Background/Objectives: Although tissue inhibitors of metalloproteinases (TIMPs) are key regulators in breast cancer, their differential expression, clinical relevance, and molecular roles remain unclear. This study aimed to compare the expression patterns of the four TIMPs in breast cancer and evaluate their molecular interactions and associated pathways through an integrated bioinformatic analysis. Methods: The expression of TIMPs and their correlations with MMPs were analyzed using the TCGA PanCancer, cBioPortal, and GEO datasets. Associations between TIMP expression and overall survival were assessed in the TCGA Breast Invasive Carcinoma PanCancer cohort. Pathway enrichment analysis was performed using GO, KEGG, and DAVID. The relationships between immune cell infiltration, stromal cells, and TIMP expression were assessed using the EPIC algorithm. Statistical analyses were performed using R. Results: TIMP1 was the only inhibitor overexpressed in breast tumors and showed significant associations with the Luminal B, HER2, TNBC, and normal-like subtypes, along with a modest increase across stages. TIMP2, TIMP3, and TIMP4 were downregulated in tumors. High expression of TIMP1 and TIMP4 correlated with better overall survival. TIMP1-associated genes were enriched in NF-kappa and PI3K–Akt signaling and actin cytoskeleton components. TIMP2 was linked to Hedgehog and MAPK pathways and actin-related elements. TIMP3 correlated with Hedgehog and PI3K–Akt signaling, DNA damage response, and membrane components. TIMP4 was associated with VEGF, MAPK, PI3K–Akt, DNA damage pathways, and actin organization. TIMP2 showed strong positive correlations with MMP2 and MMP14, while TIMP4 showed negative correlations with MMP1 and MMP9. Interestingly, we found a strong positive correlation between TIMP2 and TIMP3 with ADAM12, as well as between TIMP2 and TIMP3 with ADAM10, and negative correlations with ADAM15. The differential expression of TIMPs favors greater infiltration of immune cells related to tumor progression and poor prognosis in breast cancer patients. Conclusions: TIMPs display contrasting expression profiles and distinct pathway associations in breast cancer. TIMP1 emerges as the only consistently overexpressed inhibitor, while TIMP4 appears as a promising prognostic marker with unique MMP correlations that may influence tumor behaviors.
Cayetano-Salazar et al. (Mon,) studied this question.