Post-radiation inflammatory reaction leads to an irreversible pulmonary fibrosis which may cause lethal respiratory insufficiency. Pathological inflammatory and fibrotic changes might be attenuated by inhibiting tumour necrosis factor (TNF)-α activity using TNF-α soluble receptors. Thus, an experimental antifibrotic gene therapy with the plasmid vector encoding a mouse soluble receptor I for TNF-α (psTNFR-I) was assessed. Soluble TNFR-I encoding gene was cloned into pcDNA3.1 plasmid. The ability of psTNFR-I expressing vector to transfect cells, and its biological activity in vitro and in vivo were examined by PCR, RT-PCR, MTT assay and ELISA. The C57Bl/6J mice received single intramuscular injection of psTNFR-I, conjugated with polyetylenimine (PEI) 25 kDa, equally divided to both hind legs, 3 days before irradiation (20 Gy, Co60), and either a single injection or ten injections once a week after irradiation. The data proved the effectiveness of psTNFR-I product to neutralise TNF-α activity in vitro. The in vivo plasmid incorporation and maintenance was confirmed. Measurements of plasma soluble TNFR-I levels showed that the in vivo gene transfer was effective. PEI was found to enhance transfection efficiency in vivo. The psTNFR-I/PEI complexes caused no toxicity in the transfected mice. C57Bl/6J mice that received prolonged psTNFR-I/PEI injections developed lethal fibrotic syndrome and died 8 weeks later than the mice treated with a double plasmid injection and the control mice treated with a control plasmid. Sequential administration of soluble TNFR-I by a nonviral, intramuscular gene transduction in the early and late post-radiation inflammatory phase prolonged survival of irradiated mice and attenuated the symptoms of lung fibrosis. The psTNFR-I gene transduction may provide a safe and simple method to partially neutralise TNF-α activity and prevent radiation-induced lung injury.
Accumulating data suggest that cancers contain a fraction of cells called cancer stem cells (CSCs), that may be responsible for upkeep and relapses of disease. In experimental settings, CSCs are regarded as most effective at tumour initiation in in vivo assays. Since the first isolation of cancer stem cells from acute myeloid leukaemia in 1994, cancer stem cells have been identified in human solid tumours and they have also been found in the established cell lines, based on ability of CSCs to form in vitro colonies of a specific morphology, called holoclones. Our study examined the ability of a mouse sarcoma cell line, derived from a lung metastasis of a BALB/c mouse and established as a stably growing line (L1), to produce holoclones in vitro. We aimed to verify a stemness signature of the holoclone cells. The L1 cell line was found to form holoclone colonies in vitro, which were shown to contain a percentage of CSC-like cells. A fraction of the L1 cells was able to repopulate the original cell line, and presented an increased clonogenic and metastatic potential (18th passage). In addition, MTT assay and flow cytometry of the side population fraction revealed that these cells were more resistant to chemotherapeutic drugs than the original cell line, and over-expressed the anti-apoptotic genes, GRP78 and GADD153. We conclude that mouse L1 sarcoma cell line contains CSC-like cells.
Protein kinase C (PKC) activity of cytosol and membrane fractions of lOT1/2 cells was studied. In cytosol of fast growing cells PKC activity was found in material eluted with 0.150 M NaCl whereas in membrane fractions activity was eluted with 0.065 and 0.150 M NaCl. In the membrane fraction of confluent cells, in contrast to cytosol, very low PKC activity was observed. The translocation pattern of PKC activity eluted with 0.065 M NaCl may be associated with proliferation.
This study aimed to evaluate the capacity of hypocalcemic analogues of 1α,25-dihydroxyvitamin D2 (1,25D2) and 1α,25-dihydroxyvitamin D3 (1,25D3) to inhibit regrowth and regulate the stemness-related gene expression in colon cancer cells undergoing renewal after exposure to 5-fluorouracil (5-FU). All of the tested analogues of 1,25D2 equally potently decreased the clonogenicity and the proliferative activity of HT-29 cells which survived the exposure to 5-FU, but differently regulated gene expression of these cells during their renewal. 1,25D2 and analogues (PRI-1907 and PRI-1917), as well as 1,25D3 and analogue PRI-2191, decreased the relative expression level of several stemness-related genes, such as NANOG, OCT3/4, PROM1, SOX2, ALDHA1, CXCR4, in HT-29/5-FU cells during their renewal, in comparison to untreated HT-29/5-FU cells. The other 1,25D2 analogues (PRI-1906 and PRI-1916) were not capable of downregulating the expression of these stemness-related genes as the analogues PRI-1907 and PRI-1917 did. All of the tested vitamin D analogues upregulated CDH1, the gene encoding E-cadherin associated with epithelial phenotype. Out of the series of analogues studied, side-chain branched analogues of 1,25D2 (PRI-1907, PRI-1917) and the analogue of 1,25D3 (PRI-2191) might be used to target cancer cells with stem-like phenotypes that survive conventional chemotherapy.
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