The role of Tet2 protein in the 5-hydroxymethylcytosine enrichment of genomic DNA in stem cell-like phenotype in pre-malignant and pre-metastatic melanocytic lesions

• Grant number: 12/25473-6
• Support type: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): March 01, 2013
• Effective date (End): November 30, 2013
• Field of knowledge: Biological Sciences - Biochemistry - Molecular Biology
• Principal researcher: Miriam Galvonas Jasiulionis
• Grantee: Guilherme Burgarelli Leite
• Home Institution: Escola Paulista de Medicina (EPM). Universidade Federal de São Paulo (UNIFESP). Campus São Paulo. São Paulo , SP, Brazil

Abstract

During the malignant transformation of melanocytes, like other cellular types, DNA methylation patterns are found altered, affecting the genetic expression. A significative quantity of methylated cytosines (5mC) appears to be hydroxylated (5hmC) by 2-oxoglutarate and Fe(II) dependent dioxygenases, Tet1, 2, and 3 (Globish et al., 2010; Ko et al., 2010). There is evidence pointing 5hmC as an intermediary product in active DNA demethylation, which could contribute to DNA methylation dynamics. Furthermore, it was demonstrated that Tet1 and Tet2 are expressed in embryonic stem cells (Ito et al., 2010) and that 5hmC appears to play an important role in the maintenance and differentiation of these cells (Koh et al., 2011). However, the role of 5hmC and Tet proteins either in normal physiology or disease like cancer is not yet clear. In this project, we intend to characterize alterations in Tet2 protein expression and 5-hydroxymethylcytosine levels in the initial phases of melanoma progression in a murine in vitro melanocytic transformation model. Additionally, we will verify a possible association between these alterations and pluripotent characteristics observed in pre-malignant melanocytes and non-metastatic melanoma cells. The alterations of Tet2 and 5-hydroxymethycytosine leves will also be measured in human lineages of metastatic melanoma and tumoral specimens. This study will contribute to the understanding of the epigenetic regulatory mechanisms involving 5-hydroxymethylcytosine and Tet proteins in DNA methylation and characterization of useful biomarkers for risk prediction, diagnostic and prognostic, as well as possible therapeutic targets in melanoma. (AU)