PTP4A3 (PRL-3) expression correlate with lymphatic metastases in gastric cancer.

Many studies have proved that protein tyrosine phosphatase type IVAmember 3 (PTP4A3, PRL-3) plays a major role in the metastasis of gastric cancer, especially to local lymph nodes. The objective of the current study was to assess the expression of PTP4A3 in gastric cancer in correlation with chosen anatomoclinical parameters and patients' survival. Atotal of 71 patients with gastric carcinomas were divided according to Lauren's, Goseki's, Bormann's and Kubo's classifications. The level of PTP4A3 was determined immunohistochemically using a mouse monoclonal anti-PTP4A3 antibody (clone 3B6, anti-human PTP4A3, Attogen Biomedical Research, USA). A statistically significant correlation was observed between PTP4A3 and Kubo's classifications (p=0.0454) and on the verge of statistical significance with Lauren's classification (p=0.0503). The expression of the protein was associated more with the poorly-differentiated mucoid carcinoma and diffused-type carcinoma (58% of cases). We demonstrated a statistically significant correlation between local lymph node involvement and positive expression of PTP4A3 in the primary tumour (p=0.0000). The current study seems to prove that PTP4A3 may have a significant impact on the lymphatic spread of gastric carcinoma. The protein expression is also significantly associated with gastric carcinomas having a worse prognosis, although patients' survival rate showed lack of correlation with PTP4A3 expression.

Cell-based high-throughput screening assay system for monitoring G protein-coupled receptor activation using beta-galactosidase enzyme complementation technology.

A novel cell-based functional assay to directly monitor G protein-coupled receptor (GPCR) activation in a high-throughput format, based on a common GPCR regulation mechanism, the interaction between beta-arrestin and ligand-activated GPCR, is described. A protein-protein interaction technology, the InteraX trade mark system, uses a pair of inactive beta-galactosidase (beta-gal) deletion mutants as fusion partners to the protein targets of interest. To monitor GPCR activation, stable cell lines expressing both GPCR- and beta-arrestin-beta-gal fusion proteins are generated. Following ligand stimulation, beta-arrestin binds to the activated GPCR, and this interaction drives functional complementation of the beta-gal mutant fragments. GPCR activation is measured directly by quantitating restored beta-gal activity. The authors have validated this assay system with two functionally divergent GPCRs: the beta2-adrenergic amine receptor and the CXCR2 chemokine-binding receptor. Both receptors are activated or blocked with known agonists and antagonists in a dose-dependent manner. The beta2-adrenergic receptor cell line was screened with the LOPAC trade mark compound library to identify both agonists and antagonists, validating this system for high-throughput screening performance in a 96-well microplate format. Hit specificity was confirmed by quantitating the level of cAMP. This assay system has also been performed in a high-density (384-well) microplate format. This system provides a specific, sensitive, and robust methodology for studying and screening GPCR-mediated signaling pathways.