RT Journal Article SR Electronic T1 Correlation between VDR Expression and Antiproliferative Activity of Vitamin D3 Compounds in Combination with Cytostatics JF Anticancer Research JO Anticancer Res FD International Institute of Anticancer Research SP 2235 OP 2240 VO 25 IS 3B A1 MARZENA PELCZYNSKA A1 JOANNA WIETRZYK A1 IWONA JAROSZEWICZ A1 DMITRY NEVOZHAY A1 MARTA SWITALSKA A1 ANDRZEJ KUTNER A1 MACIEJ ZABEL A1 ADAM OPOLSKI YR 2005 UL http://ar.iiarjournals.org/content/25/3B/2235.abstract AB Calcitriol is a potent antiproliferative agent against various tumour cells in vitro. Its biological activity is mediated by the vitamin D receptors (VDRs). Here, we present the results of a study on vitamin D3 compounds (calcitriol and its analogue PRI-2191) as potential agents in combined antitumour therapy in vitro. Applying antiproliferative SRB and MTT assays, we measured the growth inhibitory effects of vitamin D compounds applied alone or in combination with either cisplatin or doxorubicin. Next, we examined the correlation of this effect with the presence of nVDR (nuclear VDR). The following cancer cell lines were applied: HL-60 (human leukaemia), SW707 (human colon cancer), A549 (human lung cancer), WEHI-3 (mouse leukaemia). The treatment of tumour cells with the combination of vitamin D compounds and cytostatics decreased the inhibitory concentration 50% (IC50) values compared with the effects of cytostatics applied alone. The synergistic effect was positively correlated with nVDR expression. Copyright© 2005 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved