Gastric cancer is the second most prevalent cause of cancer death worldwide. DNA methylation is a common event in gastric carcinogenesis. hTERT seems to be the rate-limiting determinant of telomerase activation, which is responsible for stability and life span. hTERT hypermethylation has been associated with telomerase expression. In the present study, we investigated the promoter methylation status and hTERT protein expression in gastric cancer and normal mucosa samples. One hundred and nine gastric cancer and 53 normal mucosa samples were investigated through methylation-specific PCR. Immunohistochemistry was analysed using peroxidase in 55 gastric cancer and 18 normal gastric mucosa samples. This is the first study evaluating hTERT methylation status in gastric carcinogenesis. We did not observe hTERT protein expression in normal gastric mucosa. Moreover, hTERT expression was observed in 80% of tumours and was associated with gastric cancer (p< 0.0001). Partial methylation was the most frequent pattern in gastric samples, even in normal mucosa. The frequency of specimens presenting hypermethylation was significantly higher in tumours than in normal mucosa samples (p = 0.0002), although the presence of hypermethylated promoter was not associated with a higher frequency of hTERT expression. A low correlation between hTERT protein expression and methylation was verified in gastric cancer samples. There was a clear difference in the frequency of hTERT expression and methylation within tumoral and non-tumoral tissues. Methylation status and telomerase expression may be useful for the diagnosis of gastric cancer and may have an impact on the anti-telomerase strategy for cancer therapy.

Here, we first evaluated SMARCA5 expression and promoter DNA methylation in gastric carcinogenesis. Immunohistochemistry and methylation-specific PCR were analyzed in 19 and 48 normal mucosa and in 52 and 92 gastric cancer samples, respectively. We observed higher immunoreactivity of SMARCA5 in gastric cancer samples than in normal mucosa. Moreover, SMARCA5 promoter methylation was associated with the absence of protein expression. Our findings suggest that SMARCA5 has a potential role in proliferation and malignancy in gastric carcinogenesis.

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The human genome is a fragile and highly conserved structure that accumulates a wide range of damaging alterations with age. Long-term alterations in the transcriptional potential of a cell are heritable and these changes are called epigenetics. The most studied alteration is the DNA methylation, which can regulate gene expression, often blocking gene transcription. The relationship between epigenetics and aging was proposed many years ago, and a decrease in the genomic global DNA methylation with age was largely observed. In this study we describe the methylation status of SIRT1, IGFBP-3 and CAV1 in a young and an older group of healthy individuals by methylation-specific PCR. SIRT1and IGFBP-3 promoter methylation frequency was significantly higher in the older than in the young adult group. Moreover, when combining promoter methylation status of several genes we observed that the total number of methylated promoters more than 85% of older individuals presented 4 promoters against only 46% of young adults. These findings may suggest that with increasing age there is an epigenetic switching to gene repression. The understanding of age-related genes methylation status can lead to a better comprehension of the role of epigenetic variation in the aging process.