title: Measurements of tumor cell autophagy predict invasiveness, resistance to chemotherapy, and survival in melanoma.
abstract: OBJECTIVE
  Autophagy consists of lysosome-dependent degradation of cytoplasmic contents sequestered by autophagic vesicles (AV). The role of autophagy in determining tumor aggressiveness and response to therapy in melanoma was investigated in this study.
  
  
  METHODS
  Autophagy was measured in tumor biopsies obtained from metastatic melanoma patients enrolled on a phase II trial of temozolomide and sorafenib and correlated to clinical outcome. These results were compared with autophagy measurements in aggressive and indolent melanoma cells grown in two- and three-dimensional (3D) culture and as xenograft tumors. The effects of autophagy inhibition with either hydroxychloroquine or inducible shRNA (short hairpin RNA) against the autophagy gene ATG5 were assessed in three-dimensional spheroids.
  
  
  RESULTS
  Patients whose tumors had a high autophagic index were less likely to respond to treatment and had a shorter survival compared with those with a low autophagic index. Differences in autophagy were less evident in aggressive and indolent melanoma cells grown in monolayer culture. In contrast, autophagy was increased in aggressive compared with indolent melanoma xenograft tumors. This difference was recapitulated when aggressive and indolent melanoma cells were grown as spheroids. Autophagy inhibition with either hydroxychloroquine or inducible shRNA against ATG5 resulted in cell death in aggressive melanoma spheroids, and significantly augmented temozolomide-induced cell death.
  
  
  CONCLUSIONS
  Autophagy is a potential prognostic factor and therapeutic target in melanoma. Three dimensional culture mimics the tumor microenvironment better than monolayer culture and is an appropriate model for studying therapeutic combinations involving autophagy modulators. Autophagy inhibition should be tested clinically in patients with melanoma.
authors.affiliation: Division of Hematology-Oncology, Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
authors.forename: Xiao-Hong
authors.initials: XH
authors.lastname: Ma
authors.forename: Shengfu
authors.initials: S
authors.lastname: Piao
authors.forename: Dan
authors.initials: D
authors.lastname: Wang
authors.forename: Quentin W
authors.initials: QW
authors.lastname: McAfee
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Nathanson
authors.forename: Julian J
authors.initials: JJ
authors.lastname: Lum
authors.forename: Lin Z
authors.initials: LZ
authors.lastname: Li
authors.forename: Ravi K
authors.initials: RK
authors.lastname: Amaravadi
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001343:Autophagy / Q000502:physiology*; D001557:Benzenesulfonates / Q000008:administration & dosage; D002452:Cell Count; D017322:Clinical Trials, Phase II as Topic; D003606:Dacarbazine / Q000008:administration & dosage / Q000031:analogs & derivatives; D019008:Drug Resistance, Neoplasm / Q000502:physiology; D006801:Humans; D008545:Melanoma / Q000175:diagnosis* / Q000188:drug therapy / Q000401:mortality / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D009361:Neoplasm Invasiveness; D009536:Niacinamide / Q000031:analogs & derivatives; D010671:Phenylurea Compounds; D011379:Prognosis; D011725:Pyridines / Q000008:administration & dosage; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000188:drug therapy / Q000401:mortality / Q000473:pathology; D000077157:Sorafenib; D016019:Survival Analysis; D000077204:Temozolomide; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
chemical_list: D001557:Benzenesulfonates; D010671:Phenylurea Compounds; D011725:Pyridines; D009536:Niacinamide; D003606:Dacarbazine; D000077157:Sorafenib; D000077204:Temozolomide