Background and aims: COM-1(P8) is thought to play a role in the formation of metastases. This appears from current evidence to be different in various types of solid tumours. We aimed to examine the role COM-1 played in the development of colorectal cancer.
Materials and methods: The expression of COM-1 mRNA was examined using a quantitative polymerase chain reaction (PCR) technique together with immunohistochemistry to examine expression and distribution of the COM-1 protein in human colorectal carcinoma and matched normal colorectal mucosa.
Results: COM-1 was expressed in 22.8% of normal colorectal mucosa samples and the expression in these tissues was 54.9 copies of COM-1 transcript per sample. In tumour tissues, 43.6% of samples expressed COM-1, at a level of 98.9 copies of COM-1 transcript per sample (p=0.012). Normal tissues demonstrated strong nuclear and peri-nuclear staining for COM-1 on immunohistochemistry (IHC) and in tumour tissues, the level of staining was found to be much greater, with a greater degree of cytoplasmic staining and little nuclear staining. Early-stage tumours showed a greater degree of staining on IHC compared to those at an advanced stage of disease.
Conclusion: COM-1, although overexpressed at the messenger level, appears to be distributed in a cytoplasmic fashion at the protein level in tumours. Tumours at advanced stage express COM-1 protein to a lesser extent than their early-stage counterparts.