Immunohistochemical telomeric-repeat binding factor-1 expression in gastrointestinal tumors.

The maintenance of telomere length has been hypothesized to be involved in the early steps of cancerogenesis. A physiologic modulation of telomere maintenance is exerted by TRF1 (telomeric-repeat binding factor-1), which deletion permits telomere elongation. Gastrointestinal neoplastic (n=19) and non-neoplastic tissues (six inflammatory disease and six normal mucosa distant from tumor at least 5 cm) were studied, by immunohistochemistry, for TRF1 expression, by using a polyclonal antibody anti-TRF1. Differentiated and not proliferating epithelial secretory cells (Ki67 and p53 negative cells) were stained by anti-TRF1, which did not stain tumor cells in all cases but one (p<0.0001). p53 was expressed by 26% of tumor cases. Inflammatory gastrointestinal non-tumor tissues showed lower expression of TRF1 in epithelial secreting cells compared to normal tissues (p=0.008). These preliminary data suggest that down-regulation of the TRF1 expression in tumor cells may be involved in cell immortalization as an initial step in gastrointestinal carcinogenesis (before p53 alteration), and may open new perspectives, when confirmed, in gastrointestinal tumor prognosis.