Immunohistochemical analysis of the biological potential of odontogenic keratocysts

A comparative study of the expression of cyclin D1, COX-2, and KI-67 in odontogenic keratocyst vs. ameloblastoma vs. orthokeratinized odontogenic cyst

BACKGROUND

Odontogenic keratocysts (OKCs) and orthokeratinized odontogenic Cysts (OOCs) are distinct clinicopathological entities. OKC appears to behave in a way more similar to that of a neoplasm, such as ameloblastoma (AB). The aim of this study is to compare the influence of Ki-67, Cyclin D1 and COX-2 in the diagnosis and pathogenesis of OKC, OOC and AB.

MATERIALS AND METHODS

A cross-sectional observational study of 41 samples was organized into 3 groups: (1) OKC n=22; (2) AB n=13 and (3) OOC n=6. Paraffin blocks were sectioned and stained with hematoxylin and eosin (H&E). Immunohistochemical study using Bond Polymer Refine Red Detection Kit, Leica, Wetzlar, Germany, was performed for the following antibodies: Ki-67, Cyclin D1 and COX-2. Double blind immunostaining was quantified subjectively. Staining: nuclear or cytoplasmic; nuclear (Ki-67 and Cyclin D1>5% positive) and cytoplasmic (COX-2; 1; 1-30 cytoplasm: 2; 31-60 cytoplasm; 3; 61-100 cytoplasm). Considering positive stained 61-100 cytoplasms.

RESULTS

The expression of Ki-67 was higher in the OKC group than in the AB group (p<0.05). Cyclin D1 showed a higher expression in OKC vs. OOC and OKC vs. AB (p<0.05). Finally, expression of COX-2 was higher in OKC vs AB (p<0.05).

CONCLUSIONS

COX-2, Ki-67 and Cyclin D1 show statistically significant differences between the groups, suggesting that they could be useful tools in the differential diagnosis between OKCs and OOC and a predictive indicator for their biologic behaviour. The higher expressions of these 3 markers of OKC vs AB highlight once more the aggressive behaviour of this now re-considered cystic lesion. These markers could prove useful in the choice of more aggressive surgical treatment in OKCs as their behaviour appears to be similar to that of a neoplasm.

The immunohistochemical profile of basal cell nevus syndrome-associated and sporadic odontogenic keratocysts: a systematic review and meta-analysis

OBJECTIVES

To provide a systematic review of the literature on studies comparing the immunoprofile of nevoid basal cell carcinoma syndrome (BCNS)-associated and sporadic odontogenic keratocysts (OKCs), in order to identify markers that could accurately distinguish the two OKC subtypes.

MATERIALS AND METHODS

We searched MEDLINE/Pubmed, Web of Science, EMBASE via OVID, and grey literature for publications until December 28th, 2019, that compared the immunohistochemical expression of the two OKC subtypes. The studies were qualitatively assessed using the Critical Appraisal Tool for Case Series (Joana Briggs Institute). Sensitivity and specificity, positive and negative likelihood ratio, diagnostic odds ratio and area under the curve, and pooled estimates were calculated, using a random-effects model.

RESULTS

Seventy-one studies were qualitatively analyzed; 61 markers were evaluated in one study and 32 in ≥ 2 studies. Twenty-five studies reported differential expression of 29 markers in the form of higher number of positive cells or greater staining intensity usually in BCNS-associated OKCs. Meta-analysis for bcl-2, Cyclin D1, CD56, CK18, p53, and PCNA showed that none of those markers is distinguishable between BCNS-associated and sporadic OKCs, in a 95% confidence interval. The risk of bias was high in 34 studies, moderate in 22, and low in 15.

CONCLUSIONS

The present systematic review and meta-analysis uncovered that, although several immunohistochemical markers might characterize the OKC phenotype, they cannot discriminate between the BCNS-associated and sporadic OKCs.

CLINICAL RELEVANCE

This study highlighted the requirement for additional screening for markers by immunohistochemistry, preferentially coupled to alternative diagnostic applications such as genomics technologies.

Gorlin-Goltz syndrome with familial manifestation

AIMS

The detection of odontogenic keratocysts (OKC) in the oral cavity is one of the main criteria for the clinical manifestation of Gorlin-Goltz syndrome (Nevoid Basal Cell Carcinoma Syndrome - NBCCS). From a clinical point of view, we distinguish between "syndromic" and "sporadic" OKC. Syndromic cysts, often multifocal, may be an accidental finding on X-ray examination. They can manifest gradually depending on the development of permanent dentition. Sporadic cysts are rather solitary lesions with clinical manifestation in adulthood.

METHODS

Mutations in the PTCH1 gene are thought to be the cause of the clinical manifestation of NBCCS. These abnormalities can be transmitted from one generation to another and lead to a familial occurrence of the disease. In 35-50% of cases, these are a newly arising mutations. It is necessary to take into account the typical manifestations which in the next generation begin at a younger age and the disease usually has a more serious course.

RESULTS

We found a familial manifestation of NBCCS in two pairs of patients (mother and daughter and two siblings). Odontogenic keratocysts and cutaneous basal cell carcinomas were diagnosed and genetic testing revealed mutations in the PTCH 1 gene in all four individuals.

CONCLUSIONS

With regard to the possibility of familial occurrence of NBCCS, it is necessary to pay increased attention to family history and, if necessary, to ensure clinical and genetic examination of parents and other family members. Patients of childbearing potential with evidence of NBCCS should be informed of the increased likelihood of the disease in the offspring.

Odontogenic keratocyst: Analysis of recurrence by AgNOR, p53 and MDM2 profiling

Background:

Odontogenic keratocyst (OKC) is a clinical entity with characteristic microscopic features, high growth potential and propensity to recur. Aggressive behavior and higher tendency for recurrence have been attributed to greater proliferative activity of epithelial lining. The incidence of recurrence in various reported series ranges from 2.5% to 62%.

Objectives:

The objective of the study was to investigate the clinical behavior of OKC by evaluating p53, MDM2 expression, AgNOR staining and to ascertain if the expression of these markers correlate with the clinical outcome and tendency for recurrence.

Materials and Methods:

All recurrent and nonrecurrent OKCs from the archives were included, and sections were subjected to AgNOR staining, p53 and MDM2 immunohistochemical staining.

Results and Conclusion:

There was a significant difference in the staining pattern of MDM2 and AgNOR in the recurrent group as compared to the nonrecurrent group. The higher expression of these markers in recurrent lesions may be important in order to consider additional surgical interventions to improve prognosis.

Management of an extensive odontogenic keratocyst: A rare case report with 10-year follow-up

INTRODUCTION

The odontogenic keratocyst (OKC), previously known as keratocystic odontogenic tumor has been the most disputable pathologies of the maxillofacial region. Patients with OKC are often asymptomatic but may present with pain, swelling, or discharge. Despite the aggressive nature, previous literature as early as 1970s reported the fact that parakeratinized OKC can be treated by means of marsupialization alone.

PATIENTS CONCERNS

The patient had reported with a complaint of pain and swelling in relation with a tooth in mandibular right quadrant.

DIAGNOSIS

This case report discusses features of a rare, extensive, panmandibular OKC that is only second of its kind mentioned in the literature.

INTERVENTION

As a usual treatment protocol, marsupialization was attempted first. Immunohistochemical analysis revealed reduced expression of Ki-67 and B cell lymphoma 2 (bcl-2) markers after marsupialization from 2 separate sites. However, due to incomplete resolution in the lower right anterior region, an aggressive approach was taken by curetting it out surgically along with associated teeth and cortical plate followed by application of Carnoy's solution.

OUTCOME

Postsurgery uneventful healing of the lesion was noted on regular follow-up visits with complete resolution at 40 months. The case has been followed for 10 years with no sign of relapse and reoccurrence.

CONCLUSIONS

Based on the expression of markers it can thus be concluded that Ki-67 and bcl-2 are site specific and bear strong relationship with the recurrence of OKCs.

Investigation of clinicopathological parameters and expression of COX-2, bcl-2, PCNA, and p53 in primary and recurrent sporadic odontogenic keratocysts

Objectives

Odontogenic keratocyst (OKC) presents considerable variation in aggressiveness and propensity for recurrence, yet hitherto, no explicit clinicopathological features have been determined to clearly demonstrate the potential for relapse. This retrospective study aims to investigate the prognostic relevance of various clinicopathological features as well as immunoexpression of COX-2, bcl-2, PCNA, and p53 in sporadic OKC.

Materials and methods

Among 41 patients with OKC treated by enucleation, the frequency of recurrence for various clinicopathological features as well as immunoexpression for COX-2, bcl-2, PCNA, and p53 was evaluated.

Results

The mean follow-up was 8.49 years, and recurrences were ascertained in 29.27% of cases. We found significant differences between recurrent and non-recurrent cysts in terms of multilocularity (P = 0.029), cortical perforation (P = 0.001), and lesion size (P < 0.001). Hazard risk for the recurrence was 3.362 (95% CI 1.066–10.598) for multilocular cysts, 7.801 (95% CI 2.1–28.985) for evidence of cortical perforation, and 1.004 (1.002–1.006) for 1 mm² of lesion size on panoramic radiographs. We also found that immunoexpression of PCNA significantly correlates with the radiographic evidence of cortical perforation (P = 0.048) and that there is significant positive correlation between expression of COX-2 and bcl-2 (P = 0.001) as well as significant negative correlation between immunoexpression of COX-2 and age (P = 0.002). None of the other analyzed factors were associated with the recurrence.

Conclusions

Larger size, multilocularity, and cortical perforation in sporadic OKC may be correlated with the relapse.

Clinical relevance

Immunohistochemical analyses of COX-2, bcl-2, PCNA, and p53 lack prognostic utility in sporadic OKC.

A comparative study of odontogenic keratocyst and orthokeratinized odontogenic cyst using Ki67 and α smooth muscle actin

Aim

This study aimed to demonstrate and evaluate the expression of stromal myofibroblasts (MFs) and epithelial cell proliferation using α-smooth muscle actin (α-SMA) and Ki67 markers, respectively, in odontogenic keratocyst (OKC) and orthokeratinized odontogenic cyst (OOC) to correlate their aggressive behavior.

Materials and Methods

Twenty cases of OKC and twenty cases of OOC were stained with α-SMA and Ki67 markers for demonstration of stromal MFs and epithelial cell proliferation, respectively, and ten cases of well-differentiated squamous cell carcinoma were used as positive control. Assessment of the number of α-SMA-positive stromal cells and Ki67-positive epithelial cells determined by MFs and proliferative epithelial cell frequency in 10 high-power fields (×400) was presented as the mean number of positive cells per field.

Statistical Analysis

Kruskal-Wallis and Mann-Whitney test were used to analyze the difference in the mean number of α-SMA- and Ki67-positive cells per field between OKC and OOC.

Results

The mean number of positively stained cells for α-SMA and Ki67 is significantly higher in OKC compared to OOC.

Conclusion

Impression is that, the different behaviors of these two entities are compatible with their immunohistochemical view. The high value of stromal MFs and proliferative epithelial cells in OKC in comparison to OOC indicates its aggressiveness and potential for recurrence.

Immunohistochemical Assessment of HER3 Expression in Odontogenic Cysts

Background:

It has been demonstrated that HER3 plays an important role in some human cancers and the HER3 expression is associated with worse survival in solid tumors.

Objectives:

This study was conducted to compare HER3 expression in epithelial lining of radicular cysts (RCs), dentigerous cysts (DCs) and odontogenic keratocysts (OKCs).

Materials and Methods:

This was a descriptive-analytical study, which assessed all 57 paraffin blocks of RCs, DCs and OKCs (21 RCs, 16 DCs, 20 OKC) from pathological archive of Dentistry College of Zahedan, Iran. The HER3 expression in cytoplasm and membrane was examined by immunohistochemical method. The data collected was analyzed using SPSS16 by ANOVA and Chi-square. P < 0.05 was considered as statistically significant.

Results:

The HER3 expression had positive results in 52.4% of OKC, 50% of DC and only 20% of RC samples. There was a significant difference between HER3 expression in OKCs and RCs.

Conclusions:

The HER3 expression in developmental odontogenic cysts was higher than that in inflammatory odontogenic cysts. The higher rate of HER3 expression in OKC may justify inherent growth potential, stimulation-independent proliferation capability, invasive growth and high recurrence rate of the cyst accepted today as a tumor.

Expression of Bcl-2 and epithelial growth factor receptor proteins in keratocystic odontogenic tumor in comparison with dentigerous cyst and ameloblastoma

Background:

Keratocystic odontogenic tumor (KCOT) is a developmental odontogenic cyst on which various investigations have been focused due to its biological activities, high tendency to recur and different growth mechanisms in comparison with other cystic lesions. Previous studies have shown different biological and proliferative activities for the lining epithelium of KCOT. The aim of this study was immunohistochemical evaluation of Bcl-2 and epidermal growth factor receptor (EGFR) expression in KCOT compared with dentigerous cyst and ameloblastoma.

Materials and Methods:

Formalin-fixed and paraffin-embedded tissue sections of 16 cases of KCOT, 16 cases of dentigerous cyst and 16 cases of ameloblastoma were immunohistochemically analyzed to determine Bcl-2 and EGFR proteins’ expression. Biotin-Stereotavidin method was used. It was observed by two oral pathologists separately, and the data were analyzed by Mann–Whitney and Kruskul–Wallis. P < 0.05 was considered as significant.

Results:

Regardless of staining intensity, all cases of ameloblastoma and KCOT except dentigerous cases were positively stained for Bcl-2. Expression of Bcl-2 was higher in the peripheral layer of ameloblastoma and basal layer of KCOT. Furthermore, all cases of ameloblastoma and dentigerous cysts except KCOT samples were positively stained for EGFR. Expression of EGFR was higher in the peripheral layer of ameloblastoma and basal layer of dentigerous cysts.

Conclusion:

According to the expression of — Bcl-2 in ameloblastoma and KCOT, and no expression of EGFR in KCOT, it can be concluded that the biological activity and growth mechanisms of KCOT are different compared with other cystic lesions. However, the aggressive potential of KCOT is not as severe as that of a neoplasm such as ameloblastoma.

Metallothionein immunoexpression in non-syndromic and syndromic keratocystic odontogenic tumour

Background

To compare the metallothionein (MT) immunoexpression in non-syndromic and syndromic keratocystic odontogenic tumour (KOT), to correlate MT with cellular proliferation, and to evaluate the influence of inflammation in MT.

Material and Methods

Fourteen cases of KOT were submitted to immunohistochemistry for MT and Ki-67 analysis. The lesions were grouped according to their grade of inflammation, and statistical analysis was performed.

Results

MT was higher in non-syndromic KOT than in syndromic KOT (p<0.05). No statistical difference in Ki-67 could be identified; however, an inverse correlation was observed between MT and Ki-67 in both lesions. When analysing inflammation, non-syndromic KOT showed no differences in either MT or Ki-67.

Conclusions

The MT immunophenotype of syndromic KOT was different from non-syndromic KOT. MT might not be involved in the proliferation control of both KOT. MT and Ki-67 immunoexpressions proved to be unaffected by inflammation in non-syndromic KOT.

Key words: Odontogenic tumours, basal cell nevus syndrome, metallothionein, Ki-67 Antigen, immunohistoche-mistry.

Participation of hMLH1, p63, and MDM2 proteins in the pathogenesis of syndromic and nonsyndromic keratocystic odontogenic tumors

OBJECTIVES

To evaluate the expression of hMLH1, p63, and MDM2 in Gorlin syndrome-associated keratocystic odontogenic tumors (SKOTs) and nonsyndromic keratocystic odontogenic tumors (NSKOTs).

STUDY DESIGN

Seventeen primary NSKOTs, 17 SKOTs, and 8 recurrent NSKOTs were analyzed by using immunohistochemistry.

RESULTS

No significant differences in the hMLH1, p63, or MDM2 labeling indices were observed between groups (P = .398; P = .232; P = .426, respectively). Higher hMLH1 immunoexpression was found in the basal layer of primary NSKOTs. Most KOTs exhibited p63 immunoexpression in the upper layers of the epithelium. MDM2 immunoexpression was observed in the upper epithelial layers of SKOTs and recurrent NSKOTs.

CONCLUSION

It was not possible to correlate the immunoexpression of hMLH1, p63, and MDM2 in SKOTs and primary and recurrent NSKOTs, suggesting that these proteins exert independent effects on the development of these groups of tumors.

Ki-67 and p53 expression in solitary sporadic, syndrome associated and recurrent keratocystic odontogenic tumor

BACKGROUND

Ki-67 and p53 are markers expressed in actively proliferating cells, particularly in neoplasms.

OBJECTIVES

(1) To study the proliferative potential of epithelia in Solitary Sporadic, Syndrome-associated and Recurrent Keratocystic odontogenic tumors (KCOTs) using Ki67 and p53 labeling indices (LI). (2) To derive a relationship if any between the expression of these proteins and the biologic behavior of Solitary Sporadic and Syndrome associated KCOTs.

STUDY DESIGN

Thirteen paraffin embedded blocks of KCOTs (Solitary Sporadic, n = 03; Recurrent, n = 03; Syndrome associated, n = 07) were stained immunohistochemically for Ki-67 and p53 and labeling indices were calculated.

STATISTICAL ANALYSIS

Z test with predetermined alpha set at 0.05 was used for the comparison of Ki-67 positivity between the three groups and p53 positivity between the three groups.

RESULTS

Ki-67 labeling indices were: 30% in solitary sporadic; 26% in recurrent; and 32% in syndrome associated KCOTs. p53 labeling indices were: 19% in solitary sporadic; 23% in recurrent; and 21% in syndrome-associated KCOTs. There was no difference seen in the rate of proliferation in the epithelial linings between the three groups. However, in our cases where Ki-67 positivity was seen there was expression of p53. Though not statistically significant a trend was seen, reflecting the loss of balance between the proliferative potential and apoptotic activity.

CONCLUSION

On the basis of proliferative index alone it is not possible to comment on biological behavior of KCOTs associated with syndrome versus those of solitary and recurrent. There is probably a mesenchymal role which needs to be researched.

A molecular insight into the role of inflammation in the behavior and pathogenesis of odontogenic cysts

Background:

Although, odontogenickeratocyst (OKC) and dentigerous cyst (DC) are considered asdevelopmental cysts inflammation has been seen in its connective tissue wall. Inflammation is seen to alter the epithelial lining of both OKC and DC butwhether it plays in altering the behavior of these cysts is not fully understood.

Aim:

The present study is conducted with the help of molecular marker proliferating cellular nuclear antigen (PCNA) to assess the proliferative activity of OKC and DC and to further evaluate and correlate the effect of inflammation on the proliferative activity and hence on biological behavior of these cysts.

Materials and Methods:

Immunohistochemicalstaining was performed using anti-PCNA antibody in 10 cases each of classical OKC, inflamed OKC, classical DC, and inflamed DC. The resulting data was tabulated on Microsoft excel and subjected to statistical analysis using two-way analysis of variance test, t test and post-hoc test followed by Bonferroni test with the application of statistical package for social sciences (SPSS) (SPSS, Chicago, IL, USA) and Epi-Info 6.04 d, Atlanta, Georgia (USA).

Results:

Total mean PCNA expression is statistically higher in inflamed OKC than classical OKC and inflamed DC also showed significantly higher PCNA expression than classical DC (P < 0.001). Correlation between inflammation and PCNA expression was not statistically significant (P ≥ 0.05).

Conclusion:

Inflammation is responsible for change in behavior of neoplastic epithelium of OKC, whereas in dentigerous it is responsible for changes in epithelial lining and hence should be treated meticulously.

Evaluation of stromal myofibroblasts expression in keratocystic odontogenic tumor and orthokeratinized odontogenic cysts: A comparative study

Objective:

Keratocystic odontogenic tumor (KCOT) has an aggressive clinical course and a high tendency of recurrence, while orthokeratinized odontogenic cyst (OOC) has different characteristics and does not show aggressive behaviour. Even the treatment of these two lesions varies considerably. A large number of epithelial molecules have been studied in order to differentiate odontogenic keratocyst (OKC) from OOC, but stromal factors have not been adequately studied. Recently, tumor stroma has evolved as a particular field of interest. In the present study, we aim to evaluate and compare the expression of stromal myofibroblasts (MFs) in these entities and correlate it to its aggressive behavior. The term ‘keratocystic odontogenic tumor’ has been introduced by WHO in 2005 for odontogenic keratocyst keeping in mind its aggressive behavior, however still many pathologists and clinicians use the term OKC synonymously.

Materials and Methods:

A total of 10 cases of KCOT and 10 cases of OOC were stained for alpha-smooth muscle actin (αSMA) for demonstration of stromal MFs. MF frequency was assessed as the number of αSMA-positive stromal cells in 10 high power fields, presented as the mean number of positive cells per field.

Results:

Counts showed that the mean number of positive cells in KCOT (20.6 ± 2.05) was significantly higher than that seen in OOC (10.4 ± 1.06) (P < 0.05).

Conclusion:

The different behaviors of these lesions are compatible with the finding of the present study. The increased number of stromal MFs in KCOT in comparison to OOC correlates with its aggressive behavior and increased tendency towards recurrence.

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.

Claudin expression and tight junction protein localization in the lining epithelium of the keratocystic odontogenic tumors, dentigerous cysts, and radicular cysts

OBJECTIVE

The aim of this study was to evaluate the expression and localization of tight junction proteins (TJPs) or claudins in the keratocystic odontogenic tumor (KCOT) and to correlate with its biological behavior.

STUDY DESIGN

Five claudins (-1, -3, -4, -5, and 7) were examined immunohistochemically in 25 KCOTs and compared with 10 dentigerous cysts (DCs) and 10 radicular cysts (RCs).

RESULTS

Marked claudin-3 loss of expression in KCOT basal layer (n=24/25; 96%) compared with DCs (n=1/10; 10%) and RCs (n=5/10; 50%) (P<.05) suggests that claudin-3 downregulation may indicate altered or loss of basal cell polarity and impaired barrier function of KCOT lining epithelium and this might contribute indirectly to its biological behavior. In contrast, claudins-1, -4, -5, and -7 distribution patterns were less distinctive in all three entities, suggesting that these TJP molecules probably play limited roles in influencing their different growth potentials.

CONCLUSION

Present findings suggest that differential claudin expressions in the lining epithelium of KCOTs, DCs, and RCs probably reflect their neoplastic or nonneoplastic nature.

Targeting the sonic hedgehog pathway in keratocystic odontogenic tumor

Keratocystic odontogenic tumors (KCOT) may occur sporadically or associated with the nevoid basal cell carcinoma syndrome. It is a benign aggressive tumor of odontogenic epithelial origin with a high rate of recurrence. A primary human keratocystic odontogenic tumor cell population, KCOT-1, has been established from a tumor explant culture. The KCOT-1 cells were characterized by growth rate, gene expression profiles of major tooth enamel matrix proteins (EMPs), amelogenin (AMELX), enamelin (ENAM), ameloblastin (AMBN), amelotin (AMTN), tumor-related proteins enamelysin (MMP-20), kallikrein-4 (KLK-4), and odontogenic ameloblast-associated protein (ODAM) using quantitative real-time reverse transcription-polymerase chain reaction. Cytokeratin 14 (CK14) was examined by immunohistochemistry. In addition, expression of the members of the sonic hedgehog (SHH) pathway, SHH, patched (PTCH-1), smoothened (SMO), GLI-1, and GLI-2 and of the NOTCH signaling pathway, NOTCH-1, NOTCH-2, NOTCH-3, JAG-2 (Jagged-2), and Delta-like-1 (DLL-1) were evaluated. KCOT-1 cells were treated with SMO antagonist cyclopamine. We found that cyclopamine significantly arrested the growth of KCOT-1 cells in a dose-dependent manner and that the effects of cyclopamine were abolished by adding SHH protein. The protein expression of the SHH pathway was down-regulated by cyclopamine, further confirming that cyclopamine inhibits the SHH signaling pathway; SHH down-regulation correlated with the down-regulation of the NOTCH signaling pathway as well. In conclusion, using an established KCOT-1 cell population, we characterized the gene expression profiles related to the EMPs, SHH, and NOTCH signaling pathway and confirmed that cyclopamine significantly arrested the growth of KCOT-1 cells and may be a viable agent as a novel therapeutic.

Immunohistochemical analysis of bone resorption regulators (RANKL and OPG), angiogenic index, and myofibroblasts in syndrome and non-syndrome odontogenic keratocysts

OBJECTIVE

The aim of this study was to immunohistochemically analyse bone resorption regulators (receptor activator of nuclear factor kappa B ligand [RANKL] and osteoprotegerin [OPG]), angiogenic index, and myofibroblasts in Gorlin syndrome-related odontogenic keratocysts (SOKCs) and non-syndrome odontogenic keratocysts (NSOKCs).

STUDY DESIGN

Twenty-two SOKCs, 22 primary NSOKCs, and eight recurrent NSOKCs were evaluated by immunohistochemistry using anti-RANKL and anti-OPG antibodies. The angiogenic index was determined by microvessel count (MVC) using anti-CD34 antibody. Anti-α-smooth muscle actin (α-SMA) antibody was used for the identification of myofibroblasts.

RESULTS

Analysis of the expression of RANKL and OPG in the epithelial lining and fibrous capsule did not reveal significant differences between groups (P>0.05). In the epithelial lining, the RANKL/OPG ratio was RANKL<OPG and RANKL=OPG in most primary NSOCKs (54.5%) and SOKCs (59.1%), respectively (P>0.05). In the fibrous capsule, the ratio was RANKL=OPG in most primary (81.8%) and recurrent NSOKCs (75.0%) and in most SOKCs (45.5%) (P>0.05). No significant differences in the angiogenic index or number of myofibroblasts were observed between primary NSOKCs, recurrent NSOKCs, and SOKCs (P>0.05).

CONCLUSIONS

The present results suggest that differences in the biological behaviour of SOKCs and NSOKCs may not be related to the expression of RANKL and OPG, to the RANKL/OPG ratio, to the angiogenic index, or to the number of myofibroblasts in these lesions.

Comprehensive keratin profiling reveals different histopathogenesis of keratocystic odontogenic tumor and orthokeratinized odontogenic cyst

Keratocystic odontogenic tumor is a cystic lesion that behaves more aggressively than other jaw cysts. One of its characteristic histologic features is a parakeratinized uniform layer of lining epithelium. A jaw cyst lined with orthokeratinized epithelium is called an orthokeratinized odontogenic cyst. These keratinized jaw cysts are thought to be separate entities, although their histopathogenesis has not been fully assessed. To better understand these lesions, we performed comprehensive immunohistochemical profiling of the keratin expression of each. Orthokeratinized odontogenic cysts expressed keratin 1, keratin 2, keratin 10, and loricrin, suggesting differentiation toward normal epidermis. Keratocystic odontogenic tumors expressed keratin 4, keratin 13, keratin 17, and keratin 19, which is a unique expression pattern reminiscent of a mucosal squamous epithelium and an epithelial appendage. In neonatal rat tooth germ, cells strongly positive for keratin 17 and keratin 19 were observed, specifically in the dental lamina, implying the origin of keratocystic odontogenic tumor. GLI2, a downstream effector of hedgehog signaling, was significantly expressed in keratocystic odontogenic tumor and basal cell carcinoma, accompanied with robust expression of keratin 17, mammalian target of rapamycin, and BCL2. The expression of these GLI2- or keratin 17-related factors was not significantly observed in orthokeratinized odontogenic cysts. These findings provide evidence to support the viewpoint that keratocystic odontogenic tumor and orthokeratinized odontogenic cyst are separate entities, and furthermore suggest their characteristic histology, pathogenesis, and biological behaviors.

Immunolocalisation of laminin-1 in keratocystic odontogenic tumors

Keratocystic odontogenic tumors (KOTs) are distinct odontogenic lesions frequently affecting the jawbones. They may be associated with nevoid basal cell carcinoma syndrome (NBCCS), and may exhibit disorders involving the extracellular matrix. The aim of this study was to investigate the immunolocalisation of laminin-1 in 20 cases of KOTs in order to contribute to the characterization of this protein, which is little studied in odontogenic tumors. Our results showed laminin-1 in all 20 KOTs studied; its labelling intensity was weak in three cases (15%), moderate in five (25%) and strong in 12 cases (60%). Laminin-1 immunolocalisation was predominantly continuous in 18 (90%) KOTs, including areas of acanthosis, subepithelial split and epithelial buds. Weak immunolabelling was observed in regions exhibiting an inflammatory process, especially in the case of intense inflammation. These findings suggest that laminin-1 does not participate in biological processes such as cystic epithelium-cystic wall separation or the formation of epithelial islands in KOTs. Furthermore, the discontinuous and weak labelling of this protein in the basement membrane of these tumors is probably a consequence of the inflammatory process in the tumor stroma.

Evaluation of collagen in connective tissue walls of odontogenic cysts--a histochemical study

BACKGROUND

The purpose of this study was to evaluate the nature of collagen in the connective tissue walls of odontogenic cysts, like the odontogenic keratocyst (OKC), dentigerous cyst and radicular cyst using picrosirius red stained sections. Furthermore, it was intended to assess if the capsular connective tissue can affect the nature of overlying epithelium, thus emphasizing the role of epithelial-mesenchymal interactions in biological behaviour of the cysts.

MATERIALS AND METHOD

The material for the study included 51 formalin-fixed paraffin-embedded tissue blocks (15 odontogenic keratocyst, 15 dentigerous cysts, 15 radicular cysts and four normal mucosa and two dental follicular tissue as controls), retrieved from the Department of Oral Pathology and Microbiology, MCODS, Manipal. Tissue blocks were sectioned at 5-μm thickness, stained with picrosirius red stain and observed with polarization and light microscopy.

RESULTS

Few sections of OKC and dentigerous cyst exhibited greenish-yellow birefringence in sub-epithelial region, whereas others showed a yellowish-orange birefringence under polarization microscopy. Most radicular cysts had yellowish-orange to orange birefringence. Shift in colour in case OKC and dentigerous cyst was attributed to the presence of inflammation in those sections. These regions also exhibited either a change in phenotype or thickness of overlying epithelium.

CONCLUSION

This technique can be used to study the nature of collagen fibres in odontogenic cyst walls. Further studies with an increased sample size and using various epithelial and mesenchymal markers and ssDNA antibodies should be carried out to confirm the effect of epithelial-mesenchymal interactions on the nature of epithelium of odontogenic cysts.

Immunohistochemical expression of vascular endothelial growth factor (VEGF) in different types of odontogenic cysts

The objective of the present study was to evaluate vascular endothelial growth factor (VEGF) expression in different types of odontogenic cysts. A total of 25 parakeratotic odontogenic keratocysts (POKCs), 16 orthokeratotic odontogenic keratocysts (OOKCs), and 28 follicular cysts (FCs) were evaluated semiquantitatively for immunohistochemical analysis of VEGF in epithelial cells, endothelial cells of blood vessels, inflammatory cells and focally stromal cells. A significant different expression of VEGF in all cell components was found in keratocysts compared to FCs. The POKCs (80%) and OOKCs (68%) showed more than 50% VEGF positive epithelial cells, whereas the majority of FCs (71%) were either negative in the epithelium or showed less than 10% positive cells. Similarly, the POKCs (88%) and OOKCs (68%) showed more than 50% positive endothelial cells, whereas the FCs (75%) were either negative or showed less than 10% VEGF positive endothelial cells. The highest percentage of cases with score 2 positivity in the stromal cells was observed in POKCs (68%); OOKCs showed a score 2 positivity in 44%, score 1 in 31% and score 0 in 25%, whereas 68% of FCs showed a score 0, 25% a score 1 and only 7% of cases showed a score 2. No statistically significant differences were observed between POKCs and OOKCs in VEGF expression in the epithelial and endothelial cells, whereas the positivity score in stromal cells was significantly higher in POKCs compared to OOKCs. The present results can support the hypothesis that angiogenesis is an active mechanism in the invasive growth of the OKC.

Characterization and management of the keratocystic odontogenic tumor in relation to its histopathological and biological features

Keratocystic odontogenic tumor (KCOT), formerly referred to as odontogenic keratocyst, is a benign neoplasm of odontogenic origin which may present an aggressive and infiltrative behavior leading to high recurrence rates. A review of the various treatment modalities, ranging from simple enucleation to radical surgery is portrayed in relation to clinical, radiological, histopathological and molecular features. Although prognostic factors based on clinico-pathologic and immunohistochemical findings for determining the potential for recurrence of KCOT still remains unclear, its use for determining the potential for recurrence of KCOT after surgical treatment may become important to successfully manage this neoplasm's aggressive behavior. The key element for future management of KCOTs will probably be based on thorough knowledge of the biological basis of this tumor, thereby enabling a more tailored treatment approach.

Review of the molecular pathogenesis of the odontogenic keratocyst

The odontogenic keratocyst (keratocystic odontogenic tumour) (OKC) is one of the most prevalent odontogenic tumours. Since its initial description, a number of studies have focused on different aspects of this lesion, attempting to explain its distinctive biological behaviour. In this review the authors address the main genetic and epigenetic alterations reported on this tumour. Although most of the knowledge on this field is not being used in the clinical practice, some perspectives of translational studies are discussed.

Immunohistochemical expression of MMPs 1, 7, and 26 in syndrome and nonsyndrome odontogenic keratocysts

OBJECTIVE

The objective of this study was to analyze the expression of matrix metalloproteinases (MMPs) 1, 7, and 26 in odontogenic keratocysts (OKCs) associated with Gorlin syndrome (SOKCs) and nonsyndrome OKCs (NSOKCs).

STUDY DESIGN

Twenty-one SOKCs and 20 NSOKCs were evaluated for epithelial expression of MMP-1, MMP-7, and MMP-26 and for mesenchymal expression of MMP-1 by immunohistochemistry.

RESULTS

Strong epithelial positivity to MMP-1 was observed in 76% of SOKCs and in 15% of NSOKCs (P < .05). Strong mesenchymal immunoreactivity to MMP-1 was observed in 38% of SOKCs and in 20% of NSOKCs (P > .05). Epithelial immunoreactivity to MMP-7 was strongly positive in 67% of SOKCs and in 40% of NSOKCs (P > .05). For MMP-26, strong positivity was found in 62% of SOKCs, in contrast to 35% of NSOKCs (P > .05).

CONCLUSION

MMPs-1, -7 and -26 may play important roles in the biology of OKCs. Furthermore, the presence of these proteases at higher levels in SOKCs may help to explain increased OKC aggressiveness associated with nevoid basal cell carcinoma syndrome.

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.

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.