Perlecan-rich epithelial linings as a background of proliferative potentials of keratocystic odontogenic tumor

Background:  The intraepithelial deposit of perlecan, a basement membrane-type heparan sulfate (HS) proteoglycan, has been demonstrated in neoplastic conditions such as salivary gland tumors, odontogenic tumors, and oral carcinoma in situ . Our aim was to determine whether perlecan turnover was enhanced in the lining cells of keratocystic odontogenic tumor (KCOT), which had been recently renamed from odontogenic keratocyst because of its accumulated evidence of neoplasm, as a possible background for neoplastic proliferation.
Methods:  Ten surgical specimens from each of KCOT, dentigerous cyst, and radicular cyst were examined for the expressions of perlecan core protein, HS chains, heparanase, and Ki-67 by immunohistochemistry and in situ hybridization.
Results:  In KCOT, perlecan core protein and HS chains were localized on the cell border from the parabasal to subkeratinized layers of the lining epithelium. Heparanase was localized in a similar fashion to those for perlecan and HS chains but was within the cytoplasm. mRNA signals for perlecan core protein and heparanase were mostly compatible with their protein signals. Ki-67-positive cells were localized mainly in the second basal cell layers with definitely higher labeling indices (approximately 31.3%, second layer). In contrast to KCOT, dentigerous cysts and radicular cysts had no perlecan, HS chains, and heparanase deposition in their linings with extremely lower Ki-67 indices (0.4–0.8%).
Conclusion:  The result suggests that the characteristic intra-lining-epithelial deposit of perlecan in KCOT, which has never been seen in other cystic jaw lesions, is a new evidence supporting the neoplastic nature of KCOT.     

Actual Proliferating Index and p53 protein expression as prognostic marker in odontogenic cysts

Background:  The purpose of this study was to evaluate the biological aggressiveness of odontogenic keratocyst/keratocystic odontogenic tumour (KCOT), radicular cyst (RC) and dentigerous cyst (DC) by observing the actual proliferative activity of epithelium, and p53 protein expression.
Methods:  The actual proliferative activity was measured by Ki-67 Labelling Index and argyrophilic nucleolar organizing regions (AgNOR) count per nucleus. The p53 protein expression was also evaluated.
Results:  Ki-67 positive cells were observed higher in suprabasal cell layers of KCOT with uniform distribution, a few of them were predominantly observed in basal cell layer in RC and DC. The AgNOR count was significantly higher in suprabasal cell layers of KCOT. The actual proliferative activity was noted to be higher in suprabasal cell layers of KCOT. The p53 immunolabelling was dense and scattered in basal and suprabasal cell layers in KCOT. The weakly stained p53 positive cells were observed diffusely distributed in KCOT, whereas they were mainly seen in basal cell layer of RC and DC.
Conclusion:  The quantitative and qualitative differences of the proliferative activity and the p53 protein expression in sporadic KCOT may be associated with intrinsic growth potential that could play a role in its development and explain locally aggressive biological behaviour. AgNOR count and p53 protein detection in odontogenic lesions can be of great consequence to predict the biological behaviour and prognosis.     

Significance of podoplanin expression in keratocystic odontogenic tumor

J Oral Pathol Med (2010) 39 : 110–114
Background:  The most important clinical features of the keratocystic odontogenic tumor (KCOT) are its potential for locally destructive behavior, a tendency to recur, and its origin in the odontogenic epithelium. The clinical features of KCOT are similar to those of ameloblastoma (AM). Histologically, KCOT is distinguished from jaw cyst with keratinization (orthokeratinized odontogenic cyst; OOC). However, current scientifically based clinical parameters cannot predict any potential for neoplastic behavior, or aggressive and localized invasiveness, in patients with KCOT. We have shown that podoplanin, a lymphatic endothelial marker, is highly expressed in AM. The purpose of this study was to determine the usefulness of podoplanin for reclassification of the odontogenic keratocyst (OKC) from cyst to tumor status.
Methods:  Paraffin-embedded tissue specimens of 57 OKCs (46 KCOTs and 11 OOCs) and 15 dentigerous cysts (DCs) were immunohistochemically examined using antibody against podoplanin.
Results:  Immunohistochemical reactivity for podoplanin was detected in the cell membrane and cytoplasm of most of the basal and suprabasal layer, areas of budding basal cell proliferation, epithelial nests and peripheral cells of daughter cysts in the stromal connective tissue in KCOTs. In the case of OOC and DC, only cases associated with inflammation were positive for podoplanin.
Conclusion:  Podoplanin is strongly expressed in KCOTs in comparison with OOCs. The pattern of staining for podoplanin in KCOT could be related to its neoplastic nature, and suggests a role of the protein in tumor invasiveness.     

磷酸化p38促分裂原活化的蛋白激酶、尿激酶型纤溶酶原激活物及Ki-67在牙源性上皮性肿瘤中的表达

目的 检测磷酸化p38促分裂原活化的蛋白激酶(phosphorylated-p38 mitogen-activated protein kinase,p-p38MAPK)、尿激酶型纤溶酶原激活物(urokinase plasminogen activator,uPA)及Ki-67在牙源性上皮性肿瘤中的表达,探讨p-p38MAPK对牙源性上皮性肿瘤细胞增殖活性及侵袭性的影响.方法 根据2005年WHO关于牙源性肿瘤的分类标准,应用免疫组化方法检测p-p38MAPK、uPA和Ki-67在成釉细胞瘤(ameloblastoma,AB)、牙源性角化囊性瘤(keratocystic odontogenic tumour,KCOT)、牙源性钙化上皮瘤(calcifying epithelial odontogenic tumor,CEOT)、牙源性腺样瘤(adenomatoid odontogenic tumour,AOT)及牙源性钙化囊性瘤(calcifying cystic odontogenic tumour,CCOT)(以上为肿瘤组)和5例牙胚(对照组)中的表达.结果 p-p38MAPK在肿瘤组的阳性表达率为26%(17/65),在肿瘤细胞胞质和胞核均可见着色;uPA在肿瘤组的阳性表达率为78%(51/65),主要表现为肿瘤细胞胞质着色;Ki-67在肿瘤组的阳性表达率为95%(62/65),为弥散的肿瘤细胞胞核着色.p-p38MAPK、uPA和Ki-67在牙源性上皮性肿瘤的阳性表达率显著高于对照组(P＜0.05),三者的阳性表达呈正相关(P＜0.05).结论 p-p38MAPK信号传导通路可能以正性调节的方式调控uPA从而促进牙源性上皮性肿瘤的发生,可能是肿瘤发生、侵袭和增殖的重要途径之一.     

Co-expression of Ki-67 and p53 protein in ameloblastoma and keratocystic odontogenic tumor

Abstract

Objectives. The purpose of this study was to evaluate the cell proliferation and p53 protein expression in ameloblastomas (ABs), keratocystic odontogenic tumor (KCOT) and dentigerous cyst (DC). Method. The immunohistochemistry were carried out for Ki-67 and p53 protein expression by using MIB-1 clone and DO-7 clone, respectively, in ABs (n = 23), KCOT (n = 32), DC (n = 30), normal oral mucosa (NOM) (n = 12) and fetal oral mucosa (FOM) (n = 10). Results. Both the Ki-67 LI Labeling index (LI) and p53 LI was significantly higher in ABs than KCOT, DC, NOM and FOM. The Ki-67 LI and p53 LI was significantly higher in KCOT as compared to DC. Ki-67 LI and p53 LI was observed in descending order in ABs, KOCT, FOM, NOM and DC. There was significant correlation between Ki-67 expression and p53 expression in ABs, KCOT, DC and NOM. The densely stained p53 positive cells were noted higher in ABs than KCOT. The very few densely p53 positive cells were noted in DC, NOM and FOM. Conclusion. The results suggest that the p53 protein expression does not necessarily imply an association with malignant disease and/or p53 gene mutation, but a tendency to be expressed in an increasing quantitative and qualitative manner, as the biologic behavior of odontogenic cyst or tumors becomes more aggressive. p53 over-expression may promote cell proliferation in odontogenic lesions. Thus, it can be stipulated that Ki-67 and p53 protein expression can be used as a prognostic marker in odontogenic lesions.     

Alterations of FHIT and P53 genes in keratocystic odontogenic tumor, dentigerous and radicular cyst

Background:  The purpose of this study was to determine fragile histidine triad (FHIT) and p53 protein expression, and to analyze FHIT and p53 gene status in keratocystic odontogenic tumor (KOT), dentigerous cysts (DC) and radicular cysts (RC).
Methods:  The methods used were immunohistochemistry and molecular genetic methods including loss of heterozygosity (LOH) and gene sequencing.
Results:  FHIT protein expression was different among groups. Aberrant expression was the highest in KOT, then in RC and DC. p53 protein expression was different among groups. LOH in paraffin-embedded specimens was detected in 22.6% and 12.9% for FHIT and p53 respectively. Mutation of p53 gene at codon 237 was observed in only two specimens (one KOT and one DC). Of the six frozen specimens, three exhibited FHIT gene LOH (two RC and one KOT). KOT showed loss of exons 6–7 at FHIT locus and mutation at codon 237 at p53 locus, but this could be a chance result.
Conclusion:  Aberrations of FHIT and p53 genes/proteins could be considered markers responsible for the development of odontogenic lesions.     

Marsupialization is the optimal treatment approach for keratocystic odontogenic tumour

Previous published studies fail to present any consensus on a uniform treatment protocol for keratocystic odontogenic tumour (KCOT). Optimal management for KCOT was investigated by comparing the treatment outcome of marsupialization to the enucleation and radical resection. An online electronic databases search was carried out through the PubMed, Embase and Web of Science. The statistical analysis was performed by RevMan version 5.2. Fourteen eligible studies were identified for analysis. Fourteen studies evaluated included 938 patients, of which 853 underwent enucleation alone or plus adjunctive therapy, 110 underwent marsupialization with or without secondary adjunctive therapy, and 86 underwent radical resection alone. The marsupialization was significantly associated with lower recurrence compared to enucleation and resection in KCOT treatment (RR = 0.56, 95% CI 0.4–0.78, P = 0.0006 and RR = 0.32, 95% CI 0.15–0.69, P = 0.004, respectively). The results suggest that the marsupialization reduce the recurrence of KCOT better than enucleation and surgical resection and it may be the optimal approach for KCOT treatment.     

Increased expression of autophagy-related proteins in keratocystic odontogenic tumours: its possible association with growth potential

The aim of this study was to evaluate the activation status of autophagy in keratocystic odontogenic tumours (KCOT), and to investigate its possible association with growth potential. We detected the expression of some key autophagy-related proteins in clinical samples of KCOT and radicular cysts and compared then by real-time quantitative polymerase chain reaction (qPCR) and immunohistochemical analysis, respectively. The correlation between the autophagy-related proteins tested, and with cell antiapoptotic (Bcl-2) or proliferative (Ki-67) markers in KCOT was explored using Spearman's rank correlation, followed by cluster analysis. The results showed that both the expression of mRNA and the immunoreactivity of the autophagy-related proteins tested were considerably increased in samples of KCOT compared with those in samples of radicular cysts. The correlation analyses showed that the immunostains of autophagy-related proteins in samples of KCOT correlated closely with each other. The immunostains of these autophagy-related proteins also correlated closely with the immunostains of Bcl-2 and Ki-67 in KCOT. More importantly, double-labelling immunofluorescence analyses also showed that the distribution of autophagic and proliferative markers was partially synchronous in samples from KCOT. We have, to our knowledge for the first time, implicated the activation of autophagy in KCOT, and showed its possible association with growth potential.     

Podoplanin expression in human tooth germ tissues and cystic odontogenic lesions: an immunohistochemical study

J Oral Pathol Med (2010) 39 : 115–120
Background:  Podoplanin expression was described in mouse tooth germ and apical bud cells. The aim of this study was to analyse the podoplanin expression of human tooth germ tissues, adult teeth and odontogenic lesions immunohistochemically.
Study Design:  Nine human tooth germ biopsies and seven healthy permanent teeth extracted for orthodontic reasons were examined. Anti-podoplanin (D2-40) reactivity was investigated immunohistochemically. Five well-defined cystic odontogenic lesions (10 radicular cysts, 10 follicular cysts, three keratocystic odontogenic tumours, five ameloblastomas, and two adenomatoid odontogenic tumours) were analysed simultaneously.
Results:  Podoplanin expression was detected in the majority of epithelial and ecto-mesenchymal cells of human tooth germ tissues, odontoblasts and superficial dental pulp fibroblasts of permanent teeth. Cystic odontogenic lesions revealed positive reactions predominantly at the invasion front edge within basal epithelial layers.
Conclusion:  Podoplanin appears to be involved in the orthologic and pathologic processes of the formation of elongated cell extensions and odontoblastic fibers, in the epithelial–mesenchymal transition and local invasion during tooth germ development as well as in both reactive and neoplastic odontogenic cystic lesions.     

Surgical treatment of keratocystic odontogenic tumour: A review article

KCOT is one of the most aggressive odontogenic cysts with a high recurrence rate, this was explained histopathologically as it typically shows a thin, friable wall, which is often difficult to enucleate from the bone in one piece, and have small satellite cysts within the fibrous wall. Multiple surgical approaches were introduced including decompression, marsupilization, enucleation with or without adjunct (Carnoy’s solution, enucleation) and resection. Depending on other studies KCOT can be conservatively treated with enucleation and application of Carnoy’s solution or cryotherapy. This can be used specially in the large lesions that when treated with resection, the continuity of the jaw will be interrupted. This technique shows comparable results to other more aggressive techniques.     

International collaborative study on ghost cell odontogenic tumours: calcifying cystic odontogenic tumour, dentinogenic ghost cell tumour and ghost cell odontogenic carcinoma

Background:  Calcifying odontogenic cyst was described first by Gorlin et al. in 1962; since then several hundreds of cases had been reported. In 1981, Prætorius et al. proposed a widely used classification. Afterwards, several authors proposed different classifications and discussed its neoplastic potential. The 2005 WHO Classification of Odontogenic Tumours re-named this entity as calcifying cystic odontogenic tumour (CCOT) and defined the clinico-pathological features of the ghost cell odontogenic tumours, the CCOT, the dentinogenic ghost cell tumour (DGCT) and the ghost cell odontogenic carcinoma (GCOC).
Methods:  The aim of this paper was to review the clinical-pathological features of 122 CCOT, DGCT and GCOC cases retrieved from the files of the oral pathology laboratories from 14 institutions in Mexico, South Africa, Denmark, the USA, Brazil, Guatemala and Peru. It attempts to clarify and to group the clinico-pathological features of the analysed cases and to propose an objective, comprehensive and useful classification under the 2005 WHO classification guidelines.
Results:  CCOT cases were divided into four sub-types: (i) simple cystic; (ii) odontoma associated; (iii) ameloblastomatous proliferating; and (iv) CCOT associated with benign odontogenic tumours other than odontomas. DGCT was separated into a central aggressive DGCT and a peripheral non-aggressive counterpart. For GCOC, three variants were identified. The first reported cases of a recurrent peripheral CCOT and a multiple synchronous, CCOT are included.
Conclusions:  Our results suggest that ghost cell odontogenic tumours comprise a heterogeneous group of neoplasms which need further studies to define more precisely their biological behaviour.     

Co-expression of Ki-67 and p53 protein in ameloblastoma and keratocystic odontogenic tumor

Abstract Objectives. The purpose of this study was to evaluate the cell proliferation and p53 protein expression in ameloblastomas (ABs), keratocystic odontogenic tumor (KCOT) and dentigerous cyst (DC). Method. The immunohistochemistry were carried out for Ki-67 and p53 protein expression by using MIB-1 clone and DO-7 clone, respectively, in ABs (n = 23), KCOT (n = 32), DC (n = 30), normal oral mucosa (NOM) (n = 12) and fetal oral mucosa (FOM) (n = 10). Results. Both the Ki-67 LI Labeling index (LI) and p53 LI was significantly higher in ABs than KCOT, DC, NOM and FOM. The Ki-67 LI and p53 LI was significantly higher in KCOT as compared to DC. Ki-67 LI and p53 LI was observed in descending order in ABs, KOCT, FOM, NOM and DC. There was significant correlation between Ki-67 expression and p53 expression in ABs, KCOT, DC and NOM. The densely stained p53 positive cells were noted higher in ABs than KCOT. The very few densely p53 positive cells were noted in DC, NOM and FOM. Conclusion. The results suggest that the p53 protein expression does not necessarily imply an association with malignant disease and/or p53 gene mutation, but a tendency to be expressed in an increasing quantitative and qualitative manner, as the biologic behavior of odontogenic cyst or tumors becomes more aggressive. p53 over-expression may promote cell proliferation in odontogenic lesions. Thus, it can be stipulated that Ki-67 and p53 protein expression can be used as a prognostic marker in odontogenic lesions.     

Prevalence of developmental odontogenic cysts in children and adolescents with emphasis on dentigerous cyst and odontogenic keratocyst (keratocystic odontogenic tumor)

Objective. To investigate the incidence and prevalence of developmental odontogenic cysts in children and adolescents and compare the features of the two most common types, dentigerous cyst and keratocystic odontogenic tumor (KCOT). Study design. A retrospective review in a series of 369 patients with all histological diagnoses of developmental odontogenic cysts in children (≤12 years) and adolescents (13–18 years) was conducted. Results. Among these, 361 (97.8%) patients were diagnosed as dentigerous cyst (n = 281) and KCOT (n = 80), with the male-to-female ratios of dentigerous cyst and KCOT both being 2:1. The average age of the patients with KCOT was older than that of those with dentigerous cyst (14.7 years vs 11.8 years, p < 0.001). Dentigerous cyst (59.1%) was more common in children, but KCOT (78.8%) was more common in adolescents (p < 0.001). Dentigerous cyst (57.6%) predominantly located on the maxilla, but KCOT (60.3%) predominantly located on the mandible (p = 0.010). Conclusions. Adolescent patients with lesions located on the mandible would favor KCOT over dentigerous cyst. This study aids in better knowledge of the prevalence of developmental odontogenic cysts in a large pediatric population, and shows that a well-supported early diagnosis is indispensable for a more adequate treatment.     

Ameloblastoma, calcifying epithelial odontogenic tumor, and glandular odontogenic cyst show a distinctive immunophenotype with some myoepithelial antigen expression

Background:  Odontogenic neoplasms have some morphologic overlap with salivary gland neoplasms, many of which show myoepithelial differentiation. In the 1980s, an ultrastructural study identified a population of myoepithelial-like cells in calcifying epithelial odontogenic tumor. Myoepithelial derived tumors have since been shown to have distinct immunohistochemical profiles.
Methods:  We examined a series of odontogenic neoplasms, including 11 ameloblastomas, four calcifying epithelial odontogenic tumors, five glandular odontogenic cysts (GOCs), and five keratocystic odontogenic tumors with a panel of myoepithelial-associated immunohistochemical stains. We also assessed representative control examples of oral mucosa, odontogenic rests, and dentigerous cysts.
Results:  All of the neoplastic and non-neoplastic oral epithelium-derived entities share a p63-positive, high molecular weight cytokeratin (CK5/6)-positive immunophenotype. Calponin reactivity was at least focally present in two of four calcifying epithelial odontogenic tumors, three of five GOCs, and 10 of 11 ameloblastomas; the sole completely non-reactive ameloblastoma represents a lung metastasis. One case of calcifying epithelial odontogenic tumor was focally positive for glial fibrillary acidic protein. However, other more definitive markers of myoepithelial differentiation, including S-100 and smooth muscle actin, were negative. Two of three calcifying epithelial odontogenic tumors and five of five GOCs were also positive for a low molecular weight cytokeratin (CK7).
Conclusions:  Ameloblastomas, GOCs, and calcifying epithelial odontogenic tumors show a distinctive immunophenotype which overlaps with that of myoepithelial-derived salivary gland neoplasms but does not provide definitive support for myoepithelial differentiation.     

Clonal nature of odontogenic tumours

Background:  Although clonal origin is an essential step in the comprehension of neoplasias, there have been no studies to examine whether odontogenic tumours are derived from a single somatic progenitor cell. The purpose of this study was to investigate the clonal origin of odontogenic tumours.
Methods:  Fresh samples of seven ameloblastomas, two odontogenic mixomas, two adenomatoid odontogenic tumour, one calcifying odontogenic cyst, one calcifying epithelial odontogenic tumour (CEOT) and six odontogenic keratocyst (OKC) of female patients were included in this study. After DNA extraction, the HUMARA gene polymorphism assay was performed.
Results:  Most of the informative odontogenic lesions studied (12 out of 16) showed a monoclonal pattern. Among the polyclonal cases, two were OKC, one CEOT and one odontogenic mixoma.
Conclusions:  Our results suggest that most odontogenic tumours are monoclonal.     

Analysis of the neoplastic nature and biological potential of sporadic and nevoid basal cell carcinoma syndrome-associated keratocystic odontogenic tumor

BACKGROUND: Keratocystic odontogenic tumor (KCOT), also known as odontogenic keratocyst, is a benign cystic neoplasm, which may be associated with nevoid basal cell carcinoma syndrome (NBCCS) and if it does, will occur as multiple cystic lesions. KCOT is locally destructive despite its bland histological features. However, the neoplastic nature of KCOT is not well established. Heparanase is an endo-d-glucuronidase enzyme that specifically cleaves heparan sulfate (HS) and the increase of its level in tumors promotes invasion, angiogenesis, and metastasis. METHODS: To investigate the neoplastic character of KCOT, we studied the localization patterns of heparanase in KCOT, focusing on the differences between sporadic and NBCCS-associated KCOTs, by immunohistochemistry and in situ hybridization. To compare the expression pattern of these cysts with non-tumorous odontogenic developmental cyst, dentigerous cyst was included. RESULTS: All the odontogenic cysts showed positive immunoreaction for heparanase protein in various intensities. The expression pattern of heparanase gene corresponded to that of protein expression. Interestingly, intense gene and protein expressions were observed in KCOT associated with NBCCS compared with sporadic ones and dentigerous cyst. CONCLUSIONS: The results implied that heparanase expression may be correlated with the neoplastic properties of KCOT, particularly in NBCCS-associated cases.     

Keratocystic odontogenic tumour: reclassification of the odontogenic keratocyst from cyst to tumour

The purpose of this paper is to review the features and behaviour of the odontogenic keratocyst (OKC), now officially known as the keratocystic odontogenic tumour (KCOT); to analyze a series of histologically confirmed KCOT cases; and to review and discuss the redesignation of KCOT and the implications for treatment. Redesignation of the OKC as the KCOT by the World Health Organization (WHO) is based on the well-known aggressive behaviour of this lesion, its histology and new information regarding its genetics. Abnormal function of PTCH, a tumour suppressor gene, is noted to be involved in both nevoid basal cell carcinoma syndrome and sporadic KCOTs. Normally, PTCH forms a receptor complex with the oncogene SMO for the SHH ligand. PTCH binding to SMO inhibits growth-signal transduction. SHH binding to PTCH releases inhibition of the signal transduction pathway. If normal functioning of PTCH is lost, the proliferation-stimulating effects of SMO are permitted to predominate. A review of the literature was conducted and results were tabulated to determine whether treatment modality is related to recurrence rate. More aggressive treatment - resection or enucleation supplemented with Carnoy"s solution with or without peripheral ostectomy - results in a lower recurrence rate than enucleation alone or marsupialization. Notably, the recurrence rate after marsupialization followed by enucleation is not significantly higher than that following the so-called aggressive modalities. Our case series consists of 21 patients treated for KCOTs. Results were organized to demonstrate recurrence as it relates to size of lesion and time since treatment and incidence as it relates to patient age and location in the jaws. In our series, the average KCOT surface area measured radiographically was 14 cm². Most lesions were within the 0-15 cm² range and lesions in this range resulted in the greatest number and proportion of recurrences. The recurrence rate of 29% in our case series was consistent with previously established data; all recurrences occurred within 2 years post-intervention. The incidence of primary lesions was highest in the age group 70-79 years; most lesions occurred in the posterior mandible. WHO"s reclassification of the OKC as the KCOT based on behaviour, histology and genetics underscores the aggressive nature of the lesion and should motivate clinicians to manage the disease in a correspondingly aggressive manner. The most effective interventions for the KCOT are either enucleation with Carnoy"s solution, or marsupialization with later cystectomy. Future treatment may involve molecular-based modalities, which may reduce or eliminate the need for aggressive surgical management.     

Immunoexpression of MMPs-1, -2, and -9 in ameloblastoma and odontogenic adenomatoid tumor

Objective:  The aim of this study was to evaluate and compare the expression of metalloproteinases-1, -2, and -9 in solid ameloblastoma and adenomatoid odontogenic tumor.
Methods:  A total of 20 cases of solid ameloblastoma and 10 cases of adenomatoid odontogenic tumors were selected and immunohistochemically assessed. Metalloproteinases-1, -2, and -9 immunoexpression and their distribution pattern were noted and semiquantitatively scored. The scores obtained were statistically analyzed.
Results:  Matrix metalloproteinase (MMP)-1 showed a predominant expression in both tumors and was found in stroma and parenchyma. For MMP-2, there was a varied expression, with 80% and 60% of immunoreactive tumor cells in ameloblastoma and adenomatoid odontogenic tumor respectively. Regarding stromal cells, 65% of ameloblastomas and 80% of adenomatoid odontogenic tumors showed positivity. There was immunoexpression of the MMP-9 in parenchymal and stromal cells in all cases of both tumors analyzed. A statistically significant difference in the expression of MMP-1 in relation to the expression of MMP-2 and -9 in ameloblastomas ( P  < 0.001) was observed.
Conclusion:  The results suggest that these metalloproteinases are related to growth and progression of tumors analyzed, and particularly in ameloblastoma, its highest aggressiveness may be, in part, a result of the active participation of the stromal cells and their products, such as the MMPs studied.     

Odontogenic keratocyst expresses vascular endothelial growth factor: an immunohistochemical study

Background:  Vascular endothelial growth factor (VEGF) expression may act as a sensitive measure of the angiogenic potential of a lesion. Furthermore, VEGF has been implicated in the pathogenesis of cystic tumors and inflammatory odontogenic cysts. Thus, we studied the expression of VEGF in the epithelium of odontogenic keratocyst (OK) in association with cell proliferation and apoptosis.
Methods:  Forty-two cases of OK, 26 cases of dentigerous cyst (DC), and 15 cases of residual cyst (RC) were retrospectively examined by immunohistochemistry for VEGF, Ki67/Mib-1 and anti-caspase-3. For VEGF and caspase-3, the intensity of immunostaining was qualitatively assessed, while for the evaluation of Ki67 the average number of positively stained nuclei in 10 high-power microscopic fields (×400) was calculated.
Results:  The VEGF expression was stronger in OK when compared with DC ( P  < 0.007). The rate of nuclear Ki67 expression in OK was significantly higher than that in DC ( P  < 0.001) and RC ( P  < 0.001). Cytoplasmic caspase-3 expression was statistically more intense in RC than in OK ( P  = 0.001) or DC ( P  < 0.001). A statistically significant correlation was seen in OK for Ki67 ( P  < 0.001) and VEGF ( P  = 0.023), but not for caspase-3. Multiple regression analysis revealed a linear relationship between VEGF and Ki67.
Conclusions:  The VEGF was expressed in the epithelium of OK, DC, and RC with a variable intensity, and in OK VEGF expression was related to Ki67. It is suggested that VEGF expression by the odontogenic epithelium is not induced solely by inflammation.     

Potential relevance of cyclooxygenase‐2 expression in keratocystic odontogenic tumours – an immunohistochemical study

J Oral Pathol Med (2010) 40 : 497–503 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.