Promoter hypermethylation patterns of P16, DAPK and MGMT in Oral Squamous Cell Carcinoma: A systematic review and meta-analysis.

Background: Oral squamous cell carcinoma (OSCC) is a common cancer world‑wide that is highly lethal due to its recurrence and metastasis. Methylation is a common epigenetic mechanism that leads to gene silencing in tumors and could be a useful biomarker in OSCC. The prevalence of P16, death‑associated protein kinase (DAPK) and O6‑methylguanine‑DNA‑methyltransferase (MGMT) promoter hypermethylation in OSCC has been evaluated for several years while the results remain controversial. Objective: The aim of this systematic review is to critically analyze and perform a meta‑analysis on the various studies in the literature that have reported the promoter hypermethylation of P16, DAPK and MGMT genes in OSCC. Search Strategy: Articles were searched and selected through PubMed. Hand search from the relevant journals was also performed. Articles were reviewed and analyzed. Results: The estimated prevalence of P16 methylation was 43%, DAPK methylation was 39.7% and MGMT methylation was 39.8%. Heterogeneity in methylation prevalences and correlations with the clinical outcomes of the disease prevailed in various studies. Conclusion: We can conclude from our systematic review that a higher prevalence of methylation of P16, DAPK and MGMT occur in OSCC. Further studies are required to substantiate the role of methylation of P16, DAPK and MGMT as a marker in OSCC.

Comparative study of various grading systems in oral squamous cell carcinoma and their value in predicting lymph node metastasis.

Background: Regional lymph node (LN) metastasis is the single most prognostic factor for oral squamous cell carcinoma (OSCC). An analysis of the prognostic factors is important for predicting prognosis and reducing the mortality in these patients. Objectives: (1) To compare the value of various grading systems in predicting LN metastasis. (2) To evaluate histopathological parameters, which could help in predicting LN metastasis. Materials and Methods: A total of 20 excisional biopsies of OSCCs, were graded according to the four grading systems that is, Broder’s, Jakobsson's, Anneroth and Hansen’s, and Brynes. We also evaluated various histopathological parameters, which could help in predicting LN metastasis. Results: Grading at the invasive front was most prognostic of LN metastasis. Tumors with total malignancy score ≥8 showed higher incidence of metastases. Conclusion: The histopathological parameters that could help in predicting lymph node metastases (LNM) are keratinization, nuclear pleomorphism (NP), and the pattern of invasion (POI) when assessed at the invasive front. When the whole tumor was considered, histopathological parameters like NP and POI were significant in predicting LNM.

Prevalence and relationship of human papilloma virus type 16 and type 18 with oral squamous cell carcinoma and oral leukoplakia in fresh scrappings: A PCR study.

Introduction: It has been always an area of diffuse clarity when you study malignancy and its pathogenesis. Recently, it has invited lot of interest among the researchers about the possibility of role of viruses in the initiation of carcinogenesis. Recent advances in the field of molecular biology and biotechnology have solved some problems with regard to pathogenesis. Human papilloma virus (HPV) and its role in the initiation of malignancy in the cervix is proven almost beyond doubt. Objectives: The present study is aimed at the role of two types of HPV 16 and 18 in the initiation of oral premalignant and squamous cell carcinoma. The study also aims at using polymerase chain reaction (PCR) in finding out the prevalence of these types diagnosed histologically as oral leukoplakia and oral squamous cell carcinoma and prevalence of its association with the habit of tobacco use. Materials and Methods:In the present study, 45 patients having histopathologically confirmed oral squamous cell carcinoma in the age range of 32-85 years were selected along with 20 histopathologically confirmed oral leukoplakia in the age range 22-66 years. All the samples were subjected to polymerase chain reaction. The PCR reaction was carried out in PTC 200 thermo-cycler [MJ Research Inc, Watertown, MA, USA]. Results: The site prevalence and co-infection rate of these two types of viruses are being analyzed using very simple non-invasive scrapings obtained from fresh scrapings and found to be really high. It was also observed that 73.3% (33/45) of the oral squamous cell carcinoma patients were positive for oral HPV type 16 while 71.1% (32/45) were positive for HPV type 18 infection and 57.7% (26/45) were found to have both HPV type 16 and HPV type 18 infections. Conclusions:HPV type 16, 18, and co-infection of both types showed high prevalence in oral squamous cell carcinoma.The prevalence of HPV type 18 was found to be higher than HPV type 16 and co-infection in oral leukoplakia. It was observed that the tongue and palate lesions in the oral squamous cell carcinoma patients showed high prevalence of HPV type 16, type 18, and co-infection compared with other sites.

Tumor associated proteins of rat skin tumor induced by 7,12-dimethylbenzaanthracene

The incidence of tumor and the time of expression, cellular localization and the molecular weight of tumor associated proteins of rat skin tumor induced by 7,12-dimethylbenz[a]anthracene (DMBA) with or without 12-O-tetradecanoyl-phorbol-13-acetate (TPA) were studied. The time of the development of skin tumors in 0.1% DMBA-TPA treated rats was significantly shorter than that in rats which were treated with DMBA alone. In the complete carcinogenesis case, papillomas developed more slowly and were less common and also squamous cell carcinomas appeared much later. From the analysis of the proteins of each experimental group by SDS-PAGE and two dimensional gel electrophoresis, at least three tumor associated proteins were identified (54kd, pl = 5.66; 27kd, pl = 5.85; 11kd, pl = 4.90). Also these proteins were found in rat dorsal skin from 14 days gestation to 21 days postpartum, and disappeared after 28 days. In conclusions, two stage skin carcinogenesis could be successfully demonstrated in Sprague-Dawley rats and abnormal proteins were produced in DMBA or DMBA-TPA induced skin tumor. The tumor associated proteins of skin tumor induced by DMBA or DMBA-TPA were appeared at the late initiation stage or early promotion stage, and they were localized in plasma membrane and were glycoproteins that are thought to be related to the epidermal differentiation process.

Tumor associated proteins of rat skin tumor induced by 7,12-dimethylbenzaanthracene

The incidence of tumor and the time of expression, cellular localization and the molecular weight of tumor associated proteins of rat skin tumor induced by 7,12-dimethylbenz[a]anthracene (DMBA) with or without 12-O-tetradecanoyl-phorbol-13-acetate (TPA) were studied. The time of the development of skin tumors in 0.1% DMBA-TPA treated rats was significantly shorter than that in rats which were treated with DMBA alone. In the complete carcinogenesis case, papillomas developed more slowly and were less common and also squamous cell carcinomas appeared much later. From the analysis of the proteins of each experimental group by SDS-PAGE and two dimensional gel electrophoresis, at least three tumor associated proteins were identified (54kd, pl = 5.66; 27kd, pl = 5.85; 11kd, pl = 4.90). Also these proteins were found in rat dorsal skin from 14 days gestation to 21 days postpartum, and disappeared after 28 days. In conclusions, two stage skin carcinogenesis could be successfully demonstrated in Sprague-Dawley rats and abnormal proteins were produced in DMBA or DMBA-TPA induced skin tumor. The tumor associated proteins of skin tumor induced by DMBA or DMBA-TPA were appeared at the late initiation stage or early promotion stage, and they were localized in plasma membrane and were glycoproteins that are thought to be related to the epidermal differentiation process.