Molecular markers of cell adhesion in ameloblastomas. An update

Immunohistochemical expression of paxillin in ameloblastoma and odontogenic keratocyst: An observational study

Background

Cell adhesion molecules (CAMs) are found on the surface of all cells, where they allow dynamic processes to take place. These include cadherins, integrins, selectins and Immunoglobulin superfamily. Directly associated with β-integrin tails is a multidomain protein known as paxillin. However, CAMs participate in cell-cell and extracellular matrix-cell interactions during histomorphogenesis in the various phases of odontogenesis. Some tumours or cysts like ameloblastoma (AB) or odontogenic keratocyst (OKC) having odontogenic origin show disturbance in the interaction of these CAMs. Hence, the assessment of paxillin expression in AB and OKC was carried out.

Materials and Methods

The present observational study comprised 30 clinically and histologically confirmed cases of AB and OKC. All the slides were stained immunohistochemically using a paxillin antibody.

Results

Upon comparison of staining intensity of paxillin among AB and OKC showed statistically significant result, whereas quantitative staining and final summation showed non-significant result. Gender-wise comparison of paxillin staining intensity, quantitative staining and final summation among OKC showed significant result; however, in AB, staining intensity showed non-significant result, whereas quantitative staining and final summation showed significant result.

Conclusion

Paxillin has the greatest influence on tissue morphogenesis and development. The regulation of cell mobility is aided by the multiple roles that paxillin plays in a range of cells and tissues. However, further studies using a large sample size, along with other molecular analytical methods, may be essential to draw a definite conclusion about the association of paxillin and its exact function in OKC and AB.

Comparative evaluation and Immunohistochemical expression of Syndecan-1 in Ameloblastoma and Dentigerous cyst

Background: Syndecans are type-1 heparan sulphate proteoglycans which play significant role in cell-cell and cell-extracellular matrix interaction. Syndecans are involved in tooth development and differentiation of mesenchymal cells. Amongst odontogenic lesions, ameloblastomas and dentigerous cysts are routinely encountered lesions with difference in treatment modality based on its aggressiveness. The objective of the present research was to study and compare immunohistochemical expression of syndecan-1 in ameloblastoma and dentigerous cyst. Method:  40 retrospectively diagnosed cases of ameloblastomas and dentigerous cysts were immunohistochemically stained against syndecan-1. The intensity of immunostaining and percentage of positive cells was assessed by three independent blind observers. Weighted kappa test was used to find out inter-observer reliability. Comparative evaluation of syndecan-1 expression between the two lesions was done using student t-test. Results:  There was statistically significant difference between the mean of score for intensity, mean of score for percentage of positive cells and total mean score of syndecan-1 between ameloblastoma and dentigerous cyst. Conclusion: Syndecan-1 may be involved in aetiopathogenesis of odontogenic lesions like ameloblastoma and dentigerous cyst. Also, weak expression in ameloblastoma indicates that tumor invasion and aggressiveness is related to cell adhesion molecule like syndecan-1.

Comparative Study of the Minichromosome Maintenance Proteins Complex (MCM 4/5/6) in Ameloblastoma and Unicystic Ameloblastoma

INTRODUCTION

Solid/conventional ameloblastoma (AM) and unicystic ameloblastoma (UAM) are the most frequent benign epithelial odontogenic tumors located in the maxillary region, and their treatment usually consists of extensive surgical resection. Therefore, it is relevant to study molecular markers to better understand the biological behavior of these tumors. The aim of this study was to describe and compare the expression of proteins related to cellular proliferation: Ki-67 and MCM4-6 complex.

MATERIALS AND METHODS

An immunohistochemistry technique was performed, with antibodies against Ki-67, MCM4, MCM5, and MCM6, in 10 AM and 10 UAM tumors. The results were quantified using label index and analyzed statistically.

RESULTS

AM and UAM had greater expression of MCM6, followed by MCM5, MCM4, and Ki-67 ( P < .05). Immunoexpression of Ki-67 and MCM5 was exclusively nuclear, whereas the expression of MCM4 and MCM6 was nuclear and cytoplasmic.

CONCLUSION

The results suggest that MCM5 is a trustable cell proliferation marker with higher sensitivity compared with Ki-67 and may be useful to predict the biological behavior of AM and UAM. Despite this, further studies are necessary, including a correlation with clinical parameters to confirm these findings.

Proteoglycans as potential biomarkers in odontogenic tumors

Proteoglycans (PGs) are essential for normal cellular development; however, alterations of their concentrations can promote tumor growth. To date, a limited number of studies report the presence of PGs in odontogenic tumors (OTs); therefore, the main purpose of this work is to gather the information published on the study of PGs. The search reported 26 articles referring to the presence of different PGs in distinct OTs from 1999 to May 2017. PGs seem to play an important role during OTs' development as they are involved in several tumor processes; however, the number of reports on the study of these molecules is low. Thus, more studies are necessary in order to gain a better understanding of the underlying pathophysiology of OTs.

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.

Molecular and genetic aspects in the etiopathogenesis of ameloblastoma: An update

Ameloblastoma is the second most common benign epithelial odontogenic tumor and though it is of a benign nature, it is locally invasive, has a high recurrence rate and could potentially become malignant. Many theories have been proposed to explain the pathogenesis of ameloblastoma. Proper understanding of the pathogenic mechanism involved in ameloblastoma and its proliferation aids in constituting proper treatment of choice at an early stage, preventing morbidity associated with extensive therapy. An attempt has been made to discuss the current concepts related to molecular and genetic changes that occur in ameloblastoma as these could affect treatment plan and prognosis.

Oral verruciform xanthoma: a clinicopathologic and immunohistochemical study of 20 cases

Verruciform xanthoma of the oral cavity is an uncommon benign lesion that usually affects the palate and gingiva mainly as a well-circumscribed solitary yellowish to whitish plaque or nodule, which is promptly recognized microscopically by identification of sub-epithelial foamy macrophages. The aim of this study was to evaluate the clinicopathologic and immunohistochemical features of 20 cases of oral verruciform xanthoma. All cases were evaluated by conventional hematoxylin/eosin staining and six of those were submitted to immunohistochemical reactions for CD68, CD63, CD163, syndecan-1 (CD138), S-100 protein and cytokeratins (CK) 8, 14 and 19. Oral verruciform xanthoma presented as yellowish papillary nodules affecting mainly the palate (30%), buccal mucosa (30%) and gingiva (25%) of middle-aged male patients. Most cases presented papillary epithelial hyperplasia and sub-epithelial foamy cells, which were immunopositive for CD68, CD63 and CD163 in all cases. The orange parakeratin superficial layer was negative for CK14 and presented a distinct granular membrane pattern of positivity for CD138. S-100 protein, CK8, and CK19 were negative.

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.

Malignant odontogenic tumors: an update on selected tumors

This is an update on selected odontogenic malignancies. The article deals with aspects of recognized odontogenic carcinomas, odontogenic sarcoma and a yet unrecognized entity, sclerosing odontogenic carcinoma. Odontogenic malignancies are exceedingly rare, complicating a thorough understanding of the biologic behavior, reproducible standardized diagnostic criteria, appropriate classification and clinical management. Without the knowledge of the tumor's biologic behavior, adequate clinical management is difficult and patient outcomes uncertain. The histopathologic features are emphasized as well as the more recent biomarker findings. These recent advances may facilitate further understanding of this group of malignancies and provide useful stratification to guide patient management.