Protein profile in breast cancer patients undergoing doxorubicin treatment : an iTRAQ-coupled LC-MS/MS approach

Abstract

Chemotherapy is a common treatment for breast cancer and Doxorubicin is a common chemotherapeutic drug used for this purpose. However drug resistance is a great limitation to the effectiveness of chemotherapy treatment. It has been discovered that patients with single nucleotide polymorphism (SNP) in Murine Double Minute 2 (MDM-2) gene promoter have higher resistance to chemotherapeutic treatment with Doxorubicin.

In this project, iTRAQ-coupled LC-MS/MS approach was used to study the protein profile of breast cancer patients undergoing Doxorubicin treatment. Protein profile of 23 patient plasma samples with SNP309 (both homogenous and heterogeneous) in MDM-2 Gene was compared with the protein profile of control sample made up by 7 patient plasma samples with wild type (WT) MDM-2 Gene. The online 2D LC-MS/MS system used involved a two dimensional application of a strong cation exchange column followed by a reverse-phased column, coupled to a tandem mass spectrometer. This approach also involved the use of four isobaric peptide derivatization reagents (iTRAQ reagents) to yield informative spectra for peptide identification and quantitation.

The experimental results from this project showed that 2 proteins, Fibrinogen alpha chain precursor and Fibrinogen gamma chain precursor, have higher expression levels in patients with SNP309 in MDM-2 gene. This indicates that Fibrinogen may play an important role in MDM-2 mediated Doxorubicin resistance.