Apoptotic Signaling Across Breast Cancer Subtypes and Cryoablation-Induced Tissue Injury

Apoptosis maintains tissue homeostasis, and its dysregulation is closely associated with breast cancer progression and therapeutic resistance. We performed an integrative analysis of apoptosis-related signaling in breast cancer tissues across five molecular subtypes and compared these patterns with systemic apoptotic responses following cryoablation of benign fibroadenomas. Gene expression profiling was conducted using mRNA microarrays and validated by qRT-PCR and ELISA. Apoptosis pathway activity was assessed with the MSigDB HALLMARK_APOPTOSIS gene set, including intrinsic and extrinsic pathway scoring and an apoptotic balance index (ABI). MicroRNA profiling combined with in silico analyses identified potential miRNA-mRNA interactions. A progressive shift toward reduced pro-apoptotic and enhanced stress-adaptive signaling was observed with increasing tumor aggressiveness, most pronounced in triple-negative and non-luminal HER2-positive cancers. This pattern included reduced intrinsic pathway activity, decreased ABI, downregulation of pro-apoptotic genes (BIK, BMF, TXNIP), and upregulation of stress-associated or cytoprotective genes (HSPB1, PPT1). Several expression patterns were accompanied by overexpression of miRNAs (miR-582-5p, miR-421, miR-106b-5p, miR-20a-5p, miR-20b-5p, miR-93-5p) predicted to target apoptosis-related genes. In contrast, fibroadenoma cryoablation was associated with transient systemic modulation of apoptosis-related genes and proteins followed by gradual normalization. These findings highlight differences between apoptosis-related dysregulation in malignant tissue and regulated systemic responses following benign tissue injury, supporting pathway-level interpretation and identifying candidate molecular networks warranting further mechanistic and translational investigation.