title: Powerful tumor cell growth-inhibiting activity of a synthetic derivative of atractyligenin: involvement of PI3K/Akt pathway and thioredoxin system.
abstract: BACKGROUND
  The semi-synthetic ent-kaurane 15-ketoatractyligenin methyl ester (SC2017) has been previously reported to possess high antiproliferative activity against several solid tumor-derived cell lines. Our study was aimed at investigating SC2017 tumor growth-inhibiting activity and the underlying mechanisms in Jurkat cells (T-cell leukemia) and xenograft tumor models.
  
  
  METHODS
  Cell viability was evaluated by MTT assay. Cell cycle progression, reactive oxygen species (ROS) elevation and apoptotic hallmarks were monitored by flow cytometry. Inhibition of thioredoxin reductase (TrxR) by biochemical assays. Levels and/or activation status of signaling proteins were assessed by western blotting. Xenograft tumors were generated with HCT 116 colon carcinoma cells.
  
  
  RESULTS
  SC2017 displayed cell growth-inhibiting activity against Jurkat cells (half maximal inhibitory concentration values (IC50)<2μM), but low cell-killing potential in human peripheral blood mononuclear cells (PBMC). The primary response of Jurkat cells to SC2017 was an arrest in G2 phase followed by caspase-dependent apoptosis. Inhibition of PI3K/Akt pathway and TrxR activity by SC2017 was demonstrated by biochemical and pharmacological approaches. At least, SC2017 was found to inhibit xenograft tumor growth.
  
  
  CONCLUSIONS
  Our results demonstrate that SC2017 inhibits tumor cell growth in in vitro and in vivo models, but displays moderate toxicity against PBMC. We also demonstrate that SC2017 promotes caspase-dependent apoptosis in Jurkat cells by affecting Akt activation status and TrxR functionality.
  
  
  CONCLUSIONS
  Our observations suggest the semi-synthetic ent-kaurane SC2017 as a promising chemotherapeutic compound. SC2017 has, indeed, shown to possess tumor growth inhibiting activity and be able to counteract PI3K/Akt and Trx system survival signaling.
authors: Department of Pharmacy, University of Salerno, 84084 Fisciano, Salerno, Italy.
authors: Roberta
authors: R
authors: Cotugno
authors: Department of Pharmacy, University of Salerno, 84084 Fisciano, Salerno, Italy.
authors: Dario
authors: D
authors: Gallotta
authors: Department of Pharmacy, University of Salerno, 84084 Fisciano, Salerno, Italy.
authors: Fabrizio Dal
authors: FD
authors: Piaz
authors: Angiogenesis Lab, Institute of Genetics and Biophysics "Adriano Buzzati-Traverso" CNR, 80131 Napoli, Italy.
authors: Ivana
authors: I
authors: Apicella
authors: Angiogenesis Lab, Institute of Genetics and Biophysics "Adriano Buzzati-Traverso" CNR, 80131 Napoli, Italy.
authors: Sandro
authors: S
authors: De Falco
authors: Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, University of Palermo, 90128 Palermo, Italy.
authors: Sergio
authors: S
authors: Rosselli
authors: Department of Biological, Chemical and Pharmaceutical Sciences and Technologies, University of Palermo, 90128 Palermo, Italy.
authors: Maurizio
authors: M
authors: Bruno
authors: Department of Pharmacy, University of Salerno, 84084 Fisciano, Salerno, Italy. Electronic address: mabelisario@unisa.it.
authors: Maria Antonietta
authors: MA
authors: Belisario
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001278:Atractyloside / Q000031:analogs & derivatives* / Q000494:pharmacology; D020169:Caspases / Q000502:physiology; D049109:Cell Proliferation / Q000187:drug effects*; D045304:Cytochromes c / Q000378:metabolism; D045786:Diterpenes, Kaurane / Q000494:pharmacology*; D006801:Humans; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology*; D013879:Thioredoxins / Q000502:physiology*; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D045786:Diterpenes, Kaurane; C462123:atractyligenine; C587222:ent-kaurane 15-ketoatractyligenin methyl ester; D001278:Atractyloside; D013879:Thioredoxins; D045304:Cytochromes c; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D020169:Caspases
keywords: Apoptosis; Cell cycle; Ent-kaurane; HCT 116 xenograft; PI3K/Akt; Thioredoxin system