Comparison of protein expression profiles of different stages of lymph nodes metastasis in breast cancer

Abstract

Breast cancer is the most common cancer among women worldwide. Breast cancer metastasis primarily happens through lymphatic system, where the extent of lymph node metastasis is the major factor influencing staging, prognosis and therapeutic decision of the disease. We aimed to study the protein expression changes in different N (regional lymph nodes) stages of breast cancer. Protein expression profiles of breast cancerous and adjacent normal tissues were mapped by proteomics approach that comprises of two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and tandem mass spectrometry (LC-MS/MS) analysis. Calreticulin and tropomyosin alpha 3 chains were the common up-regulated proteins in N0, N1 and N2 stages of breast cancer. Potential biomarker for each N stage was HSP 70 for N0, 80 k protein H precursor and PDI for N1 stage while 78 kDa glucose-regulated protein was found useful for N2 stage. In addition, significant up-regulation of PDI A3 was detected only in the metastasized breast cancer. The up-regulation expression of these proteins in cancerous tissues can potentially use as indicators for diagnosis, treatment and prognosis of different N stages of breast cancer.

Keywords: 2D-PAGE; Breast cancer; LC-MS/MS.; lymph nodes; proteomic.

Figure 1

2D gel images of TLB extracts: (i) breast normal tissue, (ii) breast cancerous tissue of the same patient. The white arrow denoted the landmark used in gel image analysis. Brown circles denoted the up-regulated proteins. Blue circled denoted the down-regulated protein. The spot number was labeled accordingly to protein list in Table 2.

Figure 2

MS analysis for calreticulin; MS spectrum, MS/MS spectrum and the amino acid sequence for peptide derived from the MS/MS spectrum.

Figure 3

Western Blot images of beta-actin (45kDa), calreticulin (48kDa) and PDI A3 (56.8kDa) from breast normal and cancerous tissues.