Implantation of reporter-labeled tumor cells in an immunocompetent host involves a risk of their immune elimination. We have studied this effect in a mouse model of breast cancer after the orthotopic implantation of mammary gland adenocarcinoma 4T1 cells genetically labelled with luciferase (Luc). Mice were implanted with 4T1 cells and two derivative Luc-expressing clones 4T1luc2 and 4T1luc2D6 exhibiting equal in vitro growth rates. In vivo, the daughter 4T1luc2 clone exhibited nearly the same, and 4T1luc2D6, a lower growth rate than the parental cells. The metastatic potential of 4T1 variants was assessed by magnetic resonance, bioluminescent imaging, micro-computed tomography, and densitometry which detected 100-μm metastases in multiple organs and bones at the early stage of their development. After 3–4 weeks, 4T1 generated 11.4 ± 2.1, 4T1luc2D6, 4.5 ± 0.6; and 4T1luc2, <1 metastases per mouse, locations restricted to lungs and regional lymph nodes. Mice bearing Luc-expressing tumors developed IFN-γ response to the dominant CTL epitope of Luc. Induced by intradermal DNA-immunization, such response protected mice from the establishment of 4T1luc2-tumors. Our data show that natural or induced cellular response against the reporter restricts growth and metastatic activity of the reporter-labelled tumor cells. Such cells represent a powerful instrument for improving immunization technique for cancer vaccine applications.

This work focuses on synthesis and characterization of targeted magnetic nanoparticles as magnetic resonance imaging (МRI) agents for in vivo visualization of gliomas. The authors utilize the fact that high-grade gliomas have extensive areas of necrosis and hypoxia, which results in increased secretion of angiogenesis vascular endothelial growth factor (VEGF). Monoclonal antibodies against vascular endothelial growth factor (mAbVEGF) were covalently conjugated to crosslinked BSA coated ferric oxide (Fe3O4) nanoparticles. The results show that these targeted nanoparticles are effective in MRI visualization of the intracranial glioma and may provide a new and promising contrast agent.

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Immunofluorescent analysis of connexin-43 was carried out on preparations of fixed and living cultures of rat and human glioma cells, HEK293 cells, and frozen sections of the rat brain with experimental glioma using monoclonal antibodies to recombinant extracellular fragment of connexin-43 (E2 second extracellular loop). These monoclonal antibodies visualized membrane and cytoplasmic pools of connexin-43 in preparations fixed with paraformaldehyde. Incubation of monoclonal antibodies to E2 extracellular loop with living cells led to visualization of only connexin hemichannels on cell membranes. No immunofluorescence characteristic of dimer connexons, organizing the gap junction, was detected. This fact indicates that antibodies to connexin-43 extracellular loop E2, obtained in our study, specifically react with target antigen solely at the stage of connexon presentation on the membrane in the form of hemichannels. These monoclonal antibodies can be used for immunophenotyping and sorting of connexin-43-positive cells in vitro and as the guide molecules in addressed delivery of diagnostic preparations and drugs to glioma cells in vivo.

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