An antiproliferative factor from interstitial cystitis patients is a frizzled 8 protein-related sialoglycopeptide.
Approximately 1 million people in the United States suffer from interstitial cystitis, a chronic painful urinary bladder disorder characterized by thinning or ulceration of the bladder epithelial lining; its etiology is unknown. We have identified a glycosylated frizzled-related peptide inhibitor of cell proliferation that is secreted specifically by bladder epithelial cells from patients with this disorder. This antiproliferative factor (APF) profoundly inhibits bladder cell proliferation by means of regulation of cell adhesion protein and growth factor production. The structure of APF was deduced by using ion trap mass spectrometry (MS), enzymatic digestion, lectin affinity chromatography, and total synthesis, and confirmed by coelution of native and synthetic APF derivatives on microcapillary reversed-phase liquid chromatography (microRPLC)/MS. APF was determined to be an acidic, heat-stable sialoglycopeptide whose peptide chain has 100% homology to the putative sixth transmembrane domain of frizzled 8. Both synthetic and native APF had identical biological activity in normal bladder epithelial cells and T24 bladder cancer cells. Northern blot analysis indicated binding of a probe containing the sequence for the frizzled 8 segment with mRNA extracted from cells of patients with interstitial cystitis but not controls. APF is therefore a frizzled-related peptide growth inhibitor shown to contain exclusively a transmembrane segment of a frizzled protein and is a potential biomarker for interstitial cystitis.
Division of Infectious Diseases, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA. skeay@medicine.umaryland.edu
Susan K
SK
Keay
Zoltan
Z
Szekely
Thomas P
TP
Conrads
Timothy D
TD
Veenstra
Joseph J
JJ
Barchi
Chen-Ou
CO
Zhang
Kristopher R
KR
Koch
Christopher J
CJ
Michejda
D000970:Antineoplastic Agents / Q000032:analysis / Q000737:chemistry*; D015815:Cell Adhesion Molecules / Q000032:analysis / Q000096:biosynthesis; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D002851:Chromatography, High Pressure Liquid; D018856:Cystitis, Interstitial / Q000209:etiology* / Q000473:pathology; D004847:Epithelial Cells / Q000473:pathology; D006023:Glycoproteins / Q000737:chemistry / Q000502:physiology; D006133:Growth Substances / Q000032:analysis / Q000096:biosynthesis; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D013058:Mass Spectrometry; D015394:Molecular Structure; D010446:Peptide Fragments / Q000032:analysis / Q000737:chemistry / Q000494:pharmacology; D012333:RNA, Messenger / Q000302:isolation & purification; D012795:Sialoglycoproteins / Q000032:analysis / Q000737:chemistry* / Q000494:pharmacology; D001745:Urinary Bladder Diseases / Q000473:pathology
D000970:Antineoplastic Agents; D015815:Cell Adhesion Molecules; D006023:Glycoproteins; D006133:Growth Substances; D036341:Intercellular Signaling Peptides and Proteins; D010446:Peptide Fragments; D012333:RNA, Messenger; D012795:Sialoglycoproteins; C490708:antiproliferative factor APF, human