Alterations in tropomyosin isoform expression in human transitional cell carcinoma of the urinary bladder

Pawlak, G., McGarvey, T. W., Nguyen, T. B., Tomaszewski, J. E., Puthiyaveettil, R., Malkowicz, S. B., Helfman, D. M. (June 2004) Alterations in tropomyosin isoform expression in human transitional cell carcinoma of the urinary bladder. Int J Cancer, 110 (3). pp. 368-73. ISSN 0020-7136 (Print)

DOI: 10.1002/ijc.20151


Previous studies of transformed rodent fibroblasts have suggested that specific isoforms of the actin-binding protein tropomyosin (TM) could function as suppressors of transformation, but an analysis of TM expression in patient tumor tissue is limited. The purpose of our study was to characterize expression of the different TM isoforms in human transitional cell carcinoma of the urinary bladder by immunohistochemistry and Western blot analysis. We found that TM1 and TM2 protein levels were markedly reduced and showed >60% reduction in 61% and 55% of tumor samples, respectively. TM5, which was expressed at very low levels in normal bladder mucosa, exhibited aberrant expression in 91% of tumor specimens. The Western blot findings were confirmed by immunohistochemical analysis in a number of tumors. We then investigated the mechanism underlying TM expression deregulation, in the T24 human bladder cancer cell line. We showed that levels of TM1, TM2 and TM3 are reduced in T24 cells, but significantly upregulated by inhibition of the mitogen-activated protein kinase-signaling pathway. In addition, inhibition of this pathway was accompanied by restoration of stress fibers. Overall, changes in TM expression levels seem to be an early event during bladder carcinogenesis. We conclude that alterations in TM isoform expression may provide further insight into malignant transformation in transitional cell carcinomas of the bladder and may be a useful target for early detection strategies.

Item Type: Paper
Uncontrolled Keywords: Blotting Western Carcinoma Transitional Cell metabolism Cell Line Tumor Down-Regulation Enzyme Inhibitors pharmacology Humans Immunohistochemistry MAP Kinase Signaling System Mucous Membrane metabolism Protein Isoforms Signal Transduction Time Factors Tropomodulin Tropomyosin biosynthesis chemistry Up-Regulation Urinary Bladder metabolism Urinary Bladder Neoplasms metabolism
Subjects: diseases & disorders > cancer
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > actin
CSHL Authors:
Depositing User: CSHL Librarian
Date: 20 June 2004
Date Deposited: 26 Jan 2012 17:34
Last Modified: 26 Jan 2012 17:34

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