Molecular mechanism of CD163(+) tumor-associated macrophage (TAM)-derived exosome-induced cisplatin resistance in ovarian cancer ascites

BACKGROUND: Studies have found that tumor-associated macrophages (TAMs) in the malignant ascites of patients with serous ovarian cancer exhibit a mixed polarization phenotype and highly variable expression of the surface marker CD163. The exosomes secreted by mesenchymal cells can be taken up by tumor cells, affecting the malignant biological behavior of them. METHODS: Using reverse transcription-polymerase chain reaction (RT-PCR) to detect the genes expression of drug resistance related factors cancer stem cells (CSCs)/multidrug resistance (MDR)/epithelial-mesenchymal transition (EMT) after CD163(+) TAMs exosomes in ovarian cancer ascites co-cultured with A2780 and A2780/cis-diamminedichloroplatinum (DDP). Differences of the level of miR-221-3p expression between CD163(+) TAMs cells (M2) and peripheral blood mononuclear cells M0 detect by microarray screening, and bioinformatics analysis predicts that its target gene is ADAMTS6. Western blot (WB) and immunohistochemical detection of ADAMTS6 expression level in epithelial ovarian cancer (EOC) clinical sample tissues, and analysis of the ADAMTS6 expression in ovarian cancer tissues and its correlation with clinicopathological factors. WB was used to detect the expression of AKT pathway and downstream EMT-related molecules [SNAIL1, ZEB1, Vimentin (VIM)] after co-culture of CD163(+) TAMs exosomes with ovarian cancer cell lines A2780, A2780/DDP. WB detects the expression of EGFR and TGF-β1 upstream molecules of the AKT signaling pathway (AKT-pAKT) and downstream EMT molecules (SNAIL1, ZEB1, VIM) after overexpression of ADAMTS6 in A2780 and A2780/DDP. RESULTS: We demonstrated that after CD163(+) TAM exosomes were taken up by EOC cells, the highly expressed miR-221-3p could downregulate the level of ADAMTS6, further activate the AKT signaling pathway, and increase the expression of EMT transcription factors SNAIL1 and ZEB1 and the mesothelial marker VIM. Decreased expression of the epithelial marker E-cadherin induced EMT, triggering a switch to a CSC-like phenotype and MDR, thereby promoting EOC cell proliferation, adhesion, migration, and resistance. Compared with benign ovarian tumors, ADAMTS6 expression was low in EOC tissues and was closely related to the clinical stage, age, and survival curve of ovarian cancer patients. CONCLUSIONS: Overexpression of ADAMTS6 reduced the IC50 of cisplatin in ovarian cancer cells. The mechanism may be related to the inhibition of EMT mediated by the EGFR/TGF-β/AKT pathway of EOC cells, which has potential value in the treatment of ovarian cancer.