Immunohistochemical Expression of Debiquitinating Enzyme OTUB1 in Colorectal Carcinoma

Abstract
Background and Objective: Colorectal Carcinoma (CRC) is the most common malignancy of the gastrointestinal tract. The overall five-year survival for colon cancer and rectal cancer are 65% and 68%, respectively with liver metastasis being the leading cause of death. Despite the use of active targeted drugs for treatment of metastatic CRC in the past decade, cure rates remain low. Therefore, research on novel markers for earlier diagnosis and target therapy of CRC is of a great concern. OTUB1 (OTU deubiquitinase, ubiquitin aldehyde binding 1) is a deubiquitinating enzyme (DUB) that belongs to the OTU (ovarian tumor) superfamily. The aim of this work is to study the immunohistochemical expression of OTUB1 in CRC and its correlation with the available clinico-pathological variables.
Material and Methods: This retrospective study was conducted on a total number of 45 cases of CRC. All cases were retrieved from the archival files of the pathology labs of Ain Shams University Hospitals (from 2012-2016). Immu-nohistochemistry using rabbit polyclonal anti OTUB 1 antibody was performed.
Results: OTUB 1 was overexpressed in CRC tissues, and the expression level of OTUB1 was correlated significantly with histologic grade (p<0.001), depth of invasion (pathological T) (p=0.03) and location of CRC (p=0.002). On the other hand, no significant correlation was found with age, gender, metastasis whether nodal or distant, TNM stage and size of tumor.
Conclusion: OTUB1 may have a possible role in tumor differentiation as well as local tumor invasion, thus could be useful in identification of biologically aggressive tumors in colonoscopic biopsies in addition to providing a basis for targeted therapy which could play a major role in the treatment of CRC.