PMID: 20651337Jul 24, 2010Paper

Function and regulatory mechanisms of the candidate tumor suppressor receptor protein tyrosine phosphatase gamma (PTPRG) in breast cancer cells

Anticancer Research
Sherry T ShuYoung C Lin

Abstract

Protein phosphorylation is one of the essential steps in cell signaling, and aberrant phosphorylation is a common event in human cancer. The expression of receptor type protein tyrosine phosphatase gamma (PTPRG) in normal breast is found to be approximately 50-60% higher than that of breast tumor tissue. Overexpression of PTPRG inhibits anchorage-independent growth and proliferation of breast cancer cells. To understand the tumor suppression characteristics of PTPRG, we studied its tumor suppressive function in an athymic mouse model and evaluated factors that can potentially regulate its expression in breast cancer cells. To investigate the function of PTPRG in vivo, athymic nude mice were implanted with MCF-7 cells overexpressing PTPRG. For in vitro study, protein levels of cell cycle regulators, cell cycle re-entry, and the phosphorylation levels of extracellular signal-regulated protein kinases 1/2 (ERK1/2) were examined. In addition, methylation assays were conducted to investigate the epigenetic modification on the promoter of PTPRG. Athymic nude mice bearing MCF-7 cells overexpressing PTPRG showed a reduction in tumor burden in comparison to animals implanted with MCF-7 cells transfected with vector alone. When these two...Continue Reading