Topical 5-Fluorouracil is a Novel Targeted Therapy for the Keratocystic Odontogenic Tumor.

PURPOSE: The antimetabolite drug, 5-fluorouracil (5-FU), is used in the treatment of various cancers, including basal cell carcinomas (BCCs). The authors hypothesized that keratocystic odontogenic tumors (KOTs) would respond to 5-FU treatment because of their similarities to BCCs in molecular etiopathogenesis. MATERIALS AND METHODS: An ambispective cohort study of the treatment efficacy of topical 5-FU on KOTs was conducted. Independent variables included the topical application of 5% 5-FU or modified Carnoy's solution (MC) after enucleation and peripheral ostectomy at the University of Toronto from 2006 through 2014. Outcome variables included time to recurrence and peripheral nerve injury. KOT specimens in these patients were immunostained with p53, Ki-67, thymidylate synthetase (TS), thymidylate phosphorylase (TP), and dihydropyrimidine dehydrogenase (DPD) antibodies. Semiquantitative staining scores were calculated for all immunohistochemistry sections examined. Descriptive statistics were computed using Fisher exact test and Kaplan-Meier analysis as appropriate with the P value set at .05. RESULTS: Thirty-two patients with 32 KOTs were reviewed (41% in women and 59% in men). There were no KOT recurrences in the 5-FU group (n = 11), whereas there were 4 recurrences in the MC group (n = 21; P = .190). There was a significantly lower incidence of inferior alveolar nerve paresthesia with 5-FU treatment (P = .039). Immunohistochemical staining showed upregulation of TP (P < .0001) and DPD (P < .0001) and no change in TS (P > .05) in inflamed KOTs. CONCLUSIONS: 5-FU effectively treats KOTs with less postoperative morbidity than conventional treatment with MC. Low TS and upregulated TP expressions in inflamed KOTs suggest increased 5-FU efficacy in inflamed KOTs. Topical 5-FU is a novel therapy for KOTs and provides a targeted molecular approach to treatment.

BRAFV600E mutation in the diagnosis of unicystic ameloblastoma.

BACKGROUND: Unicystic ameloblastoma, an odontogenic neoplasm, presents clinical and radiographic similarities with dentigerous and radicular cysts, non-neoplastic lesions. It is not always possible to reach a final diagnosis with the incisional biopsy, leading to inappropriate treatment. The BRAFV600E activating mutation has been reported in a high proportion of ameloblastomas. The purpose of the study was to assess the utility of the detection of the BRAFV600E mutation in the differential diagnosis of unicystic ameloblastoma with dentigerous and radicular cysts. METHODS: Twenty-six archival samples were included, comprising eight unicystic ameloblastomas (UAs), nine dentigerous and nine radicular cysts. The mutation was assessed in all samples by anti-BRAFV600E (clone VE1) immunohistochemistry (IHC) and by TaqMan mutation detection qPCR assay. Sanger sequencing was further carried out when samples showed conflicting results in the IHC and qPCR. RESULTS: Although all UAs (8/8) showed positive uniform BRAFV600E staining along the epithelial lining length, the mutation was not confirmed by qPCR and Sanger sequencing in three samples. Positive staining for the BRAFV600E protein was observed in one dentigerous cyst, but it was not confirmed by the molecular methods. Furthermore, 2/9 dentigerous cysts and 2/9 radicular cysts showed non-specific immunostaining of the epithelium or plasma cells. None of the dentigerous or radicular cysts cases presented the BRAFV600E mutation in the qPCR assay. CONCLUSIONS: The BRAFV600E antibody (clone VE1) IHC may show non-specific staining, but molecular assays may be useful for the diagnosis of unicystic ameloblastoma, in conjunction with clinical, radiological and histopathological features.

Immunohistochemical expression of matrix metalloproteinases in ameloblastomas and pericoronal follicles.

BACKGROUND: Ameloblastoma (AM) is a benign odontogenic neoplasm characterized by local invasiveness and recurrence. We compared the immunohistochemical expression of matrix metalloproteinases in different clinical types of AM as well as in normal odontogenic tissue. METHODS: Thirteen cases of solid AMs, five cases of unicystic AM and eight pericoronal follicles (PF) were selected and subjected to immunohistochemical investigation for matrix metalloproteinase-1, matrix metalloproteinase-2 and matrix metalloproteinase-9 expressions. RESULTS: The expressions of MMP-1 and MMP-2 were very high in the cytoplasm of cells throughout the entire epithelium and in fibroblasts from the adjacent connective tissue. MMP-9 expression was observed in the same location although with weaker staining. The Kruskal-Wallis test showed statistically significant differences in the epithelial expressions of MMP-1 and MMP-2; there was lower expression among solid AMs when compared with unicystic AM and PF. Compared to both types of AM, higher stromal expression of MMP-9 was found in PF. CONCLUSION: MMP-1, MMP-2 and MMP-9 seem to be associated with AM tumour behaviour as well as physiological tissue remodelling within PF.

Comparative analysis of the immunohistochemical expression of vascular endothelial growth factor and matrix metalloproteinase-9 in keratocystic odontogenic tumor, dentigerous cyst and radicular cyst.

BACKGROUND: Vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) have been implicated in the pathogenesis of cysts. Both these factors seem to be interrelated to each other. The importance of the MMPs in the induction of the angiogenic process has recently been described. MMPs, which are produced by microvascular endothelial cells, break down the extracellular matrix. This is one of the earliest and sustained events in the process of new capillary formation. Thus, we studied the expression of VEGF and MMP-9 in Keratocystic odontogenic tumors (KCOTs), dentigerous cysts (DCs) and radicular cysts (RCs). MATERIALS AND METHODS: Ten cases each of KCOTs, DCs and RCs and were included in the study and immunohistochemistry was performed using anti-VEGF and anti-MMP-9 antibody using standard protocol. RESULT: When the data of positive cells in the epithelium of KCOTs was compared with DCs and RCs, it showed highly significant results (P<0.05). Furthermore, the expression of VEGF and MMP-9 in the stroma of KCOTs showed a significant result when compared to DCs and RCs. The expression of VEGF in inflammatory cells was more in RCs when compared to DCs. Also, the expression of MMP-9 was more in RCs and DCs as compared to KCOTs. CONCLUSION: Higher expression of VEGF and MMP-9 in KCOTs could be responsible for the aggressive behavior of this cyst that is currently considered a cystic tumor rather than a developmental cyst.

A positive correlation between immunohistochemical expression of CD31 and mast cell tryptase in odontogenic tumors.

In this study, we compared mast cell tryptase and CD31 expression between odontogenic tumors with the aim of predicting the clinical behavior of these lesions at the time of initial biopsy. We also evaluated the correlation between mast cell tryptase and CD31 expression to clarify the role of mast cells (MCs) in the growth of odontogenic tumors. Immunohistochemical staining with anti-MC tryptase and anti-CD31 antibodies was performed on 48 cases of odontogenic tumors including solid ameloblastoma (SAM), unicystic ameloblastoma (UAM), odontogenic myxoma (OM), cystic calcifying odontogenic tumor (CCOT) and adenomatoid odontogenic tumor (AOT). Ten high power fields were analyzed for each sample. Total MC count was significantly increased in SAM compared to other odontogenic tumors (p<0.05). Microvessel density was statistically higher in SAM and AOT compared to remaining odontogenic tumors (p<0.05). A significant correlation was observed between MCs and microvessels in odontogenic tumors (p=0.018, r=0.34). Our findings suggest a role for MCs in aggressive clinical behavior of odontogenic tumors. The significant correlation found between MC count and microvessel density in odontogenic tumors is in agreement with the theory of participation of MCs in tumor progression. Targeting MC activity may represent an important nonsurgical therapeutic approach, especially for aggressive odontogenic tumors.

Defects of the Carney complex gene (PRKAR1A) in odontogenic tumors.

The surgical treatment of some odontogenic tumors often leads to tooth and maxillary bone loss as well as to facial deformity. Therefore, the identification of genes involved in the pathogenesis of odontogenic tumors may result in alternative molecular therapies. The PRKAR1A gene displays a loss of protein expression as well as somatic mutations in odontogenic myxomas, an odontogenic ectomesenchymal neoplasm. We used a combination of quantitative RT-PCR (qRT-PCR), immunohistochemistry, loss of heterozygosity (LOH) analysis, and direct sequencing of all PRKAR1A exons to assess if this gene is altered in mixed odontogenic tumors. Thirteen tumors were included in the study: six ameloblastic fibromas, four ameloblastic fibro-odontomas, one ameloblastic fibrodentinoma, and two ameloblastic fibrosarcomas. The epithelial components of the tumors were separated from the mesenchymal by laser microdissection in most of the cases. We also searched for odontogenic pathology in Prkar1a(+) (/) (-) mice. PRKAR1A mRNA/protein expression was decreased in the benign mixed odontogenic tumors in association with LOH at markers around the PRKAR1A gene. We also detected a missense and two synonymous mutations along with two 5'-UTR and four intronic mutations in mixed odontogenic tumors. Prkar1a(+) (/) (-) mice did not show evidence of odontogenic tumor formation, which indicates that additional genes may be involved in the pathogenesis of such tumors, at least in rodents. We conclude that the PRKAR1A gene and its locus are altered in mixed odontogenic tumors. PRKAR1A expression is decreased in a subset of tumors but not in all, and Prkar1a(+) (/) (-) mice do not show abnormalities, which indicates that additional genes play a role in this tumor's pathogenesis.

DNA methyltransferase immunohistochemical expression in odontogenic tumours.

BACKGROUND: Odontogenic tumours are a heterogeneous group of lesions formed from tissues that give rise to the tooth. DNA methylation, a covalent addition of a methyl group to the 5-carbon position of a cytosine nucleotide, is considered an important regulator of gene expression. The addition of the methyl radical is catalysed by DNA methyltransferases (DNMTs). Although some epigenetic studies have been conducted in odontogenic tumours, a study with the three types of DNMTs in several different members of this group is missing. This study analyses the expression of DNMTs in odontogenic tumours. METHODS: Formalin-fixed and paraffin-embedded tissue samples of 20 ameloblastomas, 10 calcifying cystic odontogenic tumours, 10 calcifying epithelial tumours, 10 adenomatoid odontogenic tumours, 10 keratocystic odontogenic tumours, five ameloblastic fibromas, two ameloblastic fibro-odontomas, four central odontogenic fibromas, seven peripheral odontogenic fibromas and 10 odontogenic myxomas were included. Immunohistochemical expression of DNMT1, 3A and 3B was assessed using a semi-quantitative analysis, and also a correlation with p21, p27 and E-cadherin immunoexpression was made. RESULTS: DNMT1, 3A and 3B were expressed in the nucleus and/or cytoplasm of all odontogenic tumours. DNMT1 expression was directly correlated with p27 expression in ameloblastomas. CONCLUSION: The high expression of DNMTs in odontogenic tumour cells suggests methylation as an important mechanism for this group of tumours.

Matrix metalloproteinase expression in keratocystic odontogenic tumors and primary cells.

UNLABELLED: Keratocystic odontogenic tumors (KCOTs) are locally invasive, rapidly proliferating cystic lesions of the jaw. The bone-invasive nature of these tumors has been previously associated with the expression of matrix metalloproteinases (MMPs), which degrade the extracellular matrix. The purpose of this study was to assess the expression and activity of MMPs in primary KCOT cells and tumor tissue. METHODS: Four independently established KCOT primary cell populations were grown in Dulbecco's modified Eagle medium supplemented with 10% FBS and antibiotics. Primary cells were analyzed by qRT-PCR and immunohistochemistry (IHC), and for secretion of active MMPs. Primary tumor sections were analyzed by IHC. RESULTS: Of the 18 human MMPs examined, 9 were consistently expressed in primary KCOT cells. MMP-2 and MMP-14 were highly expressed in all KCOT populations, while MMP-1, 3, 11, 12, 16, 17, and 19 were moderately expressed. MMP-3, 11, 12, 16, 17 and 19 were shown to be expressed in KCOTs for the first time. No significant differences in MMPS profiles were found between syndromic (KCOT-3) and non-syndromic cell populations (KCOT-1/2/4). Protein expression of MMP-1, 11, 12, 14 and 16 was confirmed in each KCOT cell populations by IHC. KCOT-3 cells secreted active MMP-2 as determined by a gel zymography assay. Expression of MMP-1, 2, 3, 11, 12, 14, and 16 was confirmed in matching primary KCOT tumor sections representing syndromic and non-syndromic KCOTs. CONCLUSION: KCOT primary cell populations and tumors express a wide range of MMPs, which likely play a role in the bone-invasive nature of these tumors.

Calcifying Cystic Odontogenic Tumour: immunohistochemical expression of matrix metalloproteinases, their inhibitors (TIMPs and RECK) and inducer (EMMPRIN).

BACKGROUND: Calcifying cyst odontogenic tumour (CCOT) is a rare benign cystic neoplasm of odontogenic origin. MMPs are responsible for extracellular matrix remodelling and, together their inhibitors and inducer, determinate the level of its turnover in pathological processes, leading to an auspicious microenvironment for tumour development. Thus, our goal was to evaluate matrix metalloproteinases (MMPs-2, -7, -9 and -14), their inhibitors (TIMPs-2, -3, -4 and RECK) and its inductor (EMMPRIN) expression in CCOT. MATERIALS AND METHODS: We used 18 cases of CCOT submitted to immunolocalization of the target proteins and analysed in both neoplastic odontogenic epithelial and stromal compartments. RESULTS: All molecules evaluated were expressed in both compartments in CCOT. In epithelial layer, immunostaining for MMPs, TIMPs, RECK and EMMPRIN was found in basal, suprabasal spindle and stellate cells surrounding ghost cells and ghost cells themselves, except for MMP-9 and TIMP-2 which were only expressed by ghost cells. In stromal compartment, extracellular matrix, mesenchymal (MC) and endothelial cells (EC) were positive for MMP-2, -7, TIMP-3 and -4, while MMP-9, TIMP-2 and RECK were positive only in MC and MMP-14 only in EC. Statistical significance difference was found between both compartments for MMP-9 (P < 0.001), RECK (P = 0.004) and EMMPRIN (P < 0.001), being more expressed in epithelium than in stroma. Positive correlation between both stromal EMMPRIN and RECK expression was found (R = 0.661, P = 0.003). CONCLUSIONS: We concluded that these proteins/enzymes are differentially expressed in both epithelium and stroma of CCOT, suggesting an imbalance between MMPs and their inducer/inhibitors may contribute on the tumour behaviour.

Correlation between radiographic area and immunolocation of MMP-2 and MMP-9 in unilocular radiographic lesions.

Unilocular bone cysts are the most common entities affecting the maxillofacial region. The mechanism of proliferation and expansion remains unclear. Metalloproteinases (MMPs) are associated to diverse pathological conditions. The aim of the present study was to correlate the radiographic aspect (area) and the presence of MMP-2 and MMP-9 in dentigerous cysts, radicular cysts and keratocystic odontogenic tumors. The radiographic area of each lesion was calculated using the mathematical formula of the ellipse area. All specimens were subjected to immunohistochemical analysis for these enzymes. The average radiographic area was 284.17 mm2, 235.81 mm2 and 381.81 mm2, respectively. Statistical analyses revealed no association between the immunoreactivity of MMPs and radiographic area of the lesions in all pathologies studied, except for MMP-2 and radicular cysts, for which smaller lesions had increased immunostaining for this enzyme. The results demonstrate that quantities of MMP-2 and MMP-9 are especially involved with dentigerous and radicular cysts in expansion, whereas these enzymes seem to be related to the biological behavior of keratocystic odontogenic tumors, indicating invasion and cell proliferation. Moreover, there is an inverse association between MMP-2 and MMP-9 in keratocystic odontogenic tumors (p=0.03; rs=-0.660), indicating activity in different regions.

Identification of the involvement of LOXL4 in generation of keratocystic odontogenic tumors by RNA-Seq analysis.

Keratocystic odontogenic tumors (KCOT) are benign, locally aggressive intraosseous tumors of odontogenic origin. KCOT have a higher stromal microvessel density (MVD) than dentigerous cysts (DC) and normal oral mucosa. To identify genes in the stroma of KCOT involved in tumor development and progression, RNA sequencing (RNA-Seq) was performed using samples from KCOT and primary stromal fibroblasts isolated from gingival tissues. Seven candidate genes that possess a function potentially related to KCOT progression were selected and their expression levels were confirmed by quantitative PCR, immunohistochemistry and enzyme-linked immunosorbent assay. Expression of lysyl oxidase-like 4 (LOXL4), the only candidate gene that encodes a secreted protein, was enhanced at both the mRNA and protein levels in KCOT stromal tissues and primary KCOT stromal fibroblasts compared to control tissues and primary fibroblasts (P<0.05). In vitro, high expression of LOXL4 could enhance proliferation and migration of the human umbilical vein endothelial cells (HUVECs). There was a significant, positive correlation between LOXL4 protein expression and MVD in stroma of KCOT and control tissues (r=0.882). These data suggest that abnormal expression of LOXL4 of KCOT may enhance angiogenesis in KCOT, which may help to promote the locally aggressive biological behavior of KCOT.

Expression of MMP-2 and MMP-9 in odontogenic myxoma in a child: report of a clinical case.

BACKGROUND: Odontogenic myxoma (OM) is a benign, locally invasive, non-metastasizing neoplasm of the jaw bones. Despite the benign nature of these lesions, there is a high rate of recurrence and the current recommended therapy, depending on the size and behaviour of the lesion, can vary from curettage with peripheral ostectomy, segmental resection up to radical resections for more aggressive lesions. OM is a rare tumour which occurs predominantly in the third decade of life and it is rare in children. Matrix metalloproteinases (MMPs) are a family of extracellular endopeptidases responsible for the degradation and remodelling of extracellular matrix, they are known to be involved in the progression and invasiveness of many types of tumour. MMPs have been studied in OM because of their well-known role in extracellular matrix degradation, tumour invasion and recurrence. CLINICAL CASE REPORT: We report a case of OM in a 6-year-old boy. A conservative excision was accomplished. The mass was excised without affecting the mandibular bone and the inferior alveolar nerve. Curettage and removal of the first right inferior molar were performed. After 6-month follow-up, no evidence of recurrence was found. EXPERIMENTAL DATA: We investigated the expression of MMP-2 and MMP-9 in this case of OM in a child. RT-PCR showed the expression of both MMP-2 and MMP-9 mRNAs. Immunohistochemistry showed a weak MMP-2 protein expression while MMP-9 protein was not detected. CONCLUSION: In this case of OM in a child, we report lack of recurrence after excision associated with low MMP-2 protein expression and absence of MMP-9. We believe it is worthy to deeply investigate the relationship between MMPs expression and OM behaviour with the aim to use MMPs as prognostic and/or therapeutic markers in OM.

Presence of myofibroblasts and matrix metalloproteinase 2 in radicular cysts, dentigerous cysts, and keratocystic odontogenic tumors: a comparative immunohistochemical study.

INTRODUCTION: The aim of this study was to analyze the presence of myofibroblasts and matrix metalloproteinase 2 (MMP-2) in radicular cysts (RCs), dentigerous cysts (DCs), and keratocystic odontogenic tumors (KOTs). METHODS: For the study, 29 RCs, 19 DCs, and 15 KOTs were selected. Immunohistochemical reactions were performed by using anti-MMP-2 and anti-α-smooth muscle actin (SMA) antibodies. For the analysis, 10 high-power fields were observed in each case to determine the percentage of positive cells, which was classified as negative, weak, or strong. RESULTS: The presence of myofibroblasts (α-SMA-positive cells) was most common in KOTs (46.67%), followed by DCs (36.84%) and RCs (31.04%); however, it was not statistically significant (P = .8). The stromal MMP-2 expression was positive in all lesions but 1 case of KOT. Most cases of RC and DC presented strong MMP-2 expression in the stroma, whereas half of the KOTs showed similar classification. The MMP-2 expression was commonly found in the epithelial lining of the lesions; it was strong in almost all KOTs. No correlation between epithelial and stromal MMP-2 and α-SMA expressions was observed. CONCLUSIONS: Myofibroblasts and MMP-2 are frequent in RCs, DCs, and KOTs and eventually can contribute to bone resorption, favoring the progression and growth of these lesions.

Isolation of protein-tyrosine phosphatase-like member-a variant from cementum.

Cementum has been shown to contain unique polypeptides that participate in cell recruitment and differentiation during cementum formation. We report the isolation of a cDNA variant for protein-tyrosine phosphatase-like (proline instead of catalytic arginine) member-a (PTPLA) from cementum. A cementifying fibroma-derived λ-ZAP expression library was screened by panning with a monoclonal antibody to cementum attachment protein (CAP), and 1435 bp cDNA (gb AC093525.3) was isolated. This cDNA encodes a 140-amino-acid polypeptide, and its N-terminal 125 amino acids are identical to those of PTPLA. This isoform, designated as PTPLA-CAP, results from a read-through of the PTPLA exon 2 splice donor site, truncating after the second putative transmembrane domain. It contains 15 amino acids encoded within the intron between PTPLA exons 2 and 3, which replace the active site for PTPLA phosphatase activity. The recombinant protein, rhPTPLA-CAP, has Mr 19 kDa and cross-reacts with anti-CAP antibody. Anti-rhPTPLA-CAP antibody immunostained cementum cells, cementum, heart, and liver. Quantitative RT-PCR showed that PTPLA was expressed in all periodontal cells; however, PTPLA-CAP expression was limited to cementum cells. The rhPTPLA-CAP promoted gingival fibroblast attachment. We conclude that PTPLA-CAP is a splice variant of PTPLA, and that, in the periodontium, cementum and cementum cells express this variant.

Potential relevance of cyclooxygenase-2 expression in keratocystic odontogenic tumours - an immunohistochemical study.

There is increasing evidence that overexpression of cyclooxygenase-2 (COX-2) plays an important role in tumour growth and spread of tumours by interfering with cell proliferation, cellular adhesion, immune surveillance, apoptosis, and angiogenesis. COX-2 levels are increased in various tumours. In this study, the expression of COX-2 in 116 specimens of keratocystic odontogenic tumours (KCOT) has been analyzed. KCOT is a benign neoplasm of odontogenic origin with an occasionally aggressive behavior leading to high recurrence rates. Formalin-fixed, paraffin-embedded blocks were sectioned and used for hematoxylin-eosin (H&E) staining and incubated with an anti-COX-2 monoclonal antibody for immunohistochemical examination. Detection of the COX-2 antibody was performed with the EnVision kit. Cellular staining pattern for COX-2 was cytoplasmatic, and the staining intensities were semi-quantitatively evaluated as follows: negative (-), mild (±) or strong (+). Mild to strong expression of COX-2 was observed in 83 (71.6%) cases; 34 (29.3%) of which were mild positive and 49 (42.2%) were strong positive. COX-2 stain was detected mainly in the epithelial lining. The expression of COX-2 in KCOT and the current knowledge of the role played by COX-2 in tumorigenesis further strengthen the current concept that the KCOT should be regarded as a neoplasm. Furthermore, the multitude of markers known to be overexpressed in KCOTs is suggestive of what could be called a 'network addiction' pattern, rather than a pathological mechanism dependant on a specific activated/suppressed gene, thus explaining its aggressive behavior.

A comparative immunohistochemical analysis of COX-2, p53, and Ki-67 expression in keratocystic odontogenic tumors.

OBJECTIVE: The aim of the present study was to investigate the association between the expression of cyclooxygenase-2 (COX-2) in keratocystic odontogenic tumors (KCOT) and more commonly used markers, such as p53 and Ki-67. STUDY DESIGN: Expression of cyclooxygenase-2 (COX-2) in 20 biopsy specimens of keratocystic odontogenic tumors (KCOT) has been analyzed and compared with the expression of previously reported markers Ki-67 and p53. Formalin-fixed, paraffin-embedded blocks were sectioned and used for hematoxylin-eosin (H&E) staining and incubated with anti-cox-2, anti-ki-67, and anti-p53 monoclonal antibodies for immunohistochemical examination. Detection of the COX-2 antibody was performed with the EnVision kit. Cellular staining pattern was cytoplasmatic for COX-2 and nuclear for both Ki-67 and p-53. Molecular expressions were semiquantitatively evaluated as negative (-), mild (±) or strong (+). RESULTS: Mild to strong expression of COX-2 was observed in 20 (100%) of the cases. Fifteen (75%) of the KCOTs stained positive for p53 and 18 (90%) stained positive for Ki-67. There was no statistically relevant difference between the expressions of COX - 2, Ki-67, and p53. CONCLUSIONS: Although COX-2 has rarely been used to assess the biological activity of the KCOT, the results portrayed in the current study and the current knowledge of the overall role known to be played by COX-2 in tumorigenesis suggest that COX-2 may be an important marker involved in the biological behavior of the KCOT. Larger studies are required to improve our knowledge of the possible role of COX-2 in the pathogenic mechanism involved in KCOT.

MMP-13 expression in keratocyst odontogenic tumour associated with NBCCS and sporadic keratocysts.

OBJECTIVE: To investigate the matrix metalloproteinase (MMP)-13 expression in associated and non-nevoid basal cell carcinoma syndrome (NBCCS) Odontogenic Keratocysts (OCKs) in order to contribute to a better understanding of the differences in the growth pattern between them. MATERIALS AND METHODS: Thirty-nine paraffin-embedded blocks of OCKs, 26 sporadic OCKs and 11 NBCCS-associated KCOTs were studied by immunohistochemistry to evaluate MMP-13 expression both in epithelial and stromal layers. A semi-quantitative scale was used to evaluate immunostaining. Obtained data were compared between the two groups, using Fischer's exact test and the chi-square test. RESULTS: Only 13 of 26 sporadic OCKs showed a positive immunostaining, whilst 11 KCOTs resulted in positive labelling for MMP-13 expression. Moreover, syndromic cysts displayed a more intense and diffuse MMP-13 labelling of the stromal tissue. Instead, in non-syndromic forms, the staining pattern of MMP-13 in stromal tissue was completely absent. Fisher's exact test showed a statistically significant greater prevalence of KCOTs-immunolabelled cysts with respect to sporadic OCKs. CONCLUSIONS: Results from this study point out that the biological behaviour of these cysts could be related not only to the epithelial layer but also to stromal tissue in that... MMP-13 overexpression in stromal tissue of NBCCS-associated KCOTs could clarify the higher aggressiveness of these cysts.

Immunohistochemical expression of matrilysins (MMP-7 and MMP-26) in ameloblastomas and adenomatoid odontogenic tumors.

OBJECTIVE: The aim was to evaluate the expression of matrix metalloproteinases (MMPs) 7 and 26 in ameloblastomas and adenomatoid odontogenic tumors (AOTs). STUDY DESIGN: Twenty intraosseous solid ameloblastomas and 10 intraosseous AOTs were evaluated regarding immunohistochemical expression of MMP-7 and -26 in the epithelium and stroma. RESULTS: There was no statistically significant difference in MMP-7 and -26 expression between the epithelium of ameloblastomas (P = .50) and AOTs (P = .90). Stromal staining for MMP-7 was evident in all cases. For MMP-26, stromal staining was observed in 65% of ameloblastomas and 50% of AOTs, and this difference was not statistically significant (P = .69). CONCLUSION: The marked expression of these matrilysins suggests their role in the process of tissue remodeling and growth in the studied tumors, but it does not relate to the their distinct patterns of aggressiveness.

Immunohistochemical expression of matrix metalloproteinases 1, 2, and 9 in odontogenic myxoma and dental germ papilla.

The aim of this study was to compare the immunohistochemical expression of matrix metalloproteinases (MMPs) 1, 2, and 9 in odontogenic myxomas and dental germ papillae. Twelve cases of odontogenic myxoma and eight tooth germ specimens were selected for analysis of the immunohistochemical expression and the pattern of distribution of MMPs 1, 2, and 9 in extracellular matrix (ECM), as well as of the number of MMP-positive cells. MMP-2 was expressed only in the ECM of myxomas (p<0.05). No significant difference was observed between ECM immunoreactivity for MMP-9 in myxomas and dental papillae (p>0.05). MMP-1 immunoreactivity was detected in most myxoma cases at a proportion similar to that observed in dental papillae (p>0.05). A significant difference was observed in the number of immunoreactive cells in myxomas (p<0.05), MMP-1 being present at higher proportions than MMPs 2 and 9. There was a gradient in the expression of MMPs in the ECM and in neoplastic cells of odontogenic myxomas, with higher immunoreactivity to MMP-1 and lower immunoreactivity to MMP-9. Taken together, our results suggest the existence of a coordinated mechanism between MMPs 1, 2, and 9 that aimed at the efficient degradation of extracellular matrix in odontogenic myxomas.

Expression of matrix metalloproteinases 2 and 9 in odontogenic myxoma in vivo and in vitro.

Odontogenic myxoma is a benign neoplasm, which presents local invasiveness and tendency for recurrence. Matrix metalloproteinases (MMPs) 2 and 9 are involved in tumor invasion. Thus, the aim of this study was to analyze the expression and activity of these MMPs in odontogenic myxoma in vivo and in vitro. Three cases of odontogenic myxoma and cultured cells derived from this tumor (Mix1 cell line) were used. The detection and activity of two MMPs (2 and 9) were performed by immunohistochemistry in formalin-fixed, paraffin-embedded sections of odontogenic myxoma and immunofluorescence of the cultured cells and, by gelatin zymographic analysis of Mix1 conditioned media, respectively. MMPs 2 and 9 were detected in vivo and in vitro. The zymographic assay detected latent MMP-2 as well as latent and active MMP-9. Based on our findings, we suggest that MMPs may be involved in local invasiveness of the odontogenic myxoma. MMP-9 is not only secreted by odontogenic myxoma but also has enzyme activity with no further stimulation. Other MMPs were not analyzed; however, our results suggest that the invasive behaviour of odontogenic myxoma could be related at least to MMP-9.