1,25-DIHYDROXYVITAMIN D-3 RECEPTORS IN NORMAL AND MALIGNANT HUMAN COLORECTAL TISSUES

1 alpha,25-Dihydroxyvitamin D-3, (1,25(OH)(2)D-3), the active metaboli te of vitamin D-3, has important physiological effects on growth and d ifferentiation in a variety of malignant and non-malignant cell types. In order to better understand the significance of 1,25(OH)(2)D-3 rece ptors (VDR) in human colorectal cancer, we determined the levels of VD R in paired samples (malignant and adjacent normal tissues) of 24 colo rectal cancer bearing patients. Our results demonstrated differences i n the relative abundance of VDR between normal and transformed tissues according to the localization of the tumor. While colonic tumors exhi bited significantly higher VDR values than their normal counterparts, the contrary seemed to occur in the rectal tumors. In colonic tumors, we found significant correlations between VDR levels and the absence o f node involvement or a low Astler-Coller stage. The increased VDR val ues in colonic tumors as compared with the normal adjacent tissues, ma y warrant, at least in this type of cancer, the action of 1,25(OH)(2)D -3 or its non-calcemic analogs, to help induce cell differentiation an d growth inhibition.