Abstract 1992: Y-box protein-associated acidic protein promotes breast cancer progression and is a potential molecular target

Abstract

Abstract The Y-Box protein- associated acidic protein (YBAP1), also known as Complement component 1, q subcomponent binding protein, is a multifunctional protein which is involved in in the regulation of complement activation, pre-mRNA splicing and mitochondrial function. As YBAP1 has been implicated in tumorigenesis, this study evaluates its role in breast cancer metastasis. YBAP1 mRNA expression was analysed by quantitative real time RT-PCR and YBAP1 protein by Western blot, immunocytochemical and immunofluorescence staining in a panel of breast cancer cell lines. Down-regulation of the YBAP1 gene in MDA-MB-231 breast cancer cells was performed by siRNA-mediated silencing and overexpression of the gene by transfection with the pCI-neo-YBAP1 plasmid, before analysis of the effects on cell migration and invasion. YBAP1 gene profiling was also performed in samples from the commercially available TissueScan Human Breast Cancer Panel 1 (Origene, Rockville, MD). YBAP1 immunohistochemical staining was carried out in breast cancer tissue microarrays constructed from 168 patients diagnosed with invasive ductal breast carcinoma. The YBAP1 immunostaining was performed using rabbit polyclonal anti-YBAP1 (RIKEN) at a dilution of 1:500. The percentage and intensity of YBAP1 immunopositive staining in malignant epithelial cells were recorded. YBAP1 was observed to be expressed in all the breast cancer cell lines (MCF-7, ZR-75, T47D and MDA-MB-231) examined. The protein was observed to be localized in the cytoplasm of breast cancer cells. Overexpression of YBAP1 increased cell migration and invasion in the highly malignant MDA-MB-231 breast cancer cells. Conversely silencing of the YBAP1 gene had the opposite effect, resulting in reduced cell migration and invasion. YBAP1 gene expression was also found to be up-regulated in the more advanced stages of breast cancer (grouped as Stage 0, I and IIa and compared with Stage II b, IIIa and IIIc; P <0.05). For the tissue microarrays, a positive correlation was observed between YBAP1 immunostaining and axillary lymph node status. YBAP1 augments the spread of breast cancer by enhancing cell migration and invasion. Hence, YBAP1 is a potential metastatic biomarker and targeting YBAP1 could be a strategy to combat breast cancer metastasis. Citation Format: Olivia J. Scully, Aye Aye Thike, George Wai-Cheong Yip, Puay Hoon Tan, Ken Matsumoto, Boon Huat Bay. Y-box protein-associated acidic protein promotes breast cancer progression and is a potential molecular target. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1992. doi:10.1158/1538-7445.AM2014-1992