kh-1060 and thiazolyl-blue

We determined the in vitro biological activities of 1 alpha, 25-dihdroxyvitamin D(3) (1,25-D(3)) and its analogue, 20-epi-22-oxa-24a, 26a, 27a-trihomo-1 alpha, 25 (OH)(2) vitamin D(3) (KH1060) in six human neuroblastoma (NB) cell lines (SH-SY5Y, NB69, SK-N-AS, IMR5, CHP-134, NGP). The ability of these compounds to inhibit cell growth and DNA synthesis was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and BrdU incorporation, respectively. The induction of cell death was monitored by caspase-3 activity. Their antineoplastic effect was assessed by clonal proliferation in soft agar. KH1060 was more effective than 1,25 D(3) in inhibiting cell growth and DNA synthesis. The IC-(50) (inhibition of 50% cell viability) indicated that KH1060 was about 10-20-fold more potent than 1,25 D(3). This growth inhibition was also accompanied by induction of caspase-3 activity, indicating that these compounds induce cell death in a caspase-dependent fashion. Moreover, KH1060 exerted potent antineoplastic activity by suppressing the clonal proliferation of the six NB cells. For the first time we demonstrate that KH1060 induces the expression of retinoic acid receptor-beta and p21(Cip1) suggesting that these proteins in part mediate the growth inhibitory effects. Taken together, all the six NB cells were more susceptible to growth inhibition by KH1060 than 1,25-D(3), suggesting its possible use in NB to potentiate the action of retinoids, which are in clinical use for this disease.

Topics: Antineoplastic Agents; Blotting, Western; Brain Neoplasms; Bromodeoxyuridine; Calcitriol; Caspase 3; Caspases; Cell Division; Cell Survival; Cholecalciferol; Coloring Agents; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; DNA; Dose-Response Relationship, Drug; Enzyme-Linked Immunosorbent Assay; Humans; Inhibitory Concentration 50; Models, Chemical; Neuroblastoma; Proto-Oncogene Proteins c-myc; Receptors, Retinoic Acid; Reverse Transcriptase Polymerase Chain Reaction; Tetrazolium Salts; Thiazoles; Tumor Cells, Cultured