Proteomic assessment of colorectal cancers and respective resection margins from patients of the Amazon state of Brazil

Abstract

Colorectal cancer (CRC) is the third most common type of cancer in the world with a low survival rate and therapeutic efficiency. Tumor surgery implies the removal of an apparently non-tumorous tissue around the tumor in an attempt to reduce recurrence chances; this tissue is referred to as the resection margin. Our analysis employed an 8-plex iTRAQ to label four adenocarcinoma biopsies and their corresponding resection margins at 5cm; our results disclose fifty-six proteins as being differentially abundant. These proteins are mainly involved in energetic metabolism (e.g. S100 calcium binding protein A11), cell migration (e.g. transgelin), formation of the cytoskeleton (e.g. profilin 1) and degradation of extracellular matrix (e.g. carbonic anhydrase 2). A gene ontology enrichment analysis revealed several proteins related to adhesion, invasion, metastasis, death, and recognition cell. Taken together, our results highlight proteins related to invasion, cell proliferation, and linked to the metastasis of colorectal cancer in tumor tissue. Finally, we argue that the expression patterns revealed in our comparison helps shed light on the development of more effective surgical strategies and add to the comprehension of this disease.

Biological significance: Colorectal cancer (CRC) is the third most common type of cancer in the world with a low survival rate and therapeutic efficiency. Tumor surgery implies the removal of an apparently non-tumorous tissue around the tumor in an attempt to reduce recurrence chances; this tissue is also referred to as the resection margin. In this regard, resection margins pose as a treasure trove for investigating the molecular characteristics of the tumorigenesis process. While most studies focus on comparing cancer versus control tissue, this study contrasts the proteomic profiles of colorectal cancer biopsies with their corresponding resection margin at 5cm apart. Our analysis employed an 8-plex iTRAQ labeling and a 4-step offline MudPIT online with a Velos. A gene ontology enrichment analysis revealed several proteins related to adhesion, invasion, metastasis, death, and recognition cell.

Keywords: Colorectal cancer; Resection margin; Shotgun proteomics; iTRAQ 8-plex.