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S onic H edgehog inhibition as a strategy to augment radiosensitivity of hepatocellular carcinoma
Author(s) -
Tsai ChiaoLing,
Hsu FengMing,
Tzen KaiYuan,
Liu WeiLin,
Cheng AnnLii,
Cheng Jason ChiaHsien
Publication year - 2015
Publication title -
journal of gastroenterology and hepatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.214
H-Index - 130
eISSN - 1440-1746
pISSN - 0815-9319
DOI - 10.1111/jgh.12931
Subject(s) - cyclopamine , cancer research , clonogenic assay , radiosensitizer , radiosensitivity , apoptosis , medicine , cell culture , in vivo , microbiology and biotechnology , radiation therapy , biology , sonic hedgehog , signal transduction , biochemistry , genetics
Background and Aim S onic H edgehog ( 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, H uh‐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 G li‐1 (a transcription factor induced by SHH ), and this effect was observed mainly in the nucleus. When combined with cyclopamine, irradiation inhibited G li‐1 and increased DNA double‐strand breakage. Radiotherapy increased SHH and G li‐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). Conclusion Combining an SHH inhibitor with radiotherapy may enhance HCC cell and orthotopic tumor radiosensitivity.