Effects Of Lung Tumor Exosomes On Mesenchymal Stem/Stromal Cells And The Underlying Molecular Mechanism

Background In tumor microenvironment,a continuous cross-talk between cancer cells and other cellular components is required to sustain tumor progression.Mesenchymal stem/stromal cells(MSCs)are a group of adult stem cells that have the capacity of self-renewing and multi lineage differentiation.They can be differentiated into several lineages including osteoblasts,adipocytes and chondrocytes.They are also known for their immunoregulatory abilities which have important clinical applications.Besides,they can be attracted to tumor sites and become an important component of the tumor microenvironment,thus contributing to tumor development.Accumulating evidence suggests that exosomes,a novel way of cell communication,play an important role in the cross-talk between MSCs and cancer cells.Exosomes could facilitate the direct intercellular transfer of proteins,lipids,and miRNA/mRNA/DNAs between cells.More and more evidence show that tumor cells could modulate surrounding cells through released exosomes.However,the mechanisms by which tumor exosomes contribute to interactions between MSCs and tumor cells remain largely unknown.Our results will bring new insights into the mechanisms underlying interactions between tumor cells exosomes and its environmental component-the MSCs.Objective In our previous research,we noticed that exosomes from human AMSCs could promote migration through Wnt signaling pathway in a breast cancer cell model.Vice versa,what’s the effect and molecular mechanisms of tumor cells derived exosomes on AMSCs?To illustrate this question,we decide to study how lung tumor cell A549-derived exosomes affect AMSCs and the underlying molecular mechanisms.Methods In the first part,we isolated AMSCs from adipose.Exosomes were harvested from lung cancer cell line A549 and added to AMSCs.Gene expression profiles were analysed through microarray.Secretion of inflammation-associated cytokines in exosomes-treated AMSCs were analysed by RT-PCR and ELISA.Cell differentiation,cell proliferation,cell migration and cell cycle were also tested.The growth-promoting effect of PMSCs on lung tumor cells was evaluated by in vivo mouse xenograft model.Signaling pathway involved in exosomes-treated MSCs was detected by PCR Array of Human Toll-like Receptor Signaling Pathway,RT-PCR and western blot.Results In this study,we found that lung tumor cell line A549-derived exosomes could change the gene expression profiles and the inflammation factors secretion profile of AMSCs.Exosomes also inhibited AMSCs osteogenic and adipogenic differentiation while increased AMSCs migration ability.More importantly,A549-derived exosomes induced a pro-inflammatory phenotype in AMSCs named PMSCs,which have significantly elevated secretion of IL-6,IL-8,and MCP-1.PMSCs possess a greatly enhanced ability in promoting lung tumor growth in a mouse xenograft model.Further signaling pathway analysis in PMSCs revealed a fast triggering of NF-κB.Genetic ablation of Toll-like receptor 2(TLR2)by siRNA and TLR2-neutralizing antibody could block NF-αB activation by exosomes.Hsp70 on the surface of lung tumor exosomes was found to be responsible for activation of NFκB-TLR signaling pathway.Conclusion Lung tumor cell A549-derived exosomes could inhibit MSCs osteogenic and adipogenic differentiation but increase cell migration.A pro-inflammatory phenotype was inducd in AMSCs by lung tumor cell A549-derived exosomes via NFκB-TLR2 signaling pathway.