Recent studies show that cancers may originate from special cells named cancer stem cells (CSCs). As miRNAs have a prominent role in regulating cell activities, a question arise, that is, if there is any difference in miRNA expression level between CSC and other cancer cells of human gastric cancer cell line MKN-45. In this study, CSCs were isolated by fluorescence-activated cell sorter based on the expression level of cell surface marker CD44. CSC characteristics were checked using spheroid formation assay and soft agar assay. Using reverse transcriptase polymerase chain reaction (RT-PCR), the expression level of some stemness genes was studied. Real-time q-PCR was used for analysis of the expression level of miRNAs. CSCs were able to make spheroids and colonies, whereas other cancer cells failed to show aforementioned features. In addition, RT-PCR resulted in a difference in the expression levels of Nanog, Sox2, Lin28 and Oct-4 between these two kinds of cells. Real-time RT-PCR analysis demonstrated an increase in mir-21 and mir-302 expression level in CSCs, relative to cancer cells, whereas let-7a expression level was decreased in CSC in comparison with cancer cells, which may be due to their different differentiation level. On the other hand, mir-372, mir-373 and mir-520c-5p were markedly increased in cancer cells in comparison with CSCs. This study shows that there is a difference in miRNA expression level between CSCs and other cancer cells, which reflects dissimilar molecular pathways in these cells. These miRNAs may be promising objects for targeting CSCs specifically and efficiently.
The therapeutic potential of bone marrow mesenchymal stem cells (MSCs) in kidney failure has been examined in some studies. However, recent findings indicate that after transplantation, these cells home to kidneys at very low levels. Interaction of stromal derived factor-1 (SDF-1) with its receptor, CXCR4, is of pivotal importance in migration and homing. Recently, CXCR7 has also been recognized as another SDF-1 receptor that interacts with CXCR4 and modulates its functions. In this study, CXCR4 and CXCR7 were separately and simultaneously overexpressed in BALB/c bone marrow MSCs by using a lentiviral vector system and the homing and renoprotective potentials of these cells were evaluated in a mouse model of cisplatin-induced acute kidney injury. Using flow cytometry, immunohistochemistry, and real-time PCR methods for detection of GFP-labeled MSCs, we found that although considerably entrapped in lungs, native MSCs home very rarely to kidneys and bone marrow and this rate cannot be significantly affected by CXCR4 and/or CXCR7 upregulation. Transplantation of neither native nor genetically engineered MSCs ameliorated kidney failure. We concluded that overexpression of CXCR4 and CXCR7 receptors in murine MSCs cannot improve the homing and therapeutic potentials of these cells and it can be due to severe chromosomal abnormalities that these cells bear during ex vivo expansion.
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