The use of in vitro-cultured cells within the life sciences is an indispensable tool for a variety of fundamental assays. Yet periodically, cell lines need to be analyzed genetically to make certain that they are not only still representative of the cells from which they were derived—as cultured cells can drift genetically over time—but more importantly that they are an actual match to the original cell type.
Now, researchers at Uppsala University have just published results from a study showing that a commonly used cell line, which was established in the same laboratory as the authors almost 50 years ago, does not originate from the patient from which it is claimed to stem. The authors noted that because a tumor-derived cells line is possibly not authentic to its origins, then two major questions emerge.
“Have the identity of the donor and the actual tumor origin of the cell line been accurately determined? To what extent does the cell line reflect the phenotype of the tumor type of origin? The importance of these questions is greatest in translational research,” the authors wrote.
Investigators studying brain tumors often employ the use of a glioma cell line called U87MG. The cells are publicly available from the American Type Culture Collection (ATCC), where researchers can order it to use it in their studies. The Uppsala team would often use the original U87MG line, and their experience led them to question the authenticity of the ATCC cell line.
“We have examined these questions using genetic profiling and transcriptome analysis in human glioma cell lines,” the authors penned. “We find that the DNA profile of the widely used glioma cell line U87MG is different from that of the original cells and that it is likely to be a bona fide human glioblastoma cell line of unknown origin.”
Lead author Marie Allen, Ph.D., professor, and expert in DNA fingerprinting, works in the same department where the U87MG line originated. DNA fingerprinting is an important tool for determining genetic identity, for instance in crime scene investigations.
“Marie and her colleagues helped us genetically compare the cell lines with each other,” explained senior study author Bengt Westermark, Ph.D., senior professor in the department of immunology, genetics and pathology at Uppsala University. “We found that the U87MG cell line from ATCC had a different DNA profile than the original cell line in Uppsala.”
The findings from this study were published recently in Science Translational Medicine in an article entitled “Origin of the U87MG Glioma Cell Line: Good News and Bad News.”
Fortuitously, when the cell line was established in the 1960s, material from the original tumor was saved as thin sections on microscope slides. Using a very sensitive DNA analysis technique that can also be employed when only minuscule amounts of DNA from old tissue are available, the researchers could compare the two current cell lines with the tumor from which the cell line was established.
“The comparison showed that the Uppsala cell line was genetically identical with the original tumor whereas the U87MG cell line from ATCC had a different, unknown origin,” noted Dr. Westermark. “We don't know at which point during the 50 years of culturing the mix-up occurred but we have been able to show that the ATCC U87MG line is most likely from a human glioma tumor.”
The new findings show that proper identification of a cell line also requires that the DNA profile matches the tissue of origin. This is essential if investigators want to claim that the cells, and thereby the research results, are true representatives of the original tumor.