Essential role for TrpC5-containing extracellular vesicles in breast cancer with chemotherapeutic resistance

Abstract

A critical challenge for chemotherapy is the development of chemoresistance in breast cancer. However, the underlying mechanisms and validated predictors remain unclear. Extracellular vesicles (EVs) have gained attention as potential means for cancer cells to share intracellular contents. In adriamycin-resistant human breast cancer cells (MCF-7/ADM), we analyzed the role of transient receptor potential channel 5 (TrpC5) in EV formation and transfer as well as the diagnostic implications. Up-regulated TrpC5, accumulated in EVs, is responsible for EV formation and trapping of adriamycin (ADM) in EVs. EV-mediated intercellular transfer of TrpC5 allowed recipient cells to acquire TrpC5, consequently stimulating multidrug efflux transporter P-glycoprotein production through a Ca 2+ -and activated T-cells isoform c3-mediated mechanism and thus, conferring chemoresistance on nonresistant cells. TrpC5-containing circulating EVs were detected in nude mice bearing MCF-7/ ADM tumor xenografts, and the level was lower after TrpC5-siRNA treatment. In breast cancer patients who underwent chemotherapy, TrpC5 expression in the tumor was significantly higher in patients with progressive or stable disease than in patients with a partial or complete response. TrpC5-containing circulating EVs were found in peripheral blood from patients who underwent chemotherapy but not patients without chemotherapy. Taken together, we found that TrpC5-containing circulating EVs may transfer chemoresistance property to nonchemoresistant recipient cells. It may be worthwhile to further explore the potential of using TrpC5-containing EVs as a diagnostic biomarker for chemoresistant breast cancer.T he development of chemotherapeutic resistance in breast cancer is a serious problem (1, 2). To date, the mechanisms underlying chemoresistance are still largely unknown, and no validated predictive factor of chemoresistance is available in the clinic. Therefore, it is important to identify the signaling pathways and search for circulating markers in breast cancer resistant to chemotherapy.The extracellular environment contains a large number of mobile membrane-limited vesicles named extracellular vesicles (EVs). Major EV populations include exosomes, microvesicles, and apoptotic bodies (1, 3-5). These dynamic EVs may have essential function in intercellular communication and immune regulation (5). Tumor cells also generate EVs (3, 4). Large quantities of tumor-derived circulating EVs have been found in the blood of patients with glioblastoma multiforme (4), pancreatic cancer (6), gastric cancer (7), and acute myeloid leukemia (8). They contain cell surface proteins, RNA, and DNA (3, 4, 9, 10). They mediate intercellular cross-talk by transferring their intravesicular contents from donor to recipient cells and participating in tumor invasion and metastasis (11-13). However, how these structures are generated and their importance in chemotherapeutic resistance in breast cancer are poorly understood.On the basis of our previous finding that transient receptor...

Breast cancer resistance protein (BCRP)-containing circulating microvesicles contribute to chemoresistance in breast cancer

“…It has previously been reported that flotillin-2 overexpression is associated with a poor prognosis and reduced survival in patients with both early-and late-stage breast cancer (17). Moreover, Ma et al (10) demonstrated that flotillin-2 expression is significantly upregulated following chemotherapy and the present study confirmed this. Based on these findings, BCRP and flotillin-2 may be indicators of the potential response to neoadjuvant chemotherapy.…”

“…To the best of our knowledge, this is the first study to investigate the association between BCRP and circulating EVs, elucidating the mechanism of clinical drug resistance. Previous studies have demonstrated that recipient cells can acquire drug resistance by the transmission of P-glycoprotein or Ca 2+ -permeable channels via EVs (10). The association between BCRP-containing EVs and poor outcomes of clinical chemotherapy were further verified.…”

“…IF staining was performed as described previously (10). Isolated EVs were resuspended in PBS, and then passed through a 0.8-µm filter (Stericup, Merck Millipore, Billerica, MA, USA), allowing EVs of diameters <0.8 µm to remain in the filtrate.…”

“…Tumor cells, in addition to other cells in the tumor microenvironment, also release EVs, and there is evidence that they contribute to tumor progression by promoting angiogenesis and metastasis (4). Our previous study demonstrated that circulating EVs containing the Ca 2+ -permeable channel TrpC5 transfer chemoresistance to previously non-chemoresistant recipient cells (10). This study led to the hypothesis that EVs may serve an essential role in clinical chemoresistance, therefore the present study aimed to investigate the association between EVs and drug resistance.…”

Exosomes: Emerging Players of Intercellular Communication in Tumor Microenvironment

“…101 It has been shown that adriamycin-resistant MCF-7 cells' derived MVs aided the resistance in recipient cells by transferring Ca 2+ permeable channel TrpC5, which after incorporation induced the expression of P-gp. 102 Exosome-antibody interaction is another way by which cancer cells evade chemotherapeutic pressure. It has been found that exosome antibody sequestration reduces the antibody-dependent cytotoxicity in cancer cells by immune effector cells.…”