Abstract 4091: Identification of epigenetic alterations associated with tumor progression and cancer metastasis

Abstract Cancer metastasis could be defined as “the point of no return” in the majority of cancers. The emergence of metastasis is still associated with the worst prognosis and high morbidity. Given the importance of the disease, researchers in this field are focusing on the discovery of new molecular biomarkers able to predict tumor progression and the development of metastasis. Thus, deciphering the molecular and cellular alterations implied in the origin of the metastasis would permit us to develop novel therapies that make a significant contribution to cancer treatment. In this line, the extant variability and versatility of microarray technology provides us a good chance to identify targets involved in cancer progression, to distinguish between cancer types, to identify the tumor type of origin, or to predict the outcome of the disease. According to the successful results obtained applying these kind of techniques, we proposed a genome-wide approach to elucidate the methylation changes associated with cancer progression. Once the first candidates were validated, we assessed the gene function and the consequences that the epigenetic silencing has in the metastatic cascade. The study was carried out in four different paired tumor cell types (11A/11B, MDA-MB-468PT/468LN, 1590PT/1590LN, and SW480/SW620) derived from primary tumor and the corresponding lymph node metastases. For that purpose, we used the new Illumina Infinium Human Methylation 450K array. This powerful platform, mapping 485,577 CpGs, has been successfully validated in our lab and has extensively demonstrated its huge resolution. In order to spot those epigenetic alterations with functional effect on gene activity, we combined these methylation data with the expression data obtained from the Human Genome U133 Plus 2.0 gene expression array performed in the same cell lines. The promoter methylation pattern of candidate genes in cell lines was validated by PCR analysis of bisulfite-modified genomic DNA. In addition, quantitative RT-PCR and Western Blot were used to make sure that the methylation change was indeed associated with a deviation in the gene expression level. DNA methylation status of candidate genes in primary and metastatic tumors was determined by methylation-specific PCR. In our preliminary results we detected several metastasis related genes methylated. Some of them have already been described in colon, breast, esophagus and head and neck cancer metastases but others were new candidates, including both protein-coding genes and microRNAs. Among these, we frequently found ontologies related to metastasis progression such as cell adhesion, cell motility and migration, protein-to-protein interaction with histone deacetylases complexes (HDAC, linked to gene transcription repression), potential members of HDAC, sponge proteins that recruit HDACs or histone acetyltransferases (HATs), and potential suppressor tumor genes. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4091. doi:1538-7445.AM2012-4091