Análise proteômica e epigenética de pacientes com câncer colorretal do estado do Amazonas

Abstract

Colorectal cancer (CRC) is the third most common cancer in the world, with a low survival rate and therapeutic efficacy. One of the treatments is tumor removal, which involves removal of apparently non-tumorous tissue around the tumor (resection margin). In this sense, the margin of resection is a very interesting region to investigate the molecular characteristics of the tumorigenic process. Thus, the objective of this study was to perform a comparative study of tumor tissue samples and margin of resection through epigenetic and proteomic analyzes of patients with colorectal cancer in the state of Amazonas (Brazil). For the epigenetic profile thirteen samples, in which six were tumoral and seven were resection margins were analyzed by polymerase chain reaction (PCR) specific for methylation (MSP). In the proteomic analysis, four CRC samples and their respective resection margins were digested with trypsin, labeled with iTRAQ 8-plex and subjected to strong cation exchange chromatography. Each fraction was analyzed by reverse phase chromatography coupled to an Orbitrap Velos mass spectrometer and, finally, the data were analyzed in the PatternLab for Proteomics program. Analysis of CDH1, CDKN2A, DAPK and TIMP2 genes was 4/14 (30.8%), 5/14 (30.8%), 11/14 (84.6%) and 12/14 (84.6%), respectively. Proteomic analysis identified 1090 proteins, of which 56 were identified as differentially abundant. These proteins are mainly involved in energy metabolism (e.g., S100 calcium binding protein A11), cell migration (e.g. transgelin), cytoskeleton formation (e.g., profilin 1) and extracellular matrix degradation (e.g., carbonic anhydrase 2). Gene Ontology analysis revealed several proteins related to adhesion, invasion, metastasis and cell death. The results show distinct methylation patterns for each patient, which in turn may contribute to the development of individualized treatments andalso differentially abundant proteins related to tumorigenesis, emphasizing the importance of the study of marker panels for CRC in the context of different Populations.