title: Sonic Hedgehog inhibition as a strategy to augment radiosensitivity of hepatocellular carcinoma.
abstract: OBJECTIVE
  Sonic Hedgehog (SHH) is a regulator in tumorigenesis of hepatocellular carcinoma (HCC). This study aimed to determine whether radiation-induced SHH signaling occurs in HCC and whether SHH inhibitor acts as a radiosensitizer.
  
  
  METHODS
  The in vitro effects of combining SHH ligand (recombinant human SHH) or inhibitor (cyclopamine) with irradiation were evaluated in the human HCC cell lines, Huh-7 and PLC/PRF/5, and murine cell line BNL. Cell survival and apoptosis were measured using a colony formation assay, annexin-V staining, and poly (ADP-ribose) polymerase activation. Western blotting and immunofluorescence staining were used to detect protein expression. The in vivo response to radiotherapy and/or cyclopamine was tested in BALB/c mice bearing an orthotopic allogeneic tumor.
  
  
  RESULTS
  Treatment of HCC cells with irradiation and SHH ligand had a protective effect on clonogenic cell survival. Treatment with irradiation and cyclopamine was a more potent inhibitor of cell proliferation than either modality alone. The antiproliferative activity of cyclopamine was attributable to apoptosis induction. Radiation dose-dependently upregulated the expression of Gli-1 (a transcription factor induced by SHH), and this effect was observed mainly in the nucleus. When combined with cyclopamine, irradiation inhibited Gli-1 and increased DNA double-strand breakage. Radiotherapy increased SHH and Gli-1 expression in allogeneic tumor. When compared with radiotherapy alone, cyclopamine with radiotherapy reduced the mean tumor size of orthotopic tumors by 67% (P < 0.05).
  
  
  CONCLUSIONS
  Combining an SHH inhibitor with radiotherapy may enhance HCC cell and orthotopic tumor radiosensitivity.
authors: Division of Radiation Oncology, National Taiwan University Hospital, Taipei, Taiwan.|Graduate Institute of Clinical Medicine, National Taiwan University College of Medicine, Taipei, Taiwan.
authors: Chiao-Ling
authors: CL
authors: Tsai
authors: Division of Radiation Oncology, National Taiwan University Hospital, Taipei, Taiwan.
authors: Feng-Ming
authors: FM
authors: Hsu
authors: Department of Nuclear Medicine, National Taiwan University Hospital, Taipei, Taiwan.|Molecular Imaging Center, National Taiwan University, Taipei, Taiwan.
authors: Kai-Yuan
authors: KY
authors: Tzen
authors: Division of Radiation Oncology, National Taiwan University Hospital, Taipei, Taiwan.
authors: Wei-Lin
authors: WL
authors: Liu
authors: Division of Medical Oncology, Department of Oncology, National Taiwan University Hospital, Taipei, Taiwan.|Graduate Institute of Oncology, National Taiwan University College of Medicine, Taipei, Taiwan.
authors: Ann-Lii
authors: AL
authors: Cheng
authors: Division of Radiation Oncology, National Taiwan University Hospital, Taipei, Taiwan.|Graduate Institute of Oncology, National Taiwan University College of Medicine, Taipei, Taiwan.
authors: Jason Chia-Hsien
authors: JC
authors: Cheng
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D063646:Carcinogenesis / Q000235:genetics; D006528:Carcinoma, Hepatocellular / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology / Q000532:radiotherapy*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D003131:Combined Modality Therapy; D053903:DNA Breaks, Double-Stranded; D004195:Disease Models, Animal; D004307:Dose-Response Relationship, Radiation; D015870:Gene Expression / Q000528:radiation effects; D053823:Hedgehog Proteins / Q000037:antagonists & inhibitors*; D006801:Humans; D008024:Ligands; D008113:Liver Neoplasms / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology / Q000532:radiotherapy*; D051379:Mice; D008807:Mice, Inbred BALB C; D058990:Molecular Targeted Therapy; D009368:Neoplasm Transplantation; D011836:Radiation Tolerance / Q000187:drug effects* / Q000235:genetics*; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology* / Q000627:therapeutic use*; D011994:Recombinant Proteins; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors; D014704:Veratrum Alkaloids / Q000494:pharmacology* / Q000627:therapeutic use*; D000071676:Zinc Finger Protein GLI1
chemical_list: C400551:GLI1 protein, human; D053823:Hedgehog Proteins; D008024:Ligands; D011838:Radiation-Sensitizing Agents; D011994:Recombinant Proteins; C509239:SHH protein, human; D014157:Transcription Factors; D014704:Veratrum Alkaloids; D000071676:Zinc Finger Protein GLI1; C000541:cyclopamine
keywords: Sonic Hedgehog; hepatocellular carcinoma; radiotherapy; sensitization