title: Sensitization to TNF-induced apoptosis by 1,25-dihydroxy vitamin D(3) involves up-regulation of the TNF receptor 1 and cathepsin B.
abstract: The active form of vitamin D(3), 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), induces caspase-independent apoptosis in MCF-7 and T47D breast cancer cells. Before the appearance of apoptotic cells at Day 4 after the addition of 1,25(OH)(2)D(3), the MCF-7 cells are sensitized to the caspase-mediated apoptosis induced by TNF. We studied the mechanism underlying the cross talk between these 2 distinct death pathways in MCF-7 and T47D cells. Whereas 1,25(OH)(2)D(3) pre-treatment enhanced TNF-induced apoptosis of TNF sensitive MCF-7 cells, it failed to render TNF resistant T47D cells sensitive to this cytokine. Opposing to an earlier report suggesting that cytosolic phospholipase A(2) (cPLA(2)) mediates the 1,25(OH)(2)D(3)-induced sensitization to TNF, we could not detect any cPLA(2) protein in MCF-7 cells and its overexpression had no effect on cellular sensitivity to 1,25(OH)(2)D(3) or the combination with TNF. The sensitization of MCF-7 cells to TNF-induced apoptosis by pre-treatment with 1,25(OH)(2)D(3) may instead be partially explained by an increased surface expression of the TNF receptor 1 (TNF-R1). In line with this, not only the TNF-induced activation of caspases and apoptosis but also that of NF-kappaB was enhanced by 1,25(OH)(2)D(3) pre-treatment. Furthermore, 1,25(OH)(2)D(3) enhanced TNF-induced NF-kappaB activation in T47D cells suggesting that it potentiates TNF signaling in general. Interestingly, the lysosomal protease cathepsin B, which expression is up-regulated by 1,25(OH)(2)D(3), was released from the lysosomes upon TNF treatment, and inhibition of its activity rescued 1,25(OH)(2)D(3) treated MCF-7 cells from TNF-induced apoptosis. In conclusion, 1,25(OH)(2)D(3) may enhance TNF-induced apoptosis by increasing the expression of both the TNF-R1 and cathepsin B.
authors: Apoptosis Laboratory, Danish Cancer Society, Strandboulevarden 49, DK 2100 Copenhagen Ø, Denmark. ism@cancer.dk
authors: I S
authors: IS
authors: Mathiasen
authors: C M
authors: CM
authors: Hansen
authors: L
authors: L
authors: Foghsgaard
authors: M
authors: M
authors: Jäättelä
mesh_terms: D015703:Antigens, CD / Q000378:metabolism*; D017209:Apoptosis; D020169:Caspases / Q000378:metabolism; D002401:Cathepsin B / Q000378:metabolism*; D004347:Drug Interactions; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D016328:NF-kappa B / Q000378:metabolism; D010741:Phospholipases A / Q000096:biosynthesis; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism*; D047888:Receptors, Tumor Necrosis Factor, Type I; D013250:Steroid Hydroxylases / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D015854:Up-Regulation
chemical_list: D015703:Antigens, CD; D016328:NF-kappa B; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D014409:Tumor Necrosis Factor-alpha; D013250:Steroid Hydroxylases; C406322:vitamin D 1-alpha hydroxylase; D010741:Phospholipases A; D020169:Caspases; D002401:Cathepsin B