Several in vitro and in vivo experiments have demonstrated potent cell regulatory effects of vitamin D compounds in cancer cells. Moreover, a promising phase I study with the vitamin D analogue Seocalcitol (EB 1089) in patients with advanced breast and colon cancer has already been carried out and more clinical trials evaluating the clinical effectiveness of EB 1089 in other cancer types are in progress (Mørk Hansen et al. [2000a]). However, only little is known about the mechanisms underlying the actions of vitamin D or about the possible development of drug resistance in the patients. Therefore, in an attempt to gain more insight into these aspects, we have developed the MCF-7/VD(R) cell line, a stable subclone of the human MCF-7 breast cancer cell line, which is resistant to the growth inhibitory and apoptosis inducing effects of 1alpha,25(OH)(2)D(3). Despite this characteristic, receptor studies on the VDR have clearly demonstrated that the MCF-7/VD(R) cells contain fully functional VDRs, although in a lower number than seen with the parental MCF-7 cells. The regulation of the 24-hydroxylase enzyme appeared to be intact in the MCF-7/VD(R) cells and no differences with regard to growth rate and morphological appearance between the MCF-7/VD(R) cells and the parental MCF-7 cells were observed. Interestingly, however, the sensitivity of the MCF-7/VD(R) cells to the pure anti-estrogen ICI 182,780 was found to be increased. The MCF-7/VD(R) cell line shows characteristics different from those of previously described vitamin D resistant breast cancer cell lines but also some similarities. Together such vitamin D resistant cell lines therefore serve as a useful tool for studying the exact mechanism of action of vitamin D and the development of vitamin D resistance.

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A new in vivo experimental model -the Subcutaneous Air Sac (SAS) model -has recently been presented to replace a previous in vivo rabbit cornea assay where neovascularisation was induced by chemical injury of the cornea or by implantation of tumour cells intracorneally, a methodology which is believed to cause severe pain to the animals. In the SAS model, an air sac is induced by injection of air subcutaneously on the back of the animal. After 10-14 days the air sac appears as an almost transparent avascular membrane in which induction of new vessels can be studied. We present recent developments of this technique: In the SAS-tumour technique, vascular endothelial growth factor-producing tumour cells are inoculated subcutaneously directly on the membrane, and the formation of new vessels is measured 8 days later. In the SAS-pellet technique, slow-release pellets containing angiogenic factors, basic fibroblast growth factor or vascular endothelial growth factor are implanted on the subcutaneous membrane by a simple operation. The formation of new vessels is measured 10 days later. The ability of the SAS-tumour-and SAS-pellet techniques to detect an antiangiogenic effect of a systemically administered compound was investigated using the fumagillin analogue TNP-470 (o-chloro-acetylcarbamoyl)-fumagillol) as a positive control given subcutaneously for 7 and 9 days, respectively. At a dose of 10 mg TNP-470/kg/day the angiogenesis was reduced by approximately 70% in the SAS-tumour technique and by 40-60% in the SASpellet technique. The animals were unaffected by the SAS methodology. The SAS-tumour and SAS-pellet models are considered complementary and make use of simple and almost similar techniques which facilitate the evaluation.

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Hyper-IgE syndromes (HIES) are characterized by skin abscesses, increased serum IgE, eczema, and recurrent pneumonias. The most common autosomal recessive (AR) HIES are homozygous dedicator of cytokinesis 8 (DOCK8) loss-of-function mutations. These patients develop atopic diseases and cannot control cutaneous infections. While AR homozygous HIES DOCK8-deficiency clinical information has increased, little is known about the impact of DOCK8 heterozygous mutations. We describe a 10y male with a novel heterozygous point mutation in the DOCK8 region at c.624-12 T>A. He initially presented at 6m with eczema, acute urticaria, potential asthma, and total IgE of 190 kU/L. Around 3y, he developed specific IgE food and environmental sensitivities and dermatitis flares, later complicated by cutaneous fungal infection. He had 3 hospitalizations for severe eczema herpeticum and MRSA skin infections. At 5y, his eosinophil count was 1.6x10 3 /mm 3 with total IgE 15,828 kU/L. To avoid future hospitalization, he was prescribed antibiotic and antiviral prophylaxis and placed on an IgE sensitivity-guided elimination diet. At age 7y, he was referred to the National Institutes of Health (NIH) for further evaluation. In the past few years, his eczema has improved, he has ongoing evidence for IgE sensitivities, and possible asthma. His absolute eosinophil count and total IgE levels have decreased, possibly related to avoidance measures. The clinical significance of heterozygous mutations in the DOCK8 region has not been described previously. This case underscores the potential importance of non-homozygous mutations. Analysis of simple and complex heterozygous mutations may improve our understanding of DOCK8 genetic variants. LB925 Non-invasive gene-expression analysis of cutaneous T-cell lymphoma