Tehran University Medical Journal

Stable molecular changes during cell division without any change in the sequence of DNA molecules is known as epigenetic. Molecular mechanisms involved in this process, including histone modifications, methylation of DNA, protein complex and RNA antisense. Cancer genome changes happen through a combination of DNA hypermethylation, long-term epigenetic silencing with heterozygosis loss and genomic regions loss. Different combinations of N-terminal’s changes cooperate with histone variants with a specific role in gene regulation. It have led to load a setting histone that determine transcription potential of a particular gene or genomic regions. DNA methylation analysis in genome region using methylation-specific digital karyotyping of normal breast tissue detect gene expression patterns and DNA specific methylation can be found in breast carcinoma too more than 100 genes in breast tumors or cell lines of breast cancer are reported hypermethylated. Important of DNA methylation on cancer has been concentrated CpG islands hypermethylation. Most of the techniques are able to identify hypermethylated areas. Often, methylated genes play important role in cell cycle regulation, apoptosis, metastasis and tissue invasion, angiogenesis and hormonal signaling. Cyclin D2 (CCND2) gene is an important regulator of cell cycle and increased of expression inhibits the transition from G1 to S cell cycle. This gene is frequently methylated in breast cancer and has been proposed as the first event. Other cell cycle regulator is p16ink4A / CDKN2A that methylated in a large number of human cancers, including breast cancer. Another regulator of the proliferation of breast cancer that methylated is tumor suppressor RAR-β cancer that has been found in lobular and ductal carcinoma. Recent studies have showed the role of epigenetic silencing in the pathogenesis of breast cancer in which tumor suppressor genes have been changed by acetylation and DNA deacetylation. Histone deacetylase inhibitors have different roles in cancer cells and could show the ways of new treatment for breast cancer. In this review, various aspects of breast cancer epigenetics and its applications in diagnosis, prediction and treatment are described.

Background: The Micronuclei has been discussed as an indicator of chromosomal damage in radiotherapy. This study aimed to investigate the changes of micronuclei in peripheral blood lymphocytes of patients with of the gastrointestinal cancers pre- and post-chemo-radiation.

Methods: This cross-sectional study was conducted in patients with gastrointestinal cancers who referred to oncology ward of Rasool Akram Hospital in Tehran from January to March, 2016. After obtaining informed consent from all patients, 3 cc of peripheral blood samples was obtained for cytogenetic assessment in two stages, before treatment and 4 weeks after treatment. The frequency of micronuclei was examined per 1,000 lymphocytes with two nuclei.

Conclusion: The number of micronuclei in peripheral blood increased significantly in patients with gastrointestinal tract cancer (esophagus and stomach) under the chemo-radiation therapy. It seems that this increase was not correlated with age, sex and type of cancer (stomach or esophagus).