The American Cancer Society’s recent estimates indicated that by the end of 2013, 232,340 women and 2,240 men were diagnosed with breast cancer; estimates also indicated 39,620 women and 410 men died from the disease.1 Early detection through routine breast exams increases the survival rate for this disease.
Increased knowledge of breast cancer progression could lead to improved diagnostics and treatments for breast cancer patients. A recent study (Yen et al., 2014) aimed at better understanding breast cancer progression sought to identify candidate biomarkers present in premalignant and malignant stages of breast cancer.2 The model of cancer progression presented in this study focused on glycoproteins, which are known to be differentially expressed during cancer progression. The researchers obtained three breast cancer cell lines: MCF10A, which represented benign tumors, and two derivatives—MCF10AT, which represented pre-malignant tumors and MCF10CA1a, which represented malignant tumors.
Yen et al. isolated glycoproteins from these cells lines through an enrichment with hydrazide magnetic beads. Once the proteins were reduced, alkylated and digested with trypsin, the resulting N-glycopeptides were released from the hydrazide beads and analyzed using liquid chromatography/electrospray ionization–tandem mass spectrometry (LC/ESI–MS/MS) on an LTQ ion trap mass spectrometer with dual Surveyor HPLC pump systems (Thermo Scientific). The researchers also obtained lysates from normal and cancerous breast tissues. A glycoprotein fraction from each lysate was analyzed by LC/ESI–MS/MS using a hybrid quadrupole-Orbitrap mass analyzer coupled with a Thermo-Dionex HPLC system (both Thermo Scientific). Total protein content was determined by performing a Bradford assay.
When the cell line analysis was compared with the analysis of breast cancer tissue, the researchers were able to determine that breast cancer progression-associated glycoproteins were among the most highly expressed in the malignant (MCF10CA1a) breast cancer cell line. Some glycoproteins such as F3, ECE1, CEACAM1 and MFI2 were seen at levels 25 to 50 times greater than in the benign (MCF10A) line, and a subset was found only in the malignant line. In total, more than 40 glycoproteins were differentially expressed in either the premalignant MCF10AT or the fully malignant MCF10CA1a cell lines. Yen and co-workers identified 11 glycoproteins in both the cell lines and the tissue lysates, but not in healthy breast tissue. Of these, the most notable protein, collagen alpha-1 (XII) chain, was expressed at dramatically higher (approximately 10-fold) levels in breast cancer tissue as compared with normal tissue. This study represents an exciting start in the search for biomarkers of breast cancer progression.
1. American Cancer Society. (2013) Breast Cancer Facts and Figures 2013–2014, Atlanta: American Cancer Society, Inc.
2. Yen, T.Y., et al. (2014, January) “Using a cell line breast cancer progression system to identify biomarker candidates,” Journal of Proteomics, 96 (pp. 173–83), doi: 10.1016/j.jprot.2013.11.006.
Post Author: Emily Humphreys. As a biology undergraduate at the University of Utah, Emily balanced a heavy class schedule while working long hours in a lab studying eye development. Following graduation, she became involved in infectious disease and aging research involving SNPS.
While she enjoyed the thrill of research, Emily has since traded bench work for science journalism.
And has been a regular contributor to Accelerating Science since 2012.