Identification and validation of Biomarkers for Breast Cancer from human White Blood Cells

There is a great need for the identification of non-invasive biomarkers for early detection, prognosis and treatment efficacy of breast cancer. Peripheral white blood cells (WBCs) carrying the information related to the presence of cancer, represent an attractive source for novel biomarkers. The main aims of the study were to develop the pipeline to discover and validate novel biomarkers in WBCs of breast cancer patients using proteomic and genomic approaches, and assess these biomarkers’ utility. Using the highthroughput mass spectrometry and 2D-gel-electrophoresis, the protein profiles of the WBCs from breast cancer patients and healthy individuals were generated and compared with publicly available gene expression data from the WBCs of breast cancer patients and the information on protein profiles of the WBCs from the metastatic breast cancer patients. The shortlisted 15 genes were then validated using Real-Time Quantitative Reverse Transcription PCR (RT-qPCR). The mRNA levels of ITGA4, LCN2, CPNE3 and SERPINB1 were found to be altered significantly in the WBCs of breast cancer patients. The levels of SERPINB1 (Serpin B1, neutrophil elastase inhibitor) and CPNE3 (Copine 3, phospholipid binding protein) were assessed using Western blotting. These analyses demonstrated the association of SERPINB1 with breast cancer metastases, and suggested its potential utility as a biomarker of poor prognosis and treatment efficacy. Further quantitative validation of SERPINB1 in a larger panel of WBCs by ELISA will be required for a clinical phase in the biomarker development pipeline. No conclusive results were obtained for CPNE3 and, together with ITGA4, LCN2 and other additional candidate biomarkers (to be selected from the initial list), they will be tested further. The data generated for this study has also given insight into differences in the molecular portraits of the cells of immune system associated with breast cancer, which will need to be validated by laboratory based functional assays.