Hypermethylation Pattern of COX-2 and Rb1 in Head and Neck Squamous Cell Carcinomas

Head and neck cancer is among the ten most common human cancers worldwide, being 90% of all cases squamous cell carcinoma histological subtype. These tumors are always associated with high rates of mortality and patients with disease presenting in the same site with the same stage that under go the similar treatment, may have different oncologic outcomes. These aspects show the necessity of developing effective molecular markers that may be able to increase survival rates. Epigenetic mechanisms contribute to the carcinogenesis process, especially by the methylation of cytosines in CpG islands. The identification of aberrantly methylated DNA may help carcinogenesis understanding as well as potential clinical targets for studies in cancer. We analyzed genes RB1 and COX-2 methylation status by the quantitative, high-throughput Q-MSP assay in cell lines, 30 tumor samples and 10 normal oral cavity mucosa samples. These two genes evaluation was not informative because the incidence of hypermethylation was completely absent (RB1) or ubiquitous (COX-2), RB1, regardless of tissue type. These results suggest that the hypermethylation pattern of both RB1 and COX-2 might not be a reasonable biomarker for head and neck squamous cell carcinomas.

Hypermethylation Status of NRGN and OLFM1 Promoter Regionsin Glioblastomas Cell Lines

Glioblastomas are the most malignant astrocytic tumors and the most common brain tumors, representing 50 to 60% of allastrocytic tumors. In a previous study, Marie et al (2005) using SAGE and cDNA microarray analyses, followed by real-time PCRvalidation in additional tumor samples, identified potential markers for astrocytomas with distinct levels of malignancy. In thepresent study, we evaluated if the hypoexpression of two of these genes - Neurogranin (NRGN) and Olfactomedin (OLFM1) – isrelated to the hypermethylation of their promoter regions. CpGs islands were identified in the promoter regions of both genesand tumour cell lines (A172 and T98G) were submitted to 5 Aza dC treatment. The treatment was able to induct the expression(1.8 to 8.9 folds) of both genes. Nevertheless, the association between NRGN and OLFM1 hypoexpression and CpG islandhypermethylation could not be established because the CpGs dinucleotides present in the promoter region of these genes wereunmethylated when evaluated by sequencing.

The libraries that made SUCEST

A large-scale sequencing of sugarcane expressed sequence tags (ESTs) was carried out as a first step in depicting the genome of this important tropical crop. Twenty-six unidirectional cDNA libraries were constructed from a variety of tissues sampled from thirteen different sugarcane cultivars. A total of 291,689 cDNA clones were sequenced in their 5' and 3' end regions. After trimming low-quality sequences and removing vector and ribosomal RNA sequences, 237,954 ESTs potentially derived from protein-encoding messenger RNA (mRNA) remained. The average insert size in all libraries was estimated to be 1,250bp with the insert length varying from 500 to 5,000 bp. Clustering the 237,954 sugarcane ESTs resulted in 43,141 clusters, from which 38 per cent had no matches with existing sequences in the public databases. Around 53 per cent of the clusters were formed by ESTs expressed in at least two libraries while 47 per cent of the clusters are formed by ESTs expressed in only one library. A global analysis of the ESTs indicated that around 33 per cent contain cDNA clones with full-length insert.