Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/9/2013
Publication Date: 8/5/2013
Citation: Rasooly, R., Hernlem, B.J., Friedman, M. 2013. Low levels of aflatoxin B1, ricin and milk enhance recombinant protein production in mammalian cells. PLoS One. 8(8):e71682. doi:10.1371/journal.pone.0071682.
Interpretive Summary: Therapeutic recombinant protein expression is widely used in medicine and agriculture. The annual global market in 2011 for recombinant proteins was estimated at more than 102.4 billion US dollars. In this study we used adenovirus as a vector, widely used in gene therapy, to introduce recombinant DNA to mammalian cells.Using this novel approach, we successfully overexpressed three different recombinant proteins. The positive findings suggest that the method has the potential to facilitate in vitro production of bioactive proteins used in medicine and agricultural sciences. Because our results show that aflatoxin B1 (AFB1)at low concentration enhanced transcription and protein production, these results may have implications for the consumption of food treated with various reagents intended to reduce AFB1 content. For example, even though it has been reported that the treatment of corn grain with citric acid reduced AFB1 and AFB2 by 96.7% , it is likely that the residual low aflatoxin levels may have unknown biological effects. The consequences of consuming food with low AFB1 content merit study.
Technical Abstract: Changing the optimal tissue culture medium by adding low levels of environmental stress such as 1 µM of the fungal toxin aflatoxin B1 (AFB1), 1 ng of the castor bean protein toxin ricin in transduced mammalian cells or 1% reconstituted milk enhances transcription and increases production of the following three recombinant proteins: firefly luciferase,ß-galactosidase, and green fluorescent protein (GFP). Higher concentrations of the stress substances damage the cells beyond recovery, resulting in inhibited gene expression and cell death. The presented findings extend methods for large-scale transient recombinant protein production in mammalian cells and suggest the need to explore the biological and medical consequences of in vivo exposure to low ‘nontoxic’ levels of the test substances. Possible applications to biomedical sciences and agriculture are discussed.