Immunological implications of alterations in the c-Ki-ras and p53 genes in the stepwise progression of colorectal cancer: indications for the improvement of prognosis, biotherapy treatment and tumor biology understanding

Abstract

Alterations in gene structure and functions involving the c-Ki-ras and p53 genes have been shown to play an important role in the various stages of human colorectal carcinogenesis. However, how these gene alterations cooperate with tumoral mechanisms at an immunological level is not known. To this aim an immunological study of a group of healthy subjects, patients with p53 gene deletions (53D), with c-Ki-ras mutations (KrM) and no gene alterations (53D-KrM-) have made. In a previous study we found that a disregulation between TH1/Th2 cell functions seems to be implicated in the establishment and progression of colorectal cancer disease and that soluble interleukin (IL)-2Receptor (sIL-2R) serum level is involved in this. On this basis we investigated the immunological implications of p53 and c.Ki-ras gene alterations, evaluating the relationhips in the immune network between sIL-2R levels in the serum and immunological parameters (IL-2, IL-4 serum levels; CD3, CD16 and CD19 expression on the surface of peripheral blood mononuclear cells--PBMC). Our results suggest that, in the stepwise progression of colorectal cancer, the c-Ki-ras gene alteration is involved in a switch of the host immune response to a suppressive type which, as we have previously reported, may be a determining or concurrent cause of malignant transformation. Alteration in the p53 gene does not appear to ulteriorly impair the patients' immunological response. Our data supports the role of c-Ki-ras gene mutations and p53 deletions as prognostic markers in the passage of normal tissue to adenoma and adenoma to carcinoma respectively. Moreover, the evaluation of the mechanisms involved in the alterations of c-Ki-ras gene seems to be more important than that of p53 suppressor gene for the improvement of prevention, biotherapy treatment and tumor biology understanding.