Electrophysiological phenotype development and paracrine action of mesenchymal stem cells (MSCs) are the critical factors that determine the therapeutic efficacy of MSCs for myocardial infarction (MI). In such respect, coculture of MSCs with cardiac cells has windowed a platform for cardiac priming of MSCs. Particularly, active gap junctional crosstalk of MSCs with cardiac cells in coculture has been known to play a major role in the MSC modification through coculture. Here, we report that iron oxide nanoparticles (IONPs) significantly augment the expression of connexin 43 (Cx43), a gap junction protein, of cardiomyoblasts (H9C2), which would be critical for gap junctional communication with MSCs in coculture for the generation of therapeutic potential-improved MSCs. MSCs cocultured with IONP-harboring H9C2 (cocultured MSCs: cMSCs) showed active cellular crosstalk with H9C2 and displayed significantly higher levels of electrophysiological cardiac biomarkers and a cardiac repair-favorable paracrine profile, both of which are responsible for MI repair. Accordingly, significantly improved animal survival and heart function were observed upon cMSC injection into rat MI models compared with the injection of unmodified MSCs. The present study highlights an application of IONPs in developing gap junctional crosstalk among the cells and generating cMSCs that exceeds the reparative potentials of conventional MSCs. On the basis of our finding, the potential application of IONPs can be extended in cell biology and stem cell-based therapies.

Background The effects of cancer-associated fibroblasts (CAF) on the progression of gastric carcinoma (GC) has recently been demonstrated. However, agents targeting the interaction between CAF and GC cells have not been applied in a clinical setting. Here, we examined if inhibition for Axl receptor tyrosine kinase (AXL) can suppress CAF-induced aggressive phenotype in GC. Methods We investigated the function of CAF-derived growth arrest-specific 6 (GAS6), a major ligand of AXL, on the migration and proliferation of GC cells. The effect of the AXL inhibitor, BGB324, on the CAF-induced aggressive phenotype of GC cells was also investigated. In addition, we performed immunohistochemistry to examine the expression of phosphorylated AXL protein in 175 GC tissues and evaluated its correlation with the prognosis. Results The qPCR and western blot analysis showed that GAS6 expression was higher in CAF relative to other cells. We found that co-culture with CAF increased the phosphorylation of AXL (P-AXL), differentiation into a mesenchymal-like phenotype, and cell survival in GC cell lines. When the expression of AXL was genetically inhibited in GC cells, the effect of CAF was reduced. BGB324, a small molecule inhibitor of AXL, suppressed the effects of CAF on GC cell lines. In GC tissues, high levels of P-AXL were significantly associated with poor overall survival (P = 0.022). Conclusions We concluded that CAF are a major source of GAS6 and that GAS6 promotes an aggressiveness through AXL activation in GC. We suggested that an AXL inhibitor may be a novel agent for GC treatment.

The present study aimed to investigate whether the Janus-activated kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) signaling pathway is a critical mechanism underlying the cancer-associated fibroblast (CAF)-induced chemoresistance of gastric cancer (GC). In addition, the present study tried to suggest a natural product to compromise the effects of CAF on the chemoresistance of GC. The results of cell proliferation assay revealed that the conditioned medium (CM) collected from CAFs further increased resistance to 5-fluorouracil (5-FU) in GC cell lines. Secretome analysis revealed that the levels of several secreted proteins, including C-C motif chemokine ligand 2, C-X-C motif chemokine ligand 1, interleukin (IL)-6 and IL-8, were increased in the CM from CAFs co-cultured with cancer cells compared to CM from cancer cells. Western blot analysis revealed that CAFs activated the JAK/STAT3 signaling pathway in cancer cells. The experimental models revealed that curcumin abrogated the CAF-mediated activation of the JAK/STAT3 signaling pathway in GC cells. In vivo data revealed the synergistic effects of curcumin with 5-FU treatment in xenograft GC tumors. These data strongly suggest that the suppression of the JAK/STAT3 signaling pathway counteracts the CAF-induced chemoresistance of GC cells. It is suggested that curcumin may be a suitable natural product which may be used to overcome chemoresistance by inhibiting the CAF-induced activation of the JAK/STAT3 signaling pathway in GC.

Developments of non-viral carriers have headed toward reducing cytotoxicity, which results from the use of conventional gene carriers, and enhancing gene delivery efficiency. Cys-(d-R9)-Cys repeated reducible poly(oligo-D-arginine) (rPOA) is one of the most efficient non-viral carriers for gene therapy; however, while its efficiency has been verified in the lung and brain, it is necessary to confirm its activity in each organ or tissue since there are differences of gene carrier susceptibility to among tissue types. We therefore tested the compatibility of rPOA in cardiac tissue by in vitro or in vivo experiments and confirmed its high transfection efficiency and low cytotoxicity. Moreover, substantial regenerative effects were observed following transfection with rPOA/pVEGF expression vector complexes (79% decreased infarct size) compared to polyethyleneimine (PEI) (34% decreased infarct size) in a rat myocardial infarction (MI) model. These findings suggest that rPOA efficiently enables DNA transfection in cardiac tissue and can be used as a useful non-viral therapeutic gene carrier for gene therapy in ischemic heart disease.

Cancer-associated fibroblasts (CAF) are a major component of tumor stroma and their effect on the progression of gastric carcinoma (GC) has recently been demonstrated. However, agents targeting the interaction between CAF and GC cells have not been applied in a clinical setting. The aim of this study was to investigate the effect of an AXL inhibitor on CAF-induced GC progression. We examined growth arrest specific factor 6 (GAS6) expression and phosphorylation of AXL in various cell lines, including GC cells and non-cancerous cells, by qPCR, western blot, and immunocytochemistry. We investigated the role of CAF-derived GAS6 on the migration and proliferation of GC cells using migration and cell survival assays. The effect of the AXL inhibitor, Bemcentinib, on the CAF-induced aggressive phenotype of GC cells was also investigated. Finally, we performed immunohistochemistry to measure the phosphorylation of AXL in a tissue microarray composed of 175 GC tissues, and evaluated its correlation with the prognosis of GC patients. qPCR and western blot analysis showed that GAS6 expression was higher in CAF relative to other cells. We found that CAF increased the phosphorylation of AXL (P-AXL), differentiation into a mesenchymal-like phenotype, and cell survival in GC cell lines. When the expression of AXL was inhibited in GC cells, the effect of CAF was reduced. In addition, Bemcentinib, a small molecule inhibitor of AXL, suppressed the effects of CAF on GC cell lines. In GC tissues, P-AXL positively correlated with the expression of vimentin (P < 0.001) and high levels of P-AXL were significantly associated with poor overall survival (P = 0.022).These findings suggest that CAF is a major source of GAS6 in the GC microenvironment and actively promotes an aggressive phenotype in GC cells through AXL activation. We conclude that an AXL inhibitor may be a novel agent for GC treatment. Citation Format: Dagyoeng Lee, Jongsu Woo, Cheong A Bae, In-Hye Ham, Hye Jung Oh, Sang-Yong Son, Sang-Uk Han, Tae-Min Kim, Jung Hwan Yoon, Won Sang Park, Hoon Hur. Inhibiting the GAS6/AXL axis suppresses tumor progression by blocking the interaction between cancer-associated fibroblasts and cancer cells in gastric carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2030.