NEW YORK (GenomeWeb) – A new genetic analysis suggests the version of the U87MG cell line available through the American Type Tissue Collection (ATCC) no longer represents the glioma tumor from which that line was originally developed.
Researchers from Uppsala University used short tandem repeat genotyping and array-based gene expression profiling to compare the ATCC U87MG line to a U87MG line from Uppsala and a sample of the tumor used to develop the cell line nearly five decades ago. Their results, appearing online today in Science Translational Medicine, indicate that the ATCC U87MG line is not glioma, but more closely resembles previously analyzed glioblastoma samples.
"The Uppsala cell line was genetically identical with the original tumor whereas the U87MG cell line from ATCC had a different, unknown origin," senior author Bengt Westermark, an immunology, genetics, and pathology researcher at Uppsala University, said in a statement. "We don't know at which point during the fifty years of culturing the mix-up occurred but we have been able to show that the ATCC U87MG line is most likely from [another] human glioma tumor."
Cell line misidentification or contamination is increasingly recognized as a problem in medical research, prompting Nature, the American Association for Cancer Research, and other publications to introduce guidelines requiring investigators to use DNA analyses to authenticate cell lines used in published studies.
Given their familiarity with the original U87MG line, first established at Uppsala University in the 1960s, Westermark and his colleagues became concerned about the authenticity of the version available through ATCC cell line. Because microscope-mounted samples of the glioma tumor used to make the line was still available at Uppsala, the team was able to directly compare purported U87MG glioma cell lines from Uppsala and ATCC with genetic and transcriptomic patterns in the original tumor.
When they genotyped the two U87MG cell lines at 16 short tandem repeat markers with Promega's PowerPlex 16 HS system, the researchers found that the ATCC and Uppsala lines differed at a dozen of the short tandem repeat markers. When the team broadened its search to 19 more human glioma cell lines from Uppsala, it found two genetically identical lines, which appeared to be due to contamination. While the U87MG line resembled the other glioma lines, the ATCC version remained distinct — results the group verified by mitochondrial DNA testing and array-based expression profiling.
The latter analyses suggested that the ATCC U87MG line likely represents human glioblastoma.
Based on their findings, the researchers recommended the use of STR-genotype verified glioma cell lines, such as their own Human Glioma Cell Culture resource, rather than relying on lines that may be mixed up or otherwise started to diverge from the original tumor samples.
"We strongly advocate the use of these or similar glioma cell lines in experimental and translational research on brain tumor biology," Westermark and his co-authors wrote. "We suggest that the research community agree on the use of a set of such cell lines as references in research on cultured glioblastoma cells and that these verified cell lines replace U87MG and other classical cell lines."