Over-expression of genes and proteins of ubiquitin specific peptidases (USPs) and proteasome subunits (PSs) in breast cancer tissue observed by the methods of RFDD-PCR and proteomics

The ubiquitin - proteasome system facilitates the degradation of damaged proteins and regulators of growth and stress response. Alterations in this proteolytic system are associated with a variety of human pathologies. By restriction fragment differential display polymerase chain reaction ( RFDD- PCR) and matrix- assisted laser desorption/ ionization tandem time- of- flight mass spectrometry ( MALDI- TOF- TOF MS) based on two- dimensional polyacrylamide gel electrophoresis ( 2- DE), differentially expressed genes and proteins of ubiquitin specific proteases ( USPs), proteasome subuinits ( PSs) and ubiquitin protein ligase E3A ( UBE3A) were analyzed between breast cancer and adjacent normal tissues. Some of them were further verified as over- expression by immunohistochemical stain. Five genes of proteasome subunits ( PSs), including PSMB5, PSMD1, PSMD2, PSMD8 and PSMD11, four genes of USPs, including USP9X, USP9Y, USP10 and USP25, and ubiquitin protein ligase E3A ( UBE3A) were over- expressed (> 3- fold) in breast cancer tissue compared to adjacent normal tissue, and over- expression (> 4- fold) of proteins of PSMA1 and SMT3A were observed in breast cancer tissue. PSMD8, PSMD11 and UBE3A were further verified as over- expression by immunohistochemical stain. The action of ubiquitin - proteasome system were obviously enhanced in breast cancer, and selectively intervention in action of ubiquitin - proteasome system may be a useful method of treating human breast cancer.