IMMUNOHISTOCHEMICAL EXPRESSION OF MMP2 & TIMP2 IN AMELOBLASTOMA AND THEIR IMPLICATIONS IN BIOLOGIC BEHAVIOUR OF THE TUMOUR

Expression of MMP2 & TIMP2 in Ameloblastoma

Abstract

of odontogenic epithelium characterized by local invasiveness, 
propensity for facial deformity, and a high rate of recurrence. 
Matrix metalloproteinases (MMPs) are proteolytic enzymes that 
play a central role in the regulation of extracellular matrix 
complemented by Tissue Inhibitors of Matrix metalloproteinases 
(TIMPs).  MMP-2 has been closely associated with ameloblastoma 
invasion. TIMP2 acts as a specific inhibitor of MMP-2 or may be 
involved in its activation. 
AIM: To determine and compare the relative immunohistochemical 
expressions of MMP2 and TIMP2 proteins in the clinical types of 
ameloblastoma. 
METHODS: Formalin-fixed paraffin embedded (FFPE) tissue 
blocks of 50 ameloblastoma cases were sectioned and stained with 
antibodies for MMP-2 and TIMP-2. Immunohistochemical staining 
of stromal and tumour cells were assessed to obtain a combined 
score of proportion and intensity of staining. Proportion of cases 
with positive expression of MMP2 and TIMP2 were determined. 
Mean score and ratios of these proteins were compared within the 
biological types using the Independent sample t- test.

RESULTS: In all the clinical types of ameloblastoma, the mean 
MMP-2 expression was higher than the mean expression of the 
inhibitor, TIMP-2. There was no significant difference in the 
expression of MMP-2 in both the conventional and unicystic types. 
TIMP2 expression was significantly higher in the unicystic type 
than in conventional type (p=0.02). However, MMP2:TIMP2 was 
significantly higher in the conventional type than in unicystic type 
(p = 0.01). 
CONCLUSION: TIMP-2 is a better predictor of the degree of 
invasiveness of the clinical types of ameloblastoma than MMP-2. 
MMP2: TIMP2 ratio also explains the effect of TIMP-2 on MMP-2 
and indicates invasiveness in the biologic types of ameloblastoma 
than MMP-2 alone.