Humoral Autoimmune Response to IGF2 mRNA-Binding Protein (IMP2/p62) and Its Tissue-Specific Expression in Colon Cancer

To understand the autoimmune response and immunogenicity of a tumour-associated antigen (TAA) and IGF2 mRNA-binding protein (IMP2/62) in colon cancer, autoantibody to this TAA was evaluated by enzyme-linked immunosorbent assay (ELISA), Western blotting and indirect immunofluorescence assay in sera from patients with colon cancer. Immunohistochemistry (IHC) study with colon cancer tissues was also performed to analyse protein expression of IMP2/p62. The result has showed that there has a relatively higher frequency of autoantibody response to IMP2/p62 in colon cancer (23.4%, 15/64) compared to patients with colonic adenomas (4.8%, 2/42) and normal individuals (2.9%, 1/34). Of 64 colon cancer tissue specimens examined, 48 tissues (75.0%, 48/64) expressed p62, while normal colon tissues did not show any expression of p62 (0/34). The positive rate of antinuclear antibody (ANA) in colon cancer was 82.8% (53/64), which is significantly higher than that in patients with colonic adenomas (21.4%, 9/42) and normal individuals (17.6%, 6/34). The data suggest that the combinational detection of anti-p62 autoantibody and ANA is of significance in diagnosing colon cancer and monitoring the prognosis of the disease.