Chemotherapy-elicited extracellular vesicle CXCL1 from dying cells promotes triple-negative breast cancer metastasis by activating TAM/PD-L1 signaling

Abstract

Background Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, and chemotherapy still serves as the cornerstone treatment functioning by inducing cytotoxic cell death. Notably, emerging evidence suggests that dying cell-released signals may induce cancer progression and metastasis by modulating the surrounding microenvironment. However, the underlying molecular mechanisms and targeting strategies are yet to be explored. Methods Apoptotic TNBC cells induced by paclitaxel or adriamycin treatment were sorted and their released extracellular vesicles (EV-dead) were isolated from the cell supernatants. Chemokine array analysis was conducted to identify the crucial molecules in EV-dead. Zebrafish and mouse xenograft models were used to investigate the effect of EV-dead on TNBC progression in vivo. Results It was demonstrated that EV-dead were phagocytized by macrophages and induced TNBC metastasis by promoting the infiltration of immunosuppressive PD-L1+ TAMs. Chemokine array identified CXCL1 as a crucial component in EV-dead to activate TAM/PD-L1 signaling. CXCL1 knockdown in EV-dead or macrophage depletion significantly inhibited EV-dead-induced TNBC growth and metastasis. Mechanistic investigations revealed that CXCL1EV-dead enhanced TAM/PD-L1 signaling by transcriptionally activating EED-mediated PD-L1 promoter activity. More importantly, TPCA-1 (2-[(aminocarbonyl) amino]-5-(4-fluorophenyl)-3-thiophenecarboxamide) was screened as a promising inhibitor targeting CXCL1 signals in EVs to enhance paclitaxel chemosensitivity and limit TNBC metastasis without noticeable toxicities. Conclusions Our results highlight CXCL1EV-dead as a novel dying cell-released signal and provide TPCA-1 as a targeting candidate to improve TNBC prognosis. Graphical abstract

Baohuoside I chemosensitises breast cancer to paclitaxel by suppressing extracellular vesicle/CXCL1 signal released from apoptotic cells

“…Significantly, immunofluorescence analysis further suggested that the Flag‐tagged EV‐Apo/CXCL1 signal was predominantly phagocytosed by CD206 + TAMs in the TME of the immunodeficient NSG mice (Figure 9d ). In fact, our previous study has confirmed that the EV‐Apo/CXCL1 signal was predominantly phagocytosed by CD206 + TAMs within the TME of immunocompetent Balb/c mice, despite the presence of other immune cells (Wang et al., 2024 ). More importantly, similarly to the effect of the GW4869 (exosome secretion inhibitor) and paclitaxel combination, BHS and paclitaxel combination also significantly decreased the infiltration of TAMs and attenuated their PD‐L1 expression, whereas the exogenous addition of CXCL1‐overexpressing EV‐Apo dramatically reversed that (Figure 9e–f ).…”

“…However, there were no significant differences in the uptake efficiencies between EV‐Apo and EV‐Apo BHS . Our previous study suggested that chemokine CXCL1 was the bioactive molecule in EV‐Apo and could activate downstream signalling PD‐L1 expression (Wang et al., 2024 ). In this study, knockdown of CXCL1 in EV‐Apo significantly inhibited EV‐Apo‐induced M2 polarization of Raw264.7 macrophages and therefore suppressed the invasion and apoptosis resistance of 4T1 cells co‐cultured with macrophages in vitro.…”