Tumor cell proliferation and microsatellite alterations in human ameloblastoma

Recurrence Rates of Intraosseous Ameloblastoma Cases With Conservative or Aggressive Treatment: A Systematic Review and Meta-Analysis

Objective

This study aimed to systematically investigate and compare the post-treatment recurrence of intraosseous ameloblastoma in patients treated with conservative or aggressive approaches.

Methods

Systemic searches of PubMed, Medline, Cochrane Library, and Embase databases from inception to October 28, 2020, were conducted. Studies that aimed to evaluate the recurrence of intraosseous ameloblastoma by conservative and aggressive treatment approaches were included.

Results

A total of 20 studies with 942 ameloblastoma cases were included. Fourteen studies included patients with ameloblastoma who received conservative treatment, and 16 studies reported the overall recurrence rate for patients undergoing aggressive treatment. The pooled results indicated that the recurrence rate for aggressive treatment [0.12, 95% confidence interval (CI) = 0.09–0.16] was significantly lower than that for conservative treatment, with a recurrence rate of 0.30 (95% CI = 0.23–0.39). Similar results were obtained when stratifying the participants by the histological classification. When trying stratification analysis following the original included studies, multicystic ameloblastoma presented a much higher recurrence rate than solid and unicystic ameloblastomas.

Conclusion

These findings supported the hypothesis that aggressive treatment might lead to a lower recurrence rate than conservative treatment. More studies and meta-analyses following the new histological classification of ameloblastomas are needed to validate and support the findings.

Expression of p63 in tooth germ, dentigerous cyst and ameloblastoma

Context:

To assess the role of p63, a p53 homolog, in the cytodifferentiation (odontogenesis) and oncogenesis of odontogenic epithelium.

Aim:

The present study aimed to compare the expression pattern of p63 in the epithelium of tooth germ, dentigerous cyst (DC) and ameloblastoma (AB).

Materials and Methods:

Tissue specimens of thirty tooth germs, thirty ABs and thirty DCs were examined by immunohistochemistry for the expression of p63. Results: p63 labeling index (LI) was observed in descending order in epithelial cells of ABs, tooth germs and DCs. p63 LI was statistically nonsignificant among all the three groups. ABs revealed the highest p63 expression, but, surprisingly, tooth germs showed higher expression than DCs.

Conclusion:

p63 plays a role in the cytodifferentiation and proliferation of odontogenic epithelial cells irrespective of the tissue (normal developing or lesional tissue). This implies that p63 cannot be used as a diagnostic marker. However, our results indicate p63 overexpression as a mark of increased proliferation. Thus, it can be stipulated that p63 can be used as a prognostic marker in odontogenic lesions with more aggressive and invasive phenotype. Our results also suggest the differential function of p63 in both developing and lesional odontogenic tissues, which, however, depends on p63 isoform predominantly being expressed. Therefore, identification of p63-predominant isoform in a particular lesion is more important than the presence or absence of p63. Consequently, we suggest the performance of polymerase chain reaction analysis along with immunohistochemical evaluation in further studies.

Global incidence and profile of ameloblastoma: A systematic review and meta-analysis

OBJECTIVES

To evaluate the global incidence of ameloblastoma and to provide a profile of ameloblastoma patients.

MATERIAL AND METHODS

A systematic review and meta-analysis was conducted. Searches were performed in PubMed, EMBASE, SCOPUS, and Web of Science for articles published from 1969 to 2018 for the global incidence and from 1995 to 2018 for the profile of ameloblastoma patients.

RESULTS

Seven studies on the incidence rate of ameloblastoma were included in the meta-analysis. These studies only covered Europe, Africa, and Australia. The pooled incidence rate was 0.92 per million person-years (95% CI: 0.57-1.49), with significant heterogeneity between studies. Forty-two articles provided profile data of 6,446 ameloblastoma patients. Mean age was 34 years and the peak age incidence in the third decade of life. In Europe and North America, ameloblastoma mostly occurred at an older age when compared to Africa and South America. A slight male preference (53%) was found, and the mandible appeared to be the preferred site. The most common type of ameloblastoma was multicystic. The histopathologic patterns were mostly follicular and plexiform.

CONCLUSIONS

This is the first study assessing the global incidence of ameloblastoma. The pooled incidence rate was determined to be 0.92 per million person-years.

Radical vs conservative treatment of intraosseous ameloblastoma: Systematic review and meta-analysis

OBJECTIVES

The aim of the present study was to assess the outcomes of radical and conservative treatment approaches of solid/multicystic and unicystic ameloblastoma in terms of recurrence rates.

MATERIAL AND METHODS

A systematic review and meta-analysis was conducted based on the PRISMA statement. Search was performed using PubMed, Embase, SCOPUS, and Web of Science for articles published from January 1969 until March 2018. Quality assessment of the selected articles was conducted using the Quality Appraisal of Case Series Studies Checklist. The meta-analysis was performed using the MedCalc program.

RESULTS

The search strategy yielded 6,984 articles; 20 studies met the eligibility criteria and were included in the meta-analysis. The pooled recurrence rate of solid/multicystic ameloblastomas following radical treatment was 8%, while conservative treatment caused recurrences in 41%. For unicystic ameloblastomas, these values were 3% and 21%, respectively. The risk of recurrences in both types of ameloblastomas following radical treatment was lower than following conservative treatment.

CONCLUSIONS

The present study showed statistically significant differences in recurrence favoring radical treatment for both unicystic and solid/multicystic ameloblastoma. The solid/multicystic type showed more recurrences than the unicystic type. Unfortunately, since only retrospective studies were available, the evidence is less strong as wished for.

Ameloblastoma RNA profiling uncovers a distinct non-coding RNA signature

Ameloblastoma of the jaws remains the top difficult to treat odontogenic tumour and has a high recurrence rate. New evidence suggests that non-coding RNAs (ncRNAs) play a critical role in tumourgenesis and prognosis of cancer. However, ameloblastoma ncRNA expression data is lacking. Here we present the first report of ameloblastoma ncRNA signatures. A total of 95 ameloblastoma cases and a global array transcriptome technology covering > 285.000 full-length transcripts were used in this two-step analysis. The analysis first identified in a test cohort 31 upregulated ameloblastoma-associated ncRNAs accompanied by signalling pathways of cancer, spliceosome, mRNA surveillance and Wnt. Further validation in an independent cohort points out the long non-coding (lncRNAs) and small nucleolar RNA (snoRNAs): LINC340, SNORD116-25, SNORA11, SNORA21, SNORA47 and SNORA65 as a distinct ncRNA signature of ameloblastoma. Importantly, the presence of these ncRNAs was independent of BRAF-V600E and SMO-L412F mutations, histology type or tumour location, but was positively correlated with the tumour size. Taken together, this study shows a systematic investigation of ncRNA expression of ameloblastoma, and illuminates new diagnostic and therapeutic targets for this invasive odontogenic tumour.

Immunohistochemical biomarkers in ameloblastomas

Ameloblastoma is an aggressive odontogenic tumour, which is locally invasive and highly recurrent. Studies show that ameloblastoma is a benign odontogenic neoplasia, being relatively rare and occasionally presenting behaviour of malignant lesions. In addition to these particularities, the histological diagnosis of ameloblastoma can be challenging when the tumour shows high rates of mitosis, absence of nuclear pleomorphism, basilar hyperplasia and neural invasion. In order to help in the diagnosis, prognosis and treatment of this neoplasia, some immunohistochemical markers were shown to be associated with tumoural epithelium. The identification of these markers as well as of their association with clinical signs can be useful to elaborate more efficient treatment strategies and to control this pathology, including improvement of the quality of life of patients affected by this neoplasia. This article aims to review some markers associated with specific molecular pathways, bone remodelling, cell proliferation, apoptosis, cell signalling and tumour suppression.

Immunohistochemical expression of K6, K8, K16, K17, K19, maspin, syndecan-1 (CD138), α-SMA, and Ki-67 in ameloblastoma and ameloblastic carcinoma: diagnostic and prognostic correlations

OBJECTIVE

To identify cutoff values of markers that correlate with the histopathologic diagnosis of ameloblastic carcinoma (AC) and/or the increased recurrence potential of ameloblastoma (AB).

STUDY DESIGN

Immunohistochemical expression (IHCE) of 9 selected markers were investigated in 18 non-recurrent ameloblastomas (NRABs), 6 recurrent ameloblastomas (RABs), and 5 ACs.

RESULTS

No significant difference in IHCE of K6, K8, K16, K17, K18, K19, maspin, or syndecan-1 was observed among study groups. α Smooth muscle actin (α-SMA)-positive area in central epithelial cells significantly differentiated between AB and AC (P = .017; t -test). Ki-67 score significantly differentiated between AB and AC (P < .005; t -test) and between AC and RAB (P = .015; ANOVA/post hoc).

CONCLUSIONS

Ki-67 score of 75 cells/HPF (ROC curve) is a potential indicator of AC. Clinical recurrence of AB may be predicted by α-SMA expression pattern. Syndecan-1 and α-SMA may indicate a higher aggressive potential of AB when expressed in the stroma.

Soft tissue recurrent ameloblastomas also show some malignant features: A clinicopathological study of a 15-year database

Background

To investigate the clinicopathological features of six cases of soft tissue recurrent ameloblastoma and explore the role of increased aggressive biological behavior in the recurrences and treatment of this type of ameloblastomas.

Material and Methods

In this study, we retrospectively reviewed recurrent ameloblastomas during a 15-year period; six cases were diagnosed as soft tissue recurrent ameloblastoma. The clinical, radiographic, cytological and immunohistochemical records of these six cases were investigated and analyzed.

Results

All the six soft tissue recurrent ameloblastomas occurred after radical bone resection, and were located in the adjacent soft tissues around the osteotomy regions. In Case 4, the patient developed pulmonary metastasis, extensive skull-base infiltration and cytological malignancy after multiple recurrences and malignant transformation was diagnosed. In the other five cases, although there were no cytological signs are sufficient to justify an ameloblastoma as malignant, some malignant features were observed. In Case 1, the tumor showed moderate atypical hyperplasia and the Ki-67 staining percentage was 40% positive, which are strongly suggestive of potential malignance. In Case 5, the patient developed a second soft tissue recurrence in the parapharyngeal region and later died of tumor-related complications. All the remaining three patients showed cytology atypia of varying degrees and high expression of PCNA or Ki-67, which confirmed active cell proliferation.

Conclusions

Increased aggressiveness is an important factor of soft tissue recurrence. An intraoperative rapid pathological examination and more radical treatment are suggested for these cases.

Key words: Ameloblastoma, soft tissue recurrence, aggressive biological behaviour.

Immunoexpression of Ki-67, MCM2, and MCM3 in Ameloblastoma and Ameloblastic Carcinoma and Their Correlations with Clinical and Histopathological Patterns

Cell proliferation assays are performed using antibodies against nuclear proteins associated with DNA replication. These nuclear proteins have gained special interest to predict the biological and clinical behaviors of various tumors. The aim of this study was to analyze the presence of Ki-67 protein and the minichromosome maintenance-2 (MCM2) and maintenance-3 (MCM3) proteins in ameloblastoma. Materials and Methods. Cell proliferation marker expression levels were assessed via immunohistochemistry in 111 ameloblastoma cases (72 unicystic ameloblastoma samples, 38 solid/multicystic ameloblastoma samples, and 1 ameloblastic carcinoma). The label index was performed as described previously. Results. MCM2 and MCM3 showed higher proliferation indexes in all variants of ameloblastoma compared to the classic marker Ki-67. No correlation between the proliferation index and the clinical and protein expression data was observed. Conclusion. The results suggest that clinical features do not directly affect tumor cell proliferation. Moreover, the high levels of cellular proliferation of MCM2 and MCM3 compared with Ki-67 may indicate that MCM2 and MCM3 are more sensitive markers for predicting the growth rate and eventually might be helpful as a tool for predicting aggressive and recurrent behaviors in these tumors.

Evidence for loss of heterozygosity (LOH) at chromosomes 9p and 17p in oral granular cell tumors: a pilot study

OBJECTIVE

The objective of this study was to assess loss of heterozygosity (LOH) in tumor suppressor gene loci in oral granular cell tumors (GCTs).

STUDY DESIGN

We assessed LOH in 8 samples of oral GCT using polymorphic microsatellite markers at chromosome regions 3p, 9p, 11q, and 17p, flanking areas close to tumor suppressor genes. We further performed immunohistochemistry to detect the p53 and Ki-67 proteins and associated these expressions with the molecular results.

RESULTS

Five samples showed LOH in 3 markers at chromosomes 9p and 17p (markers P53, AFM238WF2 and D9S162) with fraction of allelic loss of 42.8% for each of these markers. No LOH was identified in any other chromosome. LOH was not associated with the immunohistochemical expression of p53 and Ki-67.

CONCLUSIONS

The present study shows LOH at chromosomes 9p and 17p in oral GCTs.

Osteogenic genes related to the canonic WNT pathway are down-regulated in ameloblastoma

OBJECTIVE

The aim of this study was to determine the expression of essential osteogenic genes related to the canonic WNT pathway, i.e., WDR5, sFRP-2, and their downstream genes, in ameloblastoma and to clarify their biologic impact on this neoplasm.

STUDY DESIGN

Forty-six paraffin-embedded ameloblastoma samples and ameloblastic (AM-1) and preosteoblastic (KUSA/A1) cell lines were used. Immunohistochemistry, Western blot, reverse-transcription polymerase chain reaction, and alkaline phosphatase (ALP) activity assay were performed.

RESULTS

WDR5, essential for osteoblast differentiation and canonic WNT pathway activation, was negative in most ameloblastoma cases and weakly expressed in AM-1 cells. Conversely, sFRP-2s was overexpressed. RUNX2 and C-MYC, downstream inductions of canonic WNT pathway activation, demonstrated weak mRNA expressions in ameloblastoma, suggesting WNT pathway impairment and WDR5 functional inactivity. Recombinant WDR5 weakly induced ALP activity of KUSA/A1 cells cultured in AM-1 conditioned medium.

CONCLUSIONS

These findings suggest that WNT-related bone-forming genes are down-regulated in ameloblastoma. Concurrent sFRP-2 overexpression suggests that both bone-forming and bone-inhibiting genes equally contributed to reduced bone formation in this neoplasm.

Quantitative assessment of myofibroblast in severe dysplasia, microinvasion and oral squamous cell carcinoma: an immunohistochemical study

Myofibroblast are essential for the integrity of human body by virtue of its role in wound healing and pathological organ remodeling. Myofibroblast is a universal cellular component in mammalian lesions, but not a typical component of normal untraumatized tissues. Therefore its presence in abundance in case of cancer is a matter of concern. Tumor microenvironment plays a pivotal role in tumor progression. These so called cancer associated fibroblast or myofibroblast are the major components and occur in stromal tissue during carcinogenesis processes. This study is a quantitative assessment of presence and distribution of myofibroblast in severe dysplasia, microinvasion and oral squamous cell carcinoma (OSCC).

KEYWORDS

Myofibroblast, Vimentin, α-SMA, OSCC, Severe dysplasia, Microinvasion. How to cite this article: Kapse SC, Rathod N, Baad R, Mandlik J, Sharma AS, Bommanavar S. Quantitative Assessment of Myofibroblast in Severe Dysplasia, Microinvasion and Oral Squamous Cell Carcinoma: An Immunohistochemical Study. J Contemp Dent Pract 2013;14(1):34-38. Source of support: Nil Conflict of interest: None declared.

Co-expression of Ki-67 and p53 protein in ameloblastoma and keratocystic odontogenic tumor

OBJECTIVES

The purpose of this study was to evaluate the cell proliferation and p53 protein expression in ameloblastomas (ABs), keratocystic odontogenic tumor (KCOT) and dentigerous cyst (DC).

METHOD

The immunohistochemistry were carried out for Ki-67 and p53 protein expression by using MIB-1 clone and DO-7 clone, respectively, in ABs (n = 23), KCOT (n = 32), DC (n = 30), normal oral mucosa (NOM) (n = 12) and fetal oral mucosa (FOM) (n = 10).

RESULTS

Both the Ki-67 LI Labeling index (LI) and p53 LI was significantly higher in ABs than KCOT, DC, NOM and FOM. The Ki-67 LI and p53 LI was significantly higher in KCOT as compared to DC. Ki-67 LI and p53 LI was observed in descending order in ABs, KOCT, FOM, NOM and DC. There was significant correlation between Ki-67 expression and p53 expression in ABs, KCOT, DC and NOM. The densely stained p53 positive cells were noted higher in ABs than KCOT. The very few densely p53 positive cells were noted in DC, NOM and FOM.

CONCLUSION

The results suggest that the p53 protein expression does not necessarily imply an association with malignant disease and/or p53 gene mutation, but a tendency to be expressed in an increasing quantitative and qualitative manner, as the biologic behavior of odontogenic cyst or tumors becomes more aggressive. p53 over-expression may promote cell proliferation in odontogenic lesions. Thus, it can be stipulated that Ki-67 and p53 protein expression can be used as a prognostic marker in odontogenic lesions.

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.

Immunohistochemical detection of p53 and PCNA in ameloblastoma and adenomatoid odontogenic tumor

Although ameloblastoma and adenomatoid odontogenic tumor (AOT) belong to the same group according to the World Health Organization, they show different biologic behaviors. PCNA, an amplifier of cell proliferation, and p53, a tumor suppressor protein, are overexpressed in some odontogenic lesions. The purpose of this study was to immunohistochemically evaluate the expression of p53 and PCNA to clarify the possible role of these proteins in different behaviors of ameloblastoma and AOT. The immunohistochemical expression of PCNA and p53 was determined in 30 solid ameloblastomas and 12 AOTs. Statistical tests including one-way ANOVA, t-test, chi-square, Mann-Whitney U and Kendall were used to analyze the data. All tissue sections (except one specimen of plexiform ameloblastoma) exhibited immunoexpression for p53. PCNA was expressed in all specimens. There was no significant difference in PCNA expression between ameloblastomas and AOTs (P > 0.05). For p53, there was no statistical difference between subtypes of ameloblastomas (P > 0.05), whereas statistical differences were observed between ameloblastomas and AOTs (P < 0.001). There was no statistical difference in PCNA intensity of staining between ameloblastomas and AOTs (P > 0.05), whereas the p53 intensity in ameloblastomas was stronger than AOTs (P < 0.05). Positive correlation between PCNA and p53 was observed. We concluded that PCNA overexpression is not responsible for the difference in clinical behavior of these two lesions, whereas the expression of p53 in ameloblastoma may explain the more aggressive nature of this tumor compared with AOT.

Review article: Current concepts of ameloblastoma pathogenesis

Ameloblastoma is a locally destructive and invasive tumour that can recur despite adequate surgical removal. Molecular studies have offered interesting findings regarding ameloblastoma pathogenesis. In the present review, the following topics are discussed regarding its molecular nature: clonality, cell cycle proliferation, apoptosis, tumour suppressor genes, ameloblastin and other enamel matrix proteins, osteoclastic mechanism and matrix metalloproteinases and other signalling molecules. It is clear from the literature reviewed that translational studies are necessary to identify prognostic markers of ameloblastoma behaviour and to establish new diagnostic tools to the differential diagnosis of unicystic from multicystic ameloblastoma. Finally, molecular biology studies are also important to develop more effective alternative approaches to the treatment of this aggressive odontogenic tumour.

EMMPRIN expression in tongue squamous cell carcinoma

BACKGROUND

Extracellular matrix metalloproteinase inducer (EMMPRIN) is identified as a tumor-cell membrane protein that stimulates matrix metalloproteinases (MMPs) production. Several studies have shown that higher EMMPRIN expression is associated with shorter survival time and correlated significantly with more advanced clinico-parameters of cancer. The aim of this study was to investigate the relationship between clinico-pathologic characteristics and EMMPRIN, and prognostic significance of EMMPRIN expression in human tongue squamous cell carcinoma.

METHODS

Extracellular MMP inducer expression was examined immunohistochemically on paraffin-embedded tissue specimens from 68 patients with tongue squamous cell carcinoma and who underwent radical surgeries from 1996 to 2006. The 68 patients were followed up from 1 to 119 months, with an average of 27.5 months. Nonparametric tests were performed for the comparison of EMMPRIN expression between two independent groups. Survival analysis was performed to find the prognostic significance of EMMPRIN expression.

RESULTS

We found that EMMPRIN expression in tongue squamous cell carcinoma is significantly higher than that in non-cancerous epithelium adjacent to carcinoma of tongue. In addition, EMMPRIN expression is significantly associated with tumor diameter and clinical stage in the samples, but did not correlate with gender, age, tumor metastasis, and pathological grade. Finally, survival analysis indicates that EMMPRIN overexpression correlates significantly with poor overall survival in the patient cohort.

CONCLUSION

These results suggest that EMMPRIN might represent an attractive target for immunotherapeutic approaches in a subgroup of patients with tongue squamous cell carcinoma.

Secreted frizzled related protein (sFRP)-2 inhibits bone formation and promotes cell proliferation in ameloblastoma

Secreted frizzled related protein (sFRP)-2, a Wnt antagonist, was strongly expressed by both stromal and tumor cells of ameloblastoma. The aim of this study is to evaluate whether sFRP-2 secreted from tumor cells have any direct role in suppressed bone formation or not. A pre-osteoblastic cell line, KUSA/A1 cells, cultured in conditioned medium of an ameloblastoma-derived cell line (AM-1CM) was used in the study. Alkaline phosphatase (ALP) activity, alizarin red staining, mineral quantification and MTS assay was performed. Wnt-canonical pathway is a major pathway for osteoblasts. Antagonists of this pathway, sFRP-1, 2 and 3, were detected by immunohistochemistry and western blot analysis. KUSA/A1 cells cultured in AM-1CM showed high cell proliferation, low ALP activity without mineralized matrix deposition. sFRP-2 was strongly expressed in ameloblastoma tissue and AM-1 cells. After sFRP-2 depletion, the cells showed diffuse mineralization. In this study, it was confirmed that ameloblastoma cells have a major role in decreased bone formation by secreting sFRP-2 in cell culture model. Though, sFRP-2 has great effect on tumor progression, inhibition of sFRP-2's anti-bone formation activity and cell proliferative activity may reduce the invasive property of ameloblastoma and possibility of recurrence rate.