Immunohistochemical expression of SPARC and MMP-9 in odontogenic keratocysts and orthokeratinized odontogenic cysts.

OBJECTIVE

Odontogenic keratocysts (OKCs) are locally aggressive odontogenic cysts with high recurrence propensity, whereas orthokeratinized odontogenic cysts (OOCs) are indolent. Secreted protein acidic and rich in cysteine (SPARC) and matrix metalloproteinase 9 (MMP-9) have been implicated in tumor invasion. This study aimed to evaluate and compare the immunohistochemical expression of SPARC and MMP-9 in sporadic OKCs and OOCs, and to further explore the potential association between these two proteins in both types of cysts.

DESIGN

SPARC and MMP-9 expression were evaluated in 24 sporadic OKCs and 22 OOCs using immunohistochemistry.

RESULTS

In the epithelium of OKCs and OOCs, SPARC was absent. In the connective tissue, SPARC was predominantly detected in fibroblast cytoplasm, with significantly higher expression in OKCs than in OOCs (p = 0.006). MMP-9 was localized in both epithelium and connective tissue. Compared with OOCs, OKCs showed upregulated MMP-9 expression in the epithelium (p = 0.035), whereas no significant difference in MMP-9 expression was observed in the connective tissue between the two types of cysts (p = 0.678). A positive correlation was observed between SPARC and MMP-9 in the connective tissue of OKC. Furthermore, both SPARC and MMP-9 demonstrated a significant positive association with inflammatory infiltration in OKCs.

CONCLUSION

Increased SPARC expression in sporadic OKCs compared to OOCs suggests that SPARC may play a role in OKC aggressiveness. Differential expression of SPARC may aid in distinguishing between OKC and OOC. Moreover, the putative association between SPARC and MMP-9 in OKCs may contribute to their local invasiveness.