Using 2-D electrophoresis followed by nano HPLC in nuclear protein analysis of MCF-7 breast cancer cell line by MALDI-TOF/TOF

The biomarker identification is an important tool in early cancer detection. The MCF-7 breast cancer cell line was chosen as a model system. The nuclear proteins were extracted utilizing a commercially manufactured kit and separated on two dimensional (2-D) sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE). The first dimension was performed on isoelectric focusing strips with pH range 4–7. Afterwards the proteins were tryptic digested and identification was performed by matrix assisted laser desorption technique with time of flight mass analyzer (MALDI-TOF/TOF). For unambiguous identification proteins with too low concentration or spots contains protein mixture the nano high performance liquid chromatography (HPLC) was used. The 2-D gel electrophoresis (2-DGE) seems to be a good tool to separate large amount of proteins using relatively simple procedure and its hyphenation with HPLC can create the perfect analytical solution for proteome identification. About 150 nuclei protein spots were visualized and the most abundant of them were identified.