Molecular pathology of odontogenic tumors

Contribution of gene polymorphisms on 3p25 to salivary gland carcinoma, ameloblastoma, and odontogenic keratocyst in the Chinese Han population

OBJECTIVE

This study aimed to investigate the contribution of gene polymorphisms in 3p25 to salivary gland carcinoma (SGC), ameloblastoma (AM), and odontogenic keratocyst (OKC) in the Chinese Han population.

STUDY DESIGN

Sixteen tag-single nucleotide polymorphisms (SNPs) within 5 genes (SYN2, TIMP4, PPARG, RAF1, and IQSEC1) in 3p25 were genotyped in 411 individuals with or without SGC, AM, and OKC. Genotype, clinical phenotype, and bioinformatics analyses were performed to evaluate the function of candidate SNPs.

RESULTS

SYN2-rs3773364, TIMP4-rs3755724, PPARG-rs10865710, and PPARG-rs1175544 were related to decreased SGC susceptibility, whereas IQSEC1-rs2600322 and IQSEC1-rs2686742 decreased and increased AM risk, respectively. Stratification analysis revealed that the significance of the identified SNPs was stronger in females or individuals younger than 46 years in SGC. PPARG-rs10865710 and PPARG-rs1175544 were associated with lower lymph node metastasis. SYN2-rs3773364 and PPARG-rs1175544 were associated with favorable SGC patient survival. Functional assessments linked PPARG-rs1175544 to PPARG expression regulation. Linkage disequilibrium analysis revealed a haplotype (SYN2-rs3773364-A, TIMP4-rs3817004-A, and TIMP4-rs3755724-C) associated with decreased susceptibility to SGC. Generalized multifactor dimensionality reduction analysis indicated the gene-gene interactions among IQSEC1, TIMP4, and PPARG in SGC, AM, and OKC progression.

CONCLUSIONS

These variants play important roles in the progression of SGC, AM, and OKC in the Chinese Han population and may be considered biomarkers for early diagnosis and prognosis prediction.

Immunohistochemical expression of Ki-67 and Glypican-3 to distinguish aggressive from nonaggressive benign odontogenic tumors

Background

The benign neoplasms are normally slow growing, indolent with no invasive potential. However, there exist a few locally aggressive benign odontogenic tumors that have a tendency to invade and deform the surrounding structures. The exact reason for the aggressiveness of these benign neoplasms remained an enigma. Their biology and clinical expression can often be destructive and ominous. An appropriate treatment protocol needs to be followed to combat the high recurrence rate and aggressiveness of these entities. Aggressive and noniaggressive epithelial odontogenic tumors were analyzed immunohistochemically with Ki-67 and glypican 3 (GPC3).

Materials and Methods

Fifty-nine cases of tumors were divided into aggressive odontogenic tumors (20 solid ameloblastomas, four unicystic ameloblastoma, and 28 keratocystic odontogenic tumors) and nonaggressive odontogenic tumors (five adenomatoid odontogenic tumors and two calcifying cystic odontogenic itumors).

Results

Statistical analysis using Pearson correlation showed Ki-67 to be a better marker for differentiating aggressive from nonaggressive odontogenic tumor as compared to GPC3 (P < 0.001, highly significant), whereas among aggressive tumors, GPC3 turned out to be more useful as compared to Ki-67 (P < 0.001, highly significant).

Conclusion

The present study provides an insight into the different biological behavior of odontogenic tumors, which can thus be helpful in determining the therapy strategies for more aggressive odontogenic tumors.

Expression Profile of Stemness Markers CD138, Nestin and Alpha-SMA in Ameloblastic Tumours

Ameloblastic carcinoma is a rare malignant odontogenic neoplasm with a poor prognosis. It can arise de novo or from a pre-existing ameloblastoma. Research into stemness marker expression in ameloblastic tumours is lacking. This study aimed to explore the immunohistochemical expression of stemness markers nestin, CD138, and alpha-smooth muscle actin (alpha-SMA) for the characterisation of ameloblastic tumours. Six cases of ameloblastoma and four cases of ameloblastic carcinoma were assessed, including one case of ameloblastic carcinoma arising from desmoplastic ameloblastoma. In all tumour samples, CD138 was positive, whilst alpha-SMA was negative. Nestin was negative in all but one tumour sample. Conversely, the presence or absence of these markers varied in stroma samples. Nestin was observed in one ameloblastic carcinoma stroma sample, whilst CD138 was positive in one ameloblastoma case, one desmoplastic ameloblastoma case, and in two ameloblastic carcinoma stroma samples. Finally, alpha-SMA was found positive only in the desmoplastic ameloblastoma stroma sample. Our results suggest nestin expression to be an indicator for ameloblastic carcinoma, and CD138 and alpha-SMA to be promising biomarkers for the malignant transformation of ameloblastoma. Our data showed that nestin, CD138, and alpha-SMA are novel biomarkers for a better understanding of the origins and behaviour of ameloblastic tumours.

Hypoxia enhances basal autophagy of epithelial-derived ameloblastoma cells

Ameloblastoma is a locally aggressive odontogenic tumor. Etiopathogenesis and locally aggressive growth properties of ameloblastoma can be attributed to a hypoxic microenvironment conducive to tumor cell survival. Epithelial-derived follicular ameloblastoma cells (EP-AMCs) display enhanced basal autophagy, but the interplay of hypoxia and autophagy in EP-AMCs survival and ameloblastoma recurrence is unclear. We evaluated differential expression of autophagic markers in primary and recurrent ameloblastomas and hypothesized that hypoxia-induced autophagy supports EP-AMC survival. Primary and recurrent ameloblastomas were comparatively assessed for expression levels of pan-cytokeratin, Vimentin, and autophagic markers SQSTM1/p62, LC3, and pS6. EP-AMCs compared with human odontoma-derived cells (HODCs) were subjected to severe hypoxia to determine the interplay of hypoxia and autophagic process in posthypoxia survival. Pan-cytokeratin and SQSTM1/p62 were expressed by both primary and recurrent ameloblastoma epithelial cells while the ameloblastoma connective tissues displayed weak reactivity to vimentin. Under hypoxia, EP-AMC expression levels of hypoxia-inducible factor (HIF)-1α, p62, and LC3 were increased while pS6 was decreased posthypoxia. The combined decrease in pS6 and enhanced LC3 in EP-AMCs under hypoxia indicate that EP-AMCs re-establish basal autophagy under hypoxia. Taken together, these suggest a possible role of LC3-associated phagocytosis (LAP) in ameloblastoma cell survival.

Insight into the molecular pathogenesis of odontogenic lesions

BACKGROUND

Odontogenic tumors, derived from epithelial, ectomesenchymal, and/or mesenchymal elements of the tooth-forming apparatus, constitute a heterogeneous group of lesions, including hamartomas, benign and malignant neoplasms with metastatic capabilities.

HIGHLIGHT

This review provides a comprehensive overviewof the pathogenesis of odontogenic tumors and explains the associated molecular events in the context of hallmarks of cancer established by Hanahan D and Weinberg RA. Diagrammatic representations depicted in the article would facilitate easier understanding.

CONCLUSION

A better understanding of the pathogenesis of the lesions may assist in determining patient's prognosis and devising better targeted therapeutic treatment, thus, reducing the morbidity and mortalityof patients.

Calcifying Epithelial Odontogenic Cyst of Maxilla: Report of A Case and Review and Discussion on the Terminology and Classification

A cyst is defined as a pathological cavity which may or may not have an epithelial lining and which has a fluid, semi-fluid, or gaseous contents and is not formed by accumulation of pus. The calcifying epithelial odontogenic cyst (CEOC) was first reported by Gorlin et al. in 1962. At that time, it was classified as a cyst related to the odontogenic apparatus. It was later renamed as calcifying cystic odontogenic tumor (CCOT) in the World Health Organization classification devised in 2005 due to its histological complexity, morphological diversity, and aggressive proliferation. CCOT was later recognized by numerous names including Gorlin cyst, calcifying ghost cell odontogenic cyst, and/or dentinogenic ghost cell tumor. It has a peak incidence during the second and third decades of life and does not demonstrate any gender predilection. Radiographically, CEOC may appear as a unilocular or multilocular radiolucent lesion with either well-circumscribed or poorly-defined margins and may also be observed in association with unerupted teeth. Calcification is an important radiographic feature for the interpretation of CEOC/CCOT. The typical histopathological features of CEOC include a fibrous wall and lining of odontogenic epithelium with either columnar or cuboidal basal cells resembling ameloblasts. The treatment of choice for CEOC is conservative surgical enucleation, however, recurrence is also not found to be uncommon. Herein, we are reporting a case of the same in a 21-year-old female which was a great dilemma during the diagnostic work-up.

Immunohistochemical expression of p53 and murine double minute 2 protein in odontogenic keratocyst versus variants of ameloblastoma

Introduction

Oncogenes and tumor suppressor genes play a major role in cancer formation, growth, and progression. One of the important findings in this area is that murine double minute 2 (MDM2) oncogene is a negative regulator of wild-type p53. In tumors, expressing wild-type p53, inhibition of MDM2 expression will stabilize p53 and allow it to perform its proapoptotic function, while simultaneously preventing MDM2 from exerting its p53-independent oncogenic effects. The intracellular levels of p53 are tightly regulated by MDM2, as it is a key player in autoregulatory feedback loop under nonstressed conditions. The p53-MDM2 relationship is vital not only for essential functions of the cell, but it also appears to be an integrated part of the complex cellular network which supports the importance of this affair and is a hallmark for its coexistence.

Subjects and Methods

This study was designed to identify immunohistochemically the expression of p53 and MDM2 gene using monoclonal antibody in 60 cases of formalin-fixed paraffin-embedded tissue blocks, of which 20 cases were of solid multicystic ameloblastoma (SMA), 20 cases were of odontogenic keratocyst (OKC), and 20 cases were of unicystic ameloblastoma (UA).

Results

Immunoexpression of p53 and MDM2 was highest in OKC followed by SMA and was minimum in UA. Further results showed positive correlation between both the molecules.

Conclusion

The studied showed that the relationship has a significant role in cancer etiology and progression and therefore is an important topic for future research which should help in the development of new therapeutic agent against cancer.

DNA damage and repair scenario in ameloblastoma

Ameloblastoma is a rare human disease of benign neoplasm odontogenic tumor with a lower prevalence but higher recurrence rate. Etiology of ameloblastoma is not fully understood thus lacks implementation of curative treatments. One of the proposed models of evolution of ameloblastoma is related to alteration in DNA damage and repair effects. Growing body of literature has associated defect in DNA damage and repair mechanisms with cancer risk and various adverse health outcomes in humans. Persistent defect of repair and escape of these genomic unstable cells from cell death mechanisms can contribute towards accumulation of oncogene driver or tumor suppressor mutations selective for malignant transformations. In addition, growth, progression and survival of tumor depends upon its DNA repair mechanisms too, thus identifying a DNA repair biomarker can be of advantageous to eliminate the tumor. Understanding the interconnection of oral lesion and role of various DNA repair mechanisms in context to ameloblastoma will assist to build up a platform for translational based research. This study is a literature review of research work published up to date in the field of ameloblastoma in regard to DNA damage and repair effects.

The dilemma of extensive unilocular radiolucent lesions of the jaws - value of immunohistochemistry as a diagnostic marker and prognostic Indicator

INTRODUCTION

Large Unilocular radiolucent lesions of the jaws often present a dilemma to both, the Oral Pathologist and the Maxillofacial surgeon with regards to their accurate diagnosis as well as their most appropriate treatment modality. A precise identification as to whether the lesion is a cyst or a tumor is imperative before any treatment is instituted. Once the correct diagnosis and likely prognosis are established, a management protocol can be planned which will completely eliminate the lesion, while at the same time, ensure least possible morbidity for the patient, such as pathological jaw fractures, persisting neurological deficits, esthetic deformity, functional debility, recurrence/persistence of the lesion, etc. AIM & OBJECTIVES: To establish the value of Immunohistochemistry (IH) as a Diagnostic marker and Prognostic indicator for extensive Unilocular radiolucent lesions of the jaws. To assess its role as an adjunct to Histopathological Examination (HPE) in distinguishing Odontogenic tumours from the cysts, by identifying the former using IH Tumor Markers; and in aiding in selection of the most appropriate and effective treatment option for each of such ambiguous lesions, based on their prognosis as indicated by the expression of lH Cell Proliferation Markers.

MATERIALS AND METHOD

Thirty cases of large Unilocular Radiolucent lesions of the jaws (Maxilla/Mandible) were managed over a period of three years. Histopathological examination (HPE) and Immunohistochemical (IH) analysis were carried out of the biopsy specimens in all the cases. Calretinin, an Immunohistochemical Tumor marker, was used to distinguish between Odontogenic cysts and tumours. Ki-67 and Proliferating Cell Nuclear Antigen (PCNA), Immunohistochemical Cell Proliferation markers, provided information on the aggressive potential of the lesions. On the basis of the above information, an appropriate management protocol was established for each of these different lesions. Nerve sparing enucleation and curettage was employed for the established cases of Odontogenic Cysts; Enucleation and curettage, peripheral ostectomy, followed by chemical cauterization was employed for the Unicystic Ameloblastomas and other Odontogenic tumours with a low Ki-67 and PCNA Proliferation Index (PI)/Labelling index (LI ≤ 3); Marginal resection was carried out for the tumours with a higher Labelling Index (LI >3 ≤5), and Segmental resection (including partial/complete Maxillectomy, Hemimandibulectomy with/without disarticulation) for the aggressive pathologies with high Labelling Index (LI > 5).

RESULTS

Of the thirty cases of large Unilocular radiolucent lesions of the Maxilla and Mandible, thirteen were diagnosed as Dentigerous cysts, one as Dentigerous cyst showing Ameloblastomatous transformation; two as Unicystic Ameloblastomas, one as the Mural variant of Unicystic Ameloblastoma; four as Follicular Ameloblastomas, two as Plexiform Ameloblastomas; four as Acanthomatous Ameloblastomas; one as Ameloblastic Fibroma and two as Adenomatoid Odontogenic Tumours. The predictive and prognostic indication of the Immunohistochemical markers correlated well with the post treatment findings.

CONCLUSION

In cases of extensive Unilocular lesions of the jaws, where ambiguity often exists in both diagnosis and appropriate treatment plan to be employed, Immunohistochemistry can serve as an invaluable tool in establishing the precise diagnosis, guiding the treatment plan, as well as indicating the likely prognosis of these lesions.

Detection of MAPK/ERK pathway proteins and KRAS mutations in adenomatoid odontogenic tumors

OBJECTIVE

This study aimed to assess the frequency of KRAS mutation and its association with the presence of the MAPK/ERK signaling pathway proteins in adenomatoid odontogenic tumors.

STUDY DESIGN

Paraffin-embedded tissue samples from nine cases of adenomatoid odontogenic tumor were used. Genomic DNA was extracted from each sample; in one case, genetic mutations in 50 cancer-associated genes were examined by next-generation sequencing. Hotspot mutations in the RAS family were analyzed by Luminex assay using the remaining eight cases. Subsequently, immunohistochemistry for KRAS, CRAF, BRAF, EGFR, ERK, MEK, and BRAFV600E was performed.

RESULTS

A KRAS G12D missense mutation was detected in the DNA sequence of the tumor cells, but it was not detected in the stromal tissue. KRAS G12V and KRAS G12R mutations were detected in two and four cases, respectively. For immunohistochemistry, all the cases were EGFR, KRAS, BRAF, CRAF positive, one case was ERK negative,and one case was MEK and ERK negative, all the other remaining cases were MEK and ERK positive.

CONCLUSION

KRAS mutation at codon 12 and the presence of MAPK/ERK pathway proteins were detected suggesting their association with tumorigenesis of adenomatoid odontogenic tumors.

Upregulation of eukaryotic translation initiation factor 3 subunit a promotes cell survival in ameloblastoma

OBJECTIVES

This study aimed to detect the expression of eukaryotic translation initiation factor 3 subunit a (eIF3a) in ameloblastoma (AB) tissues compared with normal oral mucosa (NOM) tissues and investigate the roles of eIF3a in the immortalized ameloblastoma cell line (AM-1) cell proliferation and apoptosis.

STUDY DESIGN

We performed immunohistochemistry to determine the expression of eIF3a in AB tissues (n = 83) and NOM tissues (n = 20). Real time-quantitative polymerase chain reaction and Western blot analyses were conducted with AB tissues (n = 30) and NOM tissues (n = 6). The correlation between eIF3a expression and the clinical/pathologic features of patients with AB is also presented. The functional role of eIF3a in AM-1 cells was assessed with lentiviral vector-mediated shRNA (small hairpin RNA).

RESULTS

Our results indicated that eIF3a was significantly upregulated in AB. Additionally, eIF3a knockdown in AM-1 cells significantly inhibited cell proliferation and promoted apoptosis.

CONCLUSIONS

These data indicate that eIF3a facilitates the survival of AB cells and may serve as a promising therapeutic target in AB.

Roles of FGF8 subfamily in embryogenesis and oral‑maxillofacial diseases (Review)

Fibroblast growth factors (FGFs) are diffusible polypeptides released by a variety of cell types. FGF8 subfamily members regulate embryonic development processes through controlling progenitor cell growth and differentiation, and are also functional in adults in tissue repair to maintain tissue homeostasis. FGF8 family members exhibit unique binding affinities with FGF receptors and tissue distribution patterns. Increasing evidence suggests that, by regulating multiple cellular signaling pathways, alterations in the FGF8 subfamily are involved in craniofacial development, odontogenesis, tongue development and salivary gland branching morphogenesis. Aberrant FGF signaling transduction, caused by mutations as well as abnormal expression or isoform splicing, plays an important role in the development of oral diseases. Targeting FGF8 subfamily members provides a new promising strategy for the treatment of oral diseases. The aim of this review was to summarize the aberrant regulations of FGF8 subfamily members and their potential implications in oral‑maxillofacial diseases.

Evaluation and Immunolocalization of BMP4 and FGF8 in Odontogenic Cyst and Tumors

Growth factors like bone morphogenetic protein 4 (BMP4) and fibroblast growth factor 8 (FGF8) play a major role in organogenesis and specifically in odontogenesis. They are also believed to have a role in oncogenesis. Thus, any discrepancies in their standard behavior and activity would lead to serious abnormalities including odontogenic cyst and tumors. The present research work investigated the expression of BMP4 and FGF8 in odontogenic tumors (OT) and cyst as well as developing tooth germs to elucidate their roles. Dental organs of various odontogenic stages and 30 OTs including solid multicystic ameloblastomas (SMA, 10 cases), ameloblastic fibroma (AF, 10 cases), odontogenic myxoma (OM, 10 cases), and odontogenic cysts: odontogenic keratocyst (OKC, 10 cases) were evaluated in both epithelial and mesenchymal components for the expression of BMP4 and FGF8 using immunohistochemistry. The epithelial nuclear expression of BMP4 was highest in OKC (9 cases) while FGF8 was highest in SMA (10 cases). The mesenchymal nuclear expression of both BMP4 (8 cases) (p = 0.001) and FGF8 (9 cases) (p = 0.045) were significantly high in OMs among all OTs. Both growth factors were actively expressed in different stages of tooth development. The expression of BMP4 and FGF8 corelates well with the proliferative component of the pathologies, indicating a possible role in the pathogenesis and progression.

Amelogenin is a Potential Biomarker for the Aggressiveness in Odontogenic Tumors

Amelogenin (AMEL), the major structural protein of the enamel organic matrix, constitutes more than 90% of the enamel’s protein content, Aberrations of amelogenin are thought to be involved in the oncogenesis of odontogenic epithelium. The expression of amelogenin is possibly an indicator of differentiation of epithelial cells in the odontogenic tumors. Aim of the study: Investigating the expression of amelogenin in some odontogenic tumors, using an anti-amelogenin polyclonal antibody, and then compare it with AMEL expression in tooth buds as control. Materials and Methods: study sample consisted of 10 formalin-fixed, paraffin- embedded specimens of ameloblastoma, 10 Keratocystic odontogenic tumors, and 10 tooth buds were conventionally stained with hematoxylin-eosin and immunohistochemically with AMEL polyclonal antibody. Results: All of the odontogenic tumors expressed AMEL in the epithelial component, Intensity of expression in ameloblastoma and Keratocystic odontogenic tumor was lower, compared with tooth buds, Statistical analysis indicated a significant differences between the tumors and tooth buds. Conclusion: Amelogenin can be used as a marker for odontogenic epithelium, and the expression of amelogenin is possibly an indicator of epithelial cells differentiation in the odontogenic tumors, and therefore in prediction of the histological behavior of odontogenic tumors.

Expression profile of polycomb group proteins in odontogenic keratocyst and ameloblastoma

Polycomb group (PcG) proteins are repressive chromatin modifiers required for proliferation and development. PcG proteins form two large repressive complexes, namely, Polycomb Repressive Complex 1 and 2. These proteins have been shown to drive tumorigenesis by repressing cell-type specific sets of target genes. Using immunohistochemistry, we investigated the expression patterns of five human PcG proteins, including Bmi-1, Ring1b, Mel-18, Ezh2, and Suz12, in various cellular components of odontogenic keratocysts (OKCs), ameloblastomas and, pericoronal follicles (PFs). In OKCs, expression of PcG proteins were found in the majority of cases while the expression pattern was relatively different for each PcG proteins. All PcG proteins were strongly expressed in the basal cells while some proteins showed variable expression in the parabasal and luminal cell layer of OKCs. In ameloblastomas, almost all PcG proteins showed a similar expression pattern of moderate to strong staining in the peripheral ameloblast-like cells and metaplastic squamous cells. Some of the central stellate reticulum-like cells also showed positive reaction to most PcG proteins. In PFs, most PcG proteins were intensely expressed in odontogenic epithelium lining the follicles, except Mel-18 and Suz12. The present study provides the initial evidence regarding epigenetic involvement by PcG proteins in these odontogenic lesions. Although these proteins are known to be in the same repressive group proteins, differential expression patterns of these proteins in OKCs and ameloblastomas indicates that these proteins may play different roles in pathogenesis of these odontogenic lesions.

Genetic study of the BRAF gene reveals new variants and high frequency of the V600E mutation among Iranian ameloblastoma patients

BACKGROUND

Ameloblastoma is a benign, slow-growing and locally invasive tumor. It is one of the most prevalent odontogenic tumors, with an incidence rate of 1% of all oral tumors and approximately 18% of odontogenic tumors. A group of genes have been investigated in patients with ameloblastoma. The BRAF V600E mutation has been implicated as the most common mutation in ameloblastoma. The presence or absence of this mutation has been associated with several clinicopathological properties, including location, age at diagnosis, histology, and prognosis. Although some populations have been investigated so far, little data are available on the Iranian population. The current research was launched to study the BRAF V600E mutation among a cohort of Iranian patients with ameloblastoma.

METHODS

In this clinicopathological and molecular biology study, a total of 19 formalin-fixed, paraffin-embedded tissues were studied. DNA extraction was performed, followed by PCR-sequencing of exons 10 and 15 of the BRAF gene to identify mutations. In silico analysis was performed for the identified variants. Results were analyzed by T test, Chi-square, and Fisher's exact test.

RESULTS

Totally, 12 of 19 samples (63%) harbored the p. V600E hotspot mutation. In addition, we identified several variants, two of which were novel. The c.1769T>G (p. V590G) and c.1751C>T (p.L584F) as the novel variants showed a possible damaging effect by in silico analysis. No variant was found within exon 10.

CONCLUSIONS

Our study confirms the role of BRAF mutations in ameloblastoma in the Iranian patients studied.

Comparative immunohistochemical study of Bcl-X in ameloblastoma, keratocystic odontogenic tumor and adenomatoid odontogenic tumor

Objectives:

Since its recognition as a physiologic process associated with tumor, among molecular mechanisms involved in tumor progression, defects in regulation of apoptosis have generated an accelerating volume of research that has sought to elucidate the role of programed cell death in pathogenesis and treatment of various tumors. Therefore, this study was performed to understand better the diverse biological profile of epithelial odontogenic tumors with the help of immunohistochemical expression of Bcl-X protein.

Materials and Methods:

We studied Bcl-X protein expression in 45 cases of epithelial odontogenic tumors which included 15 cases each of ameloblastomas, keratocystic odontogenic tumor (KCOT) and adenomatoid odontogenic tumor (AOT) and correlated the expression with their growth pattern.

Results:

Cytoplasmic staining of Bcl-X revealed overexpression in ameloblastoma when compared to KCOT and AOT. Percentage of positive cells showed a statistically significant difference, P = 0.007 between ameloblastoma and KCOT, whereas P < 0.001 between ameloblastoma and AOT. However, no significance was observed between KCOT and AOT (P = 0.132).

Conclusion:

The present study supports the fact that epithelial odontogenic tumors show diverse growth profiles. An increased Bcl-X expression was seen in ameloblastoma compared to KCOT and least expression in case of AOT which could be indicative of more aggressive biological behavior and increased cell survival activity of ameloblastoma than KCOT and AOT. This signifies the diagnostic relevance of this biomarker and also could be a possible regulator of the proliferative compartment by contributing in tumor progression and cytodifferentiation of epithelial odontogenic tumors.

Role of podoplanin expression in deciding the invasive potential of ameloblastoma - A retrospective IHC study

BACKGROUND

The aim of this study was to investigate the podoplanin expression in epithelial odontogenic tumors both non-aggressive and aggressive, tumors with and without ectomesenchyme and remnants of the odontogenic epithelium from dental follicles (DF) of unerupted teeth and to examine its role in progression and invasion of tumors.

METHOD

Thirty paraffin embedded specimens AM (15 were non-aggressive ameloblastomas and 15 ameloblastoma showing aggressive behavior), 15 paraffin embedded specimens of AOT, 15 paraffin embedded specimens of CEOT, 15 paraffin embedded specimens of CCOT were obtained and were analyzed by immunohistochemistry using anti-human podoplanin. Podoplanin expression in odontogenic epithelial cells was evaluated using a scoring method, along with calculation of the percentage of positive odontogenic cells.

RESULTS

Podoplanin was expressed strongly at the invasive front (in the peripheral odontogenic epithelial cells) of most tumors and dental follicles. Membranous expression of podoplanin in ameloblastomas was stronger in cases of ameloblastomas showing aggressive behavior than (NA) non-aggressive ameloblastomas.

CONCLUSION

Expression of podoplanin at the invasive front (in peripheral cells) of odontogenic tumors considered to be associated with neoplastic odontogenic tissues. This molecule might play a role in progression and local invasion of odontogenic tumors. The migration and invasion mediated by podoplanin in odontogenic tumors could be related to cytoskeletal reorganization.

CD166 expression in dentigerous cyst, keratocystic odontogenic tumor and ameloblastoma

Background

CD166 is a glycoprotein of an immunoglobulin super family of adhesion molecules that has been associated with aggressive characteristics and high recurrence rate of tumors. Different odontogenic lesions exhibit considerable histological variation and different clinical behavior. In an attempt to clarify the mechanisms underlying this different behavior, the present study investigates the immunohistochemical expression of CD166 in these lesions.

Material and Methods

In this study 69 formalin-fixed, paraffin embedded tissue blocks of odontogenic lesion consist of 15 unicystic ameloblastoma (UA), 17 solid ameloblastoma (SA), 18 keratocystic odontogenic tumors (KCOT), and 19 dentigerous cysts (DC) were reviewed by immunohistochemistry for CD166 staining.

Results

In this study, CD166 immune staining was evident in all specimen groups except dentigerous cyst. In positive cases, protein localization was cytoplasmic and/or membranous. CD166 expression was seen in76.5% (13) of SA, 73.5% (11) of UA, and 66.7% (12) of KCOTs. Statistical analysis showed that CD166 expression levels were significantly higher in ameloblastoma (SA and UA) and KCOTs than dentigerous cyst (P <0.001), but there was no statistically significant difference between CD166 expression in the other groups (P>0.05).

Conclusions

This data demonstrates that overexpression of CD166 may have a role in the pathogenesis of ameloblastoma and KCOT.

Key words:CD166, ameloblastoma, dentigerous cyst, odontogenic keratocyst.

Immunohistochemistry of Five Molecular Markers for Typing and Management of Ameloblastomas: A Retrospective Analysis of 40 Cases

PURPOSE

The aims of this study are to elucidate if molecular markers can be used to differentiate between the two main types of ameloblastoma (unicystic and solid/multicystic), and to determine whether a biologically 'less-aggressive' subtype exists.

METHODS

A retrospective analysis of 33 solid/multicystic ameloblastomas and six unicystic ameloblastomas was completed using immunohistochemistry for five molecular markers: P16, P53, MMP-9, Survivin, and Ki-67. Tumors were graded as either negative or positive (mild, moderate, strong), and the results were related to both ameloblastoma subtypes and outcomes following treatment.

RESULTS

Unicystic ameloblastomas were more likely to test strongly positive for P53 than solid/multicystic ameloblastomas (p < 0.05), whereas the latter were more likely to be negative for Survivin (p < 0.05). Solid/multicystic and Type 3 unicystic ameloblastomas that were positive for P16, but also negative for MMP-9 and Survivin, were less likely to recur than all other tumors (p < 0.05). The proliferation index of an ameloblastic carcinoma (11 %) was shown to be higher than benign ameloblastomas (4.5 %).

CONCLUSIONS

Immunohistochemistry can be valuable in lesions where histological sub-typing of an ameloblastoma is unclear. A biologically 'less-aggressive' subtype may exist, and hence further research into this area is required.

Immunohistochemical expression of WNT5A and MMPs in odontogenic epithelial tumors and cysts

OBJECTIVE

The aim of this study was compare the expression of WNT5A and MMP2, 7 and 20, in frequent benign odontogenic tumors and odontogenic cysts, since these lesions have a different biological behavior.

MATERIALS AND METHODS

Eighty-one paraffin-embedded specimens of odontogenic tumors, including ameloblastoma and keratocystic odontogenic tumor, and thirty-two odontogenic cysts were used for immunohistochemical analysis.

RESULTS

The expression of WNT5A in odontogenic tumors and inflammatory cyst was higher than in developmental odontogenic cyst. There was no statistical difference (p<0.05) in the expression of WNT5A when comparing the analyzed tumors. The expression of MMP7 was lower in RC with a statistical difference when compared with all tumors and cysts. Statistical differences also occurred when comparing glandular odontogenic cyst (GOC) to keratocyst odontogenic tumor (KOT) and calcifying cystic odontogenic tumor (CCOT). MMP20 expression was higher in ameloblastoma when compared to adenomatoid odontogenic tumor (AOT), DC and GOC. The expression of MMP20 was lower in CCOT when compared to all tumors and cysts.

CONCLUSIONS

The expression of WNT5A in a group of odontogenic lesions suggests the participation of a non-canonical WNT signaling pathway in the progression and maintenance of these lesions. These molecules are possibly involved in the biological differences between odontogenic tumors and cysts. Considering previous studies, WNT5A may help promote the calcification seen in AOT, CCOT and CEOT by activating MMP7.

Pediatric Metastatic Odontogenic Ghost Cell Carcinoma: A Multimodal Treatment Approach

Odontogenic ghost cell carcinoma (OGCC) is a rare and aggressive tumor wherein optimal treatment remains uncertain. We report the first pediatric metastatic OGCC case treated with multimodal therapy: surgery, adjuvant chemoradiation, and adjuvant immunotherapy. Adjuvant therapy was utilized due to locally advanced disease with pathologic features indicative of high recurrence risk. This multimodal approach was modeled after management of primary head and neck cancer, where adjuvant chemoradiation and immunotherapy are associated with improved outcomes. Our patient is alive and disease free at 14 months indicating a potentially positive role for multimodal therapy in the management of OGCC.

Amelogenin in odontogenic cysts and tumors: An immunohistochemical study

Background:

Amelogenins are the major enamel proteins that play a major role in the biomineralization and structural organization of enamel. Aberrations of enamel-related proteins are thought to be involved in oncogenesis of odontogenic epithelium. The expression of amelogenin is possibly an indicator of differentiation of epithelial cells in the odontogenic lesions.

Aims and Objectives:

The present study aimed to observe the expression of amelogenin immunohistochemically in various odontogenic lesions.

Materials and Methods:

Paraffin sections of 40 odontogenic lesions were stained immunohistochemically with amelogenin antibodies. The positivity, pattern and intensity of expression of the amelogenin antibody were assessed, graded and statistically compared between groups of odontogenic cysts and tumors.

Results:

Almost all the odontogenic lesions expressed amelogenin in the epithelial component with the exception of an ameloblastic carcinoma. Differing grades of intensity and pattern were seen between the cysts and tumors. Intensity of expression was uniformly prominent in all odontogenic lesions with hard tissue formation. Statistical analysis however did not indicate significant differences between the two groups.

Conclusion:

The expression of amelogenin antibody is ubiquitous in odontogenic tissues and can be used as a definitive marker for identification of odontogenic epithelium.

Immunohistochemical assessment of ATG7, LC3, and p62 in ameloblastomas

BACKGROUND

To investigate the roles of autophagy in tumorigenesis, cytodifferentiation, and prognosis of odontogenic tumors, we analyzed the immunohistochemical expression of ATG7, LC3, and p62 in odontogenic tissues.

METHODS

Tissue specimens of nine dental follicles and 69 ameloblastomas were immunohistochemically examined with antibodies against ATG7, LC3, and p62.

RESULTS

Immunohistochemical reactivity for ATG7, LC3, and p62 was detected in many odontogenic epithelial cells and several endothelial cells and fibroblasts in dental follicles and ameloblastomas. ATG7 reactivity in ameloblatomas was significantly higher than that in dental follicles. Expression of ATG7, LC3, and p62 was found markedly in neoplastic cells near the basement membrane rather than central polyhedral cells in ameloblastomas. Reactivity for these molecules was significantly higher in unicystic ameloblastomas than in solid ameloblastomas. Granular cells in granular cell ameloblastomas showed obvious reactivity for the autophagy- related molecules, and LC3 reactivity in granular cell ameloblastomas was significantly higher than in other ameloblastoma variations. Recurrent ameloblastomas showed significantly lower reactivity of LC3 and p62 than primary ameloblastomas.

CONCLUSIONS

Expression of ATG7, LC3, and p62 in dental follicles and ameloblastomas suggests that autophagy regulation might be affected by microenvironment alterations during tumorigenesis. The molecular machinery for autophagy is possibly involved in tissue architecture, neoplastic cell differentiation, and prognosis of the benign epithelial odontogenic tumor.

Proteomics profiling of keratocystic odontogenic tumours reveals AIDA as novel biomarker candidate

BACKGROUND

Keratocystic odontogenic tumour (KCOT) is a benign, yet aggressive odontogenic tumour. Herein, proteome analysis of KCOT lesions in comparison with control patient-matched tissue unaffected by the disease and with inflammatory odontogenic cysts, namely radicular cysts is presented.

METHODS

For the proteomics profiling, two complementary proteomics techniques MALDI-MS/MS and LC-ESI-MS/MS were employed. Potential candidate biomarkers were validated by immunohistochemistry.

RESULTS

More than 43 proteins were found to be differentially expressed or up-regulated in KCOT lesions in comparison with patient-matched unaffected oral mucosa. These proteins bear important biological functions and are involved in cell proliferation, cytoskeletal re-organization, transcription, cellular motility and apoptosis. In particular, a number of differentially expressed proteins participate in autocrine regulation and signalization within JNK and p38 MAPK signalling pathways.

CONCLUSIONS

Immunohistochemical validation of chosen putative biomarkers revealed axin interaction partner and dorsalization-antagonist (AIDA), known as a protein that blocks activation of JNK signalling pathway, as a differential biomarker for KCOT lesions on an independent cohort of KCOT tissue samples in comparison with most prevalent intra-oseal lesions inflammatory odontogenic cysts.

c-Myc oncogene expression in selected odontogenic cysts and tumors: An immunohistochemical study

Aim:

To investigate the role of c-Myc oncogene in selected odontogenic cysts and tumors.

Materials and Methods:

Ten cases each of ameloblastoma, adenomatoid odontogenic tumor (AOT), odontogenic keratocyst (OKC), dentigerous cyst, and radicular cyst were selected and primary monoclonal mouse anti-human c-Myc antibody was used in a dilution of 1: 50. Statistical Analysis was performed using Mann Whitney U test.

Results:

80% positivity was observed in ameloblastoma, AOT and OKC; 50% positivity in radicular cyst and 20% positivity in dentigerous cyst. Comparison of c-Myc expression between ameloblastoma and AOT did not reveal significant results. Similarly, no statistical significance was observed when results of OKC were compared with ameloblastoma and AOT. In contrast, significant differences were seen on comparison of dentigerous cyst with ameloblastoma and AOT and radicular cyst with AOT.

Conclusion:

From the above data we conclude that (1) Ameloblastoma and AOT have similar proliferative potential and their biologic behavior cannot possibly be attributed to it. (2) OKC has an intrinsic growth potential which is absent in other cysts and reinforces its classification as keratocystic odontogenic tumor.

Detection of epidermal growth factor receptor intensity in asymptomatic fully impacted lower third molar follicles of smoking and nonsmoking patients

OBJECTIVE

The objective of this study was to determine whether smoking causes pathological changes, comparing intensity of epidermal growth factor receptor (EGFR) expression in smokers' and nonsmokers' pericoronal follicles located around asymptomatic impacted lower third molars.

STUDY DESIGN

Eighty-two dental follicles were collected from asymptomatic mandibular third molars of 41 smoker and 41 nonsmoker patients. Specimens were examined immunohistochemically using antibody against EGFR.

RESULTS

The expression of EGFR in smokers' pericoronal follicles was higher as compared with nonsmokers (P = 0.036). Also, high EGFR expression was detected in female smokers than in female nonsmokers (P = 0.01). There was a statistically significant correlation between pack-years and EGFR expression intensity in male patients.

CONCLUSIONS

The risk of pathological differentiation in pericoronal tissues of smoking patients is higher than in the nonsmoking patients. This factor may be taken into account when deciding whether to remove an asymptomatic impacted lower third molar.

TGF-β1, Smad-2/-3, Smad-1/-5/-8, and Smad-4 signaling factors are expressed in ameloblastomas, adenomatoid odontogenic tumors, and calcifying cystic odontogenic tumors: an immunohistochemical study

OBJECTIVES

The TGF-β/Smad signaling pathway regulates diverse cellular functions, including tooth development, and is involved in numerous pathological processes such as tumorigenesis. The aim of this study was to investigate the immunoexpression of the TGF-β/Smad signaling pathway members in ameloblastoma (AM), calcifying cystic odontogenic tumor (CCOT), and adenomatoid odontogenic tumor (AOT).

MATERIALS AND METHODS

This retrospective cross-sectional study included 65 tissue specimens: 34 AMs, 13 CCOTs, and 18 AOTs. Serial sections were immunohistochemically stained with TGF-β1, Smad-4, Smad-1/-5/-8, and Smad-2/-3 antibodies, and a semiquantitative measurement of the positive cells was carried out by two oral pathologists using a 0-3 scale (0: no immunoreactivity, 1: <20% positive cells, 2: 20-50% positive cells, 3: >50% positive cells).

RESULTS

All biomarkers studied were found significantly decreased in AM compared to CCOT and AOT. AOT and CCOT expressed Smad-1/-5/-8 more strongly compared to AM (OR = 11.66, P < 0.001 and OR = 5.34, P = 0.013, respectively), and Smad-2/-3 immunostaining was found significantly increased in CCOT (OR = 10.42, P = 0.001) and AOT (OR = 5.16, P < 0.004) compared to AM. Similarly, Smad-4 was expressed more strongly in AOT and CCOT compared to AM (P = 0.001), while AOT demonstrated a fivefold higher chance to express TGF-β1 compared to AM (P = 0.011).

CONCLUSION

TGF-β/Smad signaling pathway is activated in AM, AOT, and CCOT. The statistically significant reduced TGF-β1/Smad immunoexpression in AM compared to AOT/CCOT could be associated with the more aggressive biological behavior of AM including increased cell proliferation and reduced apoptosis and differentiation. Thus, the biomarkers TGF-β, Smad-4, Smad-1/-5/-8, and Smad-2/-3 could serve as supplementary diagnostic indices between odontogenic tumors of high and low neoplastic dynamics.

Epigenetic regulation of matrix metalloproteinase expression in ameloblastoma

BACKGROUND

An ameloblastoma is a benign odontogenic neoplasm with aggressive behaviour and high recurrence rates. The increased expression of matrix metalloproteinases (MMPs) has been reported in ameloblastomas. In the present study, we hypothesised that epigenetic alterations may regulate MMP expression in ameloblastomas.

METHODS

We investigated the methylation status of the genes MMP-2 and MMP-9 in addition to mRNA transcription and protein expression in ameloblastomas. Methylation analysis was performed by both methylation-specific polymerase chain reaction (MSP-PCR) and restriction enzyme digestion to evaluate the methylation profile of MMP-2 and MMP-9 in 12 ameloblastoma samples and 12 healthy gingiva fragments, which were included as controls. Furthermore, we investigated the transcription levels of the genes by quantitative reverse-transcription PCR (qRT-PCR). Zymography was performed to verify protein expression in ameloblastomas.

RESULTS

The ameloblastomas showed a high frequency of unmethylated MMP-2 and MMP-9, whereas the healthy gingival samples presented a sharp prevalence of methylated MMPs. Higher expression levels of MMP-9 were found in ameloblastomas compared to healthy gingiva. However, no significant differences in the MMP-2 mRNA expression between groups was found. All ameloblastomas showed positive expression of MMP-2 and MMP-9 proteins.

CONCLUSIONS

Our findings suggest that expression of MMP-9 is increased in ameloblastomas and is possibly modulated by unmethylation of the gene.

N-methyl-N-nitrosourea-induced changes in epithelial rests of Malassez and the development of odontomas in rats

Morphological changes in the epithelial rests of Malassez (ERM) and the development of odontogenic tumors in the molars of female Lewis rats treated at 4 weeks of age with a single intraperitoneal injection of 50 mg/kg of N-methyl-N-nitrosourea (MNU) were examined at 12, 18 and 30 weeks of age. Following MNU exposure, the total number and average area of ERM in the cervical and furcational regions of the first, second and third molars of the mandible and maxilla were compared with age-matched control animals. The number of ERM at each time point was significantly greater in the MNU-treated group compared to the control group, but there was no time-dependent increase in the number of ERM in either group. The area of ERM was significantly larger in the MNU-treated group compared to the control group at each time point, and it increased in a time-dependent manner in the MNU-treated group. No increases in the number or area of ERM were observed in the control group. At 30 weeks of age, 23% of the MNU-treated rats had developed odontomas (complex type) in the molar region as well as in the incisor region. Immunohistochemically, the expression of tyrosine receptor kinase A (TrkA) and cytokeratin 14 (CK14) decreased, whereas p63 expression remained high during ERM enlargement. In tumors, ameloblast-like cells were positive for amelogenin, TrkA and CK14 but negative for p63, whereas odontoblast-like cells were negative for all antigens examined. In conclusion, a single intraperitoneal injection of MNU caused the development of odontomas in the molar region; these tumors were possibly derived from ERM.

Deregulated HOX genes in ameloblastomas are located in physical contiguity to keratin genes

The expression of the HOX gene network in mid-stage human tooth development mostly concerns the epithelial tooth germ compartment and involves the C and D HOX loci. To further dissect the HOX gene implication with tooth epithelium differentiation we compared the expression of the whole HOX network in human ameloblastomas, as paradigm of epithelial odontogenic tumors, with tooth germs. We identified two ameloblastoma molecular types with respectively low and high number of active HOX C genes. The highly expressing HOX C gene ameloblastomas were characterized by a strong keratinized phenotype. Locus C HOX genes are located on chromosome 12q13-15 in physical contiguity with one of the two keratin gene clusters included in the human genome. The most posterior HOX C gene, HOX C13, is capable to interact with hair keratin genes located on the other keratin gene cluster in physical contiguity with the HOX B locus on chromosome 17q21-22. Inside the HOX C locus, a 2.2 kb ncRNA (HOTAIR) able to repress transcription, in cis, along the entire HOX C locus and, in trans, at the posterior region of the HOX D locus has recently been identified. Interestingly both loci are deregulated in ameloblastomas. Our finding support an important role of the HOX network in characterizing the epithelial tooth compartment. Furthermore, the physical contiguity between locus C HOX and keratin genes in normal tooth epithelium and their deregulation in the neoplastic counterparts suggest they may act on the same mechanism potentially involved with epithelial tumorigenesis.

Loss of heterozygosity (LOH) in tumour suppressor genes in benign and malignant mixed odontogenic tumours

Although molecular alterations are reported in different types of odontogenic tumours, their pathogenesis remains to be established. Loss of heterozygosity (LOH) studies allow the identification of minimal regions of deletions of known or putative tumour suppressor genes, the losses of which may promote neoplastic growth. The purpose of this study was to investigate LOH in a set of odontogenic mixed tumours. Tumour suppressor gene loci on 3p, 9p, 11p, 11q and 17p chromosomes were analysed in five samples of ameloblastic fibroma (AF), three samples of ameloblastic fibro-odontoma (AFO) and three samples of ameloblastic fibrosarcoma (AFS). The most frequently lost genetic loci were p53 (17p13, 62%) and CHRNB1 (17p13, 55%). LOH at the chromosome regions 3p24.3, 9p22 and 9p22-p21 was identified only in AFS. No sample showed LOH at the chromosomal loci 3p21.2 and 11q13.4. For the region 9p22-p13, LOH occurred in one sample of AFO. The fractional allelic loss (FAL) was calculated for each sample. The mean FAL of the benign lesions (i.e. AF and AFO) was 22%, whereas the mean FAL of the malignant lesions (i.e. AFS) was 74.6%. In conclusion, our results show a higher FAL in AFS compared to its benign counterparts and reveal a different pattern of LOH of tumour suppressor genes in AFS, which may regulate changes in tumour behaviour.

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.

[Maxillary and mandibular carcinogenesis: research and prospects]

Development and growth of odontogenic tumours depend on impairment of numerous genes and molecules. In recent years, most of the genes involved in dental development were identified. This produced a new basis for the study of oral pathology and maxillofacial carcinogenesis. A better understanding of these molecular phenomena should allow to better determine the evolution of such lesions. Research breakthroughs should facilitate the development of new molecular and genetic therapeutic perspectives.

Detection of CD133, Bmi-1, and ABCG2 in ameloblastic tumors

BACKGROUND

To investigate the roles of stem cell-related molecules in oncogenesis and cytodifferentiation of odontogenic tumors, expression of CD133, Bmi-1, and ATP-binding cassette subfamily G member 2 (ABCG2) was analyzed in ameloblastic tumors as well as in tooth germs.

METHODS

Tissue specimens of 12 tooth germs, 47 ameloblastomas, and six malignant ameloblastic tumors were examined using reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry to determine the expression of CD133, Bmi-1, and ABCG2.

RESULTS

mRNA expression of CD133, Bmi-1, and ABCG2 was detected in all samples of normal and neoplastic odontogenic tissues. Immunohistochemical reactivity for CD133 and Bmi-1 was evident in odontogenic epithelial cells neighboring the basement membrane in tooth germs, ameloblastomas, and metastasizing ameloblastomas, and ameloblastic carcinomas and clear cell odontogenic carcinomas showed reactivity for CD133 and Bmi-1 in most neoplastic cells. The level of CD133 immunoreactivity in malignant ameloblastic tumors was significantly higher than the levels in tooth germs and ameloblastomas. Immunoreactivity for ABCG2 in odontogenic epithelial components was detected in some ameloblastic tumors but not in tooth germ tissues. Some granular neoplastic cells in granular cell ameloblastomas showed ABCG2 expression. The level of ABCG2 immunoreactivity in malignant ameloblastic tumors was significantly higher than that in tooth germs.

CONCLUSION

Expression of CD133, Bmi-1, and ABCG2 in tooth germs and ameloblastic tumors suggests that stem cell-related molecules might control the maintenance of odontogenic tissues. Expression of these molecules is possibly involved in oncogenesis, cell differentiation, and malignant potential of odontogenic epithelium.

Suppression of local invasion of ameloblastoma by inhibition of matrix metalloproteinase-2 in vitro

Background

Ameloblastomas are odontogenic neoplasms characterized by local invasiveness. This study was conducted to address the role of matrix metalloproteinase-2 (MMP-2) in the invasiveness of ameloblastomas.

Methods

Plasmids containing either MMP-2 siRNA or tissue inhibitor of metalloproteinase-2 (TIMP-2) cDNA were created and subsequently transfected into primary ameloblastoma cells. Zymography, RT-PCR, and Western blots were used to assess MMP-2 activity and expression of MMP-2 and TIMP-2, as well as protein levels.

Results

Primary cultures of ameloblastoma cells expressed cytokeratin (CK) 14 and 16, and MMP-2, but only weakly expressed CK18 and vimentin. MMP-2 mRNA and protein levels were significantly inhibited by RNA interference (P < 0.05). Both MMP-2 siRNA and TIMP-2 overexpression inhibited MMP-2 activity and the in vitro invasiveness of ameloblastoma.

Conclusion

These results indicate that inhibition of MMP-2 activity suppresses the local invasiveness of ameloblastoma cells. This mechanism may serve as a novel therapeutic target in ameloblastomas pursuant to additional research.