title: Small interfering RNA (siRNA) against Slug induces apoptosis and sensitizes human anaplastic thyroid carcinoma cells to doxorubicin.
abstract: OBJECTIVE
  Anaplastic thyroid carcinoma (ATC) is one of the most aggressive human cancers and often shows resistance to multimodal therapeutic approaches. It has been shown that the transcriptional repressor Slug inhibits the chemotherapeutic agent-induced apoptosis of cancer cells. We evaluated whether targeting of Slug could augment doxorubicin (DOX)-induced apoptosis of ATC cells. We also determined changes in PUMA (p53-upregulated modulator of apoptosis) expression levels to identify possible mechanisms of their combined actions.
  
  
  METHODS
  SW1736 cells were transfected with Slug siRNA or/and PUMA siRNA and then exposed to DOX (0.1, 1, and 5 μ M) for selected times. Scrambled siRNA was used as a control. The effects on cell viability were determined via MTT assay. Apoptosis was assessed using TUNEL assays and annexin V staining, and was confirmed by flow cytometry analyses. Slug and PUMA levels were determined using western blotting, RT-PCR and immunofluorescence analyses. We used a subcutaneous implanted tumor model of SW1736 cells in nude mice to assess the effects of Slug silencing in combination with DOX on tumor development. Apoptosis was assessed via TUNEL assay.
  
  
  RESULTS
  Targeting of Slug using siRNA inhibits growth of SW1736 cells and sensitizes SW1736 cells to DOX in vitro and vivo. Targeting of Slug combined with DOX led to lower cell viability than treatment with DOX alone in SW1736 cells. TUNEL and flow cytometry analyses showed that targeting of Slug enhanced DOX-induced apoptosis of SW1736 cells. In addition, targeting of Slug increased PUMA expression, and targeting of PUMA restored the chemoresistance of SW1736/Slug siRNA cells to DOX.
  
  
  CONCLUSIONS
  Knockdown of Slug enhanced the antitumor activity of DOX in SW1736 cells via induction of PUMA upregulation. Our results suggest that targeting of Slug has good potential for the development of new therapeutic strategies for ATC.
authors.affiliation: Department of Imaging, Yantai Yu-Huang-Ding Hospital, Yantai, Shandong, China.|Department of Imaging, Yantai Yu-Huang-Ding Hospital, Yantai, Shandong, China.
authors.forename: Yinghua
authors.initials: Y
authors.lastname: Pan
authors.affiliation: Department of Radiotherapy, Yantai Yu-Huang-Ding Hospital, Yantai, Shandong, China.|Department of Imaging, Yantai Yu-Huang-Ding Hospital, Yantai, Shandong, China.
authors.forename: Peiji
authors.initials: P
authors.lastname: Liu
authors.affiliation: Department of Surgery, the Second Affiliated Hospital of Qingdao University, Qingdao, Shandong, China.
authors.forename: Deng
authors.initials: D
authors.lastname: Chen
authors.affiliation: Department of Health Care, People's Hospital of Weifang, Weifang, Shandong, China.
authors.forename: Linying
authors.initials: L
authors.lastname: Dou
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000235:genetics*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004317:Doxorubicin / Q000008:administration & dosage; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006801:Humans; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D034741:RNA, Small Interfering / Q000235:genetics; D000071250:Snail Family Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics*; D065646:Thyroid Carcinoma, Anaplastic / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology
chemical_list: D051017:Apoptosis Regulatory Proteins; C438378:BBC3 protein, human; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; C000604407:SNAI1 protein, human; D000071250:Snail Family Transcription Factors; D004317:Doxorubicin
keywords: Anaplastic thyroid carcinoma; PUMA; Slug; chemotherapy