Collagen, the main non-cellular component of the extracellular matrix (ECM), is profoundly reorganized during tumorigenesis and has a strong impact on tumor behavior. The main source of collagen in tumors is cancer-associated fibroblasts. Cancer cells can also participate in the synthesis of ECM; however, the contribution of both types of cells to collagen rearrangements during the tumor progression is far from being clear. Here, we investigated the processes of collagen biosynthesis and remodeling in parallel with the transcriptome changes during cancer cells and fibroblasts interactions. Combining immunofluorescence, RNA sequencing, and second harmonic generation microscopy, we have explored the relationships between the ratio of epithelial (E) and mesenchymal (M) components of hybrid E/M cancer cells, their ability to activate fibroblasts, and the contributions of both cell types to collagen remodeling. To this end, we studied (i) co-cultures of colorectal cancer cells and normal fibroblasts in a collagen matrix, (ii) patient-derived cancer-associated fibroblasts, and (iii) mouse xenograft models. We found that the activation of normal fibroblasts that form dense collagen networks consisting of large, highly oriented fibers depends on the difference in E/M ratio in the cancer cells. The more-epithelial cells activate the fibroblasts more strongly, which correlates with a dense and highly ordered collagen structure in tumors in vivo. The more-mesenchymal cells activate the fibroblasts to a lesser degree; on the other hand, this cell line has a higher innate collagen remodeling capacity. Normal fibroblasts activated by cancer cells contribute to the organization of the extracellular matrix in a way that is favorable for migratory potency. At the same time, in co-culture with epithelial cancer cells, the contribution of fibroblasts to the reorganization of ECM is more pronounced. Therefore, one can expect that targeting the ability of epithelial cancer cells to activate normal fibroblasts may provide a new anticancer therapeutic strategy.
Targeted sodium-iodide symporter (NIS) gene transfer can be considered as a promising approach for diagnostics of specific types of cancer. For this purpose we used targeted polyplexes based on PEI–PEG–MC1SP block-copolymer containing MC1SP-peptide, a ligand specific for melanocortin receptor-1 (MC1R) overexpressed on melanoma cells. Targeted polyplexes demonstrated enhanced NIS gene transfer compared to non-targeted (lacking MC1SP) ones in vitro. Using dorsal skinfold chamber and intravital microscopy we evaluated accumulation and microdistribution of quantum dot-labeled polyplexes in tumor and normal subcutaneous tissues up to 4 hours after intravenous injection. Polyplexes demonstrated significantly higher total accumulation in tumor tissue in comparison with subcutaneous ones (control). Targeted and non-targeted polyplexes extravasated and penetrated into the tumor tissue up to 20 μm from the vessel walls. In contrast, in normal subcutaneous tissue polyplexes penetrated less than 5 μm from the vessel walls with the level of extravasated polyplexes 400-fold less than in tumor. Accumulated polyplexes in tumor tissue caused NIS gene expression. Subsequent 123I- intravenous injection resulted in 6.8 ± 1.1 and 4.5 ± 0.8 % ID/g (p < 0.001) iodide accumulation in tumors in the case of targeted and non-targeted polyplexes, respectively, as was shown using SPECT/CT.
Simultaneous expression of multiple target genes is often required in biotechnology. Multicistronic vectors coding for several proteins are being actively developed for this purpose. In commercially available vectors different variants ofencephalomyocarditis virus internal ribosome entry site (IRES EMCV) are used most often. However, many researchers consider that utilization ofself-cleaving 2A peptides sequences within multi- and bicistronic vectors is more promising. In this work, we compared the efficiency of gene expression in cells transfected with bicistronic vectors based on IRES EMCV and 2A peptide sequence derived form porcine teschovirus-1 (P2A). Efficiency ofgene expression was determined in three mammalian cell lines by measurement of co-expression levels of genes coding for RFP and EGFP proteins linked by IRES or P2A sequence. Higher level oftransgene expression was exhibited by cells transfected with the vector containing the 2A peptide sequence.
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