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Colorectal cancer (CRC) is distinguished by epigenetic elements like DNA methylation, histone modification, histone acetylation and RNA remodeling which is related with genomic instability and tumor initiation. Correspondingly, as a main epigenetic regulation, DNA methylation has an impressive ability in order to be used in CRC targeted therapy. Meaningly, DNA methylation is identified as one of most important epigenetic regulators in gene expression and is considered as a notable potential driver in tumorigenesis and carcinogenesis through gene-silencing of tumor suppressors genes. Abnormal methylation situation, even in the level of promoter regions, does not essentially change the gene expression levels, particularly if the gene was become silenced, leaving the mechanisms of methylation without any response. According to the methylation situation which has a strong eagerness to be highly altered on CpG islands in carcinogenesis and tumorigenesis, considering its epigenetic fluctuations in finding new biomarkers is of great importance. Modifications in DNA methylation pattern and also enrichment of methylated histone signs in the promoter regions of some certain genes like MUTYH, KLF4/6 and WNT1 in different signaling pathways could be a notable key contributors to the upregulation of tumor initiation in CRC. These epigenetic alterations could be employed as a practical diagnostic biomarkers for colorectal cancer. In this review, we will be discuss these fluctuations of MUTYH, KLF4/6 and WNT1 genes in CRC.

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Background: Alzheimer Disease (AD) is an age-related neurodegenerative disorder with a progressive impairment of cognitive function. The pineal gland hormone melatonin (MEL) has been known as a protection agent against AD. However, the effect of melatonin in various doses is inconsistent. Objectives: In this study, we aimed to investigate two doses of MEL on learning and memory in the amyloid-βeta (Aβ)-induced AD in the rats. Materials & Methods: Forty-eight male Wistar rats were used in the experiment and randomly divided control, sham, vehicle, AD, AD+MEL10 mg/kg, and AD+MEL 20 mg/kg groups. Intracerebroventricular injection of Aβ1–42 was used to develop the animal model of AD. Also, MEL-treated groups received an intraperitoneal injection of MEL for 4 next weeks. The Morris Water Maze (MWM) and Passive Avoidance Learning (PAL) tests were used to examine animals’ learning and memory. The brain of animals was removed for immunohistochemistry for anti- Amyloid Precursor Protein (APP). Results: Intra-peritoneal injection of MEL significantly improve learning and memory in MWM (P=0.000) and PAL test (P=0.000), but there were no significant changes in the two groups that received the melatonin (P>0.05). Histopathological analysis revealed that the clearance of APP deposition in the AD+MEL20 group was considerable compared with the AD+MEL10 group (P=0.000). Conclusion: Our findings indicate that 10 and 20 mg/kg doses of melatonin have similar results on learning and memory in the AD model. But 20 mg/kg of melatonin has significantly more effect on the clearance of APP deposition.