Darinaparsin is a dimethylated arsenic linked to glutathione. It is cytotoxic to DU145, LNCaP, and PC3 prostate cancer cells (IC50s = 5-10 µM) and patient-derived primary prostate cancer cells (IC50s = 2.5-20 µM), as well as Jurkat T cell lymphoma and L540 Hodgkin lymphoma cells (IC50s = 2.7 and 1.3 µM, respectively). [1][2] It decreases the tumor-initiating subpopulation in DU145 and PC3 cells and halts the cell cycle in the G2/M phase. Darinaparsin decreases transcription of Gli-2, a transcription factor that mediates Sonic hedgehog signaling, when used at a concentration of 1.5 but not 3 µM. It decreases SHP1 phosphatase activity and increases ERK phosphorylation. [2] Darinaparsin reduces tumor growth in DU145 and PC3 prostate cancer mouse xenograft models when administered at a dose of 100 mg/kg every other day.[1]
C2 Phytoceramide is a bioactive semisynthetic sphingolipid that inhibits formyl peptide-induced oxidant release (IC50 = 0.38 μM) in suspended polymorphonuclear cells. It increases COX-2 protein levels 15-fold through ERK signaling. It induces death of keratinocytes (20% viability) with an ED50 value of 30 μM, the same concentration at which 35% of cells in a TUNEL assay are apoptotic. C2 Phytoceramide also has antiproliferative effects in CHO cells, with greater than 80% cytotoxicity achieved at a concentration of 20 μM, and induces internucleosomal DNA fragmentation. In addition, it inhibits the activation of phospholipase D (PLD) mediated by muscarinic acetylcholine receptors in vitro.