Background As one of the main functional forms of mesenchymal stem cells (MSCs), MSC-derived extracellular vesicles (MSC-EVs) have shown an alternative therapeutic option in experimental models of allergic asthma. Oxygen concentration plays an important role in the self-renewal, proliferation, and EV release of MSCs and a recent study found that the anti-asthma effect of MSCs was enhanced by culture in hypoxic conditions. However, the potential of hypoxic MSC-derived EVs (Hypo-EVs) in asthma is still unknown. Methods BALB/c female mice were sensitized and challenged with ovalbumin (OVA), and each group received PBS, normoxic human umbilical cord MSC-EVs (Nor-EVs), or Hypo-EVs weekly. After treatment, the animals were euthanized, and their lungs and bronchoalveolar lavage fluid (BALF) were collected. With the use of hematoxylin and eosin (HE), periodic acid-Schiff (PAS) and Masson’s trichrome staining, enzyme-linked immune sorbent assay (ELISA), Western blot analysis, and real-time PCR, the inflammation and collagen fiber content of airways and lung parenchyma were investigated. Results Hypoxic environment can promote human umbilical cord MSCs (hUCMSCs) to release more EVs. In OVA animals, the administration of Nor-EVs or Hypo-EVs significantly ameliorated the BALF total cells, eosinophils, and pro-inflammatory mediators (IL-4 and IL-13) in asthmatic mice. Moreover, Hypo-EVs were generally more potent than Nor-EVs in suppressing airway inflammation in asthmatic mice. Compared with Nor-EVs, Hypo-EVs further prevented mouse chronic allergic airway remodeling, concomitant with the decreased expression of pro-fibrogenic markers α-smooth muscle actin (α-SMA), collagen-1, and TGF-β1-p-smad2/3 signaling pathway. In vitro, Hypo-EVs decreased the expression of p-smad2/3, α-SMA, and collagen-1 in HLF-1 cells (human lung fibroblasts) stimulated by TGF-β1. In addition, we showed that miR-146a-5p was enriched in Hypo-EVs compared with that in Nor-EVs, and Hypo-EV administration unregulated the miR-146a-5p expression both in asthma mice lung tissues and in TGF-β1-treated HLF-1. More importantly, decreased miR-146a-5p expression in Hypo-EVs impaired Hypo-EV-mediated lung protection in OVA mice. Conclusion Our findings provided the first evidence that hypoxic hUCMSC-derived EVs attenuated allergic airway inflammation and airway remodeling in chronic asthma mice, potentially creating new avenues for the treatment of asthma.
Hepatocellular carcinoma (HCC) is notoriously refractory to chemotherapy because of its tendency to develop multi-drug resistance (MDR), whose various underlying mechanisms make it difficult to target. The calcium signalling pathway is associated with many cellular biological activities, and is also a critical player in cancer. However, its role in modulating tumour MDR remains unclear. In this study, stimulation by doxorubicin, hypoxia and ionizing radiation was used to induce MDR in HCC cells. A sustained aggregation of intracellular calcium was observed upon these stimuli, while inhibition of calcium signalling enhanced the cells’ sensitivity to various drugs by attenuating epithelial-mesenchymal transition (EMT), Hif1-α signalling and DNA damage repair. The effect of calcium signalling is mediated via transient receptor potential canonical 6 (TRPC6), a subtype of calcium-permeable channel. An in vivo xenograft model of HCC further confirmed that inhibiting TRPC6 enhanced the efficacy of doxorubicin. In addition, we deduced that STAT3 activation is a downstream signalling pathway in MDR. Collectively, this study demonstrated that the various mechanisms regulating MDR in HCC cells are calcium dependent through the TRPC6/calcium/STAT3 pathway. We propose that targeting TRPC6 in HCC may be a novel antineoplastic strategy, especially combined with chemotherapy.
Numerous F-actin containing structures are involved in regulating protrusion of membrane at the leading edge of motile cells. We have investigated the structure and dynamics of filopodia as they relate to events at the leading edge and the function of the trailing actin networks. We have found that although filopodia contain parallel bundles of actin, they contain a surprisingly nonuniform spatial and temporal distribution of actin binding proteins. Along the length of the actin filaments in a single filopodium, the most distal portion contains primarily T-plastin, while the proximal portion is primarily bound by α-actinin and coronin. Some filopodia are stationary, but lateral filopodia move with respect to the leading edge. They appear to form a mechanical link between the actin polymerization network at the front of the cell and the myosin motor activity in the cell body. The direction of lateral filopodial movement is associated with the direction of cell migration. When lateral filopodia initiate from and move toward only one side of a cell, the cell will turn opposite to the direction of filopodial flow. Therefore, this filopodia-myosin II system allows actin polymerization driven protrusion forces and myosin II mediated contractile force to be mechanically coordinated.
Doxorubicin is a conventional and effective chemotherapy drug against hepatocellular carcinoma (HCC). However, during long-term doxorubicin monotherapy, HCC cells may eventually develop acquired-resistance to doxorubicin which results in recurrence and a poor prognosis. Salinomycin, an ionophore antibiotic, was recently reported to selectively kill human cancer stem cells (CSCs) which were response for chemoresistance. In this study, salinomycin was found to exert synergistic cytotoxicity with doxorubicin in HCC cells and be capable of inhibiting doxorubicin-induced epithelial-mesenchymal transition (EMT), an important cellular process involved in the acquired chemoresistance of tumors. Further experiments revealed that FOXO3a, a multifunctional transcription factor that can be activated by salinomycin, was vital in mediating doxorubicin-induced EMT. In addition, activated FOXO3a disturbed the interaction between β-catenin and TCF and inhibited the expression of β-catenin/TCF target genes (ZEB1, c-Myc and CyclinD1), which played important roles in doxorubicin-induced EMT in HCC cells. Finally, the enhanced curative efficacy of combination treatment of doxorubicin and salinomycin for HCC was confirmed in established xenograft models. In summary, the present study identifies a new doxorubicin-based chemotherapy for advanced HCC and provides a potential anti-cancer strategy targeting FOXO3a and related cell pathway molecules.
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