PANX1-mediated NLRP3 inflammasome activation promotes an adaptive doxorubicin resistance through IL-1β signaling in breast cancer.

[BACKGROUND] Acquired resistance to chemotherapy is a major clinical obstacle in breast cancer treatment. While inflammasome activation is often induced during chemotherapy, its role in regulating therapeutic resistance remains poorly understood. Pannexin-1 (PANX1), a transmembrane channel protein, is a potential regulator of inflammation, but its function in chemoresistance has not been explored.

[METHODS] We used a multifaceted approach combining single-cell/spatial transcriptomics of patient cohorts and functional validation. The role of PANX1 was investigated using pharmacological inhibitors and genetic knockdown cell lines and animal models.

[RESULTS] High PANX1 expression correlates with worsened overall survival (log-rank p = 0.012), genomic instability, and chemoresistance in breast cancer patients. Mechanistically, doxorubicin (DOX) treatment triggers a PANX1-dependent activation of the NLR family pyrin domain containing 3 (NLRP3) inflammasome and downstream maturation of interleukin-1β (IL-1β). Pharmacological or genetic inhibition of PANX1 re-sensitized resistant breast cancer cells to DOX both in vitro and in vivo. This effect was mechanistically reversed by the addition of exogenous IL-1β, identifying it as the key downstream effector of resistance. In an external neoadjuvant chemotherapy cohort, the interaction of PANX1 and NLRP3 expression was validated to be a predictor for the probability of achieving a pathological complete response (pCR) to DOX-based treatment.

[CONCLUSIONS] Our study delineates a critical mechanism of adaptive chemoresistance in breast cancer orchestrated by the PANX1-NLRP3-IL-1β signaling. We provide a preclinical rationale for PANX1 not only as a biomarker for pCR prediction in patients receiving DOX-based neoadjuvant chemotherapy, but also as a targetable molecule to resensitize DOX-resistant tumors.