Comparative Glycoproteomic Analysis of Mouse 4T1 Breast Cancer Model.

Glycosylation is a post-translational modification process that plays a fundamental role in malignant transformation. Moreover, aberrant glycosylation is known to be associated with cancer progression. Thus, the characterization of cancer-specific protein glycosylation profiles might reveal important diagnostic and/or prognostic biomarkers for cancer. In the present study, we have analysed serum protein and glycoprotein profiles during breast cancer progression using a mouse model. Specifically, 4T1 tumour cells were injected into the mammary fat pad of BALB/c mice to induce tumours. Sera samples were subsequently collected weekly for four weeks and examined using two-dimensional electrophoresis (2D-E) coupled with lectin-based analysis, followed by mass spectrometry. This glycoproteomic profiling identified eight differentially expressed proteins, of which alpha-1 protease inhibitor 2, contraption (CON), haptoglobin (HP), and kininogen-1 were significantly up-regulated during the first 4 weeks of tumour progression. Notably, aberrantly N-glycosylated prothrombin was also detected in sera samples from all mice over the 4 weeks post-tumour injection. Additionally, O-glycosylated alpha-2-macroglobulin, CON, and HP were detected in weeks 1 and 2, whereas O-glycosylated alpha-2-HS-glycoprotein and CON were detected on weeks 3 and 4 post-implantation. Our findings indicate that the combination of 2D-E with lectin-based chromatography represents an effective approach for identifying prognostic biomarkers for breast cancer.