title: Phenethyl isothiocyanate upregulates death receptors 4 and 5 and inhibits proliferation in human cancer stem-like cells.
abstract: BACKGROUND
  The cytokine TRAIL (tumor necrotic factor-related apoptosis-inducing ligand) selectively induces apoptosis in cancer cells, but cancer stem cells (CSCs) that contribute to cancer-recurrence are frequently TRAIL-resistant. Here we examined hitherto unknown effects of the dietary anti-carcinogenic compound phenethyl isothiocyanate (PEITC) on attenuation of proliferation and tumorigenicity and on up regulation of death receptors and apoptosis in human cervical CSC.
  
  
  METHODS
  Cancer stem-like cells were enriched from human cervical HeLa cell line by sphere-culture method and were characterized by CSC-specific markers' analyses (flow cytometry) and Hoechst staining. Cell proliferation assays, immunoblotting, and flow cytometry were used to assess anti-proliferative as well as pro-apoptotic effects of PEITC exposure in HeLa CSCs (hCSCs). Xenotransplantation study in a non-obese diabetic, severe combined immunodeficient (NOD/SCID) mouse model, histopathology, and ELISA techniques were further utilized to validate our results in vivo.
  
  
  RESULTS
  PEITC attenuated proliferation of CD44(high/+)/CD24(low/-), stem-like, sphere-forming subpopulations of hCSCs in a concentration- and time-dependent manner that was comparable to the CSC antagonist salinomycin. PEITC exposure-associated up-regulation of cPARP (apoptosis-associated cleaved poly [ADP-ribose] polymerase) levels and induction of DR4 and DR5 (death receptor 4 and 5) of TRAIL signaling were observed. Xenotransplantation of hCSCs into mice resulted in greater tumorigenicity than HeLa cells, which was diminished along with serum hVEGF-A (human vascular endothelial growth factor A) levels in the PEITC-pretreated hCSC group. Lung metastasis was observed only in the hCSC-injected group that did not receive PEITC-pretreatment.
  
  
  CONCLUSIONS
  The anti-proliferative effects of PEITC in hCSCs may at least partially result from up regulation of DR4 and possibly DR5 of TRAIL-mediated apoptotic pathways. PEITC may offer a novel approach for improving therapeutic outcomes in cancer patients.
authors.forename: Dan
authors.initials: D
authors.lastname: Wang
authors.forename: Bijaya
authors.initials: B
authors.lastname: Upadhyaya
authors.forename: Yi
authors.initials: Y
authors.lastname: Liu
authors.forename: David
authors.initials: D
authors.lastname: Knudsen
authors.affiliation: Health and Nutritional Sciences, South Dakota State University, Box 2203, Brookings, SD 57007, USA. Moul.Dey@sdstate.edu.
authors.forename: Moul
authors.initials: M
authors.lastname: Dey
mesh_terms: D000818:Animals; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D017209:Apoptosis; D018929:Cell Culture Techniques; D049109:Cell Proliferation / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D017879:Isothiocyanates / Q000494:pharmacology*; D008175:Lung Neoplasms / Q000188:drug therapy / Q000473:pathology* / Q000556:secondary*; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000378:metabolism; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D023041:Xenograft Model Antitumor Assays
chemical_list: D016588:Anticarcinogenic Agents; D017879:Isothiocyanates; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; C058305:phenethyl isothiocyanate