Abstract 5605: Differential expression of fatty-acid binding proteins 3 and 5: Role in survival disparity among African-American women with breast cancer

Abstract

Abstract African-American (AA) patients present with more advanced breast cancer and have lower survival at all ages compared with Caucasian-Americans (CA). While AA women have a lower overall breast cancer incidence than CA women, AA women have a higher mortality rate. These differences may be due in part to socioeconomic factors; however emerging evidence suggests that biological factors may also play a role in this health disparity. Altered fatty acid binding protein (FABP) expression has been demonstrated in breast cancer. FABP3 is a protective tumor suppressor that has been shown to inhibit breast cell proliferation, and is downregulated in breast cancer tissues. Levels of FABP3 correspond with mammary differentiation, and reach their height during pregnancy and lactation, in response to very high prolactin expression. Thus, FABP3 is correlated with the protective effect against breast cancer induced by lactation. FABP5, another member of the FABP family, is associated with metastasis and is upregulated in breast cancer tissues. Hence, increased levels of FABP5 may compensate for decreased levels of FABP3. Since FABP3 is associated with decreased breast cell proliferation, and FABP5 is associated with increased proliferation, we reasoned that differential expression of these proteins in breast tissues would correlate with breast cancer incidence and progression. Therefore, we hypothesized that higher incidence of breast cancer is associated with lower FABP3 and consequently, higher FABP5. We analyzed protein and mRNA levels of the FABPs in paired breast tissue samples from AA and CA women by Western blot analysis and RT-PCR. Data was divided into two groups- ages below 50, and ages 50 and above. Protein measurements showed that the ratio of FABP3 to FABP5 levels (FABP ratio) was significantly higher in AA patients below 50 compared to those 50 and older (p=0.059) and compared to age-matched CA patients (p=0.049). FABP3 mRNA levels were significantly higher in AA malignant (AAM) tissues from ages below 50 (p=0.003), and significantly lower in AAM tissues from ages 50 and older (p<0.001), relative to CA malignant (CAM) counterparts. FABP5 mRNA levels were significantly higher in AAM tissues from ages 50 and older (p=0.023), relative to CAM counterparts. These findings, particularly in the older age group, demonstrate that differential FABP expression may contribute to the survival disparity between AA and CA breast cancer patients. Our studies provide much needed information about the mechanisms involved in the protective effect lactation induces in the breast and will potentially offer new tools for preventive breast cancer treatment. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5605. doi:10.1158/1538-7445.AM2011-5605