Raghu Radhakrishnan

Salivary IL-6 levels in oral leukoplakia with dysplasia and its clinical relevance to tobacco habits and periodontitis

The development of oral cancer proceeds through discrete molecular changes that are acquired from loss of genomic integrity after continued exposure to environmental risk factors. It is preceded in the majority of cases by clinically evident oral potentially malignant disorders, the most common of which is leukoplakia. Early detection of these oral lesions by screening methods using suitable markers is critical as it mirrors molecular alterations, long before cancer phenotypes are manifested. Assessment of salivary interleukin-6 (IL-6) as a marker of malignant progression was undertaken in patients with leukoplakia having coexisting periodontitis (n = 20), periodontitis patients without leukoplakia (n = 20), and healthy controls (n = 20) by competitive enzyme-linked immunosorbent assay. Results showed elevation of IL-6 levels in leukoplakia with coexisting periodontitis and in periodontitis patients when compared to healthy control (P < 0.001). Within the leukoplakia group, IL-6 level was found to be increased with increase in the severity of dysplasia. The use of tobacco was seen to play a significant role in the elevation of salivary IL-6.The importance of IL-6 as a specific marker for leukoplakia with dysplasia and the role of tobacco as an independent risk factor has been highlighted.

Molecular changes in invasive front of oral cancer

Treatment planning for oral squamous cell carcinoma (OSCC) is based on the clinical TNM (Tumor, Node and Metastasis) classification. This system operates on the assumption that small tumours without clinical spread have a better prognosis than larger tumours with metastases. However, it is a well-known fact that some tumours with the same clinical staging show different growth patterns and clinical behaviour. This makes the prognosis for patients with OSCC difficult to predict on the basis of clinical staging alone. Although many histopathological characteristics of OSCC have been identified as prognostic factors, none is believed to be completely infallible. Therefore, a great need exists for more reliable prognostic markers, which will assist in treatment decisions. It is now well documented that several molecular events of significance for tumour spread, such as gain and loss of adhesion molecules, secretion of proteolytic enzymes, increased cell proliferation and initiation of angiogenesis occur at the tumour–host interface or invasive front, where the deepest and presumably most aggressive cells reside. This review describes the various molecular events and interactions, which take place in the invasive front of the OSCC, and elucidates their role as prognostic markers.

The role of MMP-2 and MMP-9 as prognostic markers in the early stages of tongue squamous cell carcinoma

BACKGROUND Tongue cancer is the most common intra-oral malignancy with a high rate of morbidity and mortality owing to its increased propensity for tumor invasion and metastasis. These processes require a controlled degradation of the extracellular matrix. Matrix Metalloproteinase-2 (MMP-2) and Matrix Metalloproteinase-9 (MMP-9) are known to be important regulators of matrix lysis and play a significant role in the metastasis of malignancies. AIM AND OBJECTIVES To study the expression of MMP-2 and MMP-9 in the early stages of tongue squamous cell carcinoma and find the association between their expression and local recurrence, metastasis, and survival rates of the subjects. MATERIALS AND METHODS Fifty-nine tumor biopsy samples of tongue squamous cell carcinoma in T1 N0 M0 and T2 N0 M0 stages were immunostained with MMP-2 and MMP-9 antibodies. The immunohistochemical expression was compared with the patient characteristics and outcome. RESULTS Cytoplasmic expression of MMP-2 correlated with that of MMP-9 (r = 0.716, P < 0.001). Greater expression of MMP-2 and MMP-9 was observed in patients who subsequently developed local recurrence (P = 0.044 and P < 0.001, respectively), regional and/or distant metastasis (P < 0.001 and P = 0.001, respectively) of the tumor. Further, a higher expression of these biomarkers was associated with shorter survival. MMP-9 was found to have better specificity for local recurrence, metastasis and survival. CONCLUSION Our results showed that these biomarkers may serve as indicators of a patients risk potential for poor prognosis and presage the need for more aggressive treatment measures.

DNA Promoter Methylation-dependent Transcription of the Double C2-like Domain β (DOC2B) Gene Regulates Tumor Growth in Human Cervical Cancer

Background: DOC2B promoter hypermethylation is an early and frequent event in cervical cancer. Results: DOC2B hypermethylation induces transcriptional repression, reactivated by demethylation; ectopic expression increases Ca2+ flux and inhibits key characteristics of tumorigenesis including proliferation, motility, and invasion. Conclusion: DOC2B gene is epigenetically regulated and inhibits cervical cancer growth. Significance: DNA methylation regulates DOC2B gene expression in cervical cancer. Double C2-like domain β (DOC2B) gene encodes for a calcium-binding protein, which is involved in neurotransmitter release, sorting, and exocytosis. We have identified the promoter region of the DOC2B gene as hypermethylated in pre-malignant, malignant cervical tissues, and cervical cancer cell lines by methylation-sensitive dimethyl sulfoxide-polymerase chain reaction and bisulfite genome sequencing; whereas, it was unmethylated in normal cervical tissues (p < 0.05). The promoter hypermethylation was inversely associated with mRNA expression in SiHa, CaSki, and HeLa cells and treatment with demethylating agent 5-aza-2-deoxycytidine restored DOC2B expression. The region −630 to +25 bp of the DOC2B gene showed robust promoter activity by a luciferase reporter assay and was inhibited by in vitro artificial methylation with Sss1 methylase prior to transient transfections. Overexpression of the DOC2B gene in SiHa cells when compared with controls showed significantly reduced colony formation, cell proliferation, induced cell cycle arrest, and repressed cell migration and invasion (p < 0.05). Ectopic expression of DOC2B resulted in anoikis-mediated cell death and repressed tumor growth in a nude mice xenograft model (p < 0.05). DOC2B expressing cells showed a significant increase in intracellular calcium level (p < 0.05), impaired AKT1 and ERK1/2 signaling, and induced actin cytoskeleton remodeling. Our results show that promoter hypermethylation and silencing of the DOC2B gene is an early and frequent event during cervical carcinogenesis and whose reduced expression due to DNA promoter methylation may lead to selective cervical tumor growth.

The role of basic fibroblast growth factor in oral submucous fibrosis pathogenesis.

BACKGROUND Oral submucous fibrosis (OSF) is a chronic fibrotic disease of oral mucosa and oropharynx, induced by betel quid chewing often resulting in restricted mouth opening. The principal cells implicated as a source of extracellular matrix in areas of fibrosis are fibroblasts. Accumulation of connective tissue matrix is secondary to factors such as cytokines and growth factors. The contribution of basic fibroblast growth factor (bFGF) in disease progression and the consequent stromal changes with increase in the severity of OSF was studied. METHODS A case series analysis of 30 cases of OSF was carried out for bFGF expression using immunohistochemistry. Connective tissue changes in these cases were corroborated using aldehyde fuchsin and Verhoeffs hematoxylin special stains. RESULTS bFGF immunoreactivity was found to be increased in fibroblasts and in endothelial cells in early OSF cases, while the expression of bFGF in stroma increased notably in advanced fibrosis. CONCLUSION Increased bFGF expression in early stages of the disease was explainable to an initial injury phase because of areca consumption, followed by cellular activation by chemotactic cytokines and other growth factors with eventual fibrosis occurring as a result of molecular alteration at the cellular level.

DNA hypermethylation as an epigenetic mark for oral cancer diagnosis

Oral cancer is the largest group of cancers which fall into the head and neck category. While genetic alterations in oral cancer have long been documented, the effect of epigenetic changes is more recent. The recent explosion in science of how chromatin organization modulates the gene expression has highlighted the epigenetic mechanism of oral cancer pathogenesis. DNA methylation, which is an important epigenetic marker, is perhaps the best characterized chemical modification of mammalian DNA and provides a stable, heritable, and critical component of epigenetic regulation. This review attempts to decipher the epigenetic aspects of oral cancer by evaluating the DNA methylation status through its various stages from normal to potentially malignant to malignant states. In doing so, we emphasize DNA methylation as a novel biomarker in oral cancer research, thus opening newer avenues in oral cancer research.

Kimura's disease - An unusual presentation involving subcutaneous tissue, parotid gland and lymph node.

Kimuras disease is a rare chronic inflammatory condition of uncertain etiology which has an affinity for the Asian population. It primarily involves the head and neck region, presenting as deep subcutaneous masses and is often accompanied by regional lymphadenopathy and salivary gland involvement. Peripheral blood eosinophilia and elevated serum immunoglobulin E (IgE) levels are characteristic features and the microscopic picture reveals lymphoid proliferation with eosinophilic infiltration. For years, Kimuras disease was believed to be identical to or part of the same disease spectrum as angiolymphoid hyperplasia with eosinophilia (ALHE). Recent reports, however, have confirmed that the two are, in fact, separate entities. We report a case of Kimuras disease in a 22-year-old Indian male who presented with a subcutaneous mass, parotid enlargement and lymphadenopathy. The clinical presentation was suggestive of Kimuras disease and microscopic examination following biopsy of the lesion allowed us to make a definitive diagnosis.

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.

Adenomatoid odontogenic tumor: A unique report with histological diversity

Odontogenic tumors are a group of heterogeneous lesions, features of which have been catalogued for several decades. Adenomatoid odontogenic tumor (AOT) is a relatively rare and distinct odontogenic tumor that is exclusively odontogenic epithelium in origin. Although considerable number of reports is available with regard to the clinical and histological spectrum of AOT, very few have highlighted its varied histological presentations. Therefore, this article focuses on the assorted histoarchitectural patterns of AOT.

Overexpression of S100A4 as a biomarker of metastasis and recurrence in oral squamous cell carcinoma

S100A4, a biomarker of epithelial mesenchymal transition (EMT), plays an important role in invasion and metastasis by promoting cancer cell motility. In oral squamous cell carcinoma (OSCC), metastasis results in 90% of cancer associated mortality. Objective To investigate the role of S100A4 expression as an important component of the epithelial mesenchymal transition (EMT) program in oral squamous cell carcinoma (OSCC). Material and Methods S100A4 protein expression was assessed semi-quantitatively by immunohistochemistry in 47 histologically confirmed cases of oral squamous cell carcinoma (OSCC) and 10 normal oral mucosal biopsies. The association between the S100A4 overexpression and the aggressive features of OSCC were analyzed by X2 test. Results Moderate to strong cytoplasmic expression of S100A4 was observed in 30 out of 47 specimens of OSCC (64%). Overexpression of S100A4 was significantly associated with the clinical stage, lymph node involvement, metastases, pattern of invasion and recurrence (p<0.05). Conclusion S100A4 expression represents an important biomarker of prognostic significance that may be used to identify a subset of patients at high risk of invasion and metast