CLIC4 Function in the Epithelial-Mesenchymal Transition of Epithelial Odontogenic Lesions.

BACKGROUND: Odontogenic lesions constitute a heterogeneous group of lesions. CLIC4 protein regulates different cellular processes, including epithelial-mesenchymal transition and fibroblast-myofibroblast transdifferentiation. This study analyzed CLIC4, E-cadherin, Vimentin, and α-SMA immunoexpression in epithelial odontogenic lesions that exhibit different biological behavior. METHODS: It analyzed the immunoexpression of CLIC4, E-cadherin, and Vimentin in the epithelial cells, as well as CLIC4 and α-SMA in the mesenchymal cells, of ameloblastoma (AM) (n = 16), odontogenic keratocyst (OKC) (n = 20), and adenomatoid odontogenic tumor (AOT) (n = 8). Immunoexpressions were categorized as score 0 (0% positive cells), 1 (< 25%), 2 (≥ 25% - < 50%), 3 (≥ 50% - < 75%), or 4 (≥ 75%). RESULTS: Cytoplasmic CLIC4 immunoexpression was higher in AM and AOT (p < 0.001) epithelial cells. Nuclear-cytoplasmic CLIC4 was higher in OKC's epithelial lining (p < 0.001). Membrane (p = 0.012) and membrane-cytoplasmic (p < 0.001) E-cadherin immunoexpression were higher in OKC, while cytoplasmic E-cadherin expression was higher in AM and AOT (p < 0.001). Vimentin immunoexpression was higher in AM and AOT (p < 0.001). Stromal CLIC4 was higher in AM and OKC (p = 0.008). Similarly, α-SMA immunoexpression was higher in AM and OKC (p = 0.037). Correlations in these proteins' immunoexpression were observed in AM and OKC (p < 0.05). CONCLUSIONS: CLIC4 seems to regulate the epithelial-mesenchymal transition, modifying E-cadherin and Vimentin expression. In mesenchymal cells, CLIC4 may play a role in fibroblast-myofibroblast transdifferentiation. CLIC4 may be associated with epithelial odontogenic lesions with aggressive biological behavior.

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

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

Comprehensive insights into the understanding of hypoxia in ameloblastoma.

Hypoxia is characterized by a disparity between supply and demand of oxygen. The association between hypoxia and head and neck tumors is a topic of significant interest. Tumors frequently encounter areas with inadequate oxygen supply, resulting in a hypoxic microenvironment. Ameloblastoma is one of the most common benign odontogenic tumors of the maxillofacial region. It is a slow-growing but locally invasive tumor with a high recurrence rate. The literature has demonstrated the correlation between hypoxia and ameloblastoma, revealing a discernible link between the heightened expression of hypoxic markers in low oxygen conditions. This association is intricately tied to the tumoral potential for invasion, progression, and malignant transformation. Hypoxia profoundly influences the molecular and cellular landscape within ameloblastic lesions. The present review sheds light on the mechanisms, implications, and emerging perspectives in understanding this intriguing association to clarify the dynamic relationship between hypoxia and ameloblastoma.

Prognostic value of the expression and localization of cell proliferation and apoptosis markers in unicystic ameloblastomas.

The aim of this study was to verify whether the expression of cell proliferation and apoptosis markers in different types of unicystic ameloblastoma (UA) is associated with the location of neoplastic cells. Immunohistochemical study with a sample of 32 cases of UA, 11 cases of conventional ameloblastoma (CAM) and ten dental follicles (DF) cases was performed. Cell proliferation was assessed using Ki-67 status, and apoptosis by caspase-3 expression. Mural UA (MUA) showed a higher immunostaining of Ki-67 (p < 0.05) and a lower immunostaining of Caspase-3 (p < 0.05) compared with luminal and intraluminal subtypes of UA and CAM. The neoplastic cells of the MUA's cystic capsule showed a higher expression of Ki-67 protein (p < 0.0001) and a lower expression of Caspase-3 (p < 0.0001) compared with the lumen. DF showed lower Ki-67 and Caspase-3 immunostaining (p < 0.05) than neoplasms. The higher immunoexpression of Ki-67 and the lower immunoexpression of Caspase-3 in MUA, in the parenchyma cells within the cystic capsule, suggest an association between the biological behaviour and location of neoplastic cells in a tumour.

Expression of stem cell markers SALL4, LIN28A, and KLF4 in ameloblastoma.

BACKGROUND: Ameloblastoma (AME) is a benign odontogenic tumour of epithelial origin characterised by slow but aggressive growth, infiltration, and recurrence; it is capable of reaching large dimensions and invading adjacent structures. Stem cell research has proven to be significant in the sphere of tumour biology through these cells' possible involvement in the aetiopathogenesis of this tumour. METHODS: Immunohistochemistry was performed on AME, dentigerous cyst (DC), and dental follicle (DF) samples, and indirect immunofluorescence was performed on the AME-hTERT cell line to determine the expression of SALL4, LIN28A, and KLF4. RESULTS: Expression of proteins related to cellular pluripotency was higher in AME cells than in DC and DF cells. The analysis revealed that the proteins in question were mainly expressed in the parenchyma of AME tissue samples and were detected in the nuclei of AME-hTERT cells. CONCLUSIONS: Stem cells may be related to the origin and progression of AME.

Connexin 43 expression in tooth germ and benign odontogenic tumors.

OBJECTIVE: The aim of this study was to investigate and compare the immunohistochemical expression of connexin 43 (Cx43) in tooth germs (TGs), ameloblastic fibromas (AFs), ameloblastic fibro-odontomas (AFOs), and conventional ameloblastomas (AMs). STUDY DESIGN: Nine TGs, 12 AFs, 12 AFOs, and 27 AMs were evaluated for Cx43 expression by immunohistochemistry. RESULTS: Most of the TGs expressed Cx43 in the mesenchyme (77.6%) and in the late stages of odontogenesis. Cx43 was more highly expressed (P < .05) in the mesenchymal layer of all groups than in the epithelial layer except for the AFOs. When comparing the expression of Cx43 in the different layers of the analyzed groups, statistically significant differences were observed between AFO vs AM (*P = .0158) in the epithelial layer and between AF vs AFO (P** = .0046) in the mesenchymal layer. CONCLUSIONS: The results obtained in this study showed that Cx43 is a protein with important expression in the mesenchymal layer of the embryonic and odontogenic tissues studied. It could be speculated that Cx43 participates in mineralization events based on the relationship of the expression of this protein between the epithelial and mesenchymal layers of odontogenic tissues.

Immunoexpression of stem cell markers SOX-2, NANOG AND OCT4 in ameloblastoma.

Background: Ameloblastoma (AME) is characterized by a locally invasive growth pattern. In an attempt to justify the aggressiveness of neoplasms, the investigation of the role of stem cells has gained prominence. The SOX-2, NANOG and OCT4 proteins are important stem cell biomarkers. Methodology: To verify the expression of these proteins in tissue samples of AME, dentigerous cyst (DC) and dental follicle (DF), immunohistochemistry was performed and indirect immunofluorescence were performed on the human AME (AME-hTERT) cell line. Results: Revealed expression of SOX-2, NANOG and OCT4 in the tissue samples and AME-hTERT lineage. Greater immunostaining of the studied proteins was observed in AME compared to DC and DF (p < 0.001). Conclusions: The presence of biomarkers indicates a probable role of stem cells in the genesis and progression of AME.

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

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

Immunohistochemical study of the plasminogen activator system in benign epithelial odontogenic lesions.

The aim of this study was to analyze and compare the immunohistochemical expression of plasminogen activator system (PAS) proteins (uPA, uPAR, and PAI-1) in ameloblastomas (AMBs), odontogenic keratocysts (OKCs), and dental follicles (DFs) representing normal odontogenic tissue, as well as to investigate possible correlations between these proteins. Twenty AMBs, 20 OKCs, and 10 DFs were selected for immunohistochemical analysis. In each case, the immunoexpression of uPA, uPAR, and PAI-1 was evaluated semiquantitatively based on the percentage of positivity in odontogenic epithelial and connective tissue cells. The epithelial immunoexpression of uPA was significantly lower in AMBs when compared to OKCs (p = 0.001) and DFs (p = 0.029). Significantly higher epithelial immunostaining for uPAR was observed in AMBs when compared to OKCs (p < 0.001). There were no significant differences in the epithelial immunoexpression of PAI-1 between AMBs and OKCs (p = 1.000). The correlations found for the expression of the studied proteins were not statistically significant (p > 0.05). However, the epithelial and connective tissue expressions of uPAR have a strong positive and statistically significant correlation in AMBs. The present results suggest that uPA is involved in the pathogenesis of OKCs and that uPAR may participate in tumorigenesis in AMBs. The high percentage of PAI-1-positive cells suggests a possible role for this protein in the development of AMBs and OKCs. Furthermore, the studied proteins do not seem to act synergistically in AMBs, OKCs, and DFs.

Immunohistochemical analysis of SHH, SMO and GLI-1 proteins in epithelial odontogenic lesions.

The present study analyzed the expression of proteins involved in the sonic hedgehog signaling pathway (SHH, SMO, and GLI-1) in benign epithelial odontogenic lesions (odontogenic keratocyst - OKC, ameloblastoma - AB, and adenomatoid odontogenic tumor - AOT) in order to identify the role of these proteins in the pathogenesis of these lesions. The sample consisted of 20 OKCs, 20 ABs, and 10 AOTs. The Kruskal-Wallis, Mann-Whitney U, and Spearman's (r) tests were used for statistical analysis, with the level of significance set at 5% (p < 0.05). The membrane/cytoplasmic expression of SHH was significantly higher in AB compared to AOT (p = 0.022) and OKC (p = 0.02). No differences were found in the membrane/cytoplasmic expression of SMO between the lesions studied. Regarding GLI-1, significant differences were observed at the nuclear level for AB and OKC compared to AOT (p < 0.0001). In addition, significant positive correlations were found between cytoplasmic and nuclear GLI-1 in AB (r = 0.482; p = 0.031) and OKC (r = 0.865; p < 0.0001), and between membrane/cytoplasmic SMO and cytoplasmic GLI-1 in AOT (r = 0.667; p = 0.035) and OKC (r = 0.535; p = 0.015). The results of this study confirm the participation of the sonic hedgehog signaling pathway in the pathogenesis of the lesions studied. Overexpression of SHH in ABs and nuclear expression of GLI-1 in ABs and OKCs indicate that these proteins contribute to the more aggressive behavior of these two lesions when compared to AOT.

DNA methylation status of MutS genes in ameloblastoma.

OBJECTIVES: Ameloblastoma is an odontogenic epithelial tumour with a low expression of mismatch repair system components. We aimed to investigate the methylation status of the genes MSH2, MSH3 and MSH6 (MutS group) in conventional ameloblastomas. MATERIALS AND METHODS: The ameloblastoma and dental follicle samples (n = 10 each) were collected from 20 different patients. Each ameloblastoma sample was sectioned into two fragments: one was paraffin-embedded while the other one, likewise the dental follicle samples, was fixed in RNAlater and frozen at -196°C. All frozen samples were investigated for the MutS genes methylation levels, using the enzymatic restriction digestion and quantitative real-time PCR (qPCR) assay. The ameloblastoma paraffin-embedded samples were submitted to immunohistochemical reactions for MutS proteins detection and digitally quantification. Correlation analyses were performed between the immunohistochemical results and the respective gene methylation percentage. RESULTS: There are no significant differences between the MutS genes methylation levels in the ameloblastoma and the dental follicle. However, a strong negative correlation was found between MSH2 and MSH6 gene methylation status and their respective proteins expressions evaluated by immunohistochemistry. CONCLUSION: Our results show that the genes methylations is in part responsible for decreasing the expression of MSH2 and MSH6 genes in ameloblastoma.

Hypoxia and proangiogenic proteins in human ameloblastoma.

Ameloblastomas are epithelial odontogenic tumours that, although benign, are locally invasive and may exhibit aggressive behaviour. In the tumour microenvironment, the concentration of oxygen is reduced, which leads to intratumoral hypoxia. Under hypoxia, the crosstalk between the HIF-1α, MMP-2, VEGF, and VEGFR-2 proteins has been associated with hypoxia-induced angiogenesis, leading to tumour progression and increased invasiveness. This work showcases 24 ameloblastoma cases, 10 calcifying odontogenic cysts, and 9 dental follicles, used to investigate the expression of these proteins by immunohistochemistry. The anti-HIF-1α, anti-MMP-2, anti-VEGF, and anti-VEGFR-2 primary antibodies are used in this work. The results have been expressed by the mean grey value after immunostaining in images acquired with an objective of 40×. The ameloblastoma samples showed higher immunoexpression of HIF-1α, MMP-2, VEGF, and VEGFR-2 when compared to the dental follicles and calcifying odontogenic cysts. Ameloblastomas show a higher degree of expression of proteins associated with intratumoral hypoxia and proangiogenic proteins, which indicates the possible role of these proteins in the biological behaviour of this tumour.

Immunohistochemical analysis of MMP-13 and EMMPRIN in epithelial odontogenic lesions.

PURPOSE: To investigate the contribution of MMP-13 in tumor aggressiveness, by acting on the reorganization of the extracellular matrix, regulating the biological activity of cytokines in odontogenic epithelial lesions, as well as to evaluate the role of EMMPRIN as an inducer of MMP-13. METHODS: Twenty solid ameloblastomas (SAs), 10 unicystic ameloblastomas (UAs), 20 odontogenic keratocysts (OKCs), and 20 adenomatoid odontogenic tumors (OATs) were selected. The expression of MMP-13 and EMMPRIN was evaluated in epithelial/connective tissue by determining the score of immunoreactive cells. RESULTS: Higher concentration of MMP-13 was observed in epithelium of SAs and OKCs (p = 0.316), while in connective, MMP-13 was more expressed in OKCs and UAs (p = 0.213). OKCs exhibited the highest immunoreactivity score for EMMPRIN in the epithelium (p = 0.091). In connective tissue, a larger number of immunoreactive cells were observed in OKCs and UACs (p = 0.357). There was a moderate correlation (r = 0.343/p = 0.004) between MMP-13/EMMPRIN in epithelium and strong correlation (r = 0.474/p < 0.001) in connective tissue. CONCLUSION: We suggest that the OKCs, SAs and UAs presented greater immunoexpression for MMP-13 and EMMPRIN, since they were lesions of more aggressive behavior, with smaller expressions in the AOTs that are admittedly indolent. However, we did not find a statistically significant difference between the expression of MMP-13 and EMMPRIN in lesions studied. The positive correlation found between MMP-13 and EMMPRIN in the epithelial and connective tissue of odontogenic lesions analyzed, seems to be related to the role of EMMPRIN as an inducer of MMP-13 expression.

The importance of BRAF-V600E mutation to ameloblastoma metabolism.

BACKGROUND: Ameloblastoma is a locally infiltrative, aggressive epithelial odontogenic neoplasm. BRAF-V600E mutation is frequently found in this tumor and has a pivotal role in its pathogenesis, but the consequences of this alteration need to be addressed. An untargeted metabolomics approach was applied to verify whether metabolic disturbances are related to tumor biology and whether BRAF-V600E mutation contributes to these alterations. METHODS: Formalin-fixed and paraffin-embedded tissue specimens from thirteen ameloblastoma and six dental follicles were included in this study. BRAF mutational status was determined by competitive allele-specific real-time PCR. Metabolite extracts were analyzed using gas chromatography coupled to mass spectrometry. Univariate and multivariate statistical methods were employed to compare the metabolic profiles of the samples. RESULTS: The abundance of eleven metabolites was significantly higher in ameloblastoma in relation to dental follicles, including amino acids, fatty acids, carbohydrates, inorganic acids, and organoheterocyclic compounds. The presence of BRAF-V600E mutations in ameloblastoma was related to decreased levels of glycerol in comparison with tumors carrying only wild-type alleles of this gene. No metabolic differences were observed between recurrent and primary manifestations of ameloblastoma. CONCLUSIONS: Ameloblastoma exhibits a distinct metabolic profile from normal odontogenic epithelium. BRAF-V600E may contribute to metabolic alterations in ameloblastoma. Collectively, our findings suggest that metabolic alterations might play a role in tumor pathogenesis.

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.

A Comparison of Ki67, Syndecan-1 (CD138), and Molecular RANK, RANKL, and OPG Triad Expression in Odontogenic Keratocyts, Unicystic Ameloblastoma, and Dentigerous Cysts.

BACKGROUND AND OBJECTIVE: Reduced expression of syndecan-1 (CD138), increased proliferation index, and modifications in the expression of the molecular RANK/RANKL/OPG triad are related to an intensified potential of aggressiveness and invasion of diverse tumors and cysts. The aim was to compare the expression of Ki-67, CD138, and the molecular triad RANK, RANKL, and OPG in odontogenic keratocysts (OKC), unicystic ameloblastomas (UA), and dentigerous cysts (DC). METHODS: Immunohistochemistry for Ki-67, CD138, RANK, RANKL, and OPG was performed in 58 odontogenic cystic lesions (22 OKC, 17 DC, and 19 UA). RESULTS: A higher expression of Ki-67 was identified in OKC as compared to UA (p < 0.0001). UA exhibited a greater loss of CD138 expression versus OKCs (p > 0.0034). RANKL was expressed higher in the epithelium (p = 0.0002) and in the stroma (p = 0.0004) of UA. DC had a lower expression of these markers. CONCLUSION: Higher RANKL expression together with the reduction on CD138 expression in UA could be linked to a greater invasive and destructive potential, while the increased proliferation rate observed in OKC could be related to its continuous intrabony growth. The expansion of DC does not seem to be related to such factors, justifying the different therapeutic approaches proposed for each of these entities.

Differences in E-Cadherin and Syndecan-1 Expression in Different Types of Ameloblastomas.

Ameloblastomas are a group of benign, locally aggressive, recurrent tumors characterized by their slow and infiltrative growth. E-Cadherin and syndecan-1 are cell adhesion molecules related to the behavior of various tumors, including ameloblastomas. Ninety-nine ameloblastoma samples were studied; the expression of E-cadherin and syndecan-1 were evaluated by immunohistochemistry. E-Cadherin and epithelial syndecan-1 were more highly expressed in intraluminal/luminal unicystic ameloblastoma than in mural unicystic ameloblastoma and solid/multicystic ameloblastoma, whereas the stromal expression of syndecan-1 was higher in mural unicystic ameloblastoma and solid/multicystic ameloblastoma. Synchronicity was observed between E-cadherin and epithelial syndecan-1; the expression was correlated with intensity in all cases. There was a strong association between expression and tumor size and recurrence. The evaluation of the expression of E-cadherin and syndecan-1 are important for determining the potential aggressiveness of ameloblastoma variants. Future studies are required to understand how the expression of these markers is related to tumor aggressiveness.

Expression of proteoglycans in two types of ameloblastoma: novel Immunohistochemical findings.

Alterations in cellular and extracellular matrix components play an important role during tumorigenesis; proteoglycans are included among these components. Ameloblastomas are odontogenic tumors distinguished as invasive and infiltrative neoplasms and are divided into different histological types, the most common of which are the unicystic ameloblastoma and the conventional ameloblastoma. The aim of this study was to identify the presence of two proteoglycans, perlecan and biglycan, in different types of ameloblastoma. Using immunohistochemistry, we determined the presence of both proteins in 28 unicystic ameloblastomas and 23 conventional ameloblastomas. We identified the cytoplasmic and nuclear presence of perlecan and the cytoplasmic presence of biglycan in both types of ameloblastoma. The mean values of immunoexpression were higher in the conventional type compared to the unicystic type. Neither the presence of biglycan in ameloblastomas nor the nuclear presence of perlecan in any odontogenic tumor has previously been reported. The differential immunoexpression of perlecan and biglycan in these types of ameloblastomas suggests their participation in the developmental process of these tumors.

EGFR is not amplified in ameloblastoma.

OBJECTIVE: The aim of this study was to investigate alterations in the EGFR gene and its protein expression for a better understanding of the biologic behavior of ameloblastoma. STUDY DESIGN: Twenty-five samples of ameloblastoma were selected, and dual-color fluorescence in situ hybridization assay was performed. The results of the assay and immunohistochemistry reaction for EGFR and Ki67 were associated with clinicopathologic features and recurrence. RESULTS: All analyzed cases presented disomy without any gene polysomy or amplification. With regard to EGFR immunoexpression, 3 cases (12%) were considered negative, and 22 (88%) were positive, of which 13 (52%) were weak and 9 (36%) were strong. All samples presented low positivity for Ki67. There was no association between EGFR expression and clinicopathologic features or recurrence (P > .05). In some cases, EGFR immunoexpression was observed without gene amplification. CONCLUSIONS: Ameloblastoma development, progression, or recurrence does not appear to be related to EGFR amplification or polysomy.

Prognostic importance of FGF2 and FGFR1 expression for patients affected by ameloblastoma.

BACKGROUND: Fibroblast growth factor 2 (FGF2) and FGF receptor 1 (FGFR1) have been investigated in different human neoplasms and were shown to play important roles in the pathogenesis of these diseases; however, very few are known regarding their prognostic importance in the context of ameloblastoma. Therefore, the aim of this study was to investigate whether the expression of FGF2 and FGFR1 is associated with ameloblastoma clinical behavior. METHODS: Fifty-eight cases of ameloblastoma arranged in tissue microarray were submitted to immunohistochemistry against FGF2 and FGFR1. Clinicopathological parameters regarding sex, age, tumor size, duration and location, treatment, recurrences, radiographic features, cortical disruptions, and follow-up data were obtained from patients' medical records and correlated with the molecules expression. Univariate and multivariate Cox regression analyses were used to investigate the prognostic potential of the biomarkers. RESULTS: Forty-four cases (75.9%) exhibited cytoplasmic positivity for FGF2 in central and peripheral epithelial cells, 46 of 58 (79.3%) showed FGFR1 cytoplasmic positivity predominantly in the columnar peripheral cells, and 43 cases (74.1%) were positive for both. Expression of FGF2 and FGF2 + FGFR1 was associated with tumor recurrences (P = .05). However, univariate and multivariate analyses did not demonstrate a significant influence of FGF2, FGFR1, or FGF2 + FGFR1 in the 5-year disease-free survival (DFS) rate (P = .27, P = .33, and P = .25, respectively). CONCLUSION: Cytoplasmic expression of FGF2 and FGF2 + FGFR1 is associated with ameloblastoma recurrence, but FGF2 and FGFR1 are not determinants of a lower DFS.