Abstract 2505: Expression profiling of cofilin-1 in breast cancer cell lines and biopsies.
Authors: Sutton Chris , ul-Shaheed Sadr , Loadman Paul , Speirs Valerie , Hanby Andrew , Hadjisavvas Andreas , Kyriacou Kyriacos 
Published: August 2014

Introduction. Despite oestrogen and human epidermal growth factor receptor (HER2) targeted therapies improving patient survival, breast cancer continues to be a significant cause of premature death since many tumors do not respond to treatment or acquire resistance. Hence there remains the need to identify novel targets for therapy and biomarkers for prediction of response to treatment. A quantitative proteomics study of matched normal and tumor biopsies identified 63 proteins to be significantly increased or decreased in stage-specific tumors. Some have previously been associated with breast cancer, while others such as cofilin-1 represent new targets for investigation. Cofilin-1 was subject to a range of analyses to determine its association with breast cancer.

Materials and Methods. Western blotting (WB) was performed on protein extracts from breast cancer cell lines and matched normal and tumor biopsies from Cypriot patients with different stages of the disease. Immunohistochemistry (IHC) was carried out on core biopsies from the Leeds Breast Tissue Bank. Multiple reaction monitoring (MRM) mass spectrometry was performed on trypsin-digested protein extracts from biopsies. Data from protein (Human Protein Atlas) and genomics (BioGPS, TiGER, UniGene) databases were assimilated with the experimental results.

Results. WB indicated that cofilin-1 was ubiquitously expressed in tumor cell lines, representative of Luminal A, Luminal B, basal-like, claudin-low and HER2 phenotypes, at higher levels than normal breast cell lines. WB also indicated increased expression of cofilin-1 in invasive carcinoma tissues, compared to matched normal. Patients with ductal carcinoma in situ or fibroadenoma exhibited less clear results, either increasing slightly or remaining unchanged. MRM analysis of three cofilin-1 peptides in tissue extracts of invasive carcinoma patients indicated expression only in tumor. IHC of core biopsies exhibited strong staining for cofilin-1 in ductal invasive carcinoma tissues with no staining in normal breast cells. Genomics and proteomics databases indicate that cofilin-1 is expressed in a diverse range of normal tissues including major organs, gastro-intestinal tract, skin and tonsils. However, mRNA and protein levels are observed to be increased in skin, lung, liver, pancreatic and breast tumors.

Discussion. The original quantitative proteomics data indicated only relatively small changes in expression (less than 2-fold) due to dynamic range limitations of the technique. Additional analytical approaches substantiated that cofilin-1 is significantly up-regulated in advanced breast cancer patients. Further patient sets are required to confirm the importance of cofilin-1 levels in early stages of breast cancer compared to benign tissues. Bioinformatics provided further confidence in our findings, highlighting the value of utilising databases for evidence of disease-specific proteins.

Citation Format: Chris Sutton, Sadr ul-Shaheed, Paul Loadman, Valerie Speirs, Andrew Hanby, Andreas Hadjisavvas, Kyriacos Kyriacou. Expression profiling of cofilin-1 in breast cancer cell lines and biopsies. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2505. doi:10.1158/1538-7445.AM2013-2505