ABSTRACT
Exosomes (extracellular vesicles/EVs) participate in cell-cell communication and contain bioactive molecules, such as microRNAs. However, the detailed characteristics of secreted EVs produced by cells grown under low pH conditions are still unknown. Here, we report that low pH in the cell culture medium significantly affected the secretion of EVs with increased protein content and zeta potential. The intracellular expression level and location of stably expressed GFP-fused CD63 (an EV tetraspanin) in HeLa cells were also significantly affected by environmental pH. In addition, increased cellular uptake of EVs was observed. Moreover, the uptake rate was influenced by the presence of serum in the cell culture medium. Our findings contribute to our understanding of the effect of environmental conditions on EV-based cell-cell communication.
Subject(s)
Cell Culture Techniques/methods , Extracellular Vesicles/metabolism , Tetraspanin 30/genetics , Biological Transport , Cell Communication , Culture Media/chemistry , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , HEK293 Cells , HeLa Cells , Humans , Hydrogen-Ion Concentration , Recombinant Fusion Proteins/metabolism , Tetraspanin 30/metabolismABSTRACT
BACKGROUND/AIM: Gefitinib is a tyrosine kinase inhibitor of epidermal growth factor receptor (EGFR) and has been approved for the treatment of non-small cell lung cancers (NSCLCs) with EGFR mutations. Here we demonstrated that gefitinib induced a significantly enhanced biological activity of succinate-tetrazolium reductase (STR) in mitochondria and mitochondrial membrane potential in HCC827 cells (EGFR mutation NSCLCs, sensitive to gefitinib) at a high cell density. MATERIALS AND METHODS: We assessed the biological activity (STR, mitochondrial membrane potential, expression level of Bcl-2 family proteins) of gefitinib on NSCLCs at different cell densities. RESULTS: The 3D cell culture experiments showed the enhanced mitochondrial biological activity in clustered cell culture treated with gefitinib. Interestingly, the expression levels of Bcl-xL and Bax, were affected by the cellular number and gefitinib treatment. We also found that gefitinib prevented additive anticancer activity in the combinational treatment with doxorubicin, which induces mitochondria-dependent apoptotic cell death. CONCLUSION: Our results indicate that gefitinib may work as a mitochondrial protector against combinational treatment with mitochondria-dependent anticancer agents in high-cell-density.
