Differentiation of neoplastic cells toward normal induced by vitamin D3 derivatives.

Two new analogs of 1,25 dihydroxy vitamin D3 (calcitriol, DHCC), the active metabolite of vitamin D3 (cholecalciferol (D3) are less active on calcium metabolism and less toxic than (DHCC). They had increased differentiation-inducing activity towards normal on human myeloblastic leukemia cell line HL-60 and on histiocytic lymphoma cell line U-937 consisting of monoblastoid cells. 1,2 tetradeconyl phorbol 1, 3 acetate (TPA) was used as a positive control in these experiments.