The role of cancer associated fibroblasts (CAF) extracellular vesicles (EVs) in mediating resistance of EGFR-TKI in NSCLC

Abstract

Tumor microenvironment consists of the extracellular matrix (ECM) tumor-associated normal epithelial and stromal cells immune cells and vascular cells Cancer associated fibroblasts (CAF) which are the major components of cancer stroma were found mediating epidermal growth factor receptor - tyrosine kinase inhibitor (EGFR-TKI) resistance via tumor-stroma interactions Growth factors like TGF-β and PDGF can be either freely secreted in the tumor microenvironment or delivered via exosomes Although most studies focus on cancer cell-secreted exosomes recent study highlighted the role of CAF-secreted exosomes However the study using systemic approach for all possible pathways interacting between tumor cell and CAF remained rare Extracellular vesicles (EVs) including exosome secreted by a variety of cell types modulate immune function angiogenesis and cell proliferation as well as tumor cell invasion and metastasis EVs from cancer associated fibroblasts were also found promoting chemoresistance in colorectal breast and pancreatic cancer cells We proposed that CAF may mediate EGFR-TKI resistance by transferring exosomal cargo and EVs from TKI-treated CAF may enhance the drug resistance We planned to verify our hypothesis in vitro and identify the cargo from CAF derived EVs and associated mechanism contributing EGFR-TKI resistance Our data first showed that CAF derived EVs can be uptaken by PC9 cells We further demonstrated PC9 cells were resistant to EGFR-TKI after CAF EVs treatment We pre-treated CAF with gefitinib and isolated EVs from culture medium the sensitivity to EGFR-TKI of PC9 cells were decreased Next we isolated EVs from CAF DMSO-treated CAF and TKI-treated CAF and performed a comparative analysis of their miRNA content Among the miRNA expression panels the miR-423-5p was the most abundant miRNA identified in TKI-treated CAF EVs The overexpression of miR-423-5p increased PC9 cells resistance to gefitinib We demonstrated that CAF EVs regulated drug resistance via transferring miR-423-5p to PC9 cells

Date of Award	2020
Original language	English
Supervisor	Wu-Chou Su (Supervisor)