ABSTRACT
Urothelial carcinoma is the most common type of bladder cancer and can be categorized as either non-muscle-invasive (Ta-T1) or muscle-invasive (⩾T2). The majority of bladder cancers are non-muscle-invasive at presentation; however, the recurrence rate for these tumors is high and a subset can progress to T2. In this study, we aimed to identify genes differentially expressed between T1 vs T2 bladder cancer to identify key regulators of bladder cancer progression and/or invasion. We performed RNA-Seq on T1 and T2 bladder cancer tissues and used publicly available bladder cancer profiling studies to prioritize differentially expressed genes for validation and functional assessment. This integrative approach nominated an extracellular matrix glycoprotein, fibulin-3 (FBLN3, also known as EFEMP1), as being highly expressed in T2 vs T1 bladder cancer and aggressive vs indolent disease. We confirmed the overexpression of fibulin-3 in ⩾T2 vs non-muscle-invasive bladder cancer (NMIBC) by quantitative reverse transcriptase-PCR. Consistent with these findings, fibulin-3 expression level correlated with the invasive ability of several bladder cancer cell lines and modulation of fibulin-3 expression directly affected invasion. Fibulin-3 knockdown in bladder cancer cells decreased the incidence of MIBCs in a murine orthotopic bladder cancer model and decreased the expression of insulin-like growth factor-binding protein-5 (IGFBP5). Restoring IGFBP5 in these cells rescued their invasive and migratory potential. These results indicate that fibulin-3 serves as a pro-invasive factor in bladder cancer, which may be mediated through modulation of IGFBP5 expression. This also suggests fibulin-3 and IGFBP5 may have potential as biomarkers of aggressive bladder cancer or therapeutic targets.
Subject(s)
Extracellular Matrix Proteins/metabolism , Urinary Bladder Neoplasms/metabolism , Urinary Bladder Neoplasms/pathology , Animals , Cell Line, Tumor , Disease Progression , Extracellular Matrix Proteins/genetics , Gene Knockdown Techniques , Heterografts , Humans , Insulin-Like Growth Factor Binding Protein 5/genetics , Insulin-Like Growth Factor Binding Protein 5/metabolism , Male , Mice , Mice, Inbred NOD , Mice, SCID , Neoplasm Invasiveness , Urinary Bladder Neoplasms/geneticsABSTRACT
West Nile virus is a pathogen of concern for both human and wildlife health. Although many aspects of the ecology of West Nile virus are well understood, the mechanisms by which this and similar mosquito-borne viruses overwinter and become reinitiated each spring in temperate regions is not known. A thorough understanding of this mechanism is crucial to risk assessment and development of control strategies. One of the hypotheses to explain the mechanism by which this virus persists from year to year is the spring recrudescence of latent virus in avian reservoir hosts. Stress-related immunosuppression is implicated in the recrudescence of latent viruses in birds. We tested the spring recrudescence hypothesis in a controlled laboratory experiment using hatching-year gray catbirds (Dumatella carolinensis) captured in northern Ohio (July-August 2006). Catbirds (n = 60) were experimentally infected (September 2006) and later examined for the effects of immunosuppression through exogenous hormones and artificially induced migratory disposition. We found no effect of either testosterone or migratory behavior on infection status in any of the treatment birds. Moreover, we detected no viral RNA in the kidney, spleen, brain, or liver upon necropsy at 24 wk postinfection.
