Matrix-Metalloproteinases, Myofibroblasts and Ki-67 Evaluation in Ameloblastomas and Pericoronal Follicles

Objectives: To better understand the interaction between tumor cells and stroma comparing to a normal odontogenic tissue, the present study aimed to evaluate the immunohistochemical expression of matrix metalloproteinases-1, -2, and -9 (MMP-1, -2 and -9), the cellular proliferation index (by immunolabeling with Ki-67) and the presence of myofibroblasts (MF) in ameloblastomas (AM) and pericoronal follicles (PF).
Methods: This study was approved by the Ethics Committee in Research with Human Beings of the authors’ institution. Thirteen cases of Solid AM (SA) and five cases of Unicystic AM (UA) were selected, and eight PF were included as normal odontogenic tissue (control). Immunohistochemical reactions were performed using a standard streptavidin-biotin protocol for the investigation of MMP-1, MMP-2, MMP-9, α-smooth muscle actin (α-SMA), and Ki-67 proteins. Immunohistochemical expression analyses were performed using NIH ImageJ 1.45q software. Kruskal–Wallis statistical test was applied to compare the groups (p<0.05).
Results: Kruskal-Wallis test showed statistically significant differences in the epithelial expression of MMP-1 and 2, with lower expression in SA when compared to UA and PF. Higher stromal expression of MMP-9 was found in PF, comparing to SA and UA. No statistical differences were found between groups for the presence of MF and the expression of Ki-67.
Conclusions: Therefore, the findings of this study allow suggesting that the pattern of expression of MMP-1, -2, -9, and Ki-67 as well as the presence of MF are similar in both groups, demonstrating that these proteins and cells may be associated with both AM tumor behavior and PF physiological tissue remodeling.