Abstract 2736: Overexpression of L-type amino acid transporter-1 in breast cancer cells and tissues: potential association with growth and progression of tumors

Abstract

Abstract For a tumor to constantly proliferate, malignant cells require nutrients, especially glucose and amino acids. There is abundant evidence that tumor growth depends heavily on glucose uptake. The L-type amino acid transporter 1 (LAT1) is a major nutrient transport system responsible for the transport of large neutral essential amino acids. In the present study, we analyzed expression levels of LAT1 mRNA and protein with RT-PCR, Western blot and immunohistochemical staining. The results showed that normal breast tissues or low malignant cell lines expressed low levels of LAT1 mRNA and protein, while LAT1 was overexpressed in highly malignant cancer cell lines and high grade breast cancer tissues. In addition, we found higher expression levels of LAT1 in breast cancer tissues were consistent with high stages of breast cancer. Furthermore, we demonstrated that blockade of LAT1 with its inhibitor, 2-amino-bicyclo[2.2.1]heptane-2-carboxylic acid (BCH), or knockdown of LAT1 with transfection of specific siRNA inhibited proliferation of breast cancer cells. A variety of 11C- and 18F-labeled amino acids have been studied for potential use in positron emission tomography (PET) oncology. A non-natural, not-metabolizable leucine analog, anti-1-amino-3-[18F]fluorocyclobutane-1-carboxylic acid ([18F]FACBC), has shown superior tumor/normal brain ratio. We tested whether [18F]FACBC would also be an excellent PET tracer for malignant breast cancer imaging using an orthotopic breast cancer animal model and an experimental animal model of breast cancer metastasis. Our results support that [18F]FACBC could be a useful PET tracer for non-invasive imaging of breast cancer. These findings suggest that overexpression of LAT1 is necessary for proliferation of breast cancer cells and may contribute to progression of tumors. LAT1 may represent a potential target for diagnosis of breast cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2736.