Abstract C031: ABCD3 expression is upregulated Caucasian and Asian breast cancer patients and is associated with non-responsiveness to endocrine therapy in luminal breast cancers

Abstract

Abstract The ABC transporters represent the largest family of transmembrane proteins. They also serve in protective roles whereby many transporters act as efflux pumps for xenobiotics. And subsequently, several members; most notably of the A, B and C subfamilies, have been implicated in cancer chemoresistance; however, D family members have not been extensively studies with regards to cancer biology and treatment. Here we report that ABCD3 transporter expression is upregulated in breast cancer (p<0.001). The gene was also upregulated across cancer stages (p<0.05). Analysis of histological subtypes revealed that ABCD3 was expressed infiltrating ductal carcinoma (IDC). Immunohistochemistry (IHC) analysis confirmed that ABCD3 protein is expressed IDC (p<0.001). Moreover, ABCD3 expression was elevated in White (p<0.001) and Asian (p<0.05) breast cancer patients but not in African-American patients. Analysis of molecular subtypes revealed that ABCD3 expression was significantly higher in the Luminal breast cancer subtype (p<0.001). Furthermore, ROC analysis of gene expression in relationship in response to treatment revealed that ABCD3 is a moderate predictor (AUC=0.644, p=0.003) of response to endocrine therapy (tamoxifen and aromatase inhibitors) and a strong predictor (AUC=08, p=0.026) to chemotherapy in luminal breast cancers. Taken collectively, ABCD3 represents a biomarker which may be important for determining therapeutic response. Citation Format: Romonia Renee Reams, Simone Heyliger, Marilyn Saulsbury. ABCD3 expression is upregulated Caucasian and Asian breast cancer patients and is associated with non-responsiveness to endocrine therapy in luminal breast cancers [abstract]. In: Proceedings of the 16th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2023 Sep 29-Oct 2;Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(12 Suppl):Abstract nr C031.