PALLAVI GARG

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Overexpression of MMP9 in colonic epithelium
mediates protection in colitis associated cancer

• PALLAVI GARG
• Ph.D.

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Disclosures
Nothing to Disclose
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Matrix Metalloproteinases (MMPs)
Are a family of zinc-dependent proteolytic
enzymes with the ability to degrade
extracellular matrix substrates such as
collagen, gelatin and proteoglycans
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Colitis Associated Cancer (CAC) Colorectal
Cancer

• CAC is an important complication of Ulcerative
  Colitis or colonic Crohns Disease that results
  in significant morbidity and mortality
• It causes 1/6 of all deaths in patients with
  ulcerative colitis
• Colon cancer develops in flat dysplastic tissue
  among IBD individuals
• CAC is often multiple, anaplastic, broadly
  infiltrating, rapidly growing and occurs at a
  younger age
• The pathogenesis of CAC is not known

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• MMP9 and its role in acute colitis

• MMP9 is not expressed in normal tissues and is
  one of the predominant MMPs that is up-regulated
  in several animal models of colitis and human IBD
• MMP9 mRNA and protein levels are increased in the
  inflamed colonic mucosa of patients with IBD
• MMP9 activity correlates with active inflammation
• MMP9 activates Notch1 signaling in colonic
  epithelium

Castaneda et al, 2005, Gastroenterology Garg et
al, 2007, Gastroenterology
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Role of MMP9 in CAC

• MMP9-/- mice show increased susceptibility to CAC
• CAC in MMP9-/- mice is associated with decreased
  apoptosis compared to WT mice
• CAC in MMP9-/- mice showed decreased levels of
  p21WAF1/Cip1 and p53
• MMP9 mediates its tumor suppressive role via
  activation of Notch1 signaling

Garg et al, 2010, Cancer Research Garg et al,
2011, Gastroenterology
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Aim
Which MMP9 protects from CAC ?
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In vivo model
C57/B6
WT
Tg-villin-MMP9
Water
DSS (3 cycles)
Water
DSS (3 cycles)
DSS Dextran Sodium Sulfate (3 in drinking water)
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In vivo protocol
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Overexpression of epithelial MMP9 exhibited
resistance to CAC

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Overexpression of epithelial MMP9 exhibited less
tumor incidence in CAC
B
A
Number of polyps
Number of dysplastic lesions

Tg-villin-MMP9 CAC
WT CAC
WT CAC
Tg-villin-MMP9 CAC
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Overexpression of epithelial MMP9 exhibited
resistance to CAC
X20
X10
WT CAC
Tg-villin-MMP9 CAC
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Overexpression of epithelial MMP9 showed
increased levels of Notch1and p53 in CAC
Tg-villin-MMP9, CAC
A
WT, CAC
MMP9, 104 kD
ß-tubulin
1
2
3
4
5
6
Tg-villin-MMP9, CAC
WT, CAC
B
NICD, 80 kD
ß-tubulin
1
2
3
4
5
6
Tg-villin-MMP9, CAC
WT, CAC
C
p53, 53 kD
GAPDH
1
2
3
4
5
6
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Overexpression of epithelial MMP9 showed
increased levels of p21WAF1/Cip1and Bax1 in CAC
Tg-villin-MMP9, CAC
WT, CAC
A
p21WAF1/Cip1, 21kD
GAPDH
1
2
3
4
5
6
Tg-villin-MMP9, CAC
B
WT, CAC
Bax-1, 37 kD
GAPDH
1
2
3
4
5
6
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Overexpression of MMP9 in MMP9-/- MEFs showed
increased levels of Notch1 and p53
WT MEFs
MMP9-/- MEFs
MMP9-/-MEFs MMP9
A
MMP-9, 104 kD
B
NICD, 80 kD
GAPDH
1
2
3
4
5
6
WT MEFs
MMP9-/- MEFs
MMP9-/-MEFs MMP9
C
p53, 53 kD
GAPDH
1
2
3
4
5
6
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Summary

• Epithelial-derived MMP9 plays a tumor suppressive
  role in CAC
• Overexpression of MMP9 in colonic epithelium is
  associated with altered levels of p53,
  Notch1, Bax1 and p21WAF1/Cip1
• Overexpression of MMP9 in MMP9-/-exhibited
  increased levels of NICD and p53

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Molecular mechanism of p53 regulation by MMP9 via
Notch1
nucleus
cytosol
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Conclusions

• Despite being a mediator of acute inflammation,
  epithelial derived- MMP9 acts as a tumor
  suppressor in CAC
• MMP9 mediated p53 activation via Notch1
  signaling is necessary and sufficient for
  its tumor suppressive effect in CAC

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Acknowledgement
Didier Merlin
Lewins Walter
Crohns Colitis Foundation of AmericaCareer
Development Award, (3057)