title: Metallothionein isoform 3 as a potential biomarker for human bladder cancer.
abstract: The goal of the present study was to determine if the expression of metallothionein isoform 3 (MT-3) might serve as a biomarker for human bladder cancer. To accomplish this goal, we defined the localization and expression of MT-3 protein and mRNA using fresh and archival biopsy specimens obtained from patients undergoing differential diagnosis for a variety of bladder disorders. We used immunohistochemistry, immunoblot, and RT-PCR analysis to define the localization and expression of MT-3 protein and mRNA. Immunohistochemical analysis disclosed no immunoreactivity for MT-3 in normal bladder cells. The absence of MT-3 expression in the normal bladder was further confirmed by demonstrating that MT-3 mRNA could not be detected using reverse transcriptase-polymerase chain reaction (RT-PCR) or MT-3 protein using immunoblot. Immunohistochemistry also disclosed no immunoreactivity for MT-3 in archival biopsy specimens from patients with interstitial cystitis and related disorders. Immunohistochemical analysis demonstrated that MT-3 was expressed in carcinoma in situ (CIS), high-grade bladder cancer, low-grade bladder cancer, and dysplastic lesions. MT-3 immunostaining was intense in both CIS and high-grade bladder cancer, and low to moderate in low-grade bladder cancer and dysplastic lesions. We determined MT-3 mRNA expression in a subset of these bladder cancer specimens; expression was elevated as compared to that of the housekeeping gene, ss-actin. The cDNA from the RT-PCR reaction primed for MT-3 contained a FokI restriction site, a site unique for MT-3 as compared to other MT family members. In conclusion, this study demonstrates that MT-3 is up-regulated in human bladder cancer and that this up-regulation increases with increasing tumor grade. The finding that MT-3 expression is minimal in normal bladder suggests that MT-3 might be developed into an effective biomarker for bladder cancer.
authors.affiliation: Robert C. Byrd Health Sciences Center, Department of Pathology, West Virginia University, Morgantown, West Virginia 26506-9251, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Sens
authors.forename: S
authors.initials: S
authors.lastname: Somji
authors.forename: D L
authors.initials: DL
authors.lastname: Lamm
authors.forename: S H
authors.initials: SH
authors.lastname: Garrett
authors.forename: F
authors.initials: F
authors.lastname: Slovinsky
authors.forename: J H
authors.initials: JH
authors.lastname: Todd
authors.forename: D A
authors.initials: DA
authors.lastname: Sens
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D001483:Base Sequence; D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism; D002295:Carcinoma, Transitional Cell / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D017931:DNA Primers / Q000235:genetics; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D008668:Metallothionein / Q000235:genetics* / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012334:RNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D001743:Urinary Bladder / Q000378:metabolism; D001749:Urinary Bladder Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D017931:DNA Primers; D020033:Protein Isoforms; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D008668:Metallothionein