologic literature since at least 1984 is likely HeLa.
And that contamination happened at Keio, they conclude:
Our analysis identified that a cross-contamination of KU7 with HeLa occurred prior to 1984 at the source institution. All KU7 clones in the urologic literature should be considered HeLa and the experimental results should be viewed in this light. Our results emphasize the need to authenticate cell lines in oncologic research.
We asked lead author Peter Black how many papers might be affected, and whether his team’s find would mean any retractions:
There are dozens. I have not attempted to quantify them. Most of our own work, for example, has included KU7 as one in a panel of cell lines, which is not particularly important. Others, especially those focusing on orthotopic animal models are more dependent on this particular cell line. I have taken the stance that it is just a model in the first place, and we have evidence now that the model is a bad one – but that nothing should be retracted.
Black raises a good point. Still, what about noting the mixed-up cell line on the papers that have used KU7?