Tumour-derived adhesion factor in colorectal cancer.

Tumour-derived adhesion factor (TAF) has been shown to be associated with breast, prostate and colorectal cancer (CRC), acting as tumour suppressor or tumour promoter by mechanisms not as yet understood. Here, we comparatively analyzed the expression profile of TAF in plasma, tumour and paired normal tissue from patients with CRC. In addition, we investigated the relationship between TAF and systemic inflammation, mirrored by the elevation of interleukin-6 (IL-6) and TAF levels in plasma. Levels of TAF and IL-6 were determined by ELISA. Immunohistochemistry was performed to investigate the site of TAF expression. We also used a TaqMan system to investigate a TAF single nucleotide polymorphism (rs2041437) with a potential effect on CRC. TAF protein levels were significantly (P<0.001) higher in colorectal tumours than in normal tissue, and were increased in patients with Dukes' stages B and C compared to A. Immunohistochemistry revealed heterogeneous TAF expression mainly in the epithelial cells of the cancer and normal tissue. The plasma TAF level was reduced in CRC patients compared with the controls (P=0.002), independent of the inflammatory marker IL-6. Regarding genotype and allelic distributions, significant differences between CRC patients and control subjects or associations between clinical characteristics and TAF levels in tissue and plasma were not observed. In conclusion, altered TAF protein expression in cancer tissue may be a potential biomarker in colorectal carcinogenesis. Further research exploring the regulation of TAF is required to evaluate whether TAF is linked to clinical outcome.