Proteomic analysis for nuclear proteins related to tumour malignant progression: a comparative proteomic study between malignant progressive cells and regressive cells.

Tumour development and progression consists a series of multiple changes in gene expression. Progressive tumour cells acquire more aggressive properties manifested by rapid growth, invasiveness and metastatic ability, as well as increased genetic instability leading to multiple genetic alterations. Therefore, it is crucial to identify the possible intracellular and extracellular molecular mechanisms that accelerate tumour progression, in particular to identify nuclear proteins which interact with DNA. Nuclear proteomics provides an opportunity to qualitatively and quantitatively examine protein effectors that contribute to cellular phenotype. This study performed a differential display analysis for the expression of nuclear proteome between regressive tumour cell clone QR-32 and malignant progressive tumour cell clone QRsP-11 using two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS). Eight nuclear proteins whose expressions were different between QR-32 and QRsP-11 cells were identified. Seven of those protein spots, zinc finger protein ZXDC, lamin-A/C, far upstream clement-binding protein 1, heterogeneous nuclear ribonucleoprotein K, heterogeneous nuclear ribonucleoprotein A/B and guanine nucleotide-binding protein G(I)/G(S)/G(T) subunit beta-1, were down-regulated in QRsP-11, while one protein, nucleolin, was up-regulated in QRsP-11.