Modulation of notch processing by gamma-secretase inhibitors causes intestinal goblet cell metaplasia and induction of genes known to specify gut secretory lineage differentiation.
It is anticipated that gamma-secretase inhibitors (gamma-Sec-I) that modulate Notch processing will alter differentiation in tissues whose architecture is governed by Notch signaling. To explore this hypothesis, Han Wistar rats were dosed for up to 5 days with 10-100 micromol/kg b.i.d. gamma-Sec-I from three chemical series that inhibit Notch processing in vitro at various potencies (Notch IC(50)). These included an arylsulfonamide (AS) (142 nM), a dibenzazepine (DBZ) (1.7 nM), and a benzodiazepine (BZ) (2.2 nM). The DBZ and BZ caused dose-dependent intestinal goblet cell metaplasia. In contrast, the AS produced no detectable in vivo toxicity, despite higher exposure to free drug. In a time course using BZ, small intestinal crypt cell and large intestinal glandular cell epithelial apoptosis was observed on days 1-5, followed by goblet cell metaplasia on days 2-5 and crypt epithelial and glandular epithelial regenerative hyperplasia on days 4-5. Gene expression profiling of duodenal samples from BZ-dosed animals revealed significant time-dependent deregulation of mRNAs for various panendocrine, hormonal, and transcription factor genes. Somatostatin, secretin, mucin, CCK, and gastrin mRNAs were elevated twofold or more by day 2, and a number of candidate "early-predictive" genes were altered on days 1-2, remaining changed for 4-5 days; these included Delta1, NeuroD, Hes1-regulated adipsin, and the Hes-regulated transcriptional activator of gut secretory lineage differentiation, the rat homolog of Drosophila atonal, Rath1. Western blotting of fecal protein from BZ-and DBZ-dosed animals exhibited increased levels of both anti-Rath1 reactive protein and anti-adipsin reactive proteins, confirming their potential value as noninvasive biomarkers of intestinal goblet metaplasia.
Safety Assessment US, AstraZeneca Pharmaceuticals, 1800 Concord Pike, Wilmington, DE 19850, USA.
Joseph
J
Milano
Jenny
J
McKay
Claude
C
Dagenais
Linda
L
Foster-Brown
Francois
F
Pognan
Reto
R
Gadient
Robert T
RT
Jacobs
Anna
A
Zacco
Barry
B
Greenberg
Paul J
PJ
Ciaccio
D053829:Amyloid Precursor Protein Secretases; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D016282:Aspartic Acid Endopeptidases; D001569:Benzodiazepines / Q000494:pharmacology; D015415:Biomarkers / Q000032:analysis; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D003984:Dibenzazepines / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D010450:Endopeptidases / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D020397:Goblet Cells / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D008297:Male; D008679:Metaplasia; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013449:Sulfonamides / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
D015415:Biomarkers; D003984:Dibenzazepines; D004791:Enzyme Inhibitors; C497761:NOTCH1 protein, human; C497763:Notch1 protein, rat; D012333:RNA, Messenger; D051881:Receptor, Notch1; D011956:Receptors, Cell Surface; D013449:Sulfonamides; D014157:Transcription Factors; D001569:Benzodiazepines; D053829:Amyloid Precursor Protein Secretases; D010450:Endopeptidases; D016282:Aspartic Acid Endopeptidases; C509280:BACE1 protein, human