Searching HPV genome for methylation sites involved in molecular progression to cervical precancer.

Background: Human Papilloma Virus has been considered as the main cause for cervical cancer. In this study we investigated epigenetic changes and especially methylation of specific sites of HPV genome. The main goal was to correlate methylation status with histological grade as well as to determine its accuracy in predicting the disease severity by establishing optimum methylation cutoffs. Methods: In total, sections from 145 cases genotyped as HPV16 were obtained from formalin- fixed, paraffin-embedded tissue of cervical biopsies, conization or hysterectomy specimens. Highly accurate pyrosequencing of bisulfite converted DNA, was used to quantify the methylation percentages of UTR promoter, enhancer and 5' UTR, E6 CpGs 494, 502, 506 and E7 CpGs 765, 780, 790. The samples were separated in different groupings based on the histological outcome. Statistical analysis was performed by SAS 9.4 for Windows and methylation cutoffs were identified by MATLAB programming language. Results: The most important methylation sites were at the enhancer and especially UTR 7535 and 7553 sites. Specifically for CIN3+ (i.e. HSIL or SCC) discrimination, a balanced sensitivity vs. specificity (68.1%, 66.2% respectively) with positive predictive value (PPV) and negative predictive value (NPV) (66.2%, 68.2% respectively) was achieved for UTR 7535 methylation of 6.1% cutoff with overall accuracy 67.1%, while for UTR 7553 a sensitivity 60.9%, specificity 69.0%, PPV=65.6%, NPV=64.5% and overall accuracy=65.0% at threshold 10.1% was observed. Conclusion: Viral HPV16 genome was found methylated in NF-1 binding sites of UTR in cases with high grade disease. Methylation percentages of E6 and E7 CpG sites were elevated at the cancer group.

p53 mutations in oral cavity carcinoma.

Head and neck squamous cell carcinoma (HNSCC) includes a variety of SCCs derived from the anatomic regions of the oral and nasal cavity and also of the pharynx and larynx. Oral cavity SCC (OCSCC) demonstrates an increasing rate due to viral -related (High Risk Human Papilloma Virus-HR HPV) persistent infection, cigarette smoking and alcohol consumption. Gross chromosomal alterations (polysomy, aneuploidy) and specific gene aberrations such as amplifications, deletions, point mutations combined or not with epigenetic ones (promoter methylations and miRNA deregulations) are responsible for the progressive transformation of normal squamous epithelia to the corresponding malignant. In the majority of OCSCC cases, critical genes, such as p53 are found to be inactivated, leading to an overactivated cell cycle correlated to carcinogenetic process. P53 (gene location: 17p13.1) is a suppressor gene acting as a key regulator of the cell's genomic stability, function and homeostasis. P53 aberrant overexpression is frequently observed in OCSCC tissues as a result of point mutation or deletion. In the current special article we explored the role of the p53 gene deregulation - especially focused on its mutation status - in OCSCCs.