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

Immunohistochemical Analysis of Dentigerous Cysts and Odontogenic Keratocysts Associated with Impacted Third Molars-A Systematic Review

OBJECTIVE

This systematic review investigates the diagnostic, prognostic, and therapeutic implications of immunohistochemical markers in dentigerous cysts (DCs) and odontogenic keratocysts (OKCs) associated with impacted third molars.

MATERIALS AND METHODS

A comprehensive search strategy was employed across major databases including MEDLINE/PubMed, EMBASE, and Web of Science, from the inception of the databases to March 2024. Keywords and Medical Subject Heading (MeSH) terms such as "dentigerous cysts", "odontogenic keratocysts", "immunohistochemistry", "Ki-67", and "p53" were used. The PRISMA 2020 guidelines were followed to ensure methodological rigor. Inclusion criteria encompassed studies on humans and animals providing definitive diagnoses or specific signs and symptoms related to DCs and OKCs, with results on protein expression derived from immunohistochemistry, immune antibody, proteomics, or protein expression methods.

RESULTS

Of the 159 studies initially identified, 138 met the inclusion criteria. Our analysis highlighted significantly higher expressions of Ki-67 (22.1% ± 4.7 vs. 10.5% ± 3.2, p < 0.001), p53 (15.3% ± 3.6 vs. 5.2% ± 1.9, p < 0.001), and Bcl-2 (18.4% ± 3.2 vs. 8.7% ± 2.4, p < 0.001) in OKCs compared to DCs, indicating a higher proliferative index, increased cellular stress, and enhanced anti-apoptotic mechanisms in OKCs. Additionally, PCNA levels were higher in OKCs (25.6% ± 4.5 vs. 12.3% ± 3.1, p < 0.001). Genetic mutations, particularly in the PTCH1 gene, were frequently observed in OKCs, underscoring their aggressive behavior and potential malignancy.

CONCLUSIONS

The findings emphasize the significant role of immunohistochemical markers in distinguishing between DCs and OKCs, with elevated levels of Ki-67, p53, Bcl-2, and PCNA in OKCs suggesting a higher potential for growth and recurrence. Genetic insights, including PTCH1 mutations, further support the need for personalized treatment approaches. These markers enhance diagnostic accuracy and inform targeted therapeutic strategies, potentially transforming patient management in oral and maxillofacial surgery.

Factors Influencing the Aggressive Behavior of Odontogenic Keratocyst: A Narrative Review

During odontogenesis, the dental lamina disintegrates, leaving behind the remnants. Odontogenic pathologies such as cysts and tumors can arise from these remnants. The odontogenic keratocyte (OKC) arises from dental lamina remnants. Among the cysts, the odontogenic keratocyst is the most controversial. There is convincing evidence that inflammation plays a significant role in the pathogenesis and expansion of OKCs. Several factors mediate the proliferative capacity of the epithelial lining. The presence of mast cells close to the epithelial lining, cystic pressure build-up by vascular endothelial growth factors (VEGFs), and other cytokines contribute to the cystic expansion. Fibroblast activation by inflammation in the connective tissue stroma and changes in the epithelial lining are responsible for the aggressive nature of OKC. The use of molecular methodologies gives more profound insights into the factors influencing the progression of the lesion and helps develop newer treatment modalities for OKC. This review describes the characteristics that determine the aggressive behavior of this unique cyst.

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.

Cyclooxygenase-2 protein expression modulates cell proliferation and apoptosis in solid ameloblastoma and odontogenic keratocyst. An immunohistochemical study

BACKGROUND

Cyclooxygenase-2 protein is a critically important mediator in inflammation that influences proliferation, apoptosis, angiogenesis and metastasis. Previous works showed a relationship between cyclooxygenase-2 and tumourigenesis in humans and animal models. In epithelial odontogenic tumours and cysts, increased cell proliferation and survival have been linked to its pathogenesis and tumour development. The aim of the present study was to analyse the immunohistochemical expression of cyclooxygenase-2 in solid ameloblastoma and odontogenic keratocyst and its association with proteins related to cell proliferation and apoptosis.

METHODS

This study was conducted on 40 cases from the Pathological Anatomy Service, University of Chile. The cases were diagnosed as solid ameloblastoma (n = 21) and odontogenic keratocyst (n = 19) according to WHO 2017. Slides prepared from paraffin-embedded sections were immunohistochemically stained for cyclooxygenase-2, cyclin D1, Ki-67, p63 and Bcl-2. Statistical evaluation was performed by the Shapiro-Wilk test, ANOVA Mann-Whitney test and Spearman's correlation coefficient (p < 0.05).

RESULTS

There were significant differences in the immunoexpression of cyclin D1, Ki-67 and Bcl-2 between solid ameloblastoma and odontogenic keratocyst. Likewise, there was a significant difference in the immunoexpression of p63 between follicular and plexiform histological types/subtypes of solid ameloblastoma. Lastly, there were statistical associations between cyclooxygenase-2 and Ki-67 for solid ameloblastoma and between cyclooxygenase-2 and p63 for odontogenic keratocyst.

CONCLUSION

A high level of cyclooxygenase-2 is related to increased cell survival and proliferative activity in solid ameloblastoma and odontogenic keratocyst. This event might contribute to tumoural progression and local invasiveness in these lesions.

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.

Changes in Cellular Regulatory Factors before and after Decompression of Odontogenic Keratocysts

Decompression followed by enucleation, which is one of the treatments used for odontogenic keratocysts (OKCs), is frequently used in OKC lesions of large sizes. This method offers the advantage of minimizing the possibility of sensory impairment without creating a wide-range bone defect; moreover, the recurrence rate can be significantly lower than following simple enucleation. This study aimed to assess the changes in histology and expression of proliferation markers in OKCs before and after decompression treatment. A total of 38 OKC tissue samples from 19 patients who had undergone decompression therapy were examined morphologically and immunohistochemically to observe changes in proliferative activity before and after decompression. The markers used for immunohistochemistry (IHC) staining were Bcl-2, epidermal growth factor receptor (EGFR), Ki-67, P53, PCNA, and SMO. The immunohistochemistry positivity of the 6 markers was scored by using software ImageJ, version 1.49, by quantifying the intensity and internal density of IHC-stained epithelium. The values of Bcl-2, Ki-67, P53, proliferating cell nuclear antigen (PCNA), and SMO in OKCs before and after decompression showed no significant change. No correlation between clinical shrinkage and morphologic changes or expression of proliferation and growth markers could be found. There was no statistical evidence that decompression treatment reduces potentially aggressive behavior of OKC within the epithelial cyst lining itself. This might indicate that decompression does not change the biological behavior of the epithelial cyst lining or the recurrence rate.

COX-2 as a determinant of lower disease-free survival for patients affected by ameloblastoma

Ameloblastoma is a locally aggressive neoplasm with a poorly understood pathogenesis. Therefore, the aim of this study is to investigate whether COX-2 expression is associated with ameloblastoma microvascular density (MVD) and with tumor aggressiveness. Sixty-three cases of primary ameloblastomas arranged in tissue microarray were submitted to immunohistochemistry against cyclooxigenase-2 (COX-2) and CD34. Clinicopathological parameters regarding sex, age, tumour size, tumour duration, tumour location, treatment, recurrences, radiographic features, vestibular/lingual and basal cortical disruption and follow-up data were obtained from patients' medical records and correlated with the proteins expression. The results on BRAF-V600E expression were obtained from our previous study and correlated with COX-2 and CD34 expressions. Log-rank univariate analysis and multivariate Cox regression model were done to investigate the prognostic potential of the molecular markers. Twenty-eight cases (44.4%) exhibited cytoplasmic positivity for COX-2, predominantly in the columnar peripheral cells, with a mean MVD of 2.2 vessels/mm². COX-2 was significantly associated with recurrences (p < 0.001) and BRAF-V600E expression (p < 0.001), whereas lower MVD was associated with the use of conservative therapy (p = 0.004). Using univariate and multivariate analyses, COX-2 was significantly associated with a lower 5-year disease-free survival (DFS) rate (p < 0.001 and p = 0.012, respectively), but not with a higher MVD (p = 0.68). In conclusion, COX-2 expression in ameloblastomas is not associated with MVD, but it is significantly associated with recurrences and with a lower DFS.

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.

Influence of surgical decompression on the expression of inflammatory and tissue repair biomarkers in periapical cysts

OBJECTIVE

The biologic effects of surgical decompression on the epithelium and connective tissues of periapical cysts are not fully understood. The aim of this study was to evaluate the expression of tissue repair and inflammatory biomarkers in periapical cysts before and after surgical decompression.

STUDY DESIGN

Nine specimens of periapical cysts treated with decompression before undergoing complete enucleation were immunohistochemically analyzed to investigate the expression of interleukin-1β, tumor necrosis factor-α, transforming growth factor-β1, matrix metalloproteinase-9, Ki-67, and epidermal growth factor receptor. Expression of the biomarkers was classified as positive, focal, or negative. Ki-67 immunoexpression was calculated as a cell proliferation index. The expression of the biomarkers was compared in the specimens from decompression and from the final surgical procedure.

RESULTS

Computed tomography demonstrated that volume was reduced in all cysts after decompression. There were no differences in the immunoexpression of the proinflammatory and tissue repair biomarkers when comparing the specimens obtained before and after the decompression.

CONCLUSIONS

Surgical decompression was efficient in reducing the volume of periapical cysts before complete enucleation. When comparing the specimens obtained from surgical decompression and from complete surgical removal, the immunohistochemical analysis did not show a decrease in proinflammatory biomarkers; neither did it show an increase in tissue repair biomarkers.

The Clinical Features and Expression of bcl-2, Cyclin D1, p53, and Proliferating Cell Nuclear Antigen in Syndromic and Nonsyndromic Keratocystic Odontogenic Tumor

The aim of this study was to describe the clinical features and expression of bcl-2, cyclin D1, p53, and proliferating cell nuclear antigen (PCNA) antibodies in syndromic (nevoid basal cell carcinoma syndrome [NBCCS]) and nonsyndromic patients diagnosed with keratocystic odontogenic tumor (KCOT).

METHODS

This descriptive study comprised 5 patients of KCOT associated with NBCCS and 8 patients of nonsyndromic type treated in the Department of Oral Maxillofacial Surgery, Universiti Kebangsaan Malaysia Medical Centre between years 1998 and 2011. The clinical features (site, size, treatment, and recurrence), demographic characteristics, and immunohistochemistry results using antibodies of bcl-2, cyclin D1, p53, and PCNA were examined. The association of the antibody expression and the type of KCOT was analyzed using Fisher exact test.

RESULTS

Altogether there were 13 patients, 5 with syndromic KCOT (1 patient met 3 major criteria of NBCCS) and 8 with sporadic KCOT. The age range for syndromic KCT was 11 to 21 years (mean 16.00 years, SD 4.36) and 10 to 54 years (median 24.50 years, interquartile range 19.00) for the nonsyndromic KCOT. Tumor recurrence occurred in 3 patients (7.7%); 1 patient from the syndromic and 2 patients from the nonsyndromic. The most positive expression was observed in PCNA for both the syndromic and nonsyndromic samples and the least positive expression involved the p53.

CONCLUSION

PCNA, bcl-2 protein, and cyclin D1 expressions could be useful in evaluating the proliferative activity of the tumor and the aggressiveness of the clinical presentation; however, the authors would propose for larger sample size research for more definitive results.

P53 Protein Expression in Dental Follicle, Dentigerous Cyst, Odontogenic Keratocyst, and Inflammatory Subtypes of Cysts: An Immunohistochemical Study

OBJECTIVES

An odontogenic keratocyst (OKC) is a developmental odontogenic cyst with aggressive clinical behavior. This cyst shows a different growth mechanism from the more common dentigerous cyst and now has been renamed as a keratocystic odontogenic tumor (KCOT). Inflammation can assist tumor growth via different mechanisms including dysregulation of the p53 gene. This study aims to assess and compare the expression of tumor suppressor gene p53 in inflamed and non-inflamed types of OKC and dentigerous cyst.

METHODS

Immunohistochemical expression of p53 was assessed in 14 cases of dental follicle, 34 cases of OKC (including 18 inflamed OKCs), and 31 cases of dentigerous cyst (including 16 inflamed cysts).

RESULTS

The mean percentage of p53 positive cells was 0.7% in dental follicles, 5.4% in non-inflamed OKCs, 17.3% in inflamed OKCs, 1.2% in non-inflamed dentigerous cysts, and 2.2% in inflamed dentigerous cysts. The differences between the groups were statistically significant (p < 0.050) except for the difference between inflamed and non-inflamed dentigerous cysts, and between dental follicle and non-inflamed dentigerous cyst.

CONCLUSIONS

The difference in p53 expression in OKC and dentigerous cyst can explain their different growth mechanism and clinical behavior. Inflammation is responsible for the change in behavior of neoplastic epithelium of OKC via p53 overexpression.

Odontogenic Cysts and Neoplasms

This article reviews a myriad of common and uncommon odontogenic cysts and tumors. The clinical presentation, gross and microscopic features, differential diagnosis, prognosis, and diagnostic pitfalls are addressed for inflammatory cysts (periapical cyst, mandibular infected buccal cyst/paradental cyst), developmental cysts (dentigerous, lateral periodontal, glandular odontogenic, orthokeratinized odontogenic cyst), benign tumors (keratocystic odontogenic tumor, ameloblastoma, adenomatoid odontogenic tumor, calcifying epithelial odontogenic tumor, ameloblastic fibroma and fibroodontoma, odontoma, squamous odontogenic tumor, calcifying cystic odontogenic tumor, primordial odontogenic tumor, central odontogenic fibroma, and odontogenic myxomas), and malignant tumors (clear cell odontogenic carcinoma, ameloblastic carcinoma, ameloblastic fibrosarcoma).

Odontogenic epithelial proliferation is correlated with COX-2 expression in dentigerous cyst and ameloblastoma

Investigation of cyclooxygenase (COX)-2 in dentigerous cyst and ameloblastoma may help to improve understanding of the nature and behavior of odontogenic cysts and tumors, and in addition may eventually represent a definitive target for a pharmacological approach in the management of these lesions. The aim of this study was to evaluate COX-2 expression and its correlation with the proliferation of odontogenic epithelium in these lesions. Dentigerous cysts (n=16) and ameloblastomas (n=17) were evaluated. Detection of Ki-67 and COX-2 protein expression was conducted by immunohistochemistry. Data were statistically analyzed using Mann-Whitney U test and Spearman's rank correlation coefficient. No significant differences were found in the expression of Ki-67 and COX-2 between dentigerous cysts and ameloblastomas (P>0.05). A significant positive correlation (P=0.018) and highly significant positive correlation (P=0.004) were found between Ki-67 and COX-2 expression in the odontogenic epithelium of dentigerous cyst and ameloblastoma, respectively. COX-2 was expressed in the odontogenic epithelium of dentigerous cyst and ameloblastoma. It may contribute to local extension of these lesions by increasing the proliferation of their odontogenic epithelial cells.

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.

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

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

Expansile keratocystic odontogenic tumor in the maxilla: immunohistochemical studies and review of literature

Keratocystic odontogenic tumors (KCOT) - previously termed odontogenic keratocysts (OKC) - are characterized by aggressive behavior and a high rate of recurrence. Histopathologically, the basal layer of KCOT shows a higher cell proliferation rate and increased expression of anti-apoptosis genes. Clinically, KCOT is frequently involved in the mandibular posterior region but is not common in the posterior maxilla. However, it should be noted that due to its expansive characteristics, KCOT involved near the maxillary sinus could easily expand to an enormous size and occupy the entire maxilla. To achieve total excision of these expanded cystic tumors in the maxilla, a more aggressive approach would be needed. In this report, we describe two cases of expansile KCOT involving the entire unilateral maxilla and maxillary sinus; they were completely excised using the Weber-Ferguson approach, showing no evidence of recurrence during the follow-up period of more than two years. In immunohistochemical analyses of the tumor specimens, p53 and p63 showed strong expression, and B-cell lymphoma 2 (BCL2) and MKI67 (Ki-67) showed moderate or weak expression, however, detection of BCL2-associated X protein (BAX) was almost negative. These data indicate that expansile KCOT possesses increased anti-apoptotic activity and cell proliferation rate but decreased apoptosis. These properties of KCOT may contribute to tumor enlargement, aggressive behavior, and high recurrence rate.

Cyclooxygenase-2 expression in keratocystic odontogenic tumour decreased following decompression

Marsupialisation or decompression is frequently performed as a conservative therapy for keratocystic odontogenic tumours (KCOTs). Positive cyclooxygenase-2 (COX-2) expression in the epithelium of KCOTs was recently reported and may be associated with neoplastic invasion and progression. The aim of the present study was to investigate the change in COX-2 expression in the KCOT epithelium following decompression. In this study, 16 pairs of KCOT biopsy specimens obtained during decompression or enucleation were collected and analysed. Formalin-fixed, paraffin-embedded blocks were sectioned and immunohistochemically investigated using anti-COX-2 antibody. The molecular expression was semi-quantitatively evaluated as follows: 0, negative; 1, weakly to moderately positive; and 2, strongly positive. In the samples obtained prior to decompression, the positive staining for COX-2 was immunolocalised to the cell membrane and the cytoplasm, it involved the full thickness of the epithelium and 15 of the 16 specimens (93.8%) exhibited mild to strong positivity. As regards the samples obtained following decompression, only 3 of the 16 specimens (18.8%) exhibited a mild positivity. The expression levels of COX-2 were significantly decreased following decompression (P<0.05). It may be concluded that loss or a significant reduction of COX-2 expression is associated with decompression in KCOTs. However, large-scale studies are required to verify these results and improve our knowledge of the possible involvement of COX-2 in the pathogenic mechanism underlying the development of KCOTs.

Matrix metalloproteinases, tissue inhibitors of metalloproteinases, and growth factors regulate the aggressiveness and proliferative activity of keratocystic odontogenic tumors

OBJECTIVE

The objective of this preliminary study was to evaluate the expression of matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs) and growth factors in keratocystic odontogenic tumors (KOTs).

STUDY DESIGN

The expression of MMPs, TIMPs, growth factors, and the extracellular signal-regulated kinase (ERK) 1/2 signaling pathway were assessed by immunohistochemistry in 15 cases of KOT and 4 cases of calcifying cystic odontogenic tumor (CCOT).

RESULTS

KOT samples expressed significantly higher amounts of MMPs, TIMPs, growth factors, epidermal growth factor receptor (EGFR), and ERK compared with CCOT samples, with the exception of MMP-2 and TIMP-1.

CONCLUSIONS

MMP-9, TIMP-2, EGF and transforming growth factor α act together and likely regulate the proliferation and aggressiveness of KOT. ERK-1/2 serves as the transducer of signals generated by these proteins, which signal through the common receptor, EGFR. This process may be related to the increased proliferation and aggressiveness observed in KOT.

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.

Ki-67 and MCM-2 in dental follicle and odontogenic cysts: the effects of inflammation on proliferative markers

The aim of this study was to investigate whether there is any association between inflammation and the expression of markers of cell cycle entry (Ki-67 and MCM-2) in dental follicle (DF) of asymptomatic impacted teeth and odontogenic cysts. The study consisted of 70 DFs and 20 odontogenic cysts (radicular cyst (RC), dentigerous cyst (DC) and keratocytic odontogenic tumor (KCOT) located at posterior mandibular region. Histological findings of inflammation for all specimen and mucous cell prosoplasia, squamous metaplasia, glandular epithelium for all DFs were stained with hematoxyline and eosin, periodic acid schiff, alcian blue, and mucin. Epithelial cell proliferation was determined by using immunohistochemical labeling for Ki-67 and MCM-2. The histologic examinations showed 16% mucous cell prosoplasia, 54% squamous metaplasia, 20% glandular epithelium, 37% inflammation. Inflammation was detected in all RCs and %62 in DF, %43 in DC and KCOT. Positive correlation was found between the inflammation of DF and odontogenic cysts (P < 0.01). The mean Ki-67 and MCM-2 expressions were found 9, 64 ± 5, 99 and 6, 34 ± 3, 81 in DF, 11, 85 ± 9, 01 and 13, 6 ± 9, 94 in odontogenic cysts, respectively. While the mean Ki-67 expressions were statistically significant in DF and KCOT (P < 0.01), MCM-2 were significant in RC and KCOT (P < 0.01). MCM-2 expresion in RCs were statistically significant than KCOT (P < 0.01). The results of this study indicated that the higher MCM-2 expressions in RC than the KCOT might be related to the inflammation and this protein might be more sensitive to inflammation.

Keratocystic odontogenic tumors: predictive factors of recurrence by Ki-67 and AgNOR labelling

PURPOSE

The purpose of the present study was to investigate the possible role of Ki-67 and argyrophilic nucleolar organizing regions (AgNOR) between the recurrent and nonrecurrent keratocystic odontogenic tumors (KCOTs). Another aim was to compare the correlation between these two markers.

MATERIALS AND METHODS

22 KCOTs were evaluated retrospectively. The actual proliferative activity of the KCOT was measured by Ki-67 labelling index and argyrophilic nucleolar organizing regions AgNOR count per nucleus.

RESULTS

Recurrence occurred in 3 patients (13.6%) during the follow-up period (mean follow-up, 37.8 months) The Ki-67 and AgNOR counts were significantly higher in the recurrent lesions comparing to the non-recurrent lesions. (p=0,045; p=0,049) The correlation between Ki-67 and AgNOR counts was found to be positive (r=0,853 p=0,0001).

CONCLUSION

Within the limit of the present study, it is thought that Ki-67 and AgNOR might be helpful as a prognostic marker for the recurrences of KCOTs. These markers reinforced the meaning of the new classification of the lesion as an odontogenic tumor. Enucleation with curettage or decompression following enucleation with curettage is a simple and appropriate surgical model for the treatment of KCOT despite the relative high recurrence rate. On the other hand, the conservative treatment can be chosen only if there is no coronoid invasion, no interruptive cortical lysis and no tissular invasion.