Caspase-1/11 deficiency and cold exposure enhance the anti-tumor activity of brown adipose tissue secretome against breast cancer cells

BACKGROUND: Adipose tissue metabolic plasticity and inflammation critically influence tumor progression through endocrine signaling. While white adipose tissue (WAT) has been linked to pro-tumorigenic effects in obesity-related cancers, the influence of brown adipose tissue (BAT) and its secretome on breast cancer remains incompletely understood. Furthermore, how caspase-1/11–mediated inflammasome signaling regulates adipose tissue endocrine function in this context is largely unexplored. This study investigated the differential effects of WAT and BAT secretomes on breast cancer aggressiveness and elucidate the impact of caspase-1/11 deficiency on adipose tissue-tumor crosstalk. METHODS: Conditioned media (CM) were generated from WAT and BAT of wild-type (WT) and caspase-1/11 knockout (KO) C57BL/6 mice, including animals subjected to cold-induced BAT activation. 4T1 breast cancer cells were exposed to these secretomes, and carcinogenic parameters were assessed, including viability (MTT), cell death (Annexin-V/PI), proliferation (CFSE), migration (wound healing assay), lipid droplet biogenesis (BODIPY and Oil Red staining and microscopy), oxidative stress (ROS and nitrite quantification), and cytokine production (ELISA). Additionally, splenocytes were also stimulated with the secretomes to assess their effect on T and NKT cell activation (Flow cytometry). Global proteomic profiling (LC-MS/MS) was performed to identify key molecular pathways affected of exposed breast cancer cells compared to controls. Statistical analyses included ANOVA with Tukey’s or Student’s t-test, as appropriate. RESULTS: WAT-CM promoted lipid droplet accumulation in 4T1 cells. In contrast, BAT-CM reduced tumor cell viability, cell proliferation, and migration further triggering oxidative stress and cell death. Immunophenotypic analysis revealed that BAT-CM modulated immune activation. These antitumor effects were amplified by caspase-1/11 deficiency and cold-induced BAT activation. Proteomic analyses revealed distinct modulation of metabolic, inflammatory, and immune-related pathways in WAT- and BAT-CM-treated tumor cells. Histological and cytokine analyses demonstrated that caspase-1/11 deficiency led to reduced adipocyte size, increased BAT macrophage infiltration, and a softened inflammatory profile. CONCLUSIONS: Our findings uncover a novel anti-tumor role for the BAT secretome in breast cancer, modulated by caspase-1/11-dependent inflammasome signaling and cold-induced activation. Targeting adipose tissue plasticity and inflammasome pathways may offer new strategies to reprogram the tumor microenvironment. These results open novel perspectives for exploring BAT-derived factors as metabolic-based therapeutics for breast cancer.