Clinical-pathological And Molecular Pathological Study Of Calcifying Odontogenic Cyst

Histological and biological transformation is often associated with alterations in the expression of normal differentiation markers. To identify early changes in differentiation markers during calcifying odontogenic cysts development, we examined the expression of cytokeratins by immunohistochemical method among 22 calcifying cyst odontogenic tumor(CCOT), 15 dentinoid ghost cell tumor(DGCT) and 9 dentinoid ghost cell carcinoma(DGCC). CK19 was detected in odontogenic epitheliums of all specimens while CK10 stained negative, and no difference in their expression was found in the different histopathological group. CK8 was detected in 90% (18 of 20) of CCOT but in 47% (7 of 15) and 56% (5 of 9) of DGCT and DGCC. The corresponding figures for CK14 expression in CCOT, DGCT and DGCC were 60%, 53% and 100%, respectively. The expression of CK8 and CK14 has statistical significance among these three groups. These results demonstrate that CK19 expression can be treated as a positive marker of odontogenic epithelium while CK10 acts as a negative marker. CK8 expression increases notably in CCOT and expresses partly in DGCT and DGCC, whereas CK14 expression is low in benign lesions and increases highly in malignant lesions. Thus, CK19, CK8 and CK14 could be markers of sequential changes in the transformation among CCOT, DGCT and DGCC.Matrix metalloproteinases(MMPs) are responsible for extracellular matrix degradation, and their functions are regulated by tissue inhibitors of MMPs (TIMPs). The research for the roles of MMPs and TIMPs in dentinogenic ghost cell tumor(DGCT) and ghost cell odontogenic carcinoma(GCOC) was extremely rare, especially in both protein and mRNA level. In the present study, the protein expression of MMP-2, MMP-9, MT1-MMP, TIMP-1 and TMP-2 was examined in 15 DGCT cases and 9 GCOC cases by immunohistochemistry. We also investigated their mRNA expression levels in one DGCT case and one GCOC case by reverse transcnptase polymerase chain reaction, meanwhile we used gelatin zymography to analyze MMP-2 and MMP-9 protein activities in the two cases. We found that MMP-9 and TIMP-1 protein expression elevated greatly in GCOC, and there was a significance difference (P<0.05) of TIMP-1 protein expression in odontogenic cells between GCOC and DGCT. MMP-2, MT1-MMP and TEVIP-2 protein levels had no obvious difference in GCOC and DGCT. In addition, pro-MMP-9, MMP-9 activated form, pro-MMP-2, and MMP-2 activated forms were detected in the GCOC case by zymography analysis, while the band at pro-MMP-9 and MMP-9 activated form were very faint in the DGCT case. Furthermore, the mRNA level of MMP-9 elevated obviously in the GCOC case, which was very similar to that of TIMP-1. So we suggested that there be a closely correlation of MMP-9 and TEVIP-1 in GCOC, and they may have important roles in regulating biological behaviors during odontogenic tumor malignant transformation.Based on these findigs, the combined expressions of CK8, 14, 19 and 10 could be helpful to identify tumor origin, insight its characteristics, reveal its biological behaviors and predict its prognosis. MMP-9 and TMP-1 may serve as important factors of biological behaviors in GCOC.