By Corinna Wu

A Cancer Cell Mix-Up

By Corinna Wu

Three of the cell lines used by researchers to study esophageal cancer are not what they seem to be, according to a study published online Jan. 14 in the Journal of the National Cancer Institute.

There are 14 different cell lines—lab-grown cells that can proliferate endlessly for research purposes—that are used to study esophageal adenocarcinoma. An international team of researchers recently traced these cell lines back to their source tissues and compared their DNA profiles. In January, they published their results: Ten lines matched the original tissues and one could not be traced, but the other three turned out to be from different cancers: a lung cancer, a colorectal cancer and a gastric cancer.

At least a hundred scientific papers have been published based on those three cell lines, says Winand Dinjens, a molecular biologist at Erasmus University Medical Center in the Netherlands who co-authored the study. And it was some of these experimental results that provided the evidence necessary to begin esophageal cancer clinical trials in 2006 with the drug Nexavar (sorafenib). A phase II trial is now under way.

Contamination of cell lines is not a new phenomenon. Some researchers estimate that up to one-third of all cell lines have an origin that differs from what scientists believe it to be. It’s not clear how the lines got contaminated, says Dinjens, but he speculates that it could have been due to mislabeling or improper lab technique, which would have caused contamination early on by cells from established, fast-growing cell cultures.

The impact of the study’s findings is also unclear. Dinjens says that if the cells were used to investigate a certain molecular pathway common to many malignancies, the exact type of cell doesn’t matter. “But,” he adds, “the studies in which these cell lines are really used as a model for esophageal adenocarcinoma—these should be reconsidered.”

According to cancer biologist Robert Shoemaker, the chief of the screening technologies branch at the National Cancer Institute, Nexavar targets a molecular pathway that is not unique to esophageal cancer cells, so the clinical trials could still be justified. And, he notes, because of studies like this one, scientists now have the opportunity to build research programs on well-characterized cell lines.