New Approach to Non-Invasive Tumor Model Monitoring via Self-Assemble Iron Containing Protein Nanocompartments

Abstract

According to the World Health Organization, breast cancer is the most common oncological disease worldwide. There are multiple animal models for different types of breast carcinoma, allowing the research of tumor growth, metastasis, and angiogenesis. When studying these processes, it is crucial to visualize cancer cells for a prolonged time via a non-invasive method, for example, magnetic resonance imaging (MRI). In this study, we establish a new genetically encoded material based on Quasibacillus thermotolerans (Q.thermotolerans, Qt) encapsulin, stably expressed in mouse 4T1 breast carcinoma cells. The label consists of a protein shell containing an enzyme called ferroxidase. When adding Fe2+, a ferroxidase oxidizes Fe2+ to Fe3+, followed by iron oxide nanoparticles formation. Additionally, genes encoding mZip14 metal transporter, enhancing the iron transport, were inserted into the cells via lentiviral transduction. The expression of transgenic sequences does not affect cell viability, and the presence of magnetic nanoparticles formed inside encapsulins results in an increase in T2 relaxivity.

Internalization of transferrin-tagged Myxococcus xanthus encapsulins into mesenchymal stem cells

“…Regarding the use of encapsulin-based nanocontainer systems for in vivo studies, it is important to address the issue of potential immunogenicity of the xenogeneic proteins. We have already discussed this problem partially: we presently know that, at least, Quasibacillus thermotolerans encapsulin-containing cells do not cause an immune response when implanted into mice [ 59 ] and rats [ 60 ]. In addition, an article was recently published evaluating in vivo behavior of Thermotoga maritima encapsulins administered intravenously into mice [ 61 ].…”

Myxococcus xanthus Encapsulin as a Promising Platform for Intracellular Protein Delivery

“…[ 17 ]. We have also already obtained a mouse carcinoma cell line stably expressing Quasibacillus thermotolerans ( Qt ) encapsulin genes which allows the tracking of carcinoma cells via MRI [ 18 ]. Thus, our previous research has focused on the study of stable expressed Mx and Qt encapsulins in mammalian cells as genetically encoded reporters that enable non-invasive cell tracking.…”

Encapsulins: Structure, Properties, and Biotechnological Applications

“…It was shown, for example, that the human mesenchymal stem cells are capable of stable expression of encapsulin genes of Myx. xanthus [ 98 ], and the cells of mouse breast carcinoma 4T1 can express the Q. thermotolerans genes [ 99 ]. It was shown both in the first and the second case that the presence of such genetic probe did not affect viability of the cells and their ability for proliferation, and T2 relaxation time for the genetically modified cells containing encapsulin was lower than for the control cells, which allowed detection of cells with MRI.…”