Purpose: To compare the expressions of p53, a tumor suppressor gene, KI67, a proliferating cell nuclear antigen, and breast cancer 1 (BRCA1), a breast cancer susceptibility gene, in patients with different molecular subtypes of breast cancer (BC) and investigate their relationships with pathology and prognosis.
Methods: A total of 134 BC postoperative tissue specimens preserved from January 2012 to August 2013 were selected. The expressions of p53, KI67, and BRCA1 in different molecular subtypes of BC were compared, their relationships with pathological features were explored, and the expression correlations among p53, KI67, and BRCA1 were analyzed at the same time.
Results: P53 expression was the lowest in Luminal A subtype and similar in human epidermal growth factor receptor 2 (HER-2)-overexpression subtype and triple-negative subtype, with higher expression rates than those in other molecular subtypes. The expression of KI67 was the lowest in Luminal A subtype, showing a significant difference (p<0.05) from that in other molecular subtypes and it was the highest in Luminal B subtype (p<0.05). BRCA1 exhibited the lowest expression in Luminal B-like subtype but the highest expression in Luminal A subtype. The protein expressions of p53 and KI67 were not related to age but correlated with tumor size, histological grade, lymph node metastasis, estrogen receptor (ER)/progesterone receptor (PR) status, and HER-2 status. The expression of p53 was increased with larger tumor size, higher histological grade, presence of lymph node metastasis (n), lower expression of ER/PR, and higher expression of HER-2. BRCA1 expression had no relation with age, tumor size, histological grade, lymph node metastasis (n), ER/PR status, and HER-2 status. A positive correlation was found between p53 and KI67 (r=0.893, p=0.021). There were negative correlations between p53 and BRCA1 (r=-0.921, p=0.011), and between KI67 and BRCA1 (r=-0.821, p=0.032). The median survival time of patients with positive expressions of p53, KI67 and BRCA1 was significantly shorter than those of patients with negative expressions.
Conclusion: The expressions of p53, KI67 and BRCA1 in different molecular subtypes of BC are evidently different and related to pathological features. The above protein expressions are helpful in predicting the prognosis, diagnosis, and treatment of BC.