New York scientists have discovered dramatic upregulation throughout the physiology of cells selected for high-productivity cell lines. The team, from the State University of New York at Albany, Dublin City University in Ireland, and the Technical University of Denmark found that Chinese Hamster Ovary (CHO) cell clones selected for high levels of drug protein production showed an increase in ribosomal protein production.
They also discovered more rapid metabolism and changes in glycosylation compared to parent cells.
According to team leader Susan Sharfstein, PhD, professor of nanoscale science and engineering at SUNY Albany, the naturally selected clones appeared to show more effective changes than engineered cells.
“One of the cool things we discovered is that nature will do things for us through selection that we might not be able to do as effectively through rational design,” she says. The work could help with the future engineering of cell lines for high protein production, she adds.
Proteomic and transcriptomic analyses
For their study, the team performed proteomic and transcriptomic analyses on two high-producing daughter clones and a parent cell line obtained from a biotechnology company. They had previously discovered that the high-productivity clones had a 2-3-fold increase in copy number for the drug protein. Moreover, ribosomal protein production was increased “across the board,” Sharfstein explains.
“Ribosomal proteins were upregulated, which makes sense because, if there’s more protein, you need more ribosomes,” she notes. The team observed 49 upregulated ribosomal proteins out of 128 possible, with no down-regulated ribosomal proteins observed. The daughter cells also had an increased metabolism which, she says, makes sense because the increase in protein production depends on energy-intensive process pathways within the cell.
Finally, the team observed a change in glycosylation-related proteins, with an increase in an enzyme and glucose transporter associated with protein productivity and cellular metabolism. “Creating higher levels of protein production places demands on cell physiology, and the cell needs to upregulate certain processes naturally to meet them,” continues Sharfstein.
In addition, there was an increase in misfolded protein-related pathways and the amplified clones grew 10-15% more slowly than their parent.
“We don’t know if that’s a precursor or a metabolism issue,” she explains. “[If you increase protein production], you’re pulling away biosynthetic precursors for cell growth.”
The team hopes their research will be useful in the future for companies seeking to improve drug yields from cell lines, especially manufacturers of bispecific and multispecific antibodies.
“Once you’re making molecules that nature never intended, you may need to be more creative in understanding CHO physiology, and that’s where our work comes into play,” points out Sharfstein.
The researchers are now studying transfer RNA production with an industry partner in an attempt to understand how the physiology of cells changes as they come under stress in a bioreactor.
Sharfstein will be speaking at the Bioprocessing Summit in Boston in August.
