ABSTRACT
This work aimed to study the expression of CD74, a protein which has an important function in antigen presentation by immune competent cells, in colorectal carcinoma to explore the feasibility of using it in antigen directed therapy in this type of cancer, we also aim to assess its prognostic value through studying its correlation with tumor grade, Ki 67 expression, and CD31 expression. Twenty three retrospective, formalin fixed, paraffin embedded specimens of colorectal carcinomas were graded using H and E stained sections after Bosman et al, [2010]. Specimens were stained using immunoperoxidase technique for CD74, Ki67, and CD31 antibodies, followed by semiquantitation of their immunoreactivities. The results were tabulated and statistically analysed using ANOVA test and Pearson's correlation coefficient. CD74 protein expression was present in 11/14 [79%] of adenocarcinoma NOS, with diffuse pattern of staining in all the positive cases except one case. The average weighted score [AWS] was 3.1: 4.5. CD74 was totally negative in mucin producing carcinomas [7cases]. CD74 was diffusely expressed in the studied case of neuroendocrine carcinoma but not in the case of medullary carcinoma. The correlation between CD74 and tumor grade was insignificant [p<0.2]. The average Ki-67 labeling index in colorectal carcinomas was 39%. The mean value for CD31 expression was 8.7: 14. Cd74 was positively correlated to Ki67 proliferation index [p<0.0004], as well as to CD31 expression [p<0.059]. Analysis of variance [ANOVA] for the three biomarkers [CD74, Cd31. Ki76] showed highly significant P value [p<0.000002]. In colorectal carcinoma CD74 expression positively correlates with Ki67 proliferation index and angiogenesis which suggests that it may be a marker of poor prognosis in such carcinoma. CD74 expressed in most of colorectal carcinomas suggesting the feasibility of using it in antigen directed immunotherapy in this type of cancer