Abstract
Objective: To investigate the differential expression of the enzymes CYP27B1 (vitamin D-activating) and CYP24A1 (vitamin D-degrading) in breast cancer and normal breast tissues with associations of tumor characteristics, including stage, grade, size, and lymph node involvement.
Methodology: This cross-sectional study included 160 breast tissue samples (80 malignant, 80 normal), for the genes and protein expression analysis of CYP27B1 and CYP24A1 enzymes. Statistical analyses were performed to determine correlations between enzyme expression and clinic-pathological parameters.
Results: There was a significant overexpression of CYP24A1 in breast tissues (p<0.001) and in the high-grade and advanced stage tumors, suggesting the relationship of CYP24A1 overexpression with the aggressiveness of the tumor. In contrast, CYP27B1 expression showed a significant decrease (p=0.84) in all levels of tumor grade and stage, representing reduced potential of vitamin D activation. The CYP24A1 expression was positively correlated with tumor stage and lymph node metastasis, indicating that CYP24A1 plays a role in tumor progression and metastasis.
Conclusion: The strong correlation between CYP24A1 expression and aggressive tumor characteristics highlights its potential as a therapeutic target.

Key words: Vitamin D metabolism, CYP24A1, CYP27B1, breast cancer, immunohistochemistry.