Null mutation for macrophage migration inhibitory factor (MIF) is associated with less aggressive bladder cancer in mice.
BACKGROUND
Inflammatory cytokines may promote tumorigenesis. Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine with regulatory properties over tumor suppressor proteins involved in bladder cancer. We studied the development of bladder cancer in wild type (WT) and MIF knockout (KO) mice given N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN), a known carcinogen, to determine the role of MIF in bladder cancer initiation and progression.


METHODS
5-month old male C57Bl/6 MIF WT and KO mice were treated with and without BBN. Animals were sacrificed at intervals up to 23 weeks of treatment. Bladder tumor stage and grade were evaluated by H&E. Immunohistochemical (IHC) analysis was performed for MIF and platelet/endothelial cell adhesion molecule 1 (PECAM-1), a measure of vascularization. MIF mRNA was analyzed by quantitative real-time polymerase chain reaction.


RESULTS
Poorly differentiated carcinoma developed in all BBN treated mice by week 20. MIF WT animals developed T2 disease, while KO animals developed only T1 disease. MIF IHC revealed predominantly urothelial cytoplasmic staining in the WT control animals and a shift toward nuclear staining in WT BBN treated animals. MIF mRNA levels were 3-fold higher in BBN treated animals relative to controls when invasive cancer was present. PECAM-1 staining revealed significantly more stromal vessels in the tumors in WT animals when compared to KOs.


CONCLUSIONS
Muscle invasive bladder cancer with increased stromal vascularity was associated with increased MIF mRNA levels and nuclear redistribution. Consistently lower stage tumors were seen in MIF KO compared to WT mice. These data suggest that MIF may play a role in the progression to invasive bladder cancer.
Taylor
John A
JA
Division of Urology, University of Connecticut Health Center, Farmington, CT, USA. jtaylor@uchc.edu
Kuchel
George A
GA
Hegde
Poornima
P
Voznesensky
Olga S
OS
Claffey
Kevin
K
Tsimikas
John
J
Leng
Lin
L
Bucala
Richard
R
Pilbeam
Carol
C
D000818:Animals; D002085:Butylhydroxybutylnitrosamine; D018450:Disease Progression; D015870:Gene Expression; D007150:Immunohistochemistry; D019746:Intramolecular Oxidoreductases / Q000235:genetics*; D008263:Macrophage Migration-Inhibitory Factors / Q000235:genetics*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D009361:Neoplasm Invasiveness / Q000235:genetics; D009367:Neoplasm Staging; D012333:RNA, Messenger / Q000032:analysis; D001749:Urinary Bladder Neoplasms / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology*
D008263:Macrophage Migration-Inhibitory Factors; D012333:RNA, Messenger; D002085:Butylhydroxybutylnitrosamine; D019746:Intramolecular Oxidoreductases; C076231:Mif protein, mouse