Among them, plants of the genus Phyllanthus (Euphorbiaceae) are widely distributed in tropical forests throughout the world and have long been used in folk medicine to treat kidney and urinary tract infections [15]. Based on this knowledge, Ratnayake et al. [16] at the NCI screened extracts of the Tanzanian plant Phyllanthus engleri and have reported the isolation of two novel bioactive sesquiterpenes, named englerin A (EA) and englerin B. Initial learn more studies by the NCI demonstrated that EA possessed very potent growth inhibitory activity (GI50 = 10–87 nM) against

most RCC with a selectivity that is approximately 1,000-fold higher compared to other cancers. Although several synthetic routes toward the synthesis of EA have been established [16–21], other than EA’s selective toxicity to RCC, recently confirmed by us [21], very little is known about its biological actions and mechanism(s) of action. Only recently, one study reported that

EA induced necrosis in RCC [22]. The most recent report concluded that EA bound and activated protein kinase C-θ (PKCθ) to inhibit insulin signaling while, concurrently, activating HSF1, a known inducer of glucose dependence [23]. This dual signaling, that promotes glucose addiction while inhibiting glucose uptake by the cells, was proposed to be the mechanism for the selective cytotoxicity of EA. Although the data presented is compelling, whether in fact this mechanism accounts for the cytotoxicity of EA is not yet clear. Based on its cytotoxicity profile against the NCI60 cell panel, EA is Selleck 5-Fluoracil clearly a very unique agent and there is much to be learned about the actions of EA Tangeritin in RCC and the mechanisms and targets involved in these actions. In this study, using the highly EA-sensitive A498 human renal carcinoma cells as our model system, we report the results of a thorough and systematic investigation to uncover the mechanisms of growth inhibition and cell death induced by EA and reveal for the first time that

EA induces multiple mechanisms of cell death as well as cell cycle arrest while inducing autophagy. Material and methods Cell lines The A498 human kidney carcinoma cell line was purchased from ATCC and maintained in RPMI medium supplemented with 10% FBS and 100 units/ml penicillin/streptomycin (complete medium). Reagents Englerin A was purchased from Cerilliant Corporation. (Round Rock, Texas). Rapamycin was purchased from Enzo Life Sciences (Farmingdale, NY) as part of the Cyto-ID® Autophagy Detection Kit. VP16 was purchased from Sigma Aldrich (St. Louis, MO). MEM 100X non-essential amino acids (NEAA) was purchased from Gibco Life Technologies (Grand Island, NY). Antibody against caspase-3 was a gift from Dr. Robert Naviaux and anti LC3B was purchased from Cell Signaling Technology (Danvers, MA).