Does YAP influence cell proliferation and apoptosis in benign epithelial odontogenic lesions?

OBJECTIVE: To analyze the immunohistochemical expression of YAP and its correlation with markers involved in cell proliferation and apoptosis in benign epithelial odontogenic lesions. STUDY DESIGN: The sample consisted of 95 cases of odontogenic lesions (25 dentigerous cysts, 30 non-syndromic odontogenic keratocysts, 30 conventional ameloblastomas, and 10 unicystic ameloblastomas) and 10 dental follicles used as normal odontogenic tissue. The histological sections were submitted to immunohistochemistry with YAP, cyclin D1, Ki-67, and Bcl-2 antibodies. Immunoexpression was analyzed qualitatively and quantitatively using an adapted method. The collected data were analyzed descriptively and statistically (p ≤ 0.05). RESULTS: The highest YAP expression was observed in odontogenic keratocysts, followed by unicystic ameloblastomas and conventional ameloblastomas, which exhibited moderate immunoreactivity predominantly in peripheral cells. Furthermore, significant differences in YAP immunoexpression were observed between the groups analyzed, with significant positive correlations between YAP and cyclin D1 in dentigerous cysts and unicystic ameloblastomas and between YAP and Ki-67 in unicystic ameloblastomas (p < 0.05). However, there were no statistically significant correlations between YAP and Bcl-2 immunoexpression in the groups studied. CONCLUSION: YAP may influence epithelial cell proliferation in odontogenic cysts and tumors, suggesting its possible participation in the progression of the odontogenic lesions studied.

The IL-1ß-p65 axis stimulates quiescent odontogenic epithelial cell rests via TGF-ß signalling to promote cell proliferation of the lining epithelia in radicular cysts: A laboratory investigation.

AIM: Cyst formation of the jaws is frequently accompanied by the proliferation of odontogenic epithelial cells located in the periodontal ligament (PDL), which consists of heterozygous cells and includes the most fibroblasts. The lining epithelium of radicular cyst, an odontogenic cyst of inflammatory origin, is derived from the proliferation of the remnants of the Hertwig epithelial root sheath (odontogenic epithelial cell rests of Malassez; ERMs) in the PDL. ERMs are maintained at a lower proliferative state under physiological conditions, but the regulatory mechanisms underlying the inflammation-dependent enhanced-proliferative capabilities of ERMs are not fully understood. The aim of this study was to evaluate the effects of cytokine pathway association between TGF-ß signalling and IL-1ß signalling on the regulation of odontogenic epithelial cell proliferation using radicular cyst pathological specimens and odontogenic epithelial cell lines. METHODOLOGY: Immunofluorescence analyses were performed to clarify the expression levels of Smad2/3 and Ki-67 in ERMs of 8-week-old mouse molar specimens. In radicular cyst (n = 52) and dentigerous cysts (n = 6) specimens from human patients, the expression of p65 (a main subunit of NF-κB), Smad2/3 and Ki-67 were investigated using immunohistochemical analyses. Odontogenic epithelial cells and PDL fibroblastic cells were co-cultured with or without an inhibitor or siRNAs. Odontogenic epithelial cells were cultured with or without TGF-ß1 and IL-1ß. The proliferative capabilities and Smad2 phosphorylation levels of odontogenic epithelial cells were examined. RESULTS: Immunohistochemically, Smad2/3-positivity was increased, and p65-positivity and Ki-67-positivity were decreased both in ERMs and in the epithelial cells in dentigerous cysts, a non-inflammatory developmental cyst. In contrast, p65-positive cells, along with the expression of Ki-67, were increased and Smad2/3-positive cells were decreased in the lining epithelia of radicular cysts. Co-culture experiments with odontogenic epithelial cells and PDL fibroblastic cells revealed that PDL cells-derived TGF-ß1/2 and their downstream signalling suppressed odontogenic epithelial cell proliferation. Moreover, TGF-ß1 stimulation induced Smad2 phosphorylation and suppressed odontogenic epithelial cell proliferation, while IL-1ß stimulation reversed these phenotypes through p65 transactivation. CONCLUSIONS: These results suggest that IL-1ß-p65 signalling promotes odontogenic epithelial cell proliferation through suppressing TGF-ß-Smad2 signalling, which would be involved in the pathogenesis of radicular cysts.

Oct-4 and CD44 in epithelial stem cells like of benign odontogenic lesions.

Benign epithelial odontogenic lesions are great clinical importance entities that develop in the jaws from the tissues that form teeth. It has been shown that benign and malignant tumors are present in a large number of tumor stem cells, which has great implications in the development of these lesions. Oct-4 and CD44 have been demonstrated as important markers for tumoral stem cells. The aim of this study was investigate the presence of stem cell markers Oct-4 and CD44 in benign epithelial odontogenic lesions. Twenty odontogenic keratocysts (OKC), 20 ameloblastomas (AMB) of the solid/multicystic type and 20 adenomatoid odontogenic tumors (AOT) were retrospectively analyzed for immunohistochemical detection of Oct-4 and CD44 in their epithelial component. All cases were positive for the two markers, with the majority exhibiting a high expression. Analysis of the expression of Oct-4 revealed no statistically significant differences (p = 0.406) between the lesions studied. Regarding CD44, there was a significant difference between the cases of AMB and AOT in relation with OKC, with the latter presenting a greater labelling (p = 0.034). No statistically significant correlation between Oct-4 and CD44 was observed in the lesions. In our findings, the presence of stem cell-like phenotype at various sites of the epithelial component of the odontogenic lesions was identified, suggesting its possible participation in histogenesis and differentiation without, however, exerting influence on the aggressiveness of the lesions.

Immunohistochemical Expression of CDC7 in Dentigerous Cyst, Odontogenic Keratocyst and Radicular Cyst.

CDC7 is a serine/threonine kinase which has an essential role in initiation of DNA proliferation and S phase. It increases the invasion and proliferation in many pathologic lesions. This study aimed to evaluate the expression of CDC7 in the most common odontogenic cysts. We evaluated 17 dentigerous cysts, 18 odontogenic keratocysts (OKC) and 13 radicular cysts immunohistochemically. The mean expression of CDC7 was analyzed using ANOVA and Post-HOC methods. All specimens revealed CDC7 expression. Higher expression of CDC7 in OKC and radicular cyst was shown in comparison to dentigerous cyst (P < 0.001), while radicular cyst and OKC groups showed no difference in CDC7 expression (P = 0.738). The high expression of CDC7 in OKC suggests that this protein could be related to the higher proliferation rate and invasiveness of OKC. On the other hand, the higher CDC7 expression in radicular cyst may simply be related to inflammation as this cyst is neither aggressive nor invasive.

Expression of astrocyte elevated gene-1 protein in ameloblastomas, keratocystic odontogenic tumors, and dentigerous cysts.

BACKGROUND: Benign epithelial odontogenic tumors such as ameloblastoma and keratocystic odontogenic tumor (KCOT) may exhibit an aggressive clinical course reminiscent of malignancies. Recent studies have indicated that astrocyte elevated gene-1 (AEG-1) is highly expressed in a variety of malignant neoplasms and its overexpression is associated with tumor invasion, metastasis, and poor survival. However, the role of AEG-1 in odontogenic tumors and cysts is still undiscovered. METHODS: Immunohistochemical staining of AEG-1 was performed in 42 cases of ameloblastoma, 29 cases of KCOT, and 19 cases of dentigerous cyst. Correlations between AEG-1 expression and clinical parameters of ameloblastomas or KCOTs were statistically analyzed. RESULTS: AEG-1-positive staining was found in 37 (88%) of 42 ameloblastomas and in 24 (83%) of 29 KCOTs. None of 19 dentigerous cysts were positive for AEG-1 protein. For ameloblastomas, AEG-1 protein expression was significantly higher in ameloblast-like cells than in stellate reticulum-like cells (P = 0.003). For KCOTs, AEG-1 protein was diffusely expressed in all lining epithelial cells except the superficial parakeratinized cells. Moreover, the frequency of cortical plate perforation was significantly higher in ameloblastomas with high AEG-1 expression than in ameloblastomas with low or negative AEG-1 expression (P = 0.043). CONCLUSION: Significantly higher expression of AEG-1 protein in ameloblastomas and KCOTs than in dentigerous cysts and significantly greater frequency of cortical plate perforation in high AEG-1-expressed ameloblastomas than in low or negative AEG-1-expressed ameloblastomas may imply the high potential of AEG-1 to serve as a locally invasive biomarker and a target for novel therapy.

Expression of podoplanin and TGF-beta in glandular odontogenic cyst and its comparison with developmental and inflammatory odontogenic cystic lesions.

BACKGROUND: The number of studies investigating the immunohistochemical characteristics of glandular odontogenic cysts (GOCs) is limited, due to its rarity. TGF-beta has been suggested to induce podoplanin expression in some lesions. We aimed to evaluate and compare podoplanin and TGF-beta expression in GOC and other odontogenic cystic lesions. METHODS: A total of 43 samples including five GOCs, 10 dentigerous cysts (DCs), eight unicystic ameloblastoma (UAs), and 20 radicular cysts (RCs) were selected and subjected to immunohistochemical staining using monoclonal antibodies against podoplanin and TGF-beta. Kruskal-Wallis test and Mann-Whitney U-test were used for statistical analysis along with Bonferroni for adjusting P-values (P < 0.05). RESULTS: Podoplanin immunoreactivity was observed in 80%, 70%, and 100% of DCs, RCs, and UAs, respectively, while none of the GOCs were positive for this marker (P = 0.004). Significant differences were only found in the GOC specimens. TGF-beta positivity occurred in the capsule and epithelium of all GOCs and DCs, while RCs and UAs demonstrated different expression percentages in the capsular and epithelial tissues. Epithelial TGF-beta showed significant differences among the studied lesions (P = 0.007) with the main difference found between DCs with RCs and DCs with UAs. CONCLUSIONS: Lack of podoplanin expression might be involved in the characteristic histologic and behavioral features of GOC, which seems to be unrelated to TGF-beta expression.

Glucose Transporter 1 Expression in Odontogenic Keratocyst, Dentigerous Cyst, and Ameloblastoma: An Immunohistochemical Study.

INTRODUCTION: An array of odontogenic lesions manifest in the maxillofacial region with variable presentations. The biological behavior of lesions, such as odontogenic keratocyst (OKC), dentigerous cyst (DC), and ameloblastoma (AM) always invite debate. Glucose transporter 1 (GLUT-1) is proven to be an indicator of metabolic behavior of several benign and malignant neoplasms. AIM: The purpose of this study was to evaluate the expression of GLUT-1 in OKC, DC, and AM to understand their metabolic behavior. MATERIALS AND METHODS: Immunohistochemical expression of GLUT-1 was evaluated in each of the 15 cases of OKC, DC, and AM. The number of labeled cells, staining intensity, and membrane or cytoplasmic expressions were the parameters assessed and analyzed using chi-square test. RESULTS: All cases showed positive GLUT-1 expression: 86.6% OKC showed more than 50% labeled cells followed by DC (40%) and AM (26.5%); 53.3% OKC showed strong intensity in comparison to AM, which showed weak intensity in 53.3% cases; 86.6% of OKCs showed both membrane and cytoplasmic expression followed by DC (40%) and AM (26.6%), whereas 73.3% of AM showed only membrane expression followed by DC (60%) and OKC (13.3%). CONCLUSION: Odontogenic keratocyst was found out to be more metabolically active followed by DC and AM.

Assessment of Proliferative Potential of Odontogenic Keratocyst and Dentigerous Cyst using Podoplanin: An Immunohistochemical Study.

INTRODUCTION: Odontogenic cysts are commonly encountered lesions among head and neck pathologies. Odontogenic keratocyst (OKC) has unique features of recurrence and local aggressiveness. Podoplanin (PDP) is a lymphatic endothelial marker and is shown to be expressed in a variety of tissues. Hence, we planned to assess the significance of PDP in OKC and dentigerous cyst (DC). MATERIALS AND METHODS: The present study included assessment of immunoexpression of PDP in OKC and DC. Twenty specimens each of OKC and DC were included in the present study and were stained with D2-40 antibody. All the sections were analyzed and were categorized as negative staining, weakly positive staining, and strongly positive staining. All the results were analyzed by Statistical Package for the Social Sciences (SPSS) software. RESULTS: We detected PDP-positive staining in the cell membrane and cytoplasm of the cells of basal cell layer and supra-basal cell layers. In DC cases, we observed positive staining only in cases associated with inflammation. CONCLUSION: Podoplanin does play a significant role in enhancing the local invasive and neoplastic properties of OKC. CLINICAL SIGNIFICANCE: Podoplanin expression in OKC is potentially associated with moderate invasive nature of the neighboring structures.

Immunohistochemical expression of GLUT-1, GLUT-3, and carbonic anhydrase IX in benign odontogenic lesions.

BACKGROUND: Some benign odontogenic lesions have a distinct biological behavior with high recurrence rates and local aggressive behavior. To determine whether glucose transporters proteins (GLUT-1 and GLUT-3) and carbonic anhydrase IX (CA IX) are associated with the development of as dentigerous cyst (DC), odontogenic keratocyst (OK), and ameloblastoma (AM), we evaluated the immunohistochemical expression of these proteins in these lesions. MATERIALS AND METHODS: Immunoexpression of GLUT-1, GLUT-3, and CA IX was evaluated semiquantitative fields in each of the 20 cases of OK, AM, and DC. The cases were classified according to the scores: 0 (0% positive cells), 1 (<10% of positive cells), 2 (10-50% of positive cells), and 3 (>50% of positive cells). The statistical analysis was performed using Pearson's chi-square, Kruskal-Wallis and Mann-Whitney tests. RESULTS: All cases were positive for GLUT-1 and 65% of OK showed scored 3. Staining was diffuse in 90% of OK and 85% of DC cases (P < 0.001). In 50% of OK and AM, staining was only observed in the membrane (P = 0.01). Most of the samples (66.7%) were negative for GLUT-3. Staining intensity for anhydrase was higher in the epithelium of DC when compared to OK (P = 0.01). Strong staining was observed in 55% of DC and 20% of OK samples (P = 0.01). CONCLUSIONS: These results suggest that GLUT-1 may be involved in the metabolic regulation of glucose in odontogenic lesions studied. In addition, CA IX appears to influence the development of AM, OK, and DC which can explain the differences their biological behavior.

The expression of cytokeratin in keratocystic odontogenic tumor, orthokeratinized odontogenic cyst, dentigerous cyst, radicular cyst and dermoid cyst.

The epithelial lining of odontogenic keratocysts exhibits either parakeratosis or orthokeratosis. In 2005, the WHO classified odontogenic keratocysts with parakeratosis as keratocystic odontogenic tumors (KCOT). Odontogenic keratocysts with orthokeratosis were not classified as odontogenic tumors, but instead referred to as orthokeratinized odontogenic cysts (OOC). To clarify the difference between these two lesions, we investigated their biological characteristics using immunohistochemical studies for cytokeratins (CK) in KCOT and OOC as well as in dentigerous cysts (DC), radicular cysts (RC) and dermoid cysts (DMC). We examined twenty-five cases of KCOT, fifteen cases each of OOC, DC and RC, and ten cases of DMC. We studied the immunohistochemical expression of CK10, 13, 17 and 19. To evaluate the immunohistochemical staining pattern, we divided the epithelial lining of the lesions into three layers (surface layer: su, spinous layer: sp, basal layer: ba). For CK10, most OOC and DMC specimens of su and sp were positive. For CK13 and 19, most KCOT, DC and RC specimens of su and sp were positive. For CK17, most KCOT specimens of su and sp were positive. The percentages of total CK expression of su and sp, and ba of CK19 differed significantly between the lesions (P < 0.001). These results support the hypothesis that OOC originate from not the odontogenic apparatus, but the oral epithelial component.

Proteomic profile of tissue-derived extracellular vesicles from benign odontogenic lesions.

BACKGROUND: Benign odontogenic lesions (BOLs) can cause severe jaw bone defects and compromise the quality of life of patients. Extracellular vesicles (EVs) are well-established and versatile players in mediating pathophysiological events. EVs in the interstitial space (tissue-derived EVs or Ti-EVs) possess higher specificity and sensitivity in disease-related biomarker discovery. However, the role of Ti-EV-loaded proteins in mediating the development of BOLs has remained untapped. Herein, we aim to explore the contribution of Ti-EV-loaded proteins to the development of BOLs. METHODS: Samples were obtained from 3 with dental follicle, 3 with dentigerous cyst (DC), 7 with odontogenic keratocyst (OKC), and 3 patients with ameloblastoma (AM). Tissue-derived EVs were then extracted, purified, and validated using ultracentrifugation, transmission electron microscopy, and western blotting. Proteins from Ti-EVs were analyzed using LC-ESI tandem mass spectroscopy and differentially expressed proteins were screened, which was then validated by immunohistochemistry and immunofluorescence assays. RESULTS: The protein profile of Ti-EVs in each group was mapped by LC-MS analysis. The top 10 abundant proteins in BOL-derived Ti-EVs were COL6A3, COL6A1, ALB, HIST1H4A, HBB, ACTB, HIST1H2BD, ANXA2, COL6A2 and FBN1. Additionally, unique proteins in the Ti-EVs from various lesions were identified. Moreover, focal adhesion kinase (FAK) and myeloid differentiation primary response 88 (MyD88) showed higher expressions in Ti-EVs derived from OKC and AM, which were confirmed by immunohistochemistry and immunofluorescence staining. CONCLUSIONS: Ti-EVs containing FAK and MyD88 might be related to the development of OKC and AM, which can be potential therapeutic targets.

Immunoexpression of CXCL12 and CXCR4 in Radicular Cysts, Dentigerous Cysts, and Odontogenic Keratocysts.

The aim of this study was to evaluate the immunoexpression of chemokine CXCL12 and its receptor CXCR4 in radicular cysts (RCs), dentigerous cysts (DCs), and odontogenic keratocysts (OKCs), and to correlate the findings with morphologic parameters of RCs (inflammatory infiltrate and cystic epithelium). Twenty RCs, 20 DCs, and 20 OKCs were submitted to immunohistochemistry. The percentages of cytoplasmic (CXCL12 and CXCR4) and nuclear (CXCR4) staining in epithelial and fibrous capsule cells were determined. RCs and DCs exhibited higher epithelial expression of CXCL12 than OKCs ( P <0.05). The expression of CXCL12 in the fibrous capsule was higher in DCs than in RCs and OKCs ( P <0.05). Higher cytoplasmic expression of CXCR4 was observed in the epithelial lining and fibrous capsule of RCs and DCs compared with OKCs ( P <0.05). In the fibrous capsule, DCs exhibited higher nuclear expression of CXCR4 than OKCs ( P <0.05). No significant differences in the immunoexpression of CXCL12 or CXCR4 were observed according to the morphologic parameters of RCs ( P >0.05). Strong positive correlations were found between cytoplasmic and nuclear expression of CXCR4 in the epithelial lining of RCs and DCs and in the fibrous capsule of all groups ( P <0.05). The results suggest the participation of CXCL12 and CXCR4 in the pathogenesis of RCs, DCs, and OKCs. These proteins may be particularly relevant for the development of odontogenic cysts with less aggressive biological behavior, irrespective of their nature (inflammatory or developmental). In RCs, the expression of CXCL12 and CXCR4 may not be related to the intensity of the inflammatory infiltrate or the status of cystic epithelium.

Identification of ferroptosis-related proteins in ameloblastoma based on proteomics analysis.

PURPOSE: We used proteomic sequencing and experimental verification to identify the potential ferroptosis-related proteins in ameloblastoma. METHODS: Samples of ameloblastoma (n = 14) and normal gingival tissues (n = 5) were collected for proteomic sequencing to identify differentially expressed proteins (DEPs) in ameloblastoma. Ferroptosis-related genes were downloaded from FerrDb V2, which were then compared with DEPs to obtain ferroptosis-related DEPs (FR-DEPs). A functional enrichment analysis was performed, and a protein-protein interaction network was built. The hub proteins were screened using the Cytoscape software, and potential drugs targeting them were retrieved from the DrugBank database. A hub protein was selected for immunohistochemical validation, and its expression was assessed in ameloblastomas, odontogenic keratocysts, dentigerous cysts, and normal gingival tissues. The primary ameloblastoma cells were cultured to explore the effect of the protein on the migratory properties of the tumour cells. RESULTS: A total of 58 FR-DEPs were screened, and six hub proteins were identified: mTOR, NFE2L2, PRKCA, STAT3, EGFR, and CDH1. Immunohistochemical analysis showed that mTOR expression was upregulated in ameloblastomas compared with that in odontogenic keratocysts, dentigerous cysts, and normal gingival tissues. p-mTOR was highly expressed in ameloblastomas, with a positivity rate of 83.3%. In addition, rapamycin, an inhibitor of mTOR, can inhibit the migratory capacity of primary cultured ameloblastoma cells. CONCLUSION: Our results revealed the ferroptosis-related proteins in ameloblastomas and their underlying biological processes. Additionally, mTOR was overexpressed and was found to be associated with the aggressiveness of ameloblastomas, which may be a potential target for future treatments.

Differential protein expression of osteoclastogenic factors in odontogenic cysts and tumors.

The osteolytic activity of odontogenic cysts and tumors is directly associated with their growth and aggressiveness. The influence of proteins expressed by epithelial and mesenchymal cells on this biological event differs between indolent cystic lesions, aggressive cystic lesions, and odontogenic tumors. The objective of this study was to compare the immunohistochemical expression of factors that stimulate (receptor activator of nuclear factor kappa-Β ligand - RANKL, cathepsin K - CatK and matrix metallopeptidase 8 - MMP-8) and inhibit (osteoprotegerin - OPG) osteoclastogenesis between dentigerous cyst (DC), glandular odontogenic cyst (GOC), odontogenic keratocyst (OKC), and ameloblastoma (AB). Paraffin-embedded sections of nine DCs, nine GOCs, 20 OKCs, 21 ABs, and four dental follicles (DFs) were subjected to immunohistochemistry. Immunoreactivity was analyzed semiquantitatively and quantitatively in epithelium and connective tissue, respectively. The proteins were immunoexpressed in epithelial and mesenchymal cells of all lesions studied. The expression of RANKL and CatK was higher in OKC, AB, and GOC (p<0.005). Higher expression of OPG was found in DF and DC compared to the other markers (p<0.005). MMP-8 expression was high in GOC and OKC. This study demonstrated the differential expression of factors that inhibit and stimulate bone resorption during the development of DC, GOC, OKC, and AB. Higher expression of RANKL and CatK was observed in more aggressive lesions. OPG appears to be one of the molecules responsible for the slower growth of DC.

IL-8 Is Upregulated in the Tissue-Derived EVs of Odontogenic Keratocysts.

Background: Interleukin 8 (IL-8) is a chemotactic cytokine released by various cells including leukocytes, endothelial cells, and epithelial cells. IL-8 has multiple functions in inflammation, tumour invasion, or angiogenesis. Human odontogenic cystic lesions are chronic and frequently inflamed. Tissue-derived extracellular vesicles (Ti-EVs) are widely present in various tissues and could more accurately reflect the characteristics of the primary tissue. However, the involvement of IL-8 in Ti-EVs of human odontogenic lesions is still unclear. This study aimed to explore the expression of IL-8 in Ti-EVs of human odontogenic lesions and the potential roles of Ti-EVs that carried IL-8. Methods: Fresh tissue samples of dentigerous cyst (DC, n = 5) and odontogenic keratocyst (OKC, n = 5) were collected for Ti-EVs isolation. Ti-EVs were characterised by transmission electron microscopy and nano-flow cytometry analysis. The cytokine profile of Ti-EVs was explored by cytokine antibody array. The IL-8 expression was examined by immunochemical staining in tissue of odontogenic lesions (DC, n =12; OKC, n =28). Antioxidants (N-acetyl-L-cysteine and diphenyleneiodonium) were employed to treat HaCaT cells, and the expression of IL-8 was detected by enzyme-linked immunosorbent assay. The gene expression of MMP9 was explored by quantitative real-time polymerase chain reaction in co-culture system of fibroblasts of OKC with Ti-EVs. Results: Compared with DC, the expression of IL-8 in Ti-EVs and fixed tissue specimens of OKC was markedly upregulated. The antioxidants decreased the expression level of IL-8 protein in the supernatant of HaCaT cells. The Ti-EVs treatment (10 µg/ml) of fibroblasts significantly induced the MMP9 mRNA expressions in OKC fibroblasts. Conclusions: IL-8 was upregulated in Ti-EVs of OKC and might be involved in the tissue destruction of OKC.

Altered expression of cell-cell adhesion molecules ß-catenin/E-cadherin and related Wnt-signaling pathway in sporadic and syndromal keratocystic odontogenic tumors.

Differential diagnosis of the keratocystic odontogenic tumor (KCOT) still represents a challenging problem especially if compared with the dentigerous cyst, which is similar in clinical and radiological course. Histological assessment of this entity may therefore draw crucial attention since various radical procedures are recommended for such lesions in contrast to dentigerous cysts. Since recent reports could prove the involvement of wingless(Wnt)-signaling pathway and ß-catenin in the pathogenesis of many odontogenic and neoplastic lesions indicating impairment of cell-cell adhesion, we investigated the expression of two Wnt-signaling pathways, Wnt-1 and Wnt-10A as well as ß-catenin and E-cadherin along with other related proteins in both lesions. We found a significant down-regulation in the expression of cell adhesion proteins ß-catenin and E-cadherin along with alteration of Wnt-1 and Wnt-10A expression in the epithelium of KCOT. We assessed a specific focal distribution pattern of p63 in the suprabasal cell layer and a significant up-regulation of cyclin D1. Furthermore, laminin α-2 was a characteristic marker labelling only the basement membrane of dentigerous cysts. These results provide a new hypothesis explaining a molecular mechanism to understand initiating and development of KCOTs and an alternative therapeutic approach, especially for syndromal patients, where these multilocal lesions may involve and destroy wide orofacial bony structures.

CD56 expression is associated with neuroectodermal differentiation in ameloblastomas: an immunohistochemical evaluation in comparison with odontogenic cystic lesions.

Ameloblastoma (AB), which is the most common odontogenic tumor, may originate from the dental lamina remnants. The expression of CD56, which is a transmembrane molecule, is associated with neuroectodermal differentiation of the embryonal cells. The aim of this study was to evaluate the expression of CD56 in AB, in comparison with other odontogenic cysts. We used formalin-fixed, paraffi n-embedded specimens from 34 cases of AB, 10 cases of keratocystic odontogenic tumor (KCOT), and 7 cases of dentigerous cyst (DC). We immunohistochemically examined CD56, NeuroD1, and N-cadherin expression in these tumors as compared with the expression patterns of various epithelial markers. Seventy-four percent of AB showed immunopositivity for CD56, and both CD56 and N-cadherin were diffusely positive in the outer columnar cells of AB. The immunopositivities for NeuroD1 and N-cadherin were also observed in the outer cells of AB. None of the DC cases was positive for CD56, whereas half the cases of KCOT were positive. Because CD56 is expressed in the inner enamel epithelium of enamel organs, the outer columnar cells of AB are likely to be the differentiation phenotype of the inner enamel epithelium, which is associated with neuroectodermal differentiation. The aberrant NeuroD1 expression may induce CD56 expression in AB and KCOT.

The differences in mitochondrial function, mitochondrial dynamics, and cell death between odontogenic cysts/tumors and normal dental follicles.

We aimed to compare mitochondrial function, mitochondrial dynamics, apoptosis, and necroptosis between odontogenic cysts/tumors, including radicular cysts, dentigerous cysts, ameloblastoma, vs. dental follicles as control. We demonstrated that mitochondrial dysregulation and imbalanced mitochondrial dynamics were observed in ameloblastoma. Apoptosis was increased in dentigerous cysts, and ameloblastoma, while necroptosis was suppressed in ameloblastoma. Necroptosis in radicular cysts was higher than that of control, suggesting that the inflammation-associated cell death occurred in radicular cysts. Our findings suggest ameloblastoma exhibited mitochondrial dysfunction, decreased mitochondrial fusion, and potential apoptosis. Therefore, alleviating mitochondrial dysregulation and apoptosis may be novel-targeted therapy for odontogenic cysts and tumors.

Pathological changes and immunoexpression of p63 gene in dental follicles of asymptomatic impacted lower third molars: an immunohistochemical study.

OBJECTIVE: The aim of this study was to examine the pathologic changes and immunoexpressivity of p63 gene in dental follicles (DFs) of asymptomatic partially and completely impacted lower third molars. STUDY DESIGN: Clinical and radiologic examinations included 50 DFs with no signs of abnormal radiolucency (follicular space <2.5 mm), taken from 50 patients. RESULTS: Histopathologic examinations of the specimens revealed 47 normal dental follicular tissues, 1 ameloblastoma, and 2 dentigerous cysts. p63 Immunoexpressivity was stronger in the DFs of the group with completely impacted teeth (64%),than it was in the case of DFs of the group with partially impacted teeth (40%). CONCLUSIONS: Stronger p63 gene immunoexpression in the group with completely impacted teeth might be a consequence of bigger number of stem cells than it is in the case of the group with partially impacted teeth. This study also supports prophylactic removal of impacted teeth because of the development of pathologies associated with them.

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 (x 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.