In vitro assessment of PD-L1+ microvesicles in the cyst fluid of non-syndromic odontogenic keratocysts.

Odontogenic keratocysts (OKCs) are jaw cystic lesions which are characterized by local invasion and high recurrence rate. The majority of OKCs are exposed to microorganisms and occur along with focal inflammatory infiltrates. Cyst fluids are biological fluids that contain a large content of cytokines and immune globulins. Inhibitory receptor such as programmed death receptor 1 (PD-1) and its ligand programmed death-ligand 1 (PD-L1), which can induce a coinhibitory signal in activated T cells, plays a vital role in the differentiation, exhaustion and apoptosis of T cells. Cell derived microvesicles, carrying a cargo of functional proteins, nucleic acids and lipids, are important communication tools in the development of diseases. However, the expression of PD-L1 in OKCs tissues and whether PD-L1 could be carried by microvesicles are unexplored. Presently, we have isolated cyst fluid microvesicles and identified cell derived PD-L1+ cyst fluid microvesicles. PD-L1 was located in the membrane of the cyst fluid microvesicles. The main cellular origins of PD-L1+ cyst fluid microvesicles were dendritic cells followed by lymphocytes. Elevated PD-L1+ cyst fluid microvesicles were detected in the OKCs compared with dentigerous cysts. Isolated cyst fluid microvesicles could bind to the membrane of activated CD8 T cells and inhibit proliferation of stimulated peripheral blood CD8 T cells. In conclusion, the present study suggests that elevated PD-L1+ cyst fluid microvesicles might be related with the cyst development of OKCs.

Analysis of GLUT-1, GLUT-3, and angiogenic index in syndromic and non-syndromic keratocystic odontogenic tumors.

The aim of this study was to evaluate the immunoexpression of glucose transporters 1 (GLUT-1) and 3 (GLUT-3) in keratocystic odontogenic tumors associated with Gorlin syndrome (SKOTs) and non-syndromic keratocystic odontogenic tumors (NSKOTs), and to establish correlations with the angiogenic index. Seventeen primary NSKOTs, seven recurrent NSKOTs, and 17 SKOTs were selected for the study. The percentage of immunopositive cells for GLUT-1 and GLUT-3 in the epithelial component of the tumors was assessed. The angiogenic index was determined by microvessel count. The results were analyzed statistically using the nonparametric Kruskal-Wallis test and Spearman's correlation test. High epithelial immunoexpression of GLUT-1 was observed in most tumors (p = 0.360). There was a higher frequency of negative cases for GLUT-3 in all groups. The few GLUT-3-positive tumors exhibited low expression of this protein in epithelial cells. No significant difference in the angiogenic index was observed between groups (p = 0.778). GLUT-1 expression did not correlate significantly with the angiogenic index (p > 0.05). The results suggest that the more aggressive biological behavior of SKOTs when compared to NSKOTs may not be related to GLUT-1 or GLUT-3 expression. GLUT-1 may play an important role in glucose uptake by epithelial cells of KOTs and this process is unlikely related to the angiogenic index. GLUT-1 could be a potential target for future development of therapeutic strategies for KOTs.

Kallikrein-related peptidase expression in odontogenic cysts and tumors: An immunohistochemical comparative study.

AIM: The aim of the present study was to profile the expression of human kallikrein (KLK)-related peptidases (KLK) in odontogenic lesions. METHODS: Paraffin-embedded, formalin-fixed, non-odontogenic (control) and odontogenic lesions were stained for KLK using a standard immunohistochemical technique. The intensity and proportion of epithelial cells stained was scored. Reverse transcription-polymerase chain reaction was utilized to evaluate KLK 1-15 mRNA expression in ameloblastomas. RESULTS: KLK 3, 4, 9, 11, and 14 were present in all lesions. KLK 3 staining was increased in ameloblastomas and keratocystic odontogenic tumors. KLK 5 was present only in Keratocystic odontogenic tumor. KLK 6 was significantly higher in ameloblastomas than in other lesions. For KLK 7, keratocystic odontogenic tumors and nasopalatine duct cysts were significantly different. KLK 6, 8, 10, 11, and 13 were significantly higher in ameloblastomas than in other lesions. KLK 9 was increased in keratocystic odontogenic tumors and dentigerous cysts. The expression of KLK 1, 4, 7, 8, 10, and 12 mRNA was found in ameloblastomas. CONCLUSION: The results suggested that KLK 6, 8, 10, and 13 could be involved in the progression of ameloblastomas. KLK 10 could have a greater role in odontogenic lesions, rather than non-odontogenic lesions. Future studies aim to define the specific roles of KLK cascades in odontogenic lesions.

Analysis of GLUT-1, GLUT-3, and angiogenic index in syndromic and non-syndromic keratocystic odontogenic tumors

Abstract The aim of this study was to evaluate the immunoexpression of glucose transporters 1 (GLUT-1) and 3 (GLUT-3) in keratocystic odontogenic tumors associated with Gorlin syndrome (SKOTs) and non-syndromic keratocystic odontogenic tumors (NSKOTs), and to establish correlations with the angiogenic index. Seventeen primary NSKOTs, seven recurrent NSKOTs, and 17 SKOTs were selected for the study. The percentage of immunopositive cells for GLUT-1 and GLUT-3 in the epithelial component of the tumors was assessed. The angiogenic index was determined by microvessel count. The results were analyzed statistically using the nonparametric Kruskal-Wallis test and Spearman’s correlation test. High epithelial immunoexpression of GLUT-1 was observed in most tumors (p = 0.360). There was a higher frequency of negative cases for GLUT-3 in all groups. The few GLUT-3-positive tumors exhibited low expression of this protein in epithelial cells. No significant difference in the angiogenic index was observed between groups (p = 0.778). GLUT-1 expression did not correlate significantly with the angiogenic index (p > 0.05). The results suggest that the more aggressive biological behavior of SKOTs when compared to NSKOTs may not be related to GLUT-1 or GLUT-3 expression. GLUT-1 may play an important role in glucose uptake by epithelial cells of KOTs and this process is unlikely related to the angiogenic index. GLUT-1 could be a potential target for future development of therapeutic strategies for KOTs.

Expression of Bcl-2 in Primary and Recurrent Odontogenic Keratocysts in Comparison with Other Odontogenic Lesions.

PURPOSE: To determine the biological behaviour of common odontogenic cystic lesions by analysing and comparing bcl-2 expression amongst them. MATERIALS AND METHODS: Our study covered 90 formalin fixed paraffin embedded tissue samples: 26 primary cases each of radicular cysts (RC), dentigerous cysts (DC) and odontogenic keratocysts (OKC) and 12 of recurrent OKCs. Bcl-2 expression was analysed immunohistochemically and data analysis was accomplished using SPSS version 17.0. Means were taken for age while for gender and site of the lesions frequencies and percentages were determined. The Chi-square test was applied to evaluate any statistically significant difference of bcl-2 expression in these lesions and p value of ≤0.05 was taken as significant. RESULTS: All the recurrent OKCs showed a strong positivity for bcl-2 that was absent in all of its primary cases (p value<0.05). Although variation in expression of bcl-2 was not found to be statistically significant between RC and DC, however, it became significant when all primary cases of these common odontogenic lesions were compared. CONCLUSIONS: Recurrent OKC showed comparatively a more aggressive behaviour than their primary counterparts and also from RC and DC. Bcl-2 proved to be a valuable adjunct in determining aggressive biological behaviour of odontogenic lesions.

Odontogenic keratocysts/keratocystic odontogenic tumours: biological characteristics, clinical manifestation and treatment.

BACKGROUND: Odontogenic keratocysts (OKCs) now reclassified as Keratocystic odontogenic tumours (KCOTs) are a clinical entity with a characteristic microscopic picture, kinetic growth and biological behaviour. They arise from the proliferation of the epithelial dental lamina in both maxilla and mandible and occur in patients of all ages. 70-80% of keratocysts are found in the mandible commonly in the angle between the jaw and mandibular branch and maxillary region of the third molar. The cysts are long latent, often symptomless and may attain remarkable dimensions without significant deformation of the jaw bones. They are often found during routine dental X-ray examination. Compared to other types of jaw cyst, odontogenic cysts have a striking tendency to rapid growth and re-occurrence. AIMS: This review focuses on the biological characteristics, clinical behaviour and treatment of KCOTs. METHODS: The databases searched were the PubMed interface of MEDLINE and LILACS. RESULTS AND CONCLUSIONS: Ondontogenic keratinocysts are not currently a diagnostic problem. Orthopantomograms which are today ordinary tools of dental investigation enable diagnosis of clinically asymptomatic cystic lesions. The problem remains the optimal therapeutic approach to reduce the still high likelihood of postoperative recurrence. There is no complete consensus on the ideal operating procedure but cystectomy with delayed extirpation is favoured. An open question also remains the timeliness of screening for postoperative recurrences. Given that the first clinical manifestation of Nevoid Basal Cell Carcioma Syndome (NBCCS) may be lesions of this type, routine histopathological classification supplemented by analysis of immunophenotype should be done. Patients with proven sporadic and especially syndromic OKC should be long term screened. In patients with NBCC preventive X ray examination is recommended only once a year.

Cyclin d1 expression in odontogenic cysts.

OBJECTIVE: In the present study expression of cyclin D1 in the epithelial lining of odontogenic keratocyst, radicular cyst, dentigerous cyst and glandular odontogenic cyst was investigated to compare proliferative activity in these lesions. MATERIAL AND METHOD: Immunohistochemical staining of cyclin D1 on formalin-fixed, paraffin-embedded tissue sections of odontogenic keratocysts (n=23), dentigerous cysts (n=20), radicular cysts (n=20) and glandular odontogenic cysts (n=5) was performed by standard EnVision method. Then, slides were studied to evaluate the following parameters in epithelial lining of cysts: expression, expression pattern, staining intensity and localization of expression. RESULTS: The data analysis showed statistically significant difference in cyclin D1 expression in studied groups (p < 0.001). Assessment of staining intensity and staining pattern showed more strong intensity and focally pattern in odontogenic keratocysts, but difference was not statistically significant among groups respectively (p=0.204, 0.469). Considering expression localization, cyclin D1 positive cells in odontogenic keratocysts and dentigerous cysts were frequently confined in parabasal layer, different from radicular cysts and glandular odontogenic cysts. The difference was statistically significant (p < 0.01). CONCLUSION: Findings showed higher expression of cyclin D1 in parabasal layer of odontogenic keratocyst and the entire cystic epithelium of glandular odontogenic cysts comparing to dentigerous cysts and radicular cysts, implying the possible role of G1-S cell cycle phase disturbances in the aggressiveness of odontogenic keratocyst and glandular odontogenic cyst.

Comparison of antioxidant enzymes activity and the concentration of uric acid in the saliva of patients with oral cavity cancer, odontogenic cysts and healthy subjects.

Chronic inflammation is related to oxidative stress and is still believed to be the cause of carcinogenesis. Patients with oral cavity cancer (OCC) exhibited lower total antioxidant capacity, uric acid (UA) concentration, salivary peroxidise (SPO) and superoxide dismutase (SOD) activity in their saliva than did healthy subjects. This could be a risk factor for tumour induction. Odontogenic cysts also arise in response to locally acting proinflammatory factors, for example, a gangrenous tooth. Furthermore, cyst development is accompanied by chronic inflammation. There are some reports in the literature concerning primary tumours such as squamous cell carcinomas arising from odontogenic cysts. The reason for this transformation is still unknown. The aim of this study was to compare the status of the antioxidant defence system in the saliva of the group with odontogenic cysts and OCC with that of the healthy control. Saliva samples were collected in the morning. SOD, SPO activity and UA concentration were determined using standard methods. Patients with odontogenic cysts and OCC exhibited lower activity of major antioxidants in their saliva (SPO, UA) than did healthy people. SOD activity and age are the main factors that distinguish these diseases. Discriminant function analysis showed that once data such as antioxidant status of saliva, age and smoking status are known 80% cases can be correctly classified as healthy, 80% as having odontogenic cysts and 40% as cancerous. To conclude, the decrease in concentrations of major antioxidants in the saliva of patients with cysts may increase the risk of neoplastic transformation especially in advanced age.

Immunohistochemical comparative study of the odontogenic keratocysts and other odontogenic lesions.

OBJECTIVES: The present study was undertaken to compare the pattern of expression of EGFR, cyclin D1, Ki-67, p-53 and carcinoembryonic antigen (CEA) in the epithelial lining of odontogenic keratocysts, dentigerous cysts, radicular cysts and ameloblastomas. METHODS: four micrometers, formalin-fixed, paraffin-embedded tissue sections from 11 odontogenic keratocysts, 10 dentigerous cysts, 10 radicular cysts and 10 ameloblastomas were immunohistochemically studied. RESULTS: There were statistically significant differences between cyclin D1 expression in odontogenic keratocysts and radicular cysts (p=0.001) and ameloblastomas (p=0.04). The differences in CEA expression between the four studied lesions were statistically significant (p<0.0005). Proliferating cells were significantly more prevalent in odontogenic keratocysts (p<0.0005) with a mean percentage of Ki-67 positively stained nuclei of 40%. In dentigerous cysts this mean was of 17%, of 15.5% in RC and of 7.8 in ameloblastomas. CONCLUSION: Some of these findings could support the theory that odontogenic keratocysts are neoplastic in origin, but other results clearly support that these lesions are developmental cysts with some neoplastic properties because of the high intrinsic growth potential.

Keratocystic odontogenic tumor associated with nevoid basal cell carcinoma syndrome: similar behavior to sporadic type?

OBJECTIVE: The objective of this study was to analyze the expression of proliferative markers and p53 in keratocystic odontogenic tumor (KCOT) sporadic type and KCOT associated with nevoid basal cell carcinoma syndrome (NBCCS). STUDY DESIGN AND SETTING: We performed a cross-sectional study. A total of 19 patients with KCOT were selected from the Oral Pathology Laboratory archives, Central University of Venezuela, from 1995 to 2005. SUBJECTS AND METHODS: Twelve cases corresponded to sporadic KCOT, and seven cases were associated with NBCCS. Immunohistochemical analysis for p53, proliferating cell nuclear antigen (PCNA), and Ki-67 was performed in all 19 cases. RESULTS: Of the seven cases associated with NBCCS, six (86%) were positive for PCNA. From the 12 sporadic cases, nine (75%) were positive for PCNA. Only one case of sporadic KCOT showed Ki-67 positivity. Five of 12 (42%) cases of sporadic KCOT were positive for p53, and only one (14%) case associated with NBCCS was positive for p53. CONCLUSION: On the basis of the analysis of the expression of PCNA, Ki-67, and p53, there appears to be no evidence to indicate higher aggressiveness in growth and infiltrative behavior in syndromic KCOT compared with the sporadic type. Therefore, surgical treatment may be approached in the same manner in KCOT sporadic and syndromic with the goal of minimizing recurrence.

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.

Prognostic factors for keratocystic odontogenic tumor (odontogenic keratocyst): analysis of clinico-pathologic and immunohistochemical findings in cysts treated by enucleation.

BACKGROUND: The purpose of this study was to determine prognostic factors for the recurrence of keratocystic odontogenic tumors (KCOTs) following simple enucleation by examining clinico-pathologic and immunohistochemical findings. METHODS: Following enucleation, the frequency of recurrence among 32 subjects diagnosed with KCOT was analyzed for tumor site, radiographic and histologic features, and immunopositivity for Ki-67 and p53. RESULTS: Keratocystic odontogenic tumors in four out of 32 subjects (12.5%) recurred during the follow-up period (median: 33 months, range: 7-114 months). Three out of four subjects (75.0%) among recurrent group showed high expression of Ki-67 (LI >10%) in basal layer and four (4/28; 14.3%) among non-recurrence group (P = 0.025). Expression of p53 among non-recurrent group was observed in 11 subjects (11/28; 39.3%), and in three subjects (3/4; 75.0%) among the recurrent group (P = 0.295). Hazard risk for the recurrence of KCOT was 4.02 (95% CI 1.42-18.14) for high Ki-67 expression in the basal layer by the Cox proportional hazard model (P = 0.009). In our study, none of the other clinico-pathologic variables were associated with the recurrence of KCOT. CONCLUSION: The results suggested that the evaluation of Ki-67 expression in KCOT at the time of pathological diagnosis might be helpful for consideration of appropriate adjunctive surgical procedures to avoid a recurrence and may serve as a prognostic marker.

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.

KAI-1 protein expression in odontogenic cysts.

The KAI-1 tumor suppressor gene is widely distributed in normal tissues and its down-regulation may be correlated with the invasive phenotype and metastases in several different epithelial tumors. The aim of the present study was an evaluation of KAI-1 expression in radicular cysts (RC), follicular cysts (FC), orthokeratinized keratocysts (OOKC), and parakeratinized keratocysts (POKC). Eighty-five odontogenic cysts, 28 RC, 22 FC, and 35 OKC (16 OOKC, 19 POKC) were selected. All the POKC were negative and only four of 16 of the OOKC were positive for KAI-1. On the contrary, all RC and FC cases were positive and immunoreactivity for KAI-1 was detected throughout all the layers of the cyst epithelium. The lack of KAI-1 expression in POKC could help to explain the differences in the clinical and pathologic behavior of OKC and, according to what has been reported for epithelial tumors, could be related to the increased aggressive behavior and invasiveness of OKC.

The influence of inflammation on the polarization colors of collagen fibers in the wall of odontogenic keratocyst.

Epithelial-mesenchymal interactions have been found to play a role in the pathogenesis of odontogenic keratocyst (OKC). In the present study we investigated the effect of inflammation in the OKC wall on the polarization colors of Picrosirius red-stained collagen fibers. 50 cases of OKC were selected and separated into two groups according to the inflammatory intensity: those with mild-to-moderate inflammation (Group A), and those with intense inflammation (Group B). The polarization colors of the collagen fibers were recorded separately for thick and thin fibers. Polarization colors of the thin fibers were in the green- to yellow spectrum, without significant differences between the groups. However, polarization colors of the thick fibers significantly differ between the groups. In Group B, the frequency of thick fibers with green birefringence decreased significantly, whereas fibers with red polarization colors increased in frequency (4.6% and 44%, respectively) compared with Group A (12.3% and 23.6%, respectively). It can than be concluded that inflammation has an impact on the packing of collagen fibers in the connective tissue wall of OKC as reflected by their birefringence colors under polarized light. In the presence of dense inflammation, the percentage of thick fibers with green birefringence decreases, with an increase in thick fibers with red birefringence which appeared more packed.

The inflammatory radicular cysts have higher concentration of tnf-alpha in comparison to odontogenic keratocysts (odontogenic tumour).

TNF-alpha is a pleiotropic cytokine that is considered as a primary modifier of inflammatory and immune reaction in response to various inflammatory diseases and tumour. We investigated levels of TNF-alpha in 43 radicular cysts and 15 odontogenic keratocysts, obtained from patients undergoing surgery, under local anaesthesia, and after aspiration of cystic fluid from non-ruptured cysts. TNF-alpha is elevated in both cysts' fluid, but higher values were found in radicular cysts in comparison to keratocysts. The significantly higher concentration of TNF-alpha was associated with smaller radicular cysts, higher protein concentration, higher presence of inflammatory cells in peri cystic tissues, and the degree of vascularisation and cysts wall thickness (Mann-Whitney U-test, p < 0.05). No correlation was found based on these parameters in odontogenic keratocyst, but all cysts have detectable concentrations of TNF-alpha. We here for the first time present that a difference in the concentration of TNF-alpha exists between these two cystic types.

Expression of p53, Ki-67, and EGFR in odontogenic keratocysts before and after decompression.

BACKGROUND: Sixteen odontogenic keratocysts were examined morphologically and immunohistochemically for changes in proliferative activity before and after decompression using p53, Ki-67, and expression of growth factor (EGFR). METHODS: p53 and Ki-67 positivity was scored by counting 500 cells and then counting the number of brown staining nuclei out of these. EGFR was scored using guidelines for scoring Herceptest [Dako (Her-2)]. A Wilcoxon test was performed on the results. RESULTS: The values of Ki-67 and p53 before and after decompression were without significant change. There was no significant change in EGFR expression either. No correlation was found between inflammation or decompression time and expression of EGFR, p53, and Ki-67. The degree of change of the epithelium was varying, yet the reduction of the cysts size was considerable (18-100%- average 47.6%). CONCLUSION: The morphologic changes in the cysts could not be correlated with expression of Ki-67, p53 or EGFR, to the clinical reduction of the cysts or the time of decompression.

Immunohistochemical analysis of the biological potential of odontogenic keratocysts.

BACKGROUND: The aim of this study was to analyse the usefulness of detecting important apoptosis and proliferation markers in assessing the biological potential of odontogenic keratocysts (OKC) and thus selecting the optimal diagnostic algorithm for these lesions. METHODS: Indirect immunohistochemistry and relevant statistical methods were used for analysis of formalin-fixed and paraffin-embedded samples from 98 patients. RESULTS: Nevoid basal cell carcinoma syndrome (NBCCS) keratocysts were characterized by higher expression of Bcl-2, p27Kip1 and c-erbB-2 as well as by lower proliferative activity measured by Ki-67 in basal cell epithelium and by a lower inflammatory response in comparison with sporadic keratocysts. Dentigerous, radicular and non-specified odontogenic cysts differed from both NBCCS and sporadic keratocysts in a wide spectrum of apoptosis and/or cell cycle-related protein expressions, higher proliferation in the basal cell layer, and vice versa, lower proliferation in the suprabasal cell layer. CONCLUSIONS: The NBCCS keratocysts have a different immunophenotype from sporadic keratocysts and both types are distinguishable from dentigerous, radicular and non-specified odontogenic cysts. These findings confirm the separate biological potential of these lesions and the results of the immunohistochemical analysis have diagnostic and prognostic implications.

The differential expression pattern of BMP-4 between the dentigerous cyst and the odontogenic keratocyst.

BACKGROUND: Bone morphogenic protein-4 (BMP-4) is widely expressed in oral cavity and involved in tooth morphogenesis, cellular differentiation and proliferation. The purpose of this study was to compare the difference in expression pattern of BMP-4 in odontogenic keratocysts (OKC) and dentigerous cysts (DC). METHODS: We evaluated 77 cysts, OKC (n = 34) or DC (n = 43). The average age of patients with OKC was 29.5 +/- 14.4 and that of patients with DC was 36.1 +/- 19.4. The male to female ratio was 20:14 for OKC and 27:16 for DC. Ten cases of OKC were recurrences. Expression of BMP-4 was determined by immunohistochemistry and in situ hybridization. RESULTS: The intensity scales were (-) for invisible or trace staining, (+) for visible staining, and (++) for dense, strong staining. OKCs exhibited the following staining patterns: the epithelium in 15/34 specimens and the mesenchymal cells in 17/34 specimens showed (++) stain. In contrast, the staining pattern of DC was (-) for epithelium in 37/43 specimens. The mesenchymal cells showed (-) degree staining in 30/43 specimens. The difference between the groups studied was significant (P < 0.001 in epithelium and mesenchymal cells). When recurrent and non-recurrent OKC were compared BMP-4 was expressed more intensely in the recurrent cases (P = 0.036 in epithelium). The difference in BMP-4 expression in mesenchymal cells was not significant. In situ hybridization demonstrated positive mRNA probes to BMP-4 were localized in epithelium and mesenchymal cells of OKCs and DCs. CONCLUSIONS: BMP-4 was expressed more intensely in OKC when compared with DC, and was more intensely expressed in recurrent cases.

Immunohistochemical assessment of extracellular matrix components in syndrome and non-syndrome odontogenic keratocysts.

OBJECTIVE: Investigate the immunohistochemical distribution of fibronectin, tenascin, laminin and collagen IV in syndrome (SOKC) and non-syndrome odontogenic keratocysts (NSOKC). MATERIALS AND METHODS: Ten cases of SOKC and five of NSOKC were selected and streptoavidin-biotin technique was applied. The specimens were analyzed taking into account the following evaluation parameters: presence, continuity and thickness in the basement membrane and intensity, distribution and association with inflammatory cells in the cyst wall. RESULTS: Differences could be detected regarding tenascin, fibronectin and collagen IV between the SOKC and NSOKC. Tenascin was present in all cases along the basement membrane in SOKC and in five cases of NSOKC predominated negative areas. Furthermore, tenascin distribution was focal in the cyst wall in SOKC whereas in NSOKC it was diffuse. Concerning fibronectin, it was detected as a discontinuous band when present in SOCK and as a continuous band in NSOKC. Collagen IV was not present in the majority of the cases in SOKC. Negative areas for laminin predominated in the basement membrane in both groups. CONCLUSIONS: These findings show differences between the immunohistochemical expression of tenascin, fibronectin and collagen IV which might indicate a more aggressive biological behavior of SOKC as compared with NSOKC.