Overexpression of fatty acid binding protein-7 correlates with basal-like subtype of breast cancer.

Fatty acid binding protein-7 (FABP-7) is normally expressed in the mammary gland. The aim of this study was to clarify the phenotype of breast cancers with respect to the overexpression of FABP-7. Reverse transcription PCR (RT-PCR) analysis was carried out on 16 cases, including 4 ER(+)/HER2(-), 2 ER(+)/HER2(+), 3 ER(-)/HER2(+), and 5 ER(-)/HER2(-) samples, and 2 non-neoplastic mammary glands as control tissue. Breast cancers categorized as ER(-)/HER2(-) revealed a high cDNA level of FABP-7 as compared to other groups of breast cancer (p=0.004). An immunohistochemical study carried out on 88 cases showed that FABP-7 overexpression had a strong relationship with triple-negative cases (45.8%, p=0.001) and the basal-like subtype (37.5%, p=0.001). Estrogen receptor (ER) and progesterone receptor (PgR) expressions had reverse correlation with FABP-7 overexpression (p=0.003, p<0.0001), but no significant associations can be identified between human epidermal growth factor receptor-2 (HER2) and FABP-7 (p=0.219). In conclusion, this study is the first to demonstrate overexpression of FABP-7 in triple-negative breast cancers [ER(-), PgR(-)/HER2(-)], especially in basal-like breast cancer, and to give a probable interpretation of the high histological grade and poor prognosis of basal-like breast cancer.