title: Proteomics profiling identify CAPS as a potential predictive marker of tamoxifen resistance in estrogen receptor positive breast cancer.
abstract: BACKGROUND
  Despite the success of tamoxifen since its introduction, about one-third of patients with estrogen (ER) and/or progesterone receptor (PgR) - positive breast cancer (BC) do not benefit from therapy. Here, we aim to identify molecular mechanisms and protein biomarkers involved in tamoxifen resistance.
  
  
  RESULTS
  Using iTRAQ and Immobilized pH gradient-isoelectric focusing (IPG-IEF) mass spectrometry based proteomics we compared tumors from 12 patients with early relapses (<2 years) and 12 responsive to therapy (relapse-free > 7 years). A panel of 13 proteins (TCEAL4, AZGP1, S100A10, ALDH6A1, AHNAK, FBP1, S100A4, HSP90AB1, PDXK, GFPT1, RAB21, MX1, CAPS) from the 3101 identified proteins, potentially separate relapse from non-relapse BC patients. The proteins in the panel are involved in processes such as calcium (Ca(2+)) signaling, metabolism, epithelial mesenchymal transition (EMT), metastasis and invasion. Validation of the highest expressed proteins in the relapse group identify high tumor levels of CAPS as predictive of tamoxifen response in a patient cohort receiving tamoxifen as only adjuvant therapy.
  
  
  CONCLUSIONS
  This data implicate CAPS in tamoxifen resistance and as a potential predictive marker.
authors: Department Oncology-Pathology, Cancer Proteomics Mass spectrometry, Science for Life Laboratory, Karolinska Institutet, SE-171 65 Stockholm, Sweden.
authors: Henrik J
authors: HJ
authors: Johansson
authors: Department Oncology-Pathology, Cancer Proteomics Mass spectrometry, Science for Life Laboratory, Karolinska Institutet, SE-171 65 Stockholm, Sweden.
authors: Betzabe C
authors: BC
authors: Sanchez
authors: Department Oncology-Pathology, Cancer Proteomics Mass spectrometry, Science for Life Laboratory, Karolinska Institutet, SE-171 65 Stockholm, Sweden.
authors: Jenny
authors: J
authors: Forshed
authors: Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden.
authors: Olle
authors: O
authors: Stål
authors: Department of Clinical and Experimental Medicine, Faculty of Health Sciences, Linköping University, Linköping, Sweden ; Regional cancer center Southeast Sweden, County Council of Östergötland, Linköping, Sweden.
authors: Helena
authors: H
authors: Fohlin
authors: Department of Oncology, Radiumhemmet, Karolinska University Hospital, Stockholm, Sweden.
authors: Rolf
authors: R
authors: Lewensohn
authors: Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Box 281, Stockholm, 17177 Sweden.
authors: Per
authors: P
authors: Hall
authors: Department Oncology-Pathology, Cancer Proteomics Mass spectrometry, Science for Life Laboratory, Karolinska Institutet, SE-171 65 Stockholm, Sweden.
authors: Jonas
authors: J
authors: Bergh
authors: Department Oncology-Pathology, Cancer Proteomics Mass spectrometry, Science for Life Laboratory, Karolinska Institutet, SE-171 65 Stockholm, Sweden.
authors: Janne
authors: J
authors: Lehtiö
authors: Department Oncology-Pathology, Cancer Proteomics Mass spectrometry, Science for Life Laboratory, Karolinska Institutet, SE-171 65 Stockholm, Sweden ; Department of Oncology, Sahlgrenska Academy and University Hospital, SE-413 45 Gothenburg, Sweden.
authors: Barbro K
authors: BK
authors: Linderholm
keywords: CAPS; Calcyphosine; Endocrine resistance; Estrogen receptor; MX1; Proteomics; Receptor-positive breast cancer