Anti-CD45 monoclonal antibody, clone SN0069-6D27

Background: Renal cell carcinoma (RCC) is a common urological cancer, and its risk correlates with environmental factors such as obesity, smoking and hypertension. Microarray technology enables analysis of the expression pattern of the whole phosphatome, members of which are involved in many cellular pathways and may act as either tumour suppressors or oncogenes in cancers. Materials and Methods: We analysed data for the expression level of 87 out of 107 known protein phosphatase genes included in the Hugo Gene Nomenclature Committee Website for 72 RCC tissues and paired healthy tissues obtained from the GEO Database. Results: Our analysis revealed overexpression of DUSP1, DUSP4, PTP4A3, PTPRC and PTPRE genes at all examined stages of RCC. Moreover, we found overexpression of PTPN12 at stage 2, overexpression of CDKN3 at stages 3 and 4, and overexpression of DUSP10 and PTPN22 at stages 2, 3 and 4. Lower expression of DUSP9, PTPR9 and PTPRO was also observed at all stages. Conclusion: Significant changes in expression patterns of protein tyrosine phosphatase genes confirm the involvement of this group in crucial carcinogenesis pathways underlying RCC. Thus, we postulate that protein tyrosine phosphatases play an important role in RCC promotion and progression, and may be considered as potential therapeutic targets.

CXCL12 governs cellular motility, a process deregulated by hematopoietic stem cell oncogenes such as p210-BCR-ABL. A phosphoproteomics approach to the analysis of a hematopoietic progenitor cell line treated with CXCL12 and the Rac 1 and 2 inhibitor NSC23766 has been employed to objectively discover novel mechanisms for regulation of stem cells in normal and malignant hematopoiesis. The proteomic data sets identified new aspects of CXCL12-mediated signaling and novel features of stem cell regulation. We also identified a novel phosphorylation event in hematopoietic progenitor cells that correlated with motile response and governed by the chemotactic factor CXCL12. The novel phosphorylation site on PTPRC/CD45; a protein tyrosine phosphatase, was validated by raising an antibody to the site and also using a mass spectrometry absolute quantification strategy. Site directed mutagenesis and inhibitor studies demonstrated that this single phosphorylation site governs hematopoietic progenitor cell and lymphoid cell motility, lies downstream from Rac proteins and potentiates Src signaling. We have also demonstrated that PTPRC/CD45 is down-regulated in leukemogenic tyrosine kinase expressing cells. The use of discovery proteomics has enabled further understanding of the regulation of PTPRC/CD45 and its important role in cellular motility in progenitor cells.