title: Cucurbitacin I inhibits tumorigenic ability and enhances radiochemosensitivity in nonsmall cell lung cancer-derived CD133-positive cells.
abstract: BACKGROUND
  Signal transducer and activator of transcription 3 (STAT3) signaling reportedly promotes tumor malignancy and recurrence in nonsmall cell lung cancer (NSCLC). It was demonstrated previously that the STAT3 pathway maintains the tumorigenicity and therapeutic resistance of malignant tumors as well as cancer stem cells (CSCs). The objective of the current study was to investigate the effect of the strong STAT3 inhibitor, cucurbitacin I, in prominin-1 (CD133)-positive lung cancer cells.
  
  
  METHODS
  CD133-positive and CD133-negative NSCLC-derived cells were isolated from 7 patients with NSCLC. CD133-positive NSCLC cells that were treated with or without cucurbitacin I were evaluated for their expression of phosphorylated STAT3 (p-STAT3), tumorigenicity, stemness properties, and resistance to chemotherapeutic drugs and ionizing radiation.
  
  
  RESULTS
  Compared with parental or CD133-negative NSCLC cells, CD133-positive NSCLC cells had greater tumorigenicity, greater radioresistance, and higher expression of octamer-binding transcription factor 4 (Oct-4), Nanog homeobox, and sex-determining region Y, box 2 (Sox2) at high p-STAT3 levels. Cucurbitacin I treatment at 100 nM effectively abrogated STAT3 activation, tumorigenic capacity, sphere formation ability, radioresistance, and chemoresistance in CD133-positive NSCLC cells. Microarray data suggested that cucurbitacin I inhibited the stemness gene signature of CD133-positive NSCLC cells and facilitated the differentiation of CD133-positive NSCLC cells into CD133-negative NSCLC cells. It is noteworthy that 150 nM cucurbitacin I effectively blocked STAT3 signaling and downstream survival targets, such as B-cell chronic lymphocytic leukemia/lymphoma 2 (Bcl-2) and Bcl-2-like 1 (Bcl-xL) expression and induced apoptosis in CD133-positive NSCLC cells. Finally, xenotransplantation experiments revealed that cucurbitacin I plus radiotherapy or chemotherapeutic drugs significantly suppressed tumorigenesis and improved survival in NSCLC-CD133-positive-transplanted, immunocompromised mice.
  
  
  CONCLUSIONS
  Targeting STAT3 signaling in CD133-positive NSCLC cells with cucurbitacin I suppressed CSC-like properties and enhanced chemoradiotherapy response. The potential of cucurbitacin I should be verified further in future anti-CSC therapy.
authors.affiliation: Institute of Emergency and Critical Care Medicine, National Yang-Ming University, Taipei, Taiwan, Republic of China. hsuhs@vghtpe.gov.tw
authors.forename: Han-Shui
authors.initials: HS
authors.lastname: Hsu
authors.forename: Pin-I
authors.initials: PI
authors.lastname: Huang
authors.forename: Yuh-Lih
authors.initials: YL
authors.lastname: Chang
authors.forename: Ching
authors.initials: C
authors.lastname: Tzao
authors.forename: Yi-Wei
authors.initials: YW
authors.lastname: Chen
authors.forename: Hsin-Chin
authors.initials: HC
authors.lastname: Shih
authors.forename: Shih-Chieh
authors.initials: SC
authors.lastname: Hung
authors.forename: Yu-Chih
authors.initials: YC
authors.lastname: Chen
authors.forename: Ling-Ming
authors.initials: LM
authors.lastname: Tseng
authors.forename: Shih-Hwa
authors.initials: SH
authors.lastname: Chiou
mesh_terms: D000071916:AC133 Antigen; D000368:Aged; D000818:Animals; D015703:Antigens, CD / Q000032:analysis*; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy; D049109:Cell Proliferation; D002469:Cell Separation; D019008:Drug Resistance, Neoplasm; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005455:Fluorescent Antibody Technique; D006023:Glycoproteins / Q000032:analysis*; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy; D008297:Male; D051379:Mice; D008875:Middle Aged; D000071317:Nanog Homeobox Protein; D009362:Neoplasm Metastasis; D009368:Neoplasm Transplantation; D014411:Neoplastic Stem Cells / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D050814:Octamer Transcription Factor-3 / Q000096:biosynthesis / Q000235:genetics; D010455:Peptides / Q000032:analysis*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics; D011836:Radiation Tolerance; D055748:SOXB1 Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D050796:STAT3 Transcription Factor / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014315:Triterpenes / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D051020:bcl-X Protein / Q000235:genetics
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D006023:Glycoproteins; D018398:Homeodomain Proteins; C486780:NANOG protein, human; D000071317:Nanog Homeobox Protein; D050814:Octamer Transcription Factor-3; C000606023:PROM1 protein, human; D010455:Peptides; C000606024:Prom1 protein, mouse; D019253:Proto-Oncogene Proteins c-bcl-2; C527782:SOX2 protein, human; D055748:SOXB1 Transcription Factors; D050796:STAT3 Transcription Factor; D014315:Triterpenes; D051020:bcl-X Protein; C038106:cucurbitacin I