Abstract 1576: Analysis of HSP10 as a putative biomarker of breast cancer

Abstract

Abstract Introduction. Detection of the very earliest stages of breast cancer remain challenging and the differentiation of those carcinomas that develop into aggressive invasive forms from those that remain benign has not been achieved. Consequently, removal of the tumor by total mastectomy, local excision (LE) plus adjuvant radiotherapy (RT), or LE alone remain the main treatments, even if they prove unnecessary. Previously, using proteomics analysis, we identified proteins that were significantly changed in expression between matched normal and tumor tissues from Cypriot patients with different stages of the disease. Heat shock protein 10 (HSP10), which is responsible for the mitochondrial protein folding, was one of the proteins identified. A range of methods were used to verify HSP10 as a possible biomarker for breast cancer. Materials and Methods. Protein extracts from breast cancer cell lines and breast tissue biopsies from Cypriot patients with different stages of the disease were analysed by (i) Western Blotting (WB) and (ii) multiple reaction monitoring mass spectrometry (MRM MS) using two proteotypic peptides unique to HSP10, in proteins extracted form fresh frozen as well as from FFPE breast tissues. Tissue microarray analysis (TMA) was carried out on core biopsies from the Leeds Breast Tissue Bank. Results. WB indicated that HSP10 was ubiquitously and evenly expressed across breast cancer cell lines representative of different phenotypes. WB and MRM MS revealed that expression was significantly increased in invasive carcinoma compared to normal tissue, but was patient specific for fibroadenoma and DCIS cases. TMA of 360 samples indicated a strong correlation between staining and type of breast cancer (invasive ductal and lobular), grade and ER positive phenotype. Discussion. Proteomics analysis using iTRAQ quantitation indicated an average of 1.6 fold increase in HSP10 in invasive carcinomas compared to matched normal tissue. By comparison, WB and MRM MS analysis indicated a significantly amplified discrimination in the expression of HSP10 as has been observed with other biomarker candidates. HSP10 protein levels were in agreement with mRNA results observed in breast cancer cell lines reported in the Cancer Cell Line Encyclopaedia. In conclusion, HSP10 represents an excellent biomarker candidate for further validation. Citation Format: Sadr-ul Shaheed, Andreas Hadjisavvas, Kleitos Sokratous, Paul Loadman, Chris Sutton, Kyriacos Kyriacou. Analysis of HSP10 as a putative biomarker of breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1576. doi:10.1158/1538-7445.AM2015-1576