In vivo effects of mesalazine or E. coli Nissle 1917 on microsatellite instability in ulcerative colitis.
BACKGROUND
Microsatellite instability (MSI) occurs in chronically inflamed colorectal tissue and may evolve to colitis-associated cancer. In vitro data suggest that mesalazine (5-ASA) improves MSI.


OBJECTIVE
To analyse the changes in MSI in 156 distal colonic biopsies of 39 patients with ulcerative colitis that had been treated within a randomized, double-blind trial comparing 5-ASA with E. coli Nissle (EcN).


METHODS
Two biopsies had been collected before and after 1 year of treatment. MSI testing was performed using a panel of eight markers, including 3 dinucleotide and 5 mononucleotide repeats.


RESULTS
No MSI was observed with any of the mono-repeats, and among dinucleotide repeats, only D5S346 (maps to APC) and D17S250 (p53) were consistently informative. Overall, 31/156 (20%) biopsies displayed MSI. After 1 year, 3/11 patients displayed MSI improvement [change to microsatellite stability (MSS); 1 on 5-ASA, 2 on EcN] at D5S346 and 4/11 showed MSI worsening (change from MSS to MSI; all 5-ASA). For D17S250, the corresponding data were for 3/9 patients (2 on 5-ASA, 1 on EcN) and 2/9 (both on 5-ASA), respectively.


CONCLUSIONS
In the set of biopsies taken from patients treated with 1.5 g 5-ASA for 1 year, there was no improvement in the prevalence of MSI in the distal colon.
Goel
A
A
Division of Gastroenterology, Department of Internal Medicine and Charles A Sammons Cancer Center, Baylor University Medical Center, Dallas, TX 75246, USA.
Mittal
A
A
Evstatiev
R
R
Nemeth
M
M
Kruis
W
W
Stolte
M
M
Boland
C R
CR
Gasche
C
C
D000328:Adult; D000368:Aged; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use*; D001706:Biopsy; D003093:Colitis, Ulcerative / Q000188:drug therapy* / Q000473:pathology; D003106:Colon / Q000473:pathology; D004311:Double-Blind Method; D004962:Estranes / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019656:Loss of Heterozygosity; D008297:Male; D019804:Mesalamine / Q000627:therapeutic use*; D053842:Microsatellite Instability / Q000187:drug effects*; D018895:Microsatellite Repeats / Q000187:drug effects*; D008875:Middle Aged; D009570:Nitriles / Q000627:therapeutic use*; D016896:Treatment Outcome; D055815:Young Adult
C115894:17-hydroxyestrane-3-carbonitrile; D000894:Anti-Inflammatory Agents, Non-Steroidal; D004962:Estranes; D009570:Nitriles; D019804:Mesalamine