Plasma CCL5 promotes EMT-medicated epirubicin-resistance in locally advanced breast cancer.

Neoadjuvant chemotherapy (NCT) is the standard treatment for locally advanced breast cancer (LABC). Pathological complete response (pCR) is commonly used as a valid predictor of NCT long-term outcomes. Blood-based tumor biomarkers have the potential to predict response to NCT at early stage non-invasively. We believed plasma CCL5 could be a potential marker to predict NCT of LABC. Its efficiency and possible mechanism was studied in this work. Human Cytokine Antibody Microarray was applied to screen different cytokine concentration in plasma between low histological regression (Low-R) and high histological regression (High-R) patients. LABC patients were divided into two groups according to pathological reactivity. The concentration of plasma CCL5 in different groups was determined by ELISA analysis. CCK8 assay was performed to analyze epirubicin susceptibility of breast cancer cells. Transwell assay was performed to determine the effect of CCL5 on breast cancer cells' migration and invasion. qRT-PCR and western blot were used to verify the EMT (epithelial-mesenchymal transition) markers in CCL5-treated and epirubicin-treated breast cancer cells. The concentration of plasma CCL5 of Low-R group was higher than High-R group before NCT. The plasma levels of CCL5 were significantly reduced after NCT in the group of high histological regression (High-R). Epirubicin susceptibility decreased in the breast cancer cells treated by recombinant CCL5. Migration and invasion were significantly enhanced in breast cancer cells treated by recombinant CCL5. E-cadherin expression was decreased whereas vimentin increased significantly in CCL5-treated breast cancer cells. The phosphorylation of ezrin in Y-567 and its downstream protein cortactin increased significantly in CCL5-treated breast cancer cells. Plasma CCL5 level could be a promised candidate to predict chemotherapy response of breast cancer. Plasma CCL5 plays an important role in EMT process of breast cancer.