1,25-Dihydroxyvitamin D3 receptors in human carcinomas: a pilot study.

1,25-Dihydroxyvitamin D3 [1,25-(OH)2D3] receptor concentration was measured by an accurate immunoradiometric assay in primary tumors from 10 patients with colorectal carcinoma and 11 patients with non-small cell carcinoma of the lung. Measurements were also performed on a noncancerous sample of the same origin as the tumor from each patient. All of the tumors contained receptor with a mean concentration of 123.4 fmol/mg protein for colorectal and 75.1 fmol/mg protein for lung carcinoma. Compared to normal tissue from the same patient, 100% of the lung tumors and 70% of the colorectal tumors had significantly higher levels of the 1,25-dihydroxyvitamin D3 receptor. A correlation was found between well-differentiated colorectal tumors with no or few metastases and high levels of 1,25-dihydroxyvitamin D3 receptor. Receptor concentration was also assayed in metastatic lesions of malignant melanoma from 7 patients. 1,25-Dihydroxyvitamin D3 receptor was present in 85% of the metastases at a mean level of 26 fmol/mg protein. For these patients an inverse correlation was found between receptor level and age. The results obtained in this pilot study suggest that an alteration in 1,25-dihydroxyvitamin D3 receptor regulation may occur in vivo when a cell undergoes malignant transformation.