Chetana Chandrashekar

β-Catenin Expression in Benign and Malignant Salivary Gland Tumors

Objective. To assess the expression of β-catenin in benign and malignant salivary gland tumors and to investigate the possible role of β-catenin in the behavior of salivary gland tumors. Study design. Paraffin embedded tissues from 45 salivary gland tumors were studied immunohistochemically for expression of β-catenin. Result. Reduced/aberrant β-catenin expression was seen in benign and malignant salivary gland tumors. Cytoplasmic localization and reduced membranous expression were comparatively observed more in malignant salivary gland tumors. Additionally, in pleomorphic adenomas (PAs), β-catenin exhibited intense staining in cells arranged in the form of ducts/tubules, whereas cells in clusters and sheets showed weaker immunoreactivity. Conclusion. Reduced and cytoplasmic localization of β-catenin could indicate lack of differentiation, invasive potential, and aggressive behavior in malignant salivary gland tumors. Furthermore, change in expression based on the arrangement of tumor cells may suggest that β-catenin may have a role in morphological variations seen in PAs.

Critical biomarkers of epithelial-mesenchymal transition in the head and neck cancers

Epithelial-mesenchymal transition (EMT), a key developmental program has been shown to occur in wound healing, organ fibrosis and in the initiation of metastasis for cancer progression. EMT is a process that describes the development of motile, mesenchymal-like cells from non-motile parent epithelial cells. Plasticity of the cells enable significant changes in cell phenotypes and this process is governed by the interplay among different functional classes of regulatory molecules. The process typically involves the control of specific gene expression programs with distinct functional impacts on the behavior of cells. An important feature of cellular plasticity, EMT has in the recent times attracted broad interest in the field of cancer research, tumor invasion and metastases. A complete understanding of the molecular events of EMT and a search for novel molecular regulators is required for prospective targets for therapeutic interventions. This review summarizes the critical biomarkers of EMT in the head and neck cancers.

Role of Immunomarkers in the Clinicopathological Analysis of Unicystic Ameloblastoma

Purpose. The clinical behavior of unicystic ameloblastoma varies according to its subtype. The assessment of its proliferative capacity, neovascularization, and invasiveness using relevant immunomarkers may aid in appropriate surgical therapeutic protocol. Methods. 18 cases of clinically and histologically confirmed unicystic ameloblastoma, categorized as luminal, intraluminal, or mural subtypes, were analyzed retrospectively. Immunomarkers such as Ki-67, CD34, MMP-2, and MMP-9 were studied to evaluate their behavior. Results. Labeling index of Ki-67 was 4.25% in the intraluminal subtype, compared with 2.14% in the luminal and 4.04% in the mural variant (P = 0.3). CD34 immunostaining was significantly higher in the mural variant (43 per high power field) than the other two subtypes (P = 0.04). MMP-2 and MMP-9 were strongly expressed in mural, moderately in intraluminal, and weakly to absent in luminal variant. Conclusions. High proliferative index, angiogenesis, and protease activity in the mural ameloblastoma, ascertained by the expression of these markers, confirm its aggressive phenotype. The intraluminal and luminal subtype exhibiting decreased expression are compatible with their indolent clinical behavior.

A curious case of central odontogenic fibroma: A novel perspective

We appraise a case of central odontogenic fibroma (COF) with unusual histologic features of entrapped neural elements and mast cells. The presence of mast cells attributed to the release of stem cell factor, the principal growth and activating factor of mast cells. A putative role for C-kit and mast cells in the pathogenesis of COF is described.

Exploring the potential of laser capture microdissection technology in integrated oral biosciences

Laser capture microdissection (LCM) is a high-end research and diagnostic technology that helps in obtaining pure cell populations for the purpose of cell- or lesion-specific genomic and proteomic analysis. Literature search on the application of LCM in oral tissues was made through PubMed. There is ample evidence to substantiate the utility of LCM in understanding the underlying molecular mechanism involving an array of oral physiological and pathological processes, including odontogenesis, taste perception, eruptive tooth movement, oral microbes, and cancers of the mouth and jaw tumors. This review is aimed at exploring the potential application of LCM in oral tissues as a high-throughput tool for integrated oral sciences. The indispensable application of LCM in the construction of lesion-specific genomic libraries with emphasis on some of the novel molecular markers thus discovered is also highlighted.

Giant-cell fibroma: Understanding the nature of the melanin-laden cells

Giant-cell fibroma is a localized, benign fibrous mucosal mass, which clinically mimics any other fibroepithelial growth, and its distinction from other lesions is on the basis of its peculiar histopathology. A case of giant-cell fibroma with stroma strewn with brown pigment-laden cells is presented herewith. Immunohistochemical staining aided with histochemical reaction to understand the origin of these cells was carried out. Various mechanisms that explain the presence of melanin granules in reactive lesions of giant-cell fibroma is discussed in the present report.

Translational approach utilizing COX-2, p53, and MDM2 expressions in malignant transformation of oral submucous fibrosis.

About 20% of the worlds population uses some form of betel nut, which suggests that the incidence of oral submucous fibrosis (OSF) is higher than current estimates. OSF has the potential to undergo malignant transformation; thus, there is a need to identify relevant markers to assess its aggressiveness. We evaluated changes in COX-2, p53, and MDM2 expressions in progressive OSF. Expressions of COX-2, p53, and MDM2 increased with OSF progression. There was a strong association between COX-2 overexpression and recurrence of oral squamous cell carcinoma (P < 0.001) and a positive relation between increased MDM2 expression and failure of radiotherapy (P = 0.007). These findings suggest that COX-2 is an important marker of disease progression and that MDM2 expression is useful for treatment planning.