Decreased Expression of PTEN in Olfactory Bulb of Rat Pub after Naris Closure

PTEN (phosphatase and tensin homolog) is a dual specific phosphatase antagonizing phosphoinositide 3-kinase activity, and has first been cloned as a tumor suppressor for glioma. Although the role of PTEN as a tumor suppressor has been well studied, little is known about signaling mechanisms regulating expression and/or activity of PTEN in the central nervous system. In this study, we investigated whether PTEN expression is regulated by sensory deprivation. P5 rat pups were unilaterally naris-closed, and olfactory bulbs were immunohistochemically analyzed with PTEN antibody at the 7th day after naris closure. PTEN immunoreactivity was found to be down-regulated in both glomerular, external plexiform and subependymal cell layers, suggesting that odor deprivation signals down-regulate expression of PTEN in the olfactory bulb. To the best of our knowledge, this is the first report to suggest that PTEN expression is regulated by sensory deprivation signals in neonatal rats.

Clinical Significance of PTEN Expression in Bladder Cancer / 대한비뇨기과학회지

PURPOSE: PTEN (phosphatase and tensin homolog) is a tumor suppressor gene located on the chromosome 10q23. PTEN plays a role in inducing cell cycle arrest and apoptosis. We determined the PTEN expression to evaluate the role of PTEN in aggressiveness and invasiveness of bladder cancer. MATERIALS AND METHODS: PTEN expression was evaluated immunohistochemically in 73 patients with bladder cancer according to grade, stage and lymph node involvement. Cases were considered positive when granular cytoplasmic staining was seen in tumor cells and negative when the tumor tissue was not stained. RESULTS: PTEN was expressed in 50 (68.5%) of 73 patients. In superficial bladder cancer (n=40), 37 patients (92.5%) were positive. Thirteen patients (39.4%) were positive in T2 or higher bladder cancer (n=33). In low grade bladder cancer (n=47), 40 patients (85.1%) were positive. Ten patients (38.5%) were positive in high grade bladder cancer (n=26). PTEN expressions were positive in 1 (11.1%) of 9 lymph node-positive and 12 (50%) of 24 lymph node-negative bladder cancers. CONCLUSIONS: These data demonstrate that loss of PTEN expression has a correlation with aggressiveness and invasiveness in bladder cancer. Therefore, our results suggest that loss of PTEN protein may be a useful marker of poor prognosis in bladder cancer.