Highlights d Mechanical tension-induced Yap activation triggers hepatocyte dedifferentiation d Confinement of cell spreading is sufficient to inhibit hepatocyte dedifferentiation d A chemical cocktail, LBDXL, maintains hepatocyte functions by targeting stress fibers d LBDXL hepatocytes resemble primary hepatocytes in gene expression and functions
Utilizing novel approaches for the green synthesis of metal nanoparticles are of great importance. Therefore, we reported biogenic synthesis of silver nanoparticles (AgNPs) using extracts of Leptolyngbya strain JSC-1, and their significant applications against pathogenic bacteria and cancerous HeLa cell line. The biofabricated AgNPs were characterized by UV-visible spectroscopy, FTIR, SEM, TEM, DLS and zeta-potential. The as prepared AgNPs were assessed for inhibition of bacterial growth and induction of apoptosis in HeLa cells by different doses of AgNPs was evaluated. UV-visible spectroscopy and FTIR of AgNPs demonstrated the surface plasmon resonance at 413 nm and interaction among extract and nanoparticles, respectively. Electron microscopy revealed the morphology and DLS demonstrated size distribution of the particles (10-100 nm). Zeta potential values were between -47 and 0 mV, indicating stability of the particles. Proliferation of HeLa cells was significantly inhibited and severe cytotoxicity with higher intracellular uptake were observed after applying high concentration of AgNPs. Efficient inhibition zones (17 ± 2 and 21 ± 2 mm) were produced at maximum concentration (100 µl from 1 mg ml stock of AgNPs) for Staphylococcus aureus and Escherichia coli, respectively. These findings reveal that the biofabricated AgNPs possess strong antibacterial activity and ability to induce apoptosis in cancer cell line (HeLa).
Recent studies have shown that metal and metal oxide have a potential function in antitumor therapy. Our previous studies demonstrated that cuprous oxide nanoparticles (CONPs) not only selectively induce apoptosis of tumor cells in vitro but also inhibit the growth and metastasis of melanoma by targeting mitochondria with little hepatic and renal toxicities in mice. As a further study, our current research revealed that CONPs induced apoptosis of human melanoma stem cells (CD271
+/high
cells) in A375 and WM266-4 melanoma cell lines and could significantly suppress the expression of MITF, SOX10 and CD271 involved in the stemness maintenance and tumorigenesis of melanoma stem cells. CD271
+/high
cells could accumulate more CONPs than CD271
−/low
through clathrin-mediated endocytosis. In addition, lower dosage of CONPs exhibited good anti-melanoma effect by decreasing the cell viability, stemness and tumorigenesis of A375 and WM266-4 cells through reducing the expression of SOX10, MITF, CD271 and genes in MAPK pathway involved in tumor progression. Finally, CONPs obviously suppressed the growth of human melanoma in tumor-bearing nonobese diabetic-severe combined immunodeficiency (NOD-SCID) mice, accompanied with tumors structural necrosis and fibrosis remarkably and decreased expression of CD271, SOX10 and MITF. These results above proved the effectiveness of CONPs in inhibiting melanoma progress through multiple pathways, especially through targeting melanoma stem cells.
Cancer immunotherapy is the use of the immune system to treat cancer. Our current research proposed an optional strategy of activating immune system involving in cancer immunotherapy. When being treated with 2% DMSO in culture medium, Hepa1-6 cells showed depressed proliferation with no significant apoptosis or decreased viability. D-hep cells, Hepa1-6 cells treated with DMSO for 7 days, could restore to the higher proliferation rate in DMSO-free medium, but alteration of gene expression profile was irreversible. Interestingly, tumors from D-hep cells, not Hepa1-6 cells, regressed in wild-type C57BL/6 mice whereas D-hep cells exhibited similar tumorigenesis as Hep1–6 cells in immunodeficient mice. As expected, additional Hepa1-6 cells failed to form tumors in the D-hep-C57 mice in which D-hep cells were eliminated. Further research confirmed that D-hep-C57 mice established anti-tumor immunity against Hepa1-6 cells. Our research proposed viable tumor cells with altered biological features by DMSO-treatment could induce anti-tumor immunity in vivo.
Spinal cord impairment involving motor neuron degeneration and demyelination can cause life-long disabilities, but effective clinical interventions for restoring neurological functions have yet been developed. In early spinal cord development, neural progenitors in the pMN (‘progenitors of motor neurons’) domain, defined by the expression of oligodendrocyte transcription factor 2 (OLIG2), in ventral spinal cord first generate motor neurons and then switch the fate to produce myelin-forming oligodendrocytes. Given their differentiation potential, pMN progenitors could be a valuable cell source for cell therapy in relevant neurological conditions such as spinal cord injury. However, fast generation and expansion of pMN progenitors in vitro while conserving their differentiation potential has so far been technically challenging. In this study, based on the chemical screening, we have developed a new recipe for efficient induction of pMN progenitors from human embryonic stem cells. More importantly, these OLIG2+ pMN progenitors can be stably maintained for multiple passages without losing their ability to produce spinal motor neurons and oligodendrocytes rapidly. Our results suggest that these self-renewing pMN progenitors could potentially be useful as a renewable source of cell transplants for spinal cord injury and demyelinating disorders.
Background
Induced hepatic stem cells (iHepSCs) with the capacities of self-renewal and bidifferentiation into hepatocytes and cholangiocytes were generated from mouse embryonic fibroblasts (MEFs) by lineage reprogramming in our previous research. However, the mechanism of iHepSC self-renewal has not been elucidated. Active demethylation regulated by Tet1 plays an important role in the self-renewal of stem cells, including pluripotent stem cells and adult stem cells. Here, we investigated the role and mechanism of Tet1-regulated demethylation in the self-renewal of iHepSCs.
Methods
The methylation levels and the expression of Tet1 in iHepSCs and MEFs were analyzed by immunofluorescent staining, quantitative reverse transcription PCR and western blotting. Then, the effects of Tet1 knockdown on the proliferation and self-renewal of iHepSCs were analyzed by CCK8, colony formation, and sphere formation assays. The mechanism by which Tet1 regulates the self-renewal of iHepSCs was investigated by chromatin immunoprecipitation, bisulfite sequence PCR, and methylation-sensitive restriction endonuclease-PCR.
Results
The high level of 5hmC and the low level of 5mC in iHepSCs were accompanied by high expression of Tet1. After Tet1 expression was knocked down by shRNA in iHepSCs, the proliferation and self-renewal capacities were inhibited, and the expression of Myc was also decreased. The higher expression level of Myc in iHepSCs maintained its self-renewal and was regulated by Tet1, which directly binds to CBS-1 and site A regions of the Myc promoter and demethylates the CpG cytosine. In addition, CTCF also binds to the CBS-1 and site A regions of the Myc promoter and regulates Myc expression along with TET1.
Conclusion
The self-renewal of iHepSCs was maintained by the higher expression of Myc, which was coregulated by TET1 and CTCF. This study may provide new insights into the self-renewal of stem cells, which can promote the research and application of ‘reprogrammed’ stem cells.
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