Immunohystochemical Expression of Vitamin D Receptor in Development Stages of Colorectal Carcinoma.

BACKGROUND: Chemo preventive and antitumor role of vitamin D is manifested through genetic and non genetic ways with a powerful antproliferatory and proapopoptic effect, which is proven by numerous epidemiologic studies. The genetic activity of vitamin D is determined through vitamin D receptors (VDR), a member of stero-thyreoidal family of nuclear receptors, which with vitamin D form a cell nucleus complex responsible for the chemo preventive and antitumor effect. VDR in tissue cells is present in the cytoplasm and the nucleus and manifests its genetic activity after transfer from the cytoplasm to the nucleus. The mechanisms for the transport and genetic control of the transport of VDR from cytoplasm to the nucleus in not yet completely understood.

SUBJECTS AND METHODS: By using immunohystochemistry we are evaluating the correlation of cytoplasmic and nuclear expression of VDR during different stages of colorectal carcinoma: normal colorectal mucosa, hyperplasic polyp, low grade adenoma (LGD), high grade adenoma (HGD) and colorectal cancer.

RESULTS: Our results confirm that the nuclear VDR expression is strongest in normal colorectal mucosa and in hyper plastic polyps, is gradually weakened in low and high grade adenoma while it is extremely weak or absent in colorectal carcinoma. At the same time the expression of cytoplasm VDR is weakest in normal colorectal mucosa and hyper plastic polyps while it grows during the adenoma stage and is most expressed during colorectal carcinoma.

CONCLUSION: We conclude that vitamin D has a strong chemo preventive and antitumor effect in normal colorectal mucosa and hyper plastic polyps, while its antitumor and chemopreventive effect is progressively weakened and ultimately absent in colorectal carcinoma.