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When growing cells in the lab, researchers routinely add antibiotics to prevent contamination. But a new study by UC San Francisco researchers raises a red flag against this standard practice, finding that it can induce unintentional genetic changes in the cells and distort test results.
These changes may be especially concerning in pharmacogenomics experiments looking at how human cells respond to drugs, an important part of precision medicine.
Nadav - Ahituv - PhD - Professor - Bioengineering
Nadav Ahituv, PhD, professor of bioengineering in the School of Pharmacy and senior author of the paper published Aug. 8, 2017, in Scientific Reports, didn't set out to challenge standard laboratory protocol. But as is often the case in science, one question led to another.
One area of study in Ahituv's lab is how genetic variations affect our response to drugs. Recently, his lab found that rifampin, a common antibiotic prescribed for tuberculosis and other infections, can cause significant changes in the expression of genes and regulatory elements in human liver cells.
Experiment - Cells - Antibiotics - Time - Cell
"While we were doing this experiment, I was thinking: we treat cells with antibiotics all the time in cell culture and nobody's looked at how this might affect gene expression and gene regulation," said Ahituv.
He and graduate student, Ann Hane Ryu, first author of the study, designed a simple experiment in which they compared a human liver cell line, HepG2, grown with and without the standard antibiotic cocktail, PenStrep, a combination of penicillin and streptomycin. They chose liver cells because the liver helps clear foreign materials from the body and would be the most responsive to drugs, said Ahituv.
Cells - Weeks - Changes - Coding - DNA
They let the cells grow for three weeks and analyzed them to identify changes in both coding and non-coding DNA.
They found altered expression in 209 genes, particularly in those related to drug and stress response. These included higher expression of genes known to be involved in...
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